prof. dr hab. inż. Andrzej Nowicki

Zakład Ultradźwięków (ZU)
stanowisko: profesor zwyczajny
telefon bezpośredni: (+48) 22 826 98 41
telefon: (+48) 22 826 12 81 wew.: 315
pokój: 510
e-mail: anowicki

Doktorat
1976Ultradźwiękowa dopplerowska impulsowa metoda i aparatura do pomiarów przepływu krwi w układzie krążenia 
promotor -- prof. dr hab. inż. Leszek Filipczyński, IPPT PAN
274 
Habilitacja
1980Ultradźwiękowe metody wizualizacji naczyń krwionośnych i przepływu krwi 
Profesura
1993Nadanie tytułu naukowego profesora
Inne
2007Członek korespondent Polskiej Akademii Nauk

Promotor prac doktorskich
1.2009-06-18Lewandowski Marcin Ultrasonografia kodowana - transmisja i kompresja w czasie rzeczywistym631
 
2.2005-11-24Trots Ihor  Transmisja kodowana i kompresja echa w ultrasonografii medycznej 
3.2005-09-20Secomski Wojciech  Wyznaczanie hematokrytu przez pomiar tłumienia fali ultradzwiękowej we krwi 
4.1998Kycia Krzysztof  Przetworniki kompozytowe do zastosowań w ultradźwiękowej diagnostyce medycznej 
5.1992Marasek Krzysztof  Wyznaczanie częstotliwości średniej i maksymalnej w analizie widmowej dopplerowskich sygnałów akustycznych 

Ostatnie publikacje
1.Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017
Kujawska T., Secomski W., Byra M., Postema M., Nowicki A., Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.008, Vol.76, pp.92-98, 2017

Abstract:
A technique using pulsed High Intensity Focused Ultrasound (HIFU) to destroy deep-seated solid tumors is a promising noninvasive therapeutic approach. A main purpose of this study was to design and test a HIFU transducer suitable for preclinical studies of efficacy of tested, anti-cancer drugs, activated by HIFU beams, in the treatment of a variety of solid tumors implanted to various organs of small animals at the depth of the order of 1–2 cm under the skin. To allow focusing of the beam, generated by such transducer, within treated tissue at different depths, a spherical, 2-MHz, 29-mm diameter annular phased array transducer was designed and built. To prove its potential for preclinical studies on small animals, multiple thermal lesions were induced in a pork loin ex vivo by heating beams of the same: 6 W, or 12 W, or 18 W acoustic power and 25 mm, 30 mm, and 35 mm focal lengths. Time delay for each annulus was controlled electronically to provide beam focusing within tissue at the depths of 10 mm, 15 mm, and 20 mm. The exposure time required to induce local necrosis was determined at different depths using thermocouples. Location and extent of thermal lesions determined from numerical simulations were compared with those measured using ultrasound and magnetic resonance imaging techniques and verified by a digital caliper after cutting the tested tissue samples. Quantitative analysis of the results showed that the location and extent of necrotic lesions on the magnetic resonance images are consistent with those predicted numerically and measured by caliper. The edges of lesions were clearly outlined although on ultrasound images they were fuzzy. This allows to conclude that the use of the transducer designed offers an effective noninvasive tool not only to induce local necrotic lesions within treated tissue without damaging the surrounding tissue structures but also to test various chemotherapeutics activated by the HIFU beams in preclinical studies on small animals.

Keywords:
Spherical annular phased array transducer, Pulsed HIFU beam, Electronically adjustable focal length, Local tissue heating, Thermal ablation, Necrotic lesion

30p.
2.Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Lewin P.A., In vitro ultrasound experiments: Standing wave and multiple reflections influence on the outcome, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2017.02.008, Vol.77, pp.203-213, 2017
Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Lewin P.A., In vitro ultrasound experiments: Standing wave and multiple reflections influence on the outcome, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2017.02.008, Vol.77, pp.203-213, 2017

Abstract:
The purpose of this work was to determine the influence of standing waves and possible multiple reflections under the conditions often encountered in examining the effects of ultrasound exposure on the cell cultures in vitro. More specifically, the goal was to quantitatively ascertain the influence of ultrasound exposure under free field (FF) and standing waves (SW) and multiple reflections (MR) conditions (SWMR) on the biological endpoint (50% cell necrosis). Such information would help in designing the experiments, in which the geometry of the container with biological tissue may prevent FF conditions to be established and in which the ultrasound generated temperature elevation is undesirable. This goal was accomplished by performing systematic, side-by-side experiments in vitro with C6 rat glioma cancer cells using 12 well and 96 well plates. It was determined that to obtain 50% of cell viability using the 12 well plates, the spatial average, temporal average (ISATA) intensities of 0.32 W/cm2 and 5.89 W/cm2 were needed under SWMR and FF conditions, respectively. For 96 well plates the results were 0.80 W/cm2 and 2.86 W/cm2 respectively. The corresponding, hydrophone measured pRMS maximum pressure amplitude values, were 0.71 MPa, 0.75 MPa, 0.75 MPa and 0.73 MPa, respectively. These results suggest that pRMS pressure amplitude was independent of the measurement set-up geometry and hence could be used to predict the cells’ mortality threshold under any in vitro experimental conditions or even as a starting point for (pre-clinical) in vivo tests. The described procedure of the hydrophone measurements of the pRMS maximum pressure amplitude at the k/2 distance (here 0.75 mm) from the cell’s level at the bottom of the dish or plate provides the guideline allowing the difference between the FF and SWMR conditions to be determined in any experimental setup. The outcome of the measurements also indicates that SWMR exposure might be useful at any ultrasound assisted therapy experiments as it permits to reduce thermal effects. Although the results presented are valid for the experimental conditions used in this study they can be generalized. The analysis developed provides methodology facilitating independent laboratories to determine their specific ultrasound exposure parameters for a given biological end-point under standing waves and multiple reflections conditions. The analysis also permits verification of the outcome of the experiments mimicking pre- and clinical environment between different, unaffiliated teams of researchers.

Keywords:
Standing wave, Ultrasound pressure, Ultrasound intensity, C6 glioma, Anticancer therapy, Sonodynamic therapy, Ultrasound bio-effects

30p.
3.Byra M., Nowicki A., Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Classification of breast lesions using segmented quantitative ultrasound maps of homodyned K distribution parameters, Medical Physics, ISSN: 0094-2405, DOI: 10.1118/1.4962928, Vol.43, No.10, pp.5561-5569, 2016
Byra M., Nowicki A., Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Classification of breast lesions using segmented quantitative ultrasound maps of homodyned K distribution parameters, Medical Physics, ISSN: 0094-2405, DOI: 10.1118/1.4962928, Vol.43, No.10, pp.5561-5569, 2016

Abstract:
Purpose:
Statistical modeling of an ultrasound backscattered echo envelope is used for tissue characterization. However, in the presence of complex structures within the analyzed area, estimation of parameters is disturbed and unreliable, e.g., in the case of breast tumor classification. In order to improve the differentiation of breast lesions, the authors proposed a method based on the segmentation of homodyned K distribution parameter maps. Regions within lesions of different scattering properties were extracted and analyzed. In order to improve the classification, the best-performing features were selected from various regions and then combined.

Methods:
A radio-frequency data set consisting of 103 breast lesions was used in the authors’ analysis. Maps of homodyned K distribution parameters were created using an algorithm based on signal-to-noise ratio, kurtosis, and skewness of fractional-order envelope moments. A Markov random field model was used to segment parametric maps. Features of different segments were extracted and evaluated based on bootstrapping and the receiver operating characteristic curve. To determine the best-performing feature subset, the authors applied the joint mutual information criterion.

Results:
It was found that there were individual features which performed better than the ones commonly used for lesion characterization, like the parameter obtained through averaging of values over the whole lesion. The authors selected and discussed the best-performing features. Properties of different extracted regions were important and improved the distinction between benign and malignant tumors. The best performance was obtained by combining four features with the area under the receiver operating curve of 0.84.

Conclusions:
The study showed that the analysis of internal changes in lesion parametric maps leads to a better classification of breast tumors. The authors recommend combining multiple features for characterization, instead of using only one parameter, especially in the case of heterogeneous lesions.

Keywords:
Cancer, Ultrasonography, Backscattering, Data sets, Medical image noise

35p.
4.Klimonda Z., Postema M., Nowicki A., Litniewski J., Tissue Attenuation Estimation by Mean Frequency Downshift and Bandwidth Limitation, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2016.2574399, Vol.63, No.8, pp.1107-1115, 2016
Klimonda Z., Postema M., Nowicki A., Litniewski J., Tissue Attenuation Estimation by Mean Frequency Downshift and Bandwidth Limitation, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2016.2574399, Vol.63, No.8, pp.1107-1115, 2016

Abstract:
Attenuation of ultrasound in tissue can be estimated from the propagating pulse center frequency downshift. This method assumes that the envelope of the emitted pulse can be approximated by a Gaussian function and that the attenuation linearly depends on frequency. The resulting downshift of the mean frequency depends not only on attenuation but also on pulse bandwidth and propagation distance. This kind of approach is valid for narrowband pulses and shallow penetration depth. However, for short pulses and deep penetration, the frequency downshift is rather large and the received spectra are modified by the limited bandwidth of the receiving system. In this paper, the modified formula modeling the mean frequency of backscattered echoes is presented. The equation takes into account the limitation of the bandwidth due to bandpass filtration of the received echoes. This approach was applied to simulate the variation of the mean frequency of the pulse propagating for both weakly and strongly attenuating media and for narrowband and wideband pulses. The behavior of both the standard and modified estimates of attenuation has been validated using RF data from a tissue-mimicking phantom. The ultrasound attenuation of the phantom, determined with a corrected equation, was close to its true value, while the result obtained using the original formula was lower by as much as 50% at a depth of 8 cm.

Keywords:
Tissue attenuation, frequency downshift, bandwidth limitation

30p.
5.Bilmin K., Kujawska T., Secomski W., Nowicki A., Grieb P., 5-Aminolevulinic acid-mediated sonosensitization of rat RG2 glioma cells in vitro, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.62233, Vol.54, No.3, pp.1-7, 2016
Bilmin K., Kujawska T., Secomski W., Nowicki A., Grieb P., 5-Aminolevulinic acid-mediated sonosensitization of rat RG2 glioma cells in vitro, FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.62233, Vol.54, No.3, pp.1-7, 2016

Abstract:
Sonodynamic therapy (SDT) is a promising technique based on the ability of certain substances, called sonosensitizers, to sensitize cancer cells to non-thermal effects of low-energy ultrasound waves, allowing their destruction. Sonosensitization is thought to induce cell death by direct physical effects such as cavitation and acoustical streaming as well as by complementary chemical reactions generating oxygen free radicals. One of the promising sonosensitizers is 5-aminolevulinic acid (ALA) which upon selective uptake by cancer cells is metabolized and accumulated as protoporphyrin IX. The objective of the study was to describe ALA-mediated sonodynamic effects in vitro on a rat RG2 glioma cell line. Glioma cells, seeded at the bottom of 96-well plates and incubated with ALA (10 μg/ml) for 6 h, were exposed to the sinusoidal US pulses with a resonance frequency of 1 MHz, 1000 μs duration, 0.4 duty-cycle, and average acoustic power varying from 2 W to 6 W. Ultrasound waves were generated by a flat circular piezoelectric transducer with a diameter of 25 mm. Cell viability was determined by MTT assay. Structural cellular changes were visualized with a fluorescence microscope. Signs of cytotoxicity such as a decrease in cell viability, chromatin condensation and apoptosis were found. ALA-mediated SDT evokes cytotoxic effects of low intensity US on rat RG2 glioma cells in vitro. This cell line is indicated for further preclinical assessment of SDT in in vivo conditions.

Keywords:
5-aminolevulinic acid, sonodynamic therapy, rat RG2 glioma cells, cell viability

20p.
6.Gambin B., Byra M., Kruglenko E., Doubrovina O., Nowicki A., Ultrasonic Measurement of Temperature Rise in Breast Cyst and in Neighbouring Tissues as a Method of Tissue Differentiation, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0076, Vol.41, No.4, pp.791-798, 2016
Gambin B., Byra M., Kruglenko E., Doubrovina O., Nowicki A., Ultrasonic Measurement of Temperature Rise in Breast Cyst and in Neighbouring Tissues as a Method of Tissue Differentiation, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0076, Vol.41, No.4, pp.791-798, 2016

Abstract:
Texture of ultrasound images contain information about the properties of examined tissues. The analysis of statistical properties of backscattered ultrasonic echoes has been recently successfully applied to differentiate healthy breast tissue from the benign and malignant lesions. We propose a novel procedure of tissue characterization based on acquiring backscattered echoes from the heated breast. We have proved that the temperature increase inside the breast modifies the intensity, spectrum of the backscattered signals and the probability density function of envelope samples. We discuss the differences in probability density functions in two types of tissue regions, e.g. cysts and the surrounding glandular tissue regions. Independently, Pennes bioheat equation in heterogeneous breast tissue was used to describe the heating process. We applied the finite element method to solve this equation. Results have been compared with the ultrasonic predictions of the temperature distribution. The results confirm the possibility of distinguishing the differences in thermal and acoustical properties of breast cyst and surrounding glandular tissues.

Keywords:
medical ultrasound, temperature changes in vivo, breast tissue, ultrasonic temperature measurement

15p.
7.Nowicki A., Dobruch-Sobczak K., Introduction to ultrasound elastography, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2016.0013, Vol.16, pp.113-124, 2016
Nowicki A., Dobruch-Sobczak K., Introduction to ultrasound elastography, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2016.0013, Vol.16, pp.113-124, 2016

Abstract:
For centuries tissue palpation has been an important diagnostic tool. During palpation, tumors are felt as tissues harder than the surrounding tissues. The significance of palpation is related to the relationship between mechanical properties of different tissue lesions. The assessment of tissue stiffness through palpation is based on the fact that mechanical properties of tissues are changing as a result of various diseases. A higher tissue stiffness translates into a higher elasticity modulus. In the 90’s, ultrasonography was extended by the option of examining the stiffness of tissue by estimating the difference in backscattering of ultrasound in compressed and non-compressed tissue. This modality is referred to as the static, compression elastography and is based on tracking the deformation of tissue subjected to the slowly varying compression through the recording of the backscattered echoes. The displacement is estimated using the methods of cross-correlation between consecutive ultrasonic lines of examined tissue, so calculating the degree of similarity of ultrasonic echoes acquired from tissue before and after the compression was applied. The next step in the development of ultrasound palpation was to apply the local remote tissue compression by using the acoustic radiation force generated through the special beam forming of the ultrasonic beam probing the tissue. The acoustic radiation force causes a slight deformation the tissue thereby forming a shear wave propagating in the tissue at different speeds dependent on the stiffness of the tissue. Shear wave elastography, carries great hopes in the field of quantitative imaging of tissue lesions. This article describes the physical basis of both elastographic methods: compression elastography and shear wave elastography.

Keywords:
elastography, static sonoelastography, dynamic sonoelastography, ultrasonography

10p.
8.Wójcik J., Byra M., Nowicki A., A spectral-based method for tissue characterization, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.369-375, 2016
Wójcik J., Byra M., Nowicki A., A spectral-based method for tissue characterization, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.369-375, 2016

Abstract:
Quantitative ultrasound methods are widely investigated as a promising tool for tissue characterization. In this paper, a novel quantitative method is developed which can be used to assess scattering properties of tissues. The proposed method is based on analysis of oscillations of the backscattered echo power spectrum. It is shown that these oscillations of the power spectrum are connected with the distances between scatterers within the medium. Two techniques are proposed to assess the scatterer’s distribution. First, we show that the inverse Fourier transform of the backscattered echo power spectrum corresponds to a histogram of the distances between scatterers. Second, the Hilbert-Huang transform is used to directly extract the power spectrum oscillations. Both methods are examined by means of a numerical experiment. A cellular gas model of a biological medium is considered. Results are presented and discussed. Both methods can be used to evaluate the scatterer’s distribution by means of the power spectrum oscillations.

Keywords:
quantitative ultrasound, signal analysis, wave scattering

6p.
9.Secomski W., Nowicki A., Generation and measurement of acoustic streaming in limited space, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.361-368, 2016
Secomski W., Nowicki A., Generation and measurement of acoustic streaming in limited space, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.361-368, 2016

Abstract:
The aim of this work was to use the streaming phenomena to assist clot dissolution in blood vessel. Such treatment is called sonothrombolysis. Acoustic streaming is a steady flow in a fluid driven by the acoustic wave propagating in a lossy medium. It is a non-linear effect and it depends on ultrasound intensity, and sound absorption in the media.

The source of ultrasound was a flat piezoceramic disc generating long pulses at 1 MHz frequency and 0.2 W/cm2 ITA acoustical intensity. The streaming was generated in a vessel simulating free space, and next repeated in a multi-well cell culture plate, and in the limited space inside the 8 mm diameter silicone tube positioned perpendicular to the ultrasonic beam. The tube was filled with a mixture of water, glycerol, and starch, so with acoustic properties similar to blood. The streaming velocity was recorded either by the Siemens Acuson Antares ultrasonic scanner operating in the color Doppler mode at 8.9 MHz, or by the custom built 20 MHz pulsed Doppler flowmeter.

The results obtained using both systems were very similar. The recorded streaming velocities were 3.2 cm/s, 6.1 cm/s and 0.3 cm/s, respectively. They were an order of magnitude smaller than that calculated theoretically. However, the results obtained confirm existence of streaming, even very close to the source, in the limited space. This effect will be explored in in-vitro experiments of blood clot dissolution within the tube simulating a blood vessel.

Keywords:
ultrasound, radiation force, blood, thrombolysis

6p.
10.Piotrzkowska-Wroblewska H., Dobruch-Sobczak K., Litniewski J., Chrapowicki E., Roszkowska-Purska K., Nowicki A., Differentiation of the breast lesions using statistics of backscattered echoes, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.319-328, 2016
Piotrzkowska-Wroblewska H., Dobruch-Sobczak K., Litniewski J., Chrapowicki E., Roszkowska-Purska K., Nowicki A., Differentiation of the breast lesions using statistics of backscattered echoes, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.319-328, 2016

Abstract:
The purpose of this study was to evaluate the accuracy of statistical properties of the backscttered ultrasound in differential diagnosis of the breast lesions. The B-mode images together with the appropriate RF echoes from the breast lesions and surrounding tissues were collected. The RF data were processed for the statistics of the backscattered echo signals using K and Nakagami distributions characterized by the M and m parameters, respectively. Based on both, M and m parameters, a set of 18 parameters was derived.

From the point of view of the sensitivity of detection of the cancer the best score was obtained using maximum value of M parameter, the best specificity was received using the differential Nakagami parameter (the differential values between lesions and surrounding tissues). In conclusion the quantitative sonography is a method which has potential to be a complementary tool for classification of the breast lesions.

Keywords:
quantitative ultrasound, breast cancer, Nakagami distribution, K dstribution

6p.
11.Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Trots I., Szubielski M., Olszewski R., Estimation of radial artery reactive response using high frequency ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.297-306, 2016
Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Trots I., Szubielski M., Olszewski R., Estimation of radial artery reactive response using high frequency ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.297-306, 2016

Abstract:
Background:
There is a growing interest in the application of non-invasive clinical tools allowing one to assess the endothelial function, preceding atherosclerosis. The precision in estimating of the artery Flow Mediated Vasodilation (FMD) using standard 10-12 MHz linear array probes does not exceed 0.2 mm, far beyond that required.

Methods:
We have introduced a wide-band, high frequency 25-30 MHz, Golay encoded wobbling type imaging to measure dilation of the radial artery instead of the brachial one. 18 young volunteers, and 4 volunteers with cardiac events history, were examined. In the second approach 20 MHz linear scanning combined with 20 MHz pulsed Doppler attached to the linear array was used. The radial artery FMD was normalized using shear rate at the radial artery wall.

Results and Conclusions:
For the “healthy” group, the FMD resulting from reactive hyperemia response was over 20%; while in the “atherosclerotic” group, the FMD was at least twice as small, not exceeding 10%. The shear rate (SR) normalized FMDSR was in the range from 7.8 to 9.9 in arbitrary units, while in patients with minor cardiac history FMDSR was clearly lower, 6.8 to 7.6. The normalized FMDSR of radial artery RARR can be an alternative to the brachial FMD where the precision of measurements is lower and the diameter dilation does not exceed 7-10%.

Keywords:
thick film transducers, atherosclerosis, flow mediated vasodilation

6p.
12.Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Quantitative sonography of basal cell carcinoma, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2014.11.016, Vol.41, No.3, pp.748-759, 2015
Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Quantitative sonography of basal cell carcinoma, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2014.11.016, Vol.41, No.3, pp.748-759, 2015

Abstract:
A 30-MHz ultrasonic scanner was used to collect B-scan images together with appropriate radiofrequency echoes from diseased and healthy skin regions of patients with diagnosed basal cell carcinoma and pre-cancerous lesions (actinic keratosis). Radiofrequency data were processed to obtain the attenuation coefficient and statistics of the backscattered echo signal determination (K-distribution and effective density of scatterers [EDS]). The attenuation coefficient was significantly higher for patients with basal cell carcinoma than for healthy patients. Also, the pre-cancerous skin lesions had increased attenuation. The averaged EDS values for cancer lesions were significantly lower than those for pre-cancerous lesions and healthy skin. The successful differentiation between the tissue groups examined suggests the potential value of the attenuation coefficient and EDS for carcinoma characterization.

Keywords:
Quantitative ultrasound, High frequency, Human skin, Skin lesions, K-distribution, Attenuation coefficient, Tissue characterization

35p.
13.Dobruch-Sobczak K., Nowicki A., Role of shear wave sonoelastography in differentiation between focal breast lesions, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2014.08.024, Vol.41, No.2, pp.366-374, 2015
Dobruch-Sobczak K., Nowicki A., Role of shear wave sonoelastography in differentiation between focal breast lesions, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2014.08.024, Vol.41, No.2, pp.366-374, 2015

Abstract:
Our goal in this study was to evaluate the relevance of shear wave sonoelastography (SWE) in the differential diagnosis of masses in the breast with respect to ultrasound (US). US and SWE were performed (Aixplorer System, SuperSonic Imagine, Aix en Provence, France) in 76 women (aged 24 to 85) with 84 lesions (43 malignant, 41 benign). The study included BI-RADS-US (Breast Imaging Reporting and Data System for Ultrsound) category 3–5 lesions. In elastograms, the following values were calculated: mean elasticity in lesions (Eav.l) and in fat tissue (Eav.f.) and maximal (Emax.adj.) and mean (Eav.adj.) elasticity in lesions and adjacent tissues. The sensitivity and specificity of the BI-RADS category 4a/4b cutoff value were 97.7% and 90.2%. For an Eav.adj. of 68.5 kPa, the cutoff sensitivity was 86.1% and the specificity was 87.8%, and for an Emax.adj. of 124.1 kPa, 74.4% and 92.7%, respectively. For BI-RADS-US category 3 lesions, Eav.l, Emax.adj. and Eav.adj. were below cutoff levels. On the basis of our findings, Eav.adj. had lower sensitivity and specificity compared with US. Emax.adj. improved the specificity of breast US with loss of sensitivity.

Keywords:
Breast ultrasound, Shear wave sonoelastography, Young's modulus, Focal breast lesions

35p.
14.Trots I., Tasinkevych Y., Nowicki A., Orthogonal Golay Codes With Local Beam Pattern Correction in Ultrasonic Imaging, IEEE SIGNAL PROCESSING LETTERS, ISSN: 1070-9908, DOI: 10.1109/LSP.2015.2423619, Vol.22, No.10, pp.1681-1684, 2015
Trots I., Tasinkevych Y., Nowicki A., Orthogonal Golay Codes With Local Beam Pattern Correction in Ultrasonic Imaging, IEEE SIGNAL PROCESSING LETTERS, ISSN: 1070-9908, DOI: 10.1109/LSP.2015.2423619, Vol.22, No.10, pp.1681-1684, 2015

Abstract:
The goal of this study is to improve the synthetic transmit aperture (STA) imaging method by employing the transducer array element beam pattern correction combined with emission of mutually orthogonal complementary Golay sequences. The transmit-receive scheme based on simultaneous emission of different Golay pairs by adjacent transmit subapertures is implemented to decrease the image reconstruction time. A brief discussion on the fundamentals of the orthogonal Golay complementary sequences is provided and their advantages for the STA imaging method are demonstrated. The performance of the developed approach was tested using FIELD II simulated synthetic aperture data from the point reflectors, which allowed to estimate both; the penetration depth and the lateral resolution. In the work the 128 element, 5 MHz, linear array transducer was used. The obtained results showed that the applying the beam pattern correction leads to the image quality improvement in the vicinity of the transducer face. Specifically, the noise level evaluated between the point reflectors at the depth of 4 mm decreased from - 14.1 dB for the case of omnidirectional source to - 38.7 dB when the element beam pattern correction was implemented. The simulation proved that the overall imaging quality was improved considerably.

Keywords:
coded excitation, element directivity, mutually orthogonal Golay codes, synthetic aperture, ultrasound imaging

30p.
15.Maj M., Warszawik-Hendzel O., Szymańska E., Walecka I., Rakowska A., Antczak-Marczak M., Kuna P., Kruszewski J., Nasierowska-Guttmejer A., Litniewski J., Nowicki A., Olszewska M., Rudnicka L., High frequency ultrasonography: a complementary diagnostic method in evaluation of primary cutaneous melanoma, GIORNALE ITALIANO DI DERMATOLOGIA E VENEREOLOGIA, ISSN: 0392-0488, Vol.150, No.5, pp.595-601, 2015
Maj M., Warszawik-Hendzel O., Szymańska E., Walecka I., Rakowska A., Antczak-Marczak M., Kuna P., Kruszewski J., Nasierowska-Guttmejer A., Litniewski J., Nowicki A., Olszewska M., Rudnicka L., High frequency ultrasonography: a complementary diagnostic method in evaluation of primary cutaneous melanoma, GIORNALE ITALIANO DI DERMATOLOGIA E VENEREOLOGIA, ISSN: 0392-0488, Vol.150, No.5, pp.595-601, 2015

Abstract:
Aim.
The aim of our study was to assess the usefulness of high frequency ultrasonography in the diagnosis of melanoma. Methods. We examined 84 patients with suspicious melanocytic skin lesions, including 19 cases of melanoma. In vivo high-resolution ultrasonography (30 MHz) was performed prior to excision.

Results.
In ultrasound scans early melanomas presented as flat oval or fusiform shaped structures and were clearly demarcated, while advanced melanomas were characterized by a roundish shape with less distinct borders. The ultrasonographic thickness of in situ melanomas ranged from 0.02 to 0.85 mm. In the case of invasive tumors, the mean thickness evaluated by high frequency ultrasonography was 10.7% higher compared to the Breslow Score (1.44±0.8 mm and 1.3±0.88 mm, respectively). In all melanomas of Breslow Score of 1 mm or more ultrasound also indicated a Breslow Score of 1 mm or more.

Conclusion.
High frequency ultrasound examination has limited value in differential diagnosis of melanoma, but it gives a clear picture of the size and depth of the tumor. The method should be used as a complementary method (after dermoscopy and, where applicable, reflectance confocal microscopy) in preoperative evaluation of the tumor. In some cases of locally advanced melanoma, ultrasound examination may allow to reduce the number of surgical procedures and favor the decision of a one-time surgical treatment (removal of primary tumor and sentinel lymph node biopsy at the same time).

Keywords:
Dermoscopy - Diagnosis - Melanoma - Microscopy, confocal - Ultrasonography

15p.
16.Trawiński Z., Wójcik J., Nowicki A., Olszewski R., Balcerzak A., Frankowska E., Zegadło A., Rydzyński P., Strain examinations of the left ventricle phantom by ultrasound and multislices computed tomography imaging, Biocybernetics and Biomedical Engineering, ISSN: 0208-5216, DOI: 10.1016/j.bbe.2015.03.001, Vol.35, pp.255-263, 2015
Trawiński Z., Wójcik J., Nowicki A., Olszewski R., Balcerzak A., Frankowska E., Zegadło A., Rydzyński P., Strain examinations of the left ventricle phantom by ultrasound and multislices computed tomography imaging, Biocybernetics and Biomedical Engineering, ISSN: 0208-5216, DOI: 10.1016/j.bbe.2015.03.001, Vol.35, pp.255-263, 2015

Abstract:
The main aim of this study was to verify the suitability of the hydrogel sonographic model of the left ventricle (LV) in the computed tomography (CT) environment and echocardiography and compare the radial strain calculations obtained by two different techniques: the speckle tracking ultrasonography and the multislices computed tomography (MSCT). The measurement setup consists of the LV model immersed in a cylindrical tank filled with water, hydraulic pump, the ultrasound scanner, hydraulic pump controller, pressure measurement system of water inside the LV model, and iMac workstation. The phantom was scanned using a 3.5 MHz Artida Toshiba ultrasound scanner unit at two angle positions: 0° and 25°. In this work a new method of assessment of RF speckles’ tracking. LV phantom was also examined using the CT 750 HD 64-slice MSCT machine (GE Healthcare). The results showed that the radial strain (RS) was independent on the insonifying angle or the pump rate. The results showed a very good agreement, at the level of 0.9%, in the radial strain assessment between the ultrasound M-mode technique and multislice CT examination. The study indicates the usefulness of the ultrasonographic LV model in the CT technique. The presented ultrasonographic LV phantom may be used to analyze left ventricle wall strains in physiological as well as pathological conditions. CT, ultrasound M-mode techniques, and author's speckle tracking algorithm, can be used as reference methods in conducting comparative studies using ultrasound scanners of various manufacturers.

Keywords:
Computed tomography, Echocardiography, Left ventricle, Speckles tracking, Strain, Ultrasound phantoms

15p.
17.Kujawska T., Secomski W., Kruglenko E., Krawczyk K., Nowicki A., Determination of Tissue Thermal Conductivity by Measuring and Modeling Temperature Rise Induced in Tissue by Pulsed Focused Ultrasound, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0094929, Vol.9, No.4, pp.e94929-1-8, 2014
Kujawska T., Secomski W., Kruglenko E., Krawczyk K., Nowicki A., Determination of Tissue Thermal Conductivity by Measuring and Modeling Temperature Rise Induced in Tissue by Pulsed Focused Ultrasound, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0094929, Vol.9, No.4, pp.e94929-1-8, 2014

Abstract:
A tissue thermal conductivity (Ks) is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of temperature-time T(t) rises induced in a tested tissue sample by a pulsed focused ultrasound with measured acoustic properties using thermocouples located on the acoustic beam axis. Measurements were performed for 20-cycle tone bursts with a 2 MHz frequency, 0.2 duty-cycle and 3 different initial pressures corresponding to average acoustic powers equal to 0.7 W, 1.4 W and 2.1 W generated from a circular focused transducer with a diameter of 15 mm and f-number of 1.7 in a two-layer system of media: water/beef liver. Measurement results allowed to determine position of maximum heating located inside the beef liver. It was found that this position is at the same axial distance from the source as the maximum peak-peak pressure calculated for each nonlinear beam produced in the two-layer system of media. Then, the method involves modeling of T(t) at the point of maximum heating and fitting it to the experimental data by adjusting Ks. The averaged value of Ks determined by the proposed method was found to be 0.5±0.02 W/(m·°C) being in good agreement with values determined by other methods. The proposed method is suitable for determining Ks of some animal tissues in vivo (for example a rat liver).

Keywords:
Acoustics, Sound pressure, Beef, Thermal conductivity, Thermocouples, Nonlinear systems, Sound waves, Bioacoustics

40p.
18.Kujawska T., Secomski W., Bilmin K., Nowicki A., Grieb P., Impact of thermal effects induced by ultrasound on viability of rat C6 glioma cells, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2014.02.002, Vol.54, pp.1366-1372, 2014
Kujawska T., Secomski W., Bilmin K., Nowicki A., Grieb P., Impact of thermal effects induced by ultrasound on viability of rat C6 glioma cells, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2014.02.002, Vol.54, pp.1366-1372, 2014

Abstract:
In order to have consistent and repeatable effects of sonodynamic therapy (SDT) on various cancer cells or tissue lesions we should be able to control a delivered ultrasound energy and thermal effects induced. The objective of this study was to investigate viability of rat C6 glioma cells in vitro depending on the intensity of ultrasound in the region of cells and to determine the exposure time inducing temperature rise above 43°C, which is known to be toxic for cells. For measurements a planar piezoelectric transducer with a diameter of 20 mm and a resonance frequency of 1.06 MHz was used. The transducer generated tone bursts with 94 μs duration, 0.4 duty-cycle and initial intensity ISATA (spatial averaged, temporal averaged) varied from 0.33 W/cm2 to 8 W/cm2 (average acoustic power varied from 1 W to 24 W). The rat C6 glioma cells were cultured on a bottom of wells in 12-well plates, incubated for 24 h and then exposed to ultrasound with measured acoustic properties, inducing or causing no thermal effects leading to cell death. Cell viability rate was determined by MTT assay (a standard colorimetric assay for assessing cell viability) as the ratio of the optical densities of the group treated by ultrasound to the control group. Structural cellular changes and apoptosis estimation were observed under a microscope. Quantitative analysis of the obtained results allowed to determine the maximal exposure time that does not lead to the thermal effects above 43°C in the region of cells for each initial intensity of the tone bursts used as well as the threshold intensity causing cell death after 3 min exposure to ultrasound due to thermal effects. The averaged threshold intensity was found to be about 5.7 W/cm2.

Keywords:
Cancer cells, Photo-sensitizers, Sonodynamic therapy, Thermal effects, Ultrasonic beam properties

30p.
19.Nowicki A, Gambin B., Ultrasonic Synthetic Apertures: Review, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/aoa-2014-0047, Vol.39, No.4, pp.427-438, 2014
Nowicki A, Gambin B., Ultrasonic Synthetic Apertures: Review, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/aoa-2014-0047, Vol.39, No.4, pp.427-438, 2014

Abstract:
In the paper the concept of synthetic aperture used for high resolution/high frame rate ultrasonic imaging is reviewed. The synthetic aperture technique allows building extended “virtual” apertures, synthesized from smaller real aperture resulting in improved lateral resolution along full penetration depth without sacrificing the frame rate.

Especially, four methods, synthetic aperture focusing (SAF), multi-element synthetic aperture focusing (M-SAF), synthetic receive aperture (SRA) and synthetic transmit aperture (STA) are addressed. The effective aperture function, describing two-way, far field radiation is a useful tool in beam pattern analysis. Some basic notations, which are used to calculate the effective aperture are introduced in Appendix.

Keywords:
synthetic aperture, effective aperture, ultrasonography

15p.
20.Klimonda Z., Litniewski J., Karwat P., Nowicki A., Spatial and Frequency Compounding in Application to Attenuation Estimation in Tissue, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/aoa-2014-0056, Vol.39, No.4, pp.519-527, 2014
Klimonda Z., Litniewski J., Karwat P., Nowicki A., Spatial and Frequency Compounding in Application to Attenuation Estimation in Tissue, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/aoa-2014-0056, Vol.39, No.4, pp.519-527, 2014

Abstract:
The soft tissue attenuation is an interesting parameter from medical point of view, because the value of attenuation coefficient is often related to the state of the tissue. Thus, the imaging of the attenuation coefficient distribution within the tissue could be a useful tool for ultrasonic medical diagnosis. The method of attenuation estimation based on tracking of the mean frequency changes in a backscattered signal is presented in this paper. The attenuation estimates are characterized by high variance due to stochastic character of the backscattered ultrasonic signal and some special methods must be added to data processing to improve the resulting images. The following paper presents the application of Spatial Compounding (SC), Frequency Compounding (FC) and the combination of both. The resulting parametric images are compared by means of root-mean-square errors. The results show that combined SC and FC techniques significantly improve the quality and accuracy of parametric images of attenuation distribution.

Keywords:
tissue attenuation estimation, parametric imaging, synthetic aperture, spatial compounding, frequency compounding

15p.
21.Nowicki A., Byra M., Litniewski J., Wójcik J., Ultrasound imaging of stiffness with two frequency pulse, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.151-160, 2014
Nowicki A., Byra M., Litniewski J., Wójcik J., Ultrasound imaging of stiffness with two frequency pulse, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.151-160, 2014

Abstract:
Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing a novel approach based on compression and rarefaction of tissue simultaneously with imaging. The propagating wave is a combination of two pulses. A low frequency pulse is expected to change the local scattering properties of the tissue due to compression/rarefaction while a high frequency pulse is used for imaging. Two transmissions are performed for each scanning line. First, with the imaging pulse that propagates on maximum compression caused by a low frequency wave. Next, the low frequency wave is inverted and the imaging pulse propagates over the maximum rarefaction. After the processing of the subtracted echoes from subsequent transmissions including wavelet transform and band-pass filtering, differential images were reconstructed. The low frequency wave has a visible impact on the scattering properties of the tissue which can be observed on a differential image.

7p.
22.Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Rat cancer cells necrosis induced by ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.179-186, 2014
Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Rat cancer cells necrosis induced by ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.179-186, 2014

Abstract:
Sonodynamic therapy is the ultrasound dependent enhancement of the cytotoxic activities of certain drugs called sonosensitizers. The study of therapeutic efficacy of ultrasound is always preceded by in-vitro tests. In this work, two in-vitro sonication procedures were compared. One with the transducer positioned bellow the cell colony, radiating upward, with standing wave reflected from the water-air surface, the second, in the free field conditions. Efficiency of the cancer cells necrosis caused by ultrasound was compared with acoustical field intensity ISPTA measured by a hydrophone. The standing wave conditions effectively increased the intensity of the ultrasonic wave at the level of cells. To achieve 50% of cell viability, the intensity ISATA, decreased from 5.8 W/cm2 to 0.3 W/cm2. In summary, sonication in the standing wave conditions can effectively and reproducibly destroy cells by ensuring the sterility and without the risk of overheating.

Keywords:
ultrasound, sonodynamic therapy, cancer cells, necrosis

7p.
23.Trawiński Z., Wójcik J., Nowicki A., Balcerzak A., Olszewski R., Frankowska E., Zegadło A., Rydzyński P., Assessment of left ventricle phantom wall compressibility by ultrasound and computed tomography methods, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.211-218, 2014
Trawiński Z., Wójcik J., Nowicki A., Balcerzak A., Olszewski R., Frankowska E., Zegadło A., Rydzyński P., Assessment of left ventricle phantom wall compressibility by ultrasound and computed tomography methods, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.211-218, 2014

Abstract:
The present work concerns the sonographic model of the left ventricle (LV) examined in the Computed Tomography (CT) environment and compare radial strain calculations obtained by two different techniques: the speckle tracking ultrasonography and the Multislices Computed Tomography (MSCT). The Left Ventricular (LF) phantom was fabricated from 10% solution of the poly(vinyl alcohol) (PVA). Our model of the LV was driven by the computer- controlled hydraulic piston Super -Pump (Vivitro Inc., Canada) with adjustable fluid volumes. The stroke volume was set at of 24ml. The fluid pressure was changed within range of 0- 60 mmHg, and the pulse rate was of 60 cycles/per minute. The relationships between computer controlled left ventricular wall deformations and its visual izations of the echocardiographic and CT imaging, both in the normal and pathological conditions were examined. The difference of assessment the Radial Strain between two methods was not exceeding 1.1%.

7p.
24.Małek G., Nowicki A., Standardy badań ultrasonograficznych Polskiego Towarzystwa Ultrasonograficznego – aktualizacja. Badanie żył kończyn dolnych, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0029, Vol.14, pp.287-296, 2014
Małek G., Nowicki A., Standardy badań ultrasonograficznych Polskiego Towarzystwa Ultrasonograficznego – aktualizacja. Badanie żył kończyn dolnych, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0029, Vol.14, pp.287-296, 2014

Abstract:
This article has been prepared on the basis of the Ultrasonography Standards of the Polish Ultrasound Society (2011) and updated based on the latest findings and reports. Ultrasound examination of the lower extremity veins is relatively easy and commonly used to confirm or rule out venous thrombosis. However, a relatively easy compression test frequently requires experience, particularly in situations when imaging is difficult(due to lymphedema, dressing or thick tissues). The technique is time-consuming and requires assessment of each deep vein every 1 cm. Lesions in the deep veins cannot be ruled out when the vessels are assessed in only 2–3 points – a full examination is needed. The value of the method is the highest when the proximal section is assessed and the lowest when crural veins are evaluated. Doppler sonography is the basic method used when patients are prepared for a surgery of varicose veins. The assessment of the superficial veins prior to this procedure is tedious and requires knowledge of anatomy together with numerous variants. A considerable challenge is posed by re-assessment of recurrent varicose veins following a previous surgery. The Standards include anatomic nomenclature proposed by the Polish Society for Vascular Surgery and Polish Society of Phlebology, which should facilitate communication with clinicians. The most beneficial patient positions have been thoroughly discussed in terms of safety and effectiveness of the examination. Sometimes during such an examination, no venous pathology is found, but other changes with symptoms that suggest deep thrombophlebitis are detected. In such a situation, it is necessary to conduct an initial (or complete, if possible) assessment of lesions as well as provide recommendations connected with further, more detailed diagnosis.

Keywords:
venous thrombosis, veins, venous insufficiency, varicose veins, standards

4p.
25.Małek G., Elwertowski M., Nowicki A., Standardy badań ultrasonograficznych Polskiego Towarzystwa Ultrasonograficznego-aktualizacja. Badania aorty i tętnic kończyn dolnych, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0019, Vol.14, No.57, pp.192-202, 2014
Małek G., Elwertowski M., Nowicki A., Standardy badań ultrasonograficznych Polskiego Towarzystwa Ultrasonograficznego-aktualizacja. Badania aorty i tętnic kończyn dolnych, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0019, Vol.14, No.57, pp.192-202, 2014

Abstract:
A Doppler ultrasound examination has an advantage over other vessel imaging methods as it can be carried out by the patient’s bedside and allows to make a diagnosis without exposing the patient to the inconveniency of transportation or an X-ray scan. The purpose of testing the lower extremities and the aorta is to objectively confirm a preliminary clinical diagnosis, localize lesions responsible for the symptoms of the disease, determine their severity and nature (e.g., if they are calcifications or soft lesions), and finally evaluate the hemodynamic criteria. In assessment of the aorta attention is paid not only to aortic diameter measurements, but also to the vascular lumen (dissections with the formation of two flow channels, detachments, balloting of atherosclerotic plaques, etc.) and the presence of atherosclerotic plaques with influx into them (PAU – penetrating ulcer in the plaque or lesions surrounding the aorta, such as retroperitoneal fibrosis or mycotic aneurysm). A correct diagnosis of an abdominal aortic aneurysm requires repeated measurements of the abdominal aorta diameter, and in particular its transverse dimension. When assessing the degree of peripheral arterial stenosis on the basis of hemodynamic parameters, degree of morphological stenosis must be taken into consideration. Collateral circulation may reduce the flow through the main vessel, and thus, the achieved systolic velocities are lower and may understate the degree of the assessed stenosis. Calf vessels are difficult to detect, which results both from the thickness of the muscle and the presence of calcifications. This article has been prepared on the basis of Standards of the Polish Ultrasound Society (2011) and updated on the basis of the latest reports from relevant literature.

Keywords:
Doppler examination, lower limb arteries, abdominal aorta, the size of stenosis, atherosclerotic plaque, ulceration in the atherosclerotic plaque, recommendations

4p.
26.Szopiński T., Nowicki A., Záťura F., Gołąbek T., Chłosta P., Nowe trendy w obrazowaniu raka stercza metodą ultrasonografii przezodbytniczej, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0031, Vol.14, No.58, pp.306-319, 2014
Szopiński T., Nowicki A., Záťura F., Gołąbek T., Chłosta P., Nowe trendy w obrazowaniu raka stercza metodą ultrasonografii przezodbytniczej, Journal of Ultrasonography, ISSN: 2084-8404, DOI: 10.15557/JoU.2014.0031, Vol.14, No.58, pp.306-319, 2014

Abstract:
Carcinoma of the prostate gland is the most common neoplasm in men. Its treatment depends on multiple factors among which local staging plays a significant role. The basic method is transrectal ultrasound imaging. This examination enables imaging of the prostate gland and its abnormalities, but it also allows ultrasound-guided biopsies to be conducted. A conventional gray-scale ultrasound examination enables assessment of the size, echostructure and outlines of the anatomic capsule, but in many cases, neoplastic lesions cannot be observed. For this reason, new sonographic techniques are implemented in order to facilitate detectability of cancer. The usage of contrast agents during transrectal ultrasound examination must be emphasized since, in combination with color Doppler, it facilitates detection of cancerous lesions by visualizing flow which is not observable without contrast enhancement. Elastography, in turn, is a different solution. It uses the differences in tissue elasticity between a neoplastic region and normal prostatic parenchyma that surrounds it. This technique facilitates detection of lesions irrespective of their echogenicity and thereby supplements conventional transrectal examinations. However, the size of the prostate gland and its relatively far location from the transducer may constitute limitations to the effectiveness of elastography. Moreover, the manner of conducting such an examination depends on the examiner and his or her subjective assessment. Another method, which falls within the novel, popular trend of combining imaging methods, is fusion of magnetic resonance imaging and transrectal sonography. The application of multidimensional magnetic resonance imaging, which is currently believed to be the best method for prostate cancer staging, in combination with the availability of a TRUS examination and the possibility of monitoring biopsies in real-time sonography is a promising alternative, but it is associated with higher costs and longer duration of the examination. This paper presents the most important novel trends in transrectal imaging in prostate cancer diagnosis based on the review of the articles available in the PubMed base and published after 2010.

Keywords:
transrectal ultrasound, TRUS, prostatic neoplasms, cancer of the prostate, neoplasm staging, elastography

4p.
27.Nowicki A., Ultrasonografia w Polsce, Inżynier i Fizyk Medyczny, ISSN: 2300-1410, Vol.3, No.1, pp.7-9, 2014
28.Danicki E.J., Nowicki A., Tasinkevych Y., Interdigitated Interdigital Transducer for Surface Elastometry of Soft Damping Tissue, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2013.2690, Vol.60, No.6, pp.1260-1262, 2013
Danicki E.J., Nowicki A., Tasinkevych Y., Interdigitated Interdigital Transducer for Surface Elastometry of Soft Damping Tissue, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2013.2690, Vol.60, No.6, pp.1260-1262, 2013

Abstract:
Measurement of the shear elastic constant of soft and highly damping tissue of high Poisson ratio is quite a challenging task. It is proposed to evaluate shear wave velocity and damping of tissue by measuring the shear skimming bulk waves using one interdigitated interdigital transducer on a piezoelectric layer, such as polyvinylidene fluoride, applied to the surface of the small tissue sample.

Keywords:
Interdigital transducer, surface acoustic waves, electrostatics, mixed boundary-value problem

35p.
29.Tasinkevych Y., Klimonda Z., Lewandowski M., Nowicki A., Lewin P.A., Modified multi-element synthetic transmit aperture method for ultrasound imaging: A tissue phantom study, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2012.10.001, Vol.53, pp.570-579, 2013
Tasinkevych Y., Klimonda Z., Lewandowski M., Nowicki A., Lewin P.A., Modified multi-element synthetic transmit aperture method for ultrasound imaging: A tissue phantom study, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2012.10.001, Vol.53, pp.570-579, 2013

Abstract:
The paper presents the modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging. It is based on coherent summation of RF echo signals with apodization weights taking into account the finite size of the transmit subaperture and of the receive element. The work presents extension of the previous study where the modified synthetic transmit aperture (STA) method was considered and verified [1]. In the case of MSTA algorithm the apodization weights were calculated for each imaging point and all combinations of the transmit subaperture and receive element using their angular directivity functions (ADFs). The ADFs were obtained from the exact solution of the corresponding mixed boundary-value problem for periodic baffle system modeling the transducer array. Performance of the developed method was tested using Field II simulated synthetic aperture data of point reflectors for 4 MHz 128-element transducer array with 0.3 mm pitch and 0.02 mm kerf to estimate the visualization depth and lateral resolution. Also experimentally determined data of the tissue-mimicking phantom (Dansk Fantom Service, model 571) obtained using 128 elements, 4 MHz, linear transducer array (model L14-5/38) and Ultrasonix SonixTOUCH Research platform were used for qualitative assessment of imaging contrast improvement. Comparison of the results obtained by the modified and conventional MSTA algorithms indicated 15 dB improvement of the noise reduction in the vicinity of transducer’s surface (1 mm depth), and concurrent increase in the visualization depth (86% augment of the scattered amplitude at the depth of 90 mm). However, this increase was achieved at the expense of minor degradation of the lateral resolution of approximately 8% at the depth of 50 mm and 5% at the depth of 90 mm.

Keywords:
Synthetic aperture imaging, Ultrasound imaging, Directivity function, Beamforming

35p.
30.Gawlikowski M., Lewandowski M., Nowicki A., Kustosz R., Walczak M., Karwat P., Karłowicz P., The Application of Ultrasonic Methods to Flow Measurement and Detection of Microembolus in Heart Prostheses, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.124.417, Vol.124, No.3, pp.417-420, 2013
Gawlikowski M., Lewandowski M., Nowicki A., Kustosz R., Walczak M., Karwat P., Karłowicz P., The Application of Ultrasonic Methods to Flow Measurement and Detection of Microembolus in Heart Prostheses, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.124.417, Vol.124, No.3, pp.417-420, 2013

Abstract:
For the last 20 years the world cardiosurgery has presented a considerable change of attitude to mechanical circulatory support. In spite of technological progress the main problems in ventricular assist devices are: thrombosis and low accuracy of flow measurements. In this paper the prototype of multi-gate Doppler flowmeter intended for cardiac assist system ReligaHeart EXT has been presented as well as the possibility of ultrasonic micro embolus detection.

Keywords:
artificial heart, microemboli, ultrasound Doppler

15p.
31.Trawiński Z., Wójcik J., Nowicki A., Olszewski R., Dynamic Ultrasonic Model of Left Ventricle, HYDROACOUSTICS, ISSN: 1642-1817, Vol.16, pp.231-236, 2013
Trawiński Z., Wójcik J., Nowicki A., Olszewski R., Dynamic Ultrasonic Model of Left Ventricle, HYDROACOUSTICS, ISSN: 1642-1817, Vol.16, pp.231-236, 2013

Abstract:
Two different tissue phantoms of the left ventricle to imitate a beating left ventricle were developed: first was prepared using a sponge material and second phantom was constructed using a polyvinyl alcohol material modeled into a homogeneous hollow cylinder: approximately 10 cm and 12 cm in length for the first and second phantom, respectively. Both phantoms were 5 cm in diameter, with a wall thickness of 1.0 cm. Additionally, a small part of the wall of the second phantom was processed to simulate the stiffness of myocardial infarction. The phantoms were connected at the end to an adjustable external pump. The pulse volume inside the cylinder was set between 12 to 50 ml at rates of 40, 60, 100, 120 beats/minute. The phantoms were immersed in water for ultrasound scanning with two different insonation angles (90 and 65 degrees). Strain and strain rate were measured with different combinations of angles and pulse rates. The main aim of this work was to develop the new method for validation of the human infarct wall strain calculation procedures using the speckles tracking.

Keywords:
soft tissue, phantom, ultrasound

7p.
32.Wójcik J., Filipczyński L., Nowicki A., Foundation of the new method of numerical calculations of the nonlinear acoustics fields, HYDROACOUSTICS, ISSN: 1642-1817, Vol.16, pp.253-262, 2013
Wójcik J., Filipczyński L., Nowicki A., Foundation of the new method of numerical calculations of the nonlinear acoustics fields, HYDROACOUSTICS, ISSN: 1642-1817, Vol.16, pp.253-262, 2013

Abstract:
We explain, motivation behind this work and briefly describe foundation of new method which we have developed for efficient solution in PC environment of the nonlinear propagation equation with the boundary conditions applied for both circular and not circular transducers (like array). Comparison between new and old method will be presented for strongly nonlinear disturbance. At the end we will demonstrate the results of the numerical calculations of the nonlinear field propagating from the array.

Keywords:
Nonliear propagation, Envelope waves, Fast calculations

7p.
33.Mlosek R.K., Malinowska S., Dębowska R., Lewandowski M., Nowicki A., The High Frequency (HF) Ultrasound as a Useful Imaging Technique for the Efficacy Assessment of Different Anti-Cellulite Treatments, Journal of Cosmetics, Dermatological Sciences and Applications, ISSN: 2161-4105, DOI: 10.4236/jcdsa.2013.31A013, Vol.3, pp.90-98, 2013
Mlosek R.K., Malinowska S., Dębowska R., Lewandowski M., Nowicki A., The High Frequency (HF) Ultrasound as a Useful Imaging Technique for the Efficacy Assessment of Different Anti-Cellulite Treatments, Journal of Cosmetics, Dermatological Sciences and Applications, ISSN: 2161-4105, DOI: 10.4236/jcdsa.2013.31A013, Vol.3, pp.90-98, 2013

Abstract:
The purpose of the research was to evaluate the role of high frequency ultrasound in monitoring and efficacy assessment of anti-cellulite treatments. A group of 66 women used 3 different types of anti-cellulite treatments; additionally a placebo group (n = 18) was created. The μ-Scan ultrasound device with a 35 MHz mechanical probe was used for the examinations. The following parameters were subjected to the ultrasound evaluation: epidermis thickness, dermis thickness, dermis echogenicity, the length and area of subcutaneous tissue bands projecting into the dermis (dermis-hypodermis junction), as well as the presence/absence of edema within the dermis. As a result of anti-cellulite treatment, the length and area of dermis-hypodermis junction significantly decreased, and dermis echogenicity significantly increased. Ultrasound imaging made it possible to evaluate the efficacy of the applied treatments. The high frequency ultrasound is a useful imaging technique for the application in aesthetic dermatology and cosmetology.

Keywords:
Aesthetic Medicine, Cellulite, Anti-Cellulite Treatment, High Frequency Ultrasound, Skin Ultrasound

34.Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Ultrasonic Scanner for In Vivo Measurement of Cancellous Bone Properties From Backscattered Data, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2012.2347, Vol.59, No.7, pp.1470-1477, 2012
Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Ultrasonic Scanner for In Vivo Measurement of Cancellous Bone Properties From Backscattered Data, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2012.2347, Vol.59, No.7, pp.1470-1477, 2012

Abstract:
A dedicated ultrasonic scanner for acquiring RF echoes backscattered from the trabecular bone was developed. The design of device is based on the goal of minimizing of custom electronics and computations executed solely on the main computer processor and the graphics card. The electronic encoder-digitizer module executing all of the transmission and reception functions is based on a single low-cost field programmable gate array (FPGA). The scanner is equipped with a mechanical sector-scan probe with a concave transducer with 50 mm focal length, center frequency of 1.5 MHz and 60% bandwidth at −6 dB. The example of femoral neck bone examination shows that the scanner can provide ultrasonic data from deeply located bones with the ultrasound penetrating the trabecular bone up to a depth of 20 mm. It is also shown that the RF echo data acquired with the scanner allow for the estimation of attenuation coefficient and frequency dependence of backscattering coefficient of trabecular bone. The values of the calculated parameters are in the range of corresponding in vitro data from the literature but their variation is relatively high.

Keywords:
cancellous bone, broadband ultrasound attenuation, FPGA

35p.
35.Mlosek R.K., Woźniak W., Malinowska S., Lewandowski M., Nowicki A., The effectiveness of anticellulite treatment using tripolar radiofrequency monitored by classic and high-frequency ultrasound, JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY AND VENEREOLOGY, ISSN: 0926-9959, DOI: 10.1111/j.1468-3083.2011.04148.x, Vol.26, pp.696-703, 2012
Mlosek R.K., Woźniak W., Malinowska S., Lewandowski M., Nowicki A., The effectiveness of anticellulite treatment using tripolar radiofrequency monitored by classic and high-frequency ultrasound, JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY AND VENEREOLOGY, ISSN: 0926-9959, DOI: 10.1111/j.1468-3083.2011.04148.x, Vol.26, pp.696-703, 2012

Abstract:
Background
Cellulite affects nearly 85% of the female population. Given the size of the phenomenon, we are continuously looking for effective ways to reduce cellulite. Reliable monitoring of anticellulite treatment remains a problem.

Objective
The main aim of the study was to evaluate the effectiveness of anticellulite treatment carried out using radiofrequency (RF), which was monitored by classical and high-frequency ultrasound.

Methods
Twenty-eight women underwent anticellulite treatment using RF, 17 women were in the placebo group. The therapy was monitored by classical and high-frequency ultrasound. The examinations evaluated the thickness of the epidermal echo, dermis thickness, dermis echogenicity, the length of the subcutaneous tissue bands growing into the dermis, the presence or absence of oedema, the thickness of subcutaneous tissue as well as thigh circumference and the stage of cellulite (according to the Nurnberger–Muller scale).

Results
Cellulite was reduced in 89.286% of the women who underwent RF treatment. After the therapy, the following observations were made: a decrease in the thickness of the dermis and subcutaneous tissue, an increase in echogenicity reflecting on the increase in the number of collagen fibres, decreased subcutaneous tissue growing into bands in the dermis, and the reduction of oedema. In the placebo group, no statistically significant changes of the above parameters were observed.

Conclusion
Radiofrequency enables cellulite reduction. A crucial aspect is proper monitoring of the progress of such therapy, which ultrasound allows.

Keywords:
anticellulite treatment, high-frequency ultrasound

35p.
36.Trawiński Z., Hilgertner L., Lewin P.A., Nowicki A., Ultrasonically assisted evaluation of the impact of atherosclerotic plaque on the pulse pressure wave propagation: A clinical feasibility study, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.10.010, Vol.52, pp.475-481, 2012
Trawiński Z., Hilgertner L., Lewin P.A., Nowicki A., Ultrasonically assisted evaluation of the impact of atherosclerotic plaque on the pulse pressure wave propagation: A clinical feasibility study, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.10.010, Vol.52, pp.475-481, 2012

Abstract:
The purpose of this work was to evaluate ultrasound modality as a non-invasive tool for determination of impact of the degree of the atherosclerotic plaque located in human internal carotid arteries on the values of the parameters of the pulse wave. Specifically, the applicability of the method to such arteries as brachial, common, and internal carotid was examined. The method developed is based on analysis of two characteristic parameters: the value of the mean reflection coefficient modulus |Γ|a of the blood pressure wave and time delay Δt between the forward (travelling) and backward (reflected) blood pressure waves. The blood pressure wave was determined from ultrasound measurements of the artery’s inner (internal) diameter, using the custom made wall tracking system (WTS) operating at 6.75 MHz. Clinical data were obtained from the carotid arteries measurements of 70 human subjects. These included the control group of 30 healthy individuals along with the patients diagnosed with the stenosis of the internal carotid artery (ICA) ranging from 20% to 99% or with the ICA occlusion. The results indicate that with increasing level of stenosis of the ICA the value of the mean reflection coefficient measured in the common carotid artery, significantly increases from |Γ|a = 0.45 for healthy individuals to |Γ|a = 0.61 for patients with stenosis level of 90–99%, or ICA occlusion. Similarly, the time delay Δt decreases from 52 ms to 25 ms for the respective groups. The method described holds promise that it might be clinically useful as a non-invasive tool for localization of distal severe artery narrowing, which can assist in identifying early stages of atherosclerosis especially in regions, which are inaccessible for the ultrasound probe (e.g. carotid sinus or middle cerebral artery).

25p.
37.Tasinkevych Y., Trots I., Nowicki A., Lewin P.A., Modified synthetic transmit aperture algorithm for ultrasound imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.09.003, Vol.52, pp.333-342, 2012
Tasinkevych Y., Trots I., Nowicki A., Lewin P.A., Modified synthetic transmit aperture algorithm for ultrasound imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.09.003, Vol.52, pp.333-342, 2012

Abstract:
The modified synthetic transmit aperture (STA) algorithm is described. The primary goal of this work was to assess the possibility to improve the image quality achievable using synthetic aperture (SA) approach and to evaluate the performance and the clinical applicability of the modified algorithm using phantoms. The modified algorithm is based on the coherent summation of back-scattered RF echo signals with weights calculated for each point in the image and for all possible combinations of the transmit–receive pairs. The weights are calculated using the angular directivity functions of the transmit–receive elements, which are approximated by a far-field radiation pattern of a narrow strip transducer element vibrating with uniform pressure amplitude over its width. In this way, the algorithm takes into account the finite aperture of each individual element in the imaging transducer array. The performance of the approach developed was tested using FIELD II simulated synthetic aperture data of the point reflectors, which allowed the visualization (penetration) depth and lateral resolution to be estimated. Also, both simulated and measured data of cyst phantom were used for qualitative assessment of the imaging contrast improvement. The experimental data were obtained using 128 elements, 4 MHz, linear transducer array of the Ultrasonix research platform. The comparison of the results obtained using the modified and conventional (unweighted) STA algorithms revealed that the modified STA exhibited an increase in the penetration depth accompanied by a minor, yet discernible upon the closer examination, degradation in lateral resolution, mainly in the proximity of the transducer aperture. Overall, however, a considerable (12 dB) improvement in the image quality, particularly in the immediate vicinity of the transducer’s surface was demonstrated. The modified STA method holds promise to be of clinical importance, especially in the applications where the quality of the ‘‘near-field’’ image, that is the image in the immediate vicinity of the scanhead is of critical importance such as for instance in skin- and breast-examinations.

Keywords:
synthetic aperture imaging, ultrasound imaging, directivity function, beamforming

25p.
38.Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Ultrasonic Echosignal Applied to Human Skin Lesions Characterization, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.1, pp.103-108, 2012
Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Ultrasonic Echosignal Applied to Human Skin Lesions Characterization, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.1, pp.103-108, 2012

Abstract:
The paper presents a classification of the healthy skin and the skin lesions (basal cell carcinoma) basing on a statistics of the envelope of ultrasonic echoes. The echoes envelopes distributions were modeled using Rayleigh and K-distribution. The distributions were compared with empirical data to find which of them better models the statistics of the echo-signal obtained from the human skin. The results indicated that the K-distribution provides a better fit. Also, a characteristic parameter of the K-distribution, the effective number of scatterers (M), was investigated. The values of the M parameter, obtained for the skin cancer (basal cell carcinoma), were lower as compared to those obtained for the healthy skin. The results indicate that the statistical quantitative ultrasound parameters have a potential for extracting information useful for characterization of the skin condition.

Keywords:
statistics, K-distribution, Rayleigh distribution, ultrasonic scattering, human dermis

15p.
39.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging Applications, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.1, pp.47-55, 2012
Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging Applications, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.1, pp.47-55, 2012

Abstract:
The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.

Keywords:
ultrasound imaging, synthetic aperture, beamforming

15p.
40.Olszewski R., Trawiński Z., Wójcik J., Nowicki A., Mathematical and Ultrasonographic Model of the Left Ventricle:in Vitro Studies, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.4, pp.583-595, 2012
Olszewski R., Trawiński Z., Wójcik J., Nowicki A., Mathematical and Ultrasonographic Model of the Left Ventricle:in Vitro Studies, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.4, pp.583-595, 2012

Abstract:
The main objective of this study is to develop an echocardiographic model of the left ventricular and numerical modeling of the speckles- markers tracking in the ultrasound (ultrasonographic) imaging of the left ventricle. The work is aimed at the creation of controlled and mobile environment that enables to examine the relationships between left ventricular wall deformations and visualizations of these states in the form of echocardiographic imaging and relations between the dynamically changing distributions of tissue markers of studied structures.

Keywords:
left ventricle, echocardiography, speckle modeling, ultrasound phantoms, strain, strain rate

15p.
41.Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Statistical Analysis of Ultrasound Echo for Skin Lesions Classification, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.171-178, 2012
Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Statistical Analysis of Ultrasound Echo for Skin Lesions Classification, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.171-178, 2012

Abstract:
Propagation of ultrasonic waves in the tissue is sensitive to the alternation of tissue composition and structure.. This paper presents the classification of healthy skin and skin lesions (basal cell carcinoma (BCC)) based on statistic parameters of the envelope of echosignal. The statistics of envelope of the ultrasonic signal was modeled using Rayleigh and non-Rayleigh (the K-distribution) statistics. Furthermore the characteristic parameter of K-distribution, the effective number of scaterrers (M) was investigated.
Comparison of the results obtained for region of the skin where the BCC was diagnosed and the regions of healthy skin has shown differences in the values of M parameter. These results indicate that this parameter has the potential for extracting information useful for characterizing skin lesions.

Keywords:
high frequency, ultrasound, basall cell carcinoma, ststistics

4p.
42.Litniewski J., Klimonda Z., Nowicki A., Parametric Sonographic Imaging – Application of Synthetic Aperture Technique to Imaging Attenuation of Ultrasound in Tissue Structures, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.99-110, 2012
Litniewski J., Klimonda Z., Nowicki A., Parametric Sonographic Imaging – Application of Synthetic Aperture Technique to Imaging Attenuation of Ultrasound in Tissue Structures, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.99-110, 2012

Abstract:
Ultrasonic imaging is a well-established technique in medicine. However, in most conventional applications of clinical ultrasonic scanners only the peak amplitude echogenicity is used to create the image. Moreover, signal envelope detection destroys potentially useful information about frequency dependence of acoustic properties of tissue comprised in RF backscattered echoes. We have explored the possibility of developing the method of imaging the distribution of the acoustic attenuation in tissue. We expect that the method will help in localization of the pathological states of tissue including tumors and diffuse liver diseases. The spatial resolution and precision of the method are crucial for medical diagnosis, hence the synthetic aperture technique was applied for ultrasonic data collection. The final goal of the presented project is to develop reliable diagnostic tool, which could be implemented in standard USG systems, as the new visualization mode.

Keywords:
soft tissue parametric imaging, attenuation imaging, synthetic aperture focusing technique

4p.
43.Wójcik J., Trots I., Lewandowski M., Nowicki A., Cumulative Method of the Image Reconstruction in Synthetic Aperture. Experimental Results, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.195-206, 2012
Wójcik J., Trots I., Lewandowski M., Nowicki A., Cumulative Method of the Image Reconstruction in Synthetic Aperture. Experimental Results, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.195-206, 2012

Abstract:
An analytical model of imaging using synthetic aperture (SA) methods is presented. This model takes into account: fundamental features of an environment, of an electric transmission/reception path and a description of SA structure - possible schemes of transmission, reception and image formation. Then two schemes are analyzed: a proposed cumulative synthetic transmit aperture (CSTA) and for comparison of the standard STA schemes. For both methods identical basic parameters - equal sequences of transmit and receive transducers were applied. The distinctive feature of CSTA is gathering (summing up) echoes of subsequent transmissions in one acquisition mat ix sufficient for image reconstruction. In traditionally applied STA methods a separate acquisition matrix for each transmission is created. Therefore there are a dozen to several dozen more matrices and the time of image reconstruction is at least several times longer than in CSTA. The presented experimental results obtained using wire and tissue mimicking phantoms have shown the comparable imaging quality in both methods.

Keywords:
ultrasound imaging, synthetic aperture

4p.
44.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Transmit Sub-aperture Optimization in MSTA Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.65, pp.422-427, 2012
Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Transmit Sub-aperture Optimization in MSTA Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.65, pp.422-427, 2012

Abstract:
The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is performed as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. Maximum penetration depth and the best lateral resolution at given depths are chosen as the optimization criteria. The optimization algorithm was tested using synthetic aperture data of point reflectors simulated by Filed II program for Matlab® for the case of 5MHz 128-element linear transducer array with 0.48 mm pitch are presented. The visualization of experimentally obtained synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver are also shown. The data were obtained using the SonixTOUCH Research systemequipped with a linear 4MHz 128 element transducerwith 0.3 mm element pitch, 0.28 mm element width and 70% fractional bandwidth was excited by one sine cycle pulse burst of transducer's center frequency.

Keywords:
synthetic aperture method, ultrasound imaging, beamforming

45.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Coded Transmission in Synthetic Transmit Aperture Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.63, pp.331-336, 2012
Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Coded Transmission in Synthetic Transmit Aperture Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.63, pp.331-336, 2012

Abstract:
The paper presents the study of synthetic transmit aperture method applying the Golay coded transmission for medical ultrasound imaging. Longer coded excitation allows to increase the total energy of the transmitted signal without increasing the peak pressure. Signal-to-noise ratio and penetration depth are improved maintaining high ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm inter-element spacing excited by one cycle and the 8 and 16-bit Golay coded sequences at nominal frequencies 4 MHz was used. Single element transmission aperture was used to generate a spherical wave covering the full image region and all the elements received the echo signals. The comparison of 2D ultrasound image s of the wire phantom as well as of the tissue mimicking phantom is presented to demonstrate the benefits of the coded transmission. The results were obtained using the synthetic aperture algorithm with transmit and receive signals correction based on a single element directivity function

Keywords:
Golay coded sequences, radiation pattern, synthetic aperture, ultrasound imaging

46.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., In Vitro Study of Coded Transmission in Synthetic Aperture Ultrasound Imaging Systems, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.6, No.6, pp.82-87, 2012
Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., In Vitro Study of Coded Transmission in Synthetic Aperture Ultrasound Imaging Systems, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.6, No.6, pp.82-87, 2012

Abstract:
In the paper the study of synthetic transmit aperture method applying the Golay coded transmission for medical ultrasound imaging is presented. Longer coded excitation allows to increase the total energy of the transmitted signal without increasing the peak pressure. Moreover signal-to-noise ratio and penetration depth are improved while maintaining high ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm inter-element spacing excited by one cycle and the 8 and 16- bit Golay coded sequences at nominal frequency 4 MHz was used. To generate a spherical wave covering the full image region a single element transmission aperture was used and all the elements received the echo signals. The comparison of 2D ultrasound images of the tissue mimicking phantom and in vitro measurements of the beef liver is presented to illustrate the benefits of the coded transmission. The results were obtained using the synthetic aperture algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:
Golay coded sequences, radiation pattern, signal, processing, synthetic aperture, ultrasound imaging

47.Wójcik J., Litniewski J., Nowicki A., Modeling and analysis of multiple scattering of acoustic waves in complex media: Application to the trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, Vol.130, No.4, pp.1908-1918, 2011
Wójcik J., Litniewski J., Nowicki A., Modeling and analysis of multiple scattering of acoustic waves in complex media: Application to the trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, Vol.130, No.4, pp.1908-1918, 2011

Abstract:
The integral equations that describe scattering in the media with step-rise changing parameters have been numerically solved for the trabecular bone model. The model consists of several hundred discrete randomly distributed elements. The spectral distribution of scattering coefficients in subse- quent orders of scattering has been presented. Calculations were carried on for the ultrasonic frequency ranging from 0.5 to 3 MHz. Evaluation of the contribution of the first, second, and higher scattering orders to total scattering of the ultrasounds in trabecular bone was done. Contrary to the approaches that use the lCT images of trabecular structure to modeling of the ultrasonic wave propagation condition, the 3D numerical model consisting of cylindrical elements mimicking the spatial matrix of trabeculae, was applied. The scattering, due to interconnections between thick trabeculae, usually neglected in trabecular bone models, has been included in calculations when the structure backscatter was evaluated. Influence of the absorption in subsequent orders of scattering is also addressed. Results show that up to 1.5 MHz, the influence of higher scattering orders on the total scattered field characteristic can be neglected while for the higher frequencies, the relatively high amplitude interference peaks in higher scattering orders clearly occur.

Keywords:
Multiple scattering, Complex media, Bone

35p.
48.Litniewski J., Cieślik L., Wójcik J., Nowicki A., Statistics of the envelope of ultrasonic backscatter from human trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, Vol.130, No.4, pp.2224-2232, 2011
Litniewski J., Cieślik L., Wójcik J., Nowicki A., Statistics of the envelope of ultrasonic backscatter from human trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, Vol.130, No.4, pp.2224-2232, 2011

Abstract:
The paper describes the investigations intended to compare the results of experimental measurements f backscattering properties of the trabecular bone with the results of computer simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in waterlike medium. For each measured or simulated RF backscatter the statistical properties of the signal envelope were determined. Experimental results suggest deviations of the backscattering properties from the Rayleigh distribution. The results of simulation suggest that deviation from Rayleigh distribution depends on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well to the deviations calculated from simulated echoes assuming trabeculae thickness variation equaled to the earlier published histomorphometric study results.

Keywords:
trabecular bone, scattering statistics, bone model

35p.
49.Mlosek R.K., Dębowska R.M., Lewandowski M., Malinowska S., Nowicki A., Eris I., Imaging of the skin and subcutaneous tissue using classical and high-frequency ultrasonographies in anti-cellulite therapy, SKIN RESEARCH AND TECHNOLOGY, ISSN: 0909-752X, Vol.17, pp.461-468, 2011
Mlosek R.K., Dębowska R.M., Lewandowski M., Malinowska S., Nowicki A., Eris I., Imaging of the skin and subcutaneous tissue using classical and high-frequency ultrasonographies in anti-cellulite therapy, SKIN RESEARCH AND TECHNOLOGY, ISSN: 0909-752X, Vol.17, pp.461-468, 2011

Abstract:
Background: The development of ultrasonography allowed for skin imaging used in dermatology and esthetic medicine. By means of classic and high-frequency ultrasonographies, changes within the dermis and subcutaneous tissue can be presented.
Objective: The aim of this study was to show the possibi­lities of applying classic and high-frequency ultrasonogra­phies in esthetic dermatology based on monitoring various types of anti-cellulite therapies.
Methods: Sixty-one women with cellulite were assigned to two smaller groups. One group was using anti-cellulite cream and the second group was a placebo group. The ultrasound examin;ition was carried out before the initiation and after the completion of the treatment and evaluated epidermal echoes, the thickness of the subcutaneous tissue and the dermis, dermis echogenicity, the length and surface rea of the subcutaneous tissue fascicles growing into the dermis, and the presence or absence of edemas.
Results: After the completion of the treatment, a statistically significant difference was observed. The most useful para­meters were as follows: the thickness of the subcutaneous tissue, echogenicity, the surface area and length of the sub­cutaneous tissue, as well as the presence of edemas. The discussed changes were not observed in the placebo group.
Conclusion: Classic and high-frequency ultrasonographies are useful methods for monitoring anti-cellulite therapies.

Keywords:
high-frequency ultrasonography - cellulite classic ultrasonography ultrasonography

25p.
50.Kujawska T., Nowicki A., Lewin P.A., Determination of nonlinear medium parameter B/A using model assisted variable-length measurement approach, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.05.016, Vol.51, No.8, pp.997-1005, 2011
Kujawska T., Nowicki A., Lewin P.A., Determination of nonlinear medium parameter B/A using model assisted variable-length measurement approach, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2011.05.016, Vol.51, No.8, pp.997-1005, 2011

Abstract:
This work addresses the difficulties in the measurements of the nonlinear medium parameter B/A and presents a modification of the finite amplitude method (FAM), one of the accepted procedures to determine this parameter. The modification is based on iterative, hybrid approach and entails the use of the versatile and comprehensive model to predict distortion of the pressure–time waveform and its subsequent comparison with the one experimentally determined. The measured p–t waveform contained at least 18 harmonics generated by 2.25 MHz, 29 mm effective diameter, single element, focused PZT source (f-number 3.5) and was recorded by Sonora membrane hydrophone calibrated in the frequency range 1– 40 MHz. The hydrophone was positioned coaxially at the distal end of the specially designed, two-section assembly comprising of one, fixed length (60 mm), water-filled cylindrical container and the second, variable length (60–120 mm) container that was filled with unknown medium. The details of the measurement chamber are described and the reasons for this specific design are analyzed. The data were collected with the variable length chamber filled with 1.3-butanediol, which was used as a close approximation of tissue mimicking phantom. The results obtained provide evidence that a novel combination of the FAM with the semi-empirical nonlinear propagation model based on the hyperbolic operator is capable of reducing the overall uncertainty of the B/A measurements as compared to those reported in the literature. The overall uncertainty of the method reported here was determined to be ±2%, which enhances the confidence in the numerical values of B/A measured for different, clinically relevant media. Optimization of the approach is also discussed and it is shown that it involves an iterative procedure that entails a careful selection of the acoustic source and its geometry and the axial distance over which the measurements need to be performed. The optimization also depends critically on the experimental determination of the source surface pressure amplitude.

Keywords:
pulsed finite-amplitude acoustic waves, nonlinear propagation, nonlinearity parameter B/A

25p.
51.Kujawska T., Secomski W., Krawczyk K., Nowicki A., Thermal Effects Induced in Liver Tissues by Pulsed Focused Ultrasonic Beams from Annular Array Transducer, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/v10168-011-0063-3, Vol.36, No.4, pp.937-944, 2011
Kujawska T., Secomski W., Krawczyk K., Nowicki A., Thermal Effects Induced in Liver Tissues by Pulsed Focused Ultrasonic Beams from Annular Array Transducer, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/v10168-011-0063-3, Vol.36, No.4, pp.937-944, 2011

Abstract:
Many therapeutic applications of pulsed focused ultrasound are based on heating of detected lesions which may be localized in tissues at different depths under the skin. In order to concentrate the acoustic energy inside tissues at desired depths a new approach using a planar multi-element annular array transducer with an electronically adjusted time-delay of excitation of its elements, was proposed. The 7-elements annular array transducer with 2.4 MHz center operating frequency and 20 mm outer diameter was produced. All its elements (central disc and 6 rings) had the same radiating area. The main purpose of this study was to investigate thermal fields induced in bovine liver in vitro by pulsed focused ultrasonic beams with various acoustic properties and electronically steered focal plane generated from the annular array transducer used. The measurements were performed for the radiating beams with the 20 mm focal depth. In order to maximize nonlinear effects introducing the important local temperature rise, the measurements have been performed in two-layer media comprising of a water layer, whose thickness was specific for the transducer used and equal to 13 mm, and the second layer of a bovine liver with a thickness of 20 mm. The thickness of the water layer was determined numerically as the axial distance where the amplitude of the second harmonics started to increase rapidly. The measurements of the temperature rise versus time were performed using a thermocouple placed inside the liver at the focus of the beam. The temperature rise induced in the bovine liver in vitro by beams with the average acoustic power of 1W, 2W, and 3W and duty cycle of 1/5, 1/15 and 1/30, respectively, have been measured. For each beam used the exposure time needed for the local tissue heating to the temperature of 43◦C (used in therapies based on ultrasonic enhancement of drug delivery or in therapies involving stimulation of immune system by enhancement of the heat shock proteins expression) and to the temperature of 56◦C (used in HIFU therapies) was determined. Two sets of measurements were done for each beam considered. First, the thermocouple measurement of the temperature rise was done and next, the real-time monitoring of dynamics of growth of the necrosis area by using ultrasonic imaging technique, while the sample was exposed to the same acoustic beam. It was found that the necrosis area becomes visible in the ultrasonic image only for beams with the average acoustic power of 3 W, although after cutting the sample the thermally ablated area was visible with the naked eye even for the beams with lower acoustic power. The quantitative analysis of the obtained results allowed to determine the exposure time needed to get the necrosis area visible in the ultrasonic image.

Keywords:
annular array transducer, pulsed focused nonlinear ultrasound, electronically moved focus, tissue heating, biological effects, tissue necrosis

15p.
52.Nowicki A., Lewandowski M., Wójcik J., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick Film Transducers for High Frequency Coded Ultrasonography, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.945-954, 2011
Nowicki A., Lewandowski M., Wójcik J., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick Film Transducers for High Frequency Coded Ultrasonography, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.945-954, 2011

Abstract:
Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature – 11 mm, 12 mm, 15 mm, 16 mm.
All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35–40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4–1.5 and finally resulting in a SNR gain of the same order.

Keywords:
transducers, thick film, high frequency ultrasound, pulse compression, Golay codes

15p.
53.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay Coded Sequences in Synthetic Aperture Imaging Systems, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.913-926, 2011
Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay Coded Sequences in Synthetic Aperture Imaging Systems, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.913-926, 2011

Abstract:
The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:
ultrasound imaging, synthetic aperture, beamforming, radiation pattern, coded sequences, Golay codes

15p.
54.Klimonda Z., Litniewski J., Nowicki A., Synthetic Aperture Technique Applied to Tissue Attenuation Imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.927-935, 2011
Klimonda Z., Litniewski J., Nowicki A., Synthetic Aperture Technique Applied to Tissue Attenuation Imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.927-935, 2011

Abstract:
The attenuating properties of biological tissue are of great importance in ultrasonic medical imaging. Investigations performed in vitro and in vivo showed the correlation between pathological changes in the tissue and variation of the attenuation coefficient. In order to estimate the attenuation we have used the downshift of mean frequency (fm) of the interrogating ultrasonic pulse propagating in the medium. To determine the fm along the propagation path we have applied the fm estimator (I/Q algorithm adopted from the Doppler mean frequency estimation technique). The mean-frequency shift trend was calculated using Single Spectrum Analysis. Next, the trends were converted into attenuation coefficient distributions and finally the parametric images were computed. The RF data were collected in simulations and experiments applying the synthetic aperture (SA) transmit-receiving scheme. In measurements the ultrasonic scanner enabling a full control of the transmission and reception was used. The resolution and accuracy of the method was verified using tissue mimicking phantom with uniform echogenicity but varying attenuation coefficient.

Keywords:
tissue attenuation imaging, synthetic aperture, diagnosis enhancing

15p.
55.Szymańska E., Maj M., Majsterek M., Litniewski J., Nowicki A., Rudnicka L., Zastosowanie ultrasonografii wysokiej częstotliwości w diagnostyce dermatologicznej – obraz ultrasonograficzny wybranych zmian skórnych, POLSKI MERKURIUSZ LEKARSKI, ISSN: 1426-9686, Vol.31, No.181, pp.37-40, 2011
Szymańska E., Maj M., Majsterek M., Litniewski J., Nowicki A., Rudnicka L., Zastosowanie ultrasonografii wysokiej częstotliwości w diagnostyce dermatologicznej – obraz ultrasonograficzny wybranych zmian skórnych, POLSKI MERKURIUSZ LEKARSKI, ISSN: 1426-9686, Vol.31, No.181, pp.37-40, 2011

Abstract:
Typical diagnostic process in dermatology includes clinical assessment, dermoscopic and histopathologic examination. Microsonography was initiated in seventies and much progress in the development of high-frequency scanners occurred since that time. The aim of the study was the assessment of high frequency ultrasonography in dermatologic diagnostics. Material and methods. Examination was performed with 30 MHz ultrasound transducer with 0,1 mm resolution and 7 mm penetration. We examined patients with benign and malignant neoplasms, cicatrical alopecia and morphea. Results. Sonographically, the normal skin is composed of three layers: an epidermal entry echo, dermis and subcutaneous tissue. In healthy skin we can image small hypoechoic areas which correspond to hair folicules, vessels and sebaceous glands. Most of small skin neoplasmatic lesions were hypoechogenic and homogeneous on examination. Extensive lesions were multicomponent with normo-, hypo- and anechogenic structures. The assessment of lesion’s boarders allows sometimes to conclude the invasiveness of the lesion. Areas of skin with clinically visible atrophy showed diffuse increasing of echogenicity. In early lesions, without accomplished fibrosis, diffuse decreasing of echogenicity can be observed, that is probably caused by inflammatory infiltration. In comparison to the healthy skin, the ultrasound scan of sclerotic skin shows a wide entry echo and highly reflective, thicker dermis as a result of the collagen fibers accumulation. Conclusions. Above data suggest that ultrasonographic examination may be a valuable dermatologic diagnostic tool that completes classical dermatologic diagnostics and helps to plan the treatment.

Keywords:
high frequency ultrasonography, benign neoplasms, malignant neoplasms, cicatrical alopecia, morphea

7p.
56.Wójcik J., Litniewski J., Nowicki A., Gambin B., Applying crystallography in analysis of trabecular bone backscatter, HYDROACOUSTICS, ISSN: 1642-1817, Vol.14, pp.255-266, 2011
Wójcik J., Litniewski J., Nowicki A., Gambin B., Applying crystallography in analysis of trabecular bone backscatter, HYDROACOUSTICS, ISSN: 1642-1817, Vol.14, pp.255-266, 2011

Abstract:
Some important details of the Backscatter Effective Cross-Sections (BECS) obtained for random scattering structures (like trabecular bone) are explain by comparison with the results obtained by means of the simplified theoretical model. The simplified model was (establish) and justified on the basis of the structural analysis of the results obtained for exact model of the field scattering on complex structures. The simplified model is commonly used in description of the scattering on the regular structures like crystal. Comparison with experimental results for the trabecular bone is also presented. The results allowed to conclude that crystallographic methods could be potentially useful for extracting characteristic features of trabecular bone.

Keywords:
Multi scattering, Random structures

4p.
57.Litniewski J., Klimonda Z., Nowicki A., The Synthetic Aperture technique for tissue attenuation imaging, Annual Report - Polish Academy of Sciences, ISSN: 1640-3754, pp.65-67, 2011
Litniewski J., Klimonda Z., Nowicki A., The Synthetic Aperture technique for tissue attenuation imaging, Annual Report - Polish Academy of Sciences, ISSN: 1640-3754, pp.65-67, 2011

Abstract:
The mean frequency correlation estimator and SSA technique were implemented for processing of the RF ultrasonic echoes. The estimated attenuation values were equal to 0.7 and 0.9 dB/(MHz∙cm) and agreed well with the real values. We have found the RF data obtained using synthetic aperture technique (SA) to be much more reliable in terms of attenuation extraction then echoes recorded using the standard delay and sum (DAS) beamforming. The imaging of attenuation in tissue seems to be a promising technique in medical diagnostics, although the precision of a single scan is often unsatisfactory.

Keywords:
tissue attenuation imaging, sythetic aperture focusing technique

58.Trots I., Tasinkevych Y, Nowicki A., Lewandowski M., Multi-Element Synthetic Transmit Aperture Method in Medical Ultrasound Imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.80, pp.562-567, 2011
Trots I., Tasinkevych Y, Nowicki A., Lewandowski M., Multi-Element Synthetic Transmit Aperture Method in Medical Ultrasound Imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.80, pp.562-567, 2011

Abstract:
The paper presents the multi-element synthetic transmit aperture (MSTA) method with a small number of elements transmitting and all elements receiving apertures in medical ultrasound imaging. Compared to other methods the MSTA allows to increase the system frame rate and provides the best compromise between penetration depth and lateral resolution.
In the experiments a 128-element linear transducer array with 0.3 mm inter-element spacing and a burst pulse of 125 ns duration were used. The comparison of 2D ultrasound images of tissue mimicking phantom obtained using the STA and the MSTA methods is presented to demonstrate the benefits of the second method. The obtained results were performed using SA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:
beamforming, frame rate, synthetic aperture, ultrasound imaging

59.Karwat P., Klimonda Z., Seklewski M., Lewandowski M., Nowicki A., Data reduction method for synthetic transmit aperture algorithm, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.635-642, 2010
Karwat P., Klimonda Z., Seklewski M., Lewandowski M., Nowicki A., Data reduction method for synthetic transmit aperture algorithm, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.635-642, 2010

Abstract:
Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method. Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation. A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease. The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.

Keywords:
ultrasonic imaging, synthetic transmit aperture, data reduction, effective aperture, reciprocity

9p.
60.Secomski W., Nowicki A., Wójcik J., Lewandowski M., Walczak M., Tymkiewicz R., Annular array transducer and matched amplifier for therapeutic ultrasound, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/v10168-010-0049-6, Vol.35, No.4, pp.653-660, 2010
Secomski W., Nowicki A., Wójcik J., Lewandowski M., Walczak M., Tymkiewicz R., Annular array transducer and matched amplifier for therapeutic ultrasound, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/v10168-010-0049-6, Vol.35, No.4, pp.653-660, 2010

Abstract:
The use of therapeutic ultrasound continues to grow. A focused ultrasonic wave can increase the tissue temperature locally for the non-invasive cancer treatment or other medical applications. The authors have designed a seven-element annular array transducer operating at 2.4 MHz. Each element was excited by sine burst supplied by a linear amplifier and FPGA control circuits. The acoustic field, generated by a transducer was initially numerically simulated in a computer and next compared to water tank hydrophone measurements performed at 20, 40 and 60 mm focal depth. The results showed good agreement of the measurements with theory and the possibility to focus the ultrasound in the preselected area. The total acoustic power radiated by the annular array was equal to 2.4W.

Keywords:
ultrasonic therapy, annular array transducer, ultrasonic field

9p.
61.Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multi-element synthetic transmit aperture in medical ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.687-699, 2010
Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multi-element synthetic transmit aperture in medical ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.687-699, 2010

Abstract:
Synthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data. The paper presents the multi-element STA (MSTA) method for medical ultrasound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property. In the experiments a 32-element linear transducer array with 0.48 mm interelement spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.

Keywords:
ultrasound imaging, synthetic aperture, beamforming

9p.
62.Wójcik J., Litniewski J., Nowicki A., Example of structure modeling and analysis of ultrasound scattering for trabecular bone, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.701-713, 2010
Wójcik J., Litniewski J., Nowicki A., Example of structure modeling and analysis of ultrasound scattering for trabecular bone, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.701-713, 2010

Abstract:
A trabecular bone consists of trabeculae whose mechanical properties differ significantly from the surrounding marrow, therefore an ultrasonic wave propagating within the bone structure is strongly scattered. The aim of this paper was to evaluate the contribution of the first, second and higher order scattering (multiple scattering) into the total scattering of ultrasound in a trabecular bone. The scattering due to the interconnections between thick trabeculae, usually neglected in trabecular bone models, has been also studied. The basic element in our model of the trabecular bone was an elastic cylinder with a various finite-length and diameter as well as orientation. The applied model was taking into account variation of both, elements size and their spatial configuration. The field scattered on the bone model was evaluated by solving numerically the integral form of the generalized Sturm-Liouville equation describing a scalar wave in inhomogeneous and lossy media. For the scattered fields calculated numerically the effective cross-sections were determined. The influence of absorption on the scattering coefficients was demonstrated. The results allowed to conclude that within the frequency range from 0.5 to 1.5 MHz contribution of the second order scattering to the effective backscattering cross-section is at least 500 times lower than that due to the first order scattering. It was noticed that for a frequency higher than 1.5 MHz fast growth of the backscattering (reflection) coefficients, calculated for the second order scattering, occurs.

Keywords:
multi-scattering, random complex structures, trabecular bone model

9p.
63.Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique – preliminary results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.643-652, 2010
Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique – preliminary results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.643-652, 2010

Abstract:
The pathological states of biological tissue are often resulted in attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently develop ing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion, is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the extraction of mean frequency trends. These trends were converted into atten uation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom (DFS, Denmark) with uniform echogenicity while attenuation coefficient underwent variation.

Keywords:
ultrasound attenuation estimation, spatial compounding, parametric imaging

9p.
64.Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: comparison of different schemes of synthetic aperture technique in ultrasonic imaging, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.243-252, 2010
Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: comparison of different schemes of synthetic aperture technique in ultrasonic imaging, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.243-252, 2010

Abstract:
The Synthetic Aperture (SA) methods are widespread and successfully used in radar technology, as well as in the sonar systems. The advantages of high framerate and its relatively good resolution in the whole area of scanning, make this technique an object of interest in medical imaging methods such as ultrasonography (US). This paper describes the possible usage of the SA method in ultrasound imaging. The introduction to the principles of the SA technique in ultrasonography is presented. The measurements of different SA schemes were conducted using the set-up consisting of the research ultrasonograph module, the PC and the special wire phantom. The results for different schemes of image reconstruction are presented. Particularly the Synthetic Transmit Aperture (STA) technique was concerned. Results of the STA method are discussed in this paper.

Keywords:
synthetic aperture focusing technique, ultrasonic imaging

6p.
65.Piotrzkowska H., Litniewski J., Szymańska E., Lewandowski M., Nowicki A., Statistics of envelope of high frequency ultrasound signal backscattered in human dermis, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.205-214, 2010
Piotrzkowska H., Litniewski J., Szymańska E., Lewandowski M., Nowicki A., Statistics of envelope of high frequency ultrasound signal backscattered in human dermis, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.205-214, 2010

Abstract:
The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in tissue. In these study K distribution of the ultrasound backscatter envelope was used to assess the structural properties of the skin tissue. The custom-designed high frequency ultrasonic scanner was applied to obtain RF B-scans of the skin in vivo at the frequency of 20-30MHz.
The results are encouraging. The K distribution models the envelope statistics very well. The parameters of the K-distribution, namely, the effective number of scatterers may be useful for the skin characterization.

Keywords:
skin characterization, ultrasound, K distribution

6p.
66.Kujawska T., Wójcik J., Nowicki A., Temperature fields induced in rat liver in vitro by pulsed low intensity focused ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.153-162, 2010
Kujawska T., Wójcik J., Nowicki A., Temperature fields induced in rat liver in vitro by pulsed low intensity focused ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.153-162, 2010

Abstract:
Beneficial biological effects in soft tissues can be induced by focused ultrasound of low intensity (LIFU). For example, increasing of cells immunity to stress can be accomplished through the enhanced heat shock proteins (Hsp) expression induced by the low intensity focused ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo can be the potential new therapeutic approach to neurodegenerative diseases that utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting the level of exposure to ultrasound energy would allow evaluating of ultrasound-mediated treatment efficiency. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced in multilayer nonlinear attenuating media by a circular focused transducer generating pulsed acoustic waves and to compare the results calculated for two-layer configuration of media: water - fresh rat liver with the experimental data. The measurements of temperature variations versus time at 5 points on the acoustic beam axis within the tissue sample were performed using 0.2-mm diameter thermocouples. Temperature fields were induced by the transducer with 15-mm diameter, 25-mm focal length and 2-MHz centre frequency generating tone bursts with the intensity ISPTA varied between 0.45 W/cm2 and 1.7 W/cm2 and duration varied between 20 and 500 cycles at the same 20-% duty cycle and 20-min exposure time. Quantitative analysis of the obtained results allowed to show that, for example, for the acoustic beam with intensity ISPTA = 1.13 W/cm2 exposure time to ultrasound should not be longer than 10 min to avoid cells necrosis following the 43-oC temperature threshold exceeding.

Keywords:
low intensity focused ultrasound, soft tissues, temperature fields, ultrasonic regimes, therapy efficiency

6p.
67.Klimonda Z., Litniewski J., Nowicki A., Preliminary results of attenuation estimation from tissue backscatter using commercial ultrasonic scanner, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.127-134, 2010
Klimonda Z., Litniewski J., Nowicki A., Preliminary results of attenuation estimation from tissue backscatter using commercial ultrasonic scanner, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.127-134, 2010

Abstract:
Ultrasonography (USG) is a widespread and powerful tool used successfully in modern diagnostics. The standard USG scanner reflects impedance variations within the tissue that is penetrated by the ultrasound pulse. Although such image provides a lot of information to the physician, there are another parameters which could be imaged. The attenuation coefficient is one of them. Imaging of attenuation seems to be a promising tool for ultrasonic medical diagnostics. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion is presented. The Doppler IQ technique is adopted to estimate the mean frequency changes directly from the raw RF data. The Singular Spectrum Analysis (SSA) technique is used for the mean frequency trend extraction. The changes of the mean frequency trend are related directly to the local attenuation coefficient. Preliminary results of the tissue phantom attenuation coefficient estimation and imaging using the commercial scanner are presented.

Keywords:
tissue attenuation imaging, ultrasound attenuation estimation

6p.
68.Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Evaluation of trabecular bone properties using ultrasonic scanner, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.39-52, 2010
Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Evaluation of trabecular bone properties using ultrasonic scanner, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.39-52, 2010

Abstract:
Signals scattered in trabecular bone contain information about properties of the bone structure. Evaluation of this properties may be essential for osteoporosis diagnosis and treatment monitoring because the standard densitometry does not provide complete information about the bone strength. It was previously demonstrated that using numerical model of backscattering in trabecular bone it is possible to estimate some microstructural characteristics of bone. Model predicts departures from the Rayleigh statistics of the scattered signal envelope depended on the scatterer physical parameters and its shape uniformity. This study concerns examination of trabecular bone (calcaneus) in vivo. Ultrasonic bone scanner operating at frequency of 1,5 MHz was used to collect backscattered signals. Data were processed in order to obtain the statistical properties of the signal envelope and to compare them with histograms resulting from modeling. This study is an approach towards developing a tool for the investigation of scattering in trabecular bone that can potentially provide clinically useful information about bone strength and condition.

Keywords:
bone structure, bone properties, calcaneus

6p.
69.Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture method in medical ultrasonic imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.64, pp.202-205, 2010
Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture method in medical ultrasonic imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.64, pp.202-205, 2010

Abstract:
The work describes the use of a synthetic transmit aperture (STA) with a single element transmitting and all elements receiving in medical ultrasound imaging. STA technique is a novel approach to today’s commercial systems, where an image is acquired sequentially one image line at a time that puts a strict limit on the frame rate and the amount of data needed for high image quality. The STA imaging allows to acquire data simultaneously from all directions over a number of emissions, and the full image can be reconstructed.
In experiments a 32-element linear transducer array with 0.48 mm inter-element spacing was used. Single element transmission aperture was used to generate a spherical wave covering the full image region. The 2D ultrasound images of wire phantom are presented obtained using the STA and commercial ultrasound scanner Antares to demonstrate the benefits of the SA imaging.

Keywords:
ultrasound imaging, synthetic aperture, frame rate, beamforming

70.Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of trabecular bone: Two scatterers’ population model, Physics Procedia, ISSN: 1875-3892, DOI: 10.1016/j.phpro.2010.01.089, Vol.3, pp.707-712, 2010
Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of trabecular bone: Two scatterers’ population model, Physics Procedia, ISSN: 1875-3892, DOI: 10.1016/j.phpro.2010.01.089, Vol.3, pp.707-712, 2010

Abstract:
The paper describes the computer simulations allowing investigating the properties of the ultrasound pulse-echo signal, as it is received on the transducer surface after scattering in trabecular bone. A novel computer simulation model provides better understanding of ultrasonic scattering in porous bone structure and it can be also used to yield an ideal environment in which, the effects of various parameters (scatterer mechanical and geometrical properties, scatterer’ concentration), the shape of incident wave and experimental conditions influencing the scattering of ultrasonic waves in trabecular bone structure can be examined individually. The results proved that the computer simulation has a particular relevance in studying scattering in cancellous bone which may be approximated as a collection of two populations of scatterers, cylindrical and spherical that imitate thick and thin trabeculae respectively.

Keywords:
bone modeling, scattering simulation, osteoporosis, trabecular bone

71.Kujawska T., Wójcik J., Nowicki A., Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experimental Results, AIP Conference Proceedings, ISSN: 0094-243X, DOI: 10.1063/1.3367179, Vol.1215, pp.353-358, 2010
Kujawska T., Wójcik J., Nowicki A., Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experimental Results, AIP Conference Proceedings, ISSN: 0094-243X, DOI: 10.1063/1.3367179, Vol.1215, pp.353-358, 2010

Abstract:
Recent research has shown that beneficial therapeutic effects in soft tissues can be induced by the low power ultrasound (LPUS). For example, increasing of cells immunity to stress can be accomplished through the heat shock proteins (Hsp) expression enhancement induced by the low intensity ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo by pulsed focused low power ultrasound may be the potential new therapeutic approach to the neuro-degenerative diseases that utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting the level and time of exposure to ultrasound energy would allow evaluating of the ultrasound-mediated treatment efficiency. Ultrasonic regimes are controlled by adjusting the pulsed ultrasound waves intensity, frequency, duration, duty cycle and exposure time. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced by a circular focused transducer generating tone bursts in multilayer nonlinear attenuating media and to compare the numerically calculated results with the experimental data obtained for soft tissues in vitro. The acoustic pressure field in multilayer biological media was calculated using our original numerical solver. For prediction of temperature fields the Pennes’ bio-heat transfer equation was employed. The measurements of temperature distributions along and across the acoustic beam axis were performed using the experimental facility containing the temperature-controlled 1% saline solution tank, the tested tissue sample immersed in the tank and the USB-TEMP module connected with 8 thermocouples positioned within the tissue sample along and across the acoustic axis. Temperature measurements in vitro were carried out in a fresh rat liver using the 15 mm diameter, 25 mm focal length and 2 MHz central frequency transducer generating tone bursts with the spatial peak temporal average acoustic intensity varied between 0.325 and 1.95 W/cm2, duration varied from 20 to 500 cycles at the same 20 % duty cycle and the exposure time varied up to 20 minutes. The measurement data were compared with numerical simulation results obtained under experimental boundary conditions. Good agreement between the theoretical and measurement results for all cases considered has verified the validity and accuracy of our numerical model. The accuracy of the proposed model most of all depends on the accuracy of the source pressure measurements, estimation of tissues attenuation coefficients and their frequency-dependence law as well as determination of the tissue thermal conductivity. The measurement results confirmed that for pulses considered the temperature rise induced in tissue depends on the duty cycle, not on the tone burst duration. Quantitative analysis of the obtained results allowed to show that, for example, for the acoustic intensity ISPTA = 1.1 W/cm2 (P0 = 0.184 MPa) exposure time of the fresh rat liver should not exceed 10 min to avoid cells necrosis (T > 43 oC).

Keywords:
low intensity focused ultrasound, soft tissues, temperature fields, ultrasonic regimes, therapy efficiency

72.Secomski W., Nowicki A., Tortoli P., Olszewski R., Multigate Doppler measurements of ultrasonic attenuation and blood hematocrit in human arteries, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2008.08.009, Vol.35, No.2, pp.230-236, 2009
Secomski W., Nowicki A., Tortoli P., Olszewski R., Multigate Doppler measurements of ultrasonic attenuation and blood hematocrit in human arteries, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2008.08.009, Vol.35, No.2, pp.230-236, 2009

Abstract:
A clinically applicable method for noninvasive measurement of hematocrit based on 20 MHz multigate Doppler ultrasound was developed. The ultrasound attenuation coefficient in blood is obtained by measuring the power of the signal coming from gates at different depths. A robust averaging method is introduced, which provides stable and repeatable results by using the echo signals from all depths inside the vessel. In vitro measurements have been done on porcine blood with hematocrit ranging from 3.0% to 65.0%. Steady and pulsatile flow conditions have been simulated using a peristaltic pump. The attenuation coefficient indicated the linear relation to hematocrit. The resulting correlation coefficient was R=0.999 for the continuous blood flow and R=0.992 for pulsatile flow. In vivo measurements have been performed in the brachial artery in 43 patients with hematocrit in the range of 32.0% to 49.3%. The mean absolute error has been 3.24% with a standard deviation of 3.72%.

Keywords:
blood, hematocrit, Doppler, ultrasonic attenuation

32p.
73.Litniewski J., Nowicki A., Lewin P.A., Semi-empirical bone model for determination of trabecular structure properties from backscattered ultrasound, Ultrasonics, ISSN: 0041-624X, Vol.49, pp.505-513, 200927p.
74.Nowicki A., Wójcik J., Kujawska T., Nonlinearly coded signals for harmonic imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.1, pp.63-74, 2009
Nowicki A., Wójcik J., Kujawska T., Nonlinearly coded signals for harmonic imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.1, pp.63-74, 2009

Abstract:
In this paper a new method utilizing nonlinear properties of tissues to improve contrast-to-noise ratio is presented. In our novel method the focused circular transducer is excited with two-tone bursts (including the 2.2 MHz fundamental and 4.4 MHz second harmonic frequencies) with specially coded polarization of each tone. This new approach was named Multitone Nonlinear Coding (MNC) because the choice of both tones polarization and amplitude law, allowing optimization of the probe receiving properties, depends on nonlinear properties of tissue. The numerical simulations of nonlinear fields in water and in tissue-like medium with absorption coefficient of 7 Np/(m•MHz) are performed. The comparison between the proposed method and the Pulse Inverse (PI) method is presented. The concept of the virtual fields was introduced to explain properties of both the Pulse Inversion and MNC methods and to compare their abilities. It was shown that for the same on-source pressure an application of the MNC method allows to decrease the mechanical index about 40 % , to improve lateral resolution from 10 to 30 % and to gain the signal-to-noise ratio up to 8 times with respect to the PI method.

Keywords:
harmonic imaging, ultrasonography, nonlinear propagation

9p.
75.Gambin B., Kujawska T., Kruglenko E., Mizera A., Nowicki A., Temperature fields induced by low power focused ultrasound during gene therapy. Numerical predictions and experimental results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.445-460, 2009
Gambin B., Kujawska T., Kruglenko E., Mizera A., Nowicki A., Temperature fields induced by low power focused ultrasound during gene therapy. Numerical predictions and experimental results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.445-460, 2009

Abstract:
The aim of this work is twofold. Firstly, to verify a theoretical model which is capable of predicting temperature fields appearing in soft tissues during their ultrasound treatment. Secondly, to analyze some aspects of the dynamics of Heat Shock Response induced by the heating process in the context of therapeutic treatment. The theoretical investigations and quantitive analysis of temperature increments at any field point versus time of heating process, depending on the heat source power, spatial distribution and duration as well as on the tissue thermal properties, has been carried out by Finite Element Method (FEM). The validation of the numerical model has been performed by comparison of the calculation results with the experimental data obtained by measuring in vitro of the 3D temperature increments induced in samples of the turkey and veal liver by the circular focused transducer with the diameter of 15 mm, focal length of 25 mm and resonance frequency of 2 MHz. Various ultrasonic regimes were considered. They were controlled by adjusting ultrasound power and exposure time. The heat shock proteins (HSP) and misfolded proteins (MFP) levels during the proposed cyclic sonification are presented.

Keywords:
heat-responsive gene therapy, temperature field, low-power focused ultrasound, soft tissues, ultrasonic regime control, heat sources distribution, heat shock proteins

9p.
76.Klimonda Z., Litniewski J., Nowicki A., Spatial resolution of attenuation imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.461-470, 2009
Klimonda Z., Litniewski J., Nowicki A., Spatial resolution of attenuation imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.461-470, 2009

Abstract:
The attenuating properties of biological tissue are of great importance in ultrasonic examination even though its anatomical variability limits diagnostics effectiveness. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The diagnostic usefulness of the proposed technique crucially depends on the precision of the attenuation estimate and the resolution of the parametric image. These two parameters are highly correlated, since the resolution is reduced whenever averaging is used to minimize the errors introduced by the random character of the backscatter. Here we report on the results of numerical processing of both, simulated and recorded from a tissue-mimicking phantom echoes. We have analyzed the parameters of the estimation technique and examined their influence on the precision of the attenuation estimate and on the parametric image resolution. The optimal selection of attenuation image parameters depending on its intended diagnostic use, was also considered.

Keywords:
ultrasound attenuation, spatial resolution, parametric imaging

9p.
77.Piotrzkowska H., Litniewski J., Lewandowski M., Szymańska E., Nowicki A., Use of quantitative ultrasound to measure acoustic properties of human skin, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.471-480, 2009
Piotrzkowska H., Litniewski J., Lewandowski M., Szymańska E., Nowicki A., Use of quantitative ultrasound to measure acoustic properties of human skin, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.471-480, 2009

Abstract:
The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in the tissue. The spectrum of the ultrasonic backscatter can be used to characterize non-invasively the structural and mechanical properties of tissue. We intend to apply the custom-designed high-frequency ultrasonic scanner for the skin and cutaneous lesions characterization by evaluating their attenuating and scattering properties. In this pilot study, we have explored the possibility of extracting the human skin backscattering coefficient (BC) from the ultrasonic B-scans obtained in vivo at 20–30 MHz. The measured BC values of normal skin (dermis) agree well with the published data. We have found also that the spatial resolution of the BC determination using our scanner is sufficient (aprox. 1 mm2) to characterize small skin lesions and assess their penetration depth.

Keywords:
attenuation coefficient, backscattering coefficient, dermis

9p.
78.Karwat P., Nowicki A., Lewandowski M., Blood scattering model for pulsed doppler, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.677-685, 2009
Karwat P., Nowicki A., Lewandowski M., Blood scattering model for pulsed doppler, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.677-685, 2009

Abstract:
The subject of this paper is a new software simulating ultrasound signal scattered on moving blood cells during Doppler examination of blood flow velocity using pulsed technique. Generated data are used for optimization and validation of Doppler signals processing algorithms.
The algorithm is based on the finite elements method FEM. A rigorous set of postulates which simplifies physics of modeled phenomenon enables to quicken the program significantly while preserving important properties (from application point of view) of generated signal.
The paper includes description of Doppler RF signal generation algorithm. The simplifying postulates are listed together with resulting signal fidelity degradation. Finally generated raw data is presented together with its Doppler Audio and Color processed version.
The signal processing results enable to reconstruct correctly the velocity profile and its time dependence. The results clearly confirm that the data generated by the algorithm are suitable for Doppler signals processing.

Keywords:
RF signal simulation, scattering on blood cells, pulsed Doppler

9p.
79.Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.685-695, 2009
Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.685-695, 2009

Abstract:
The paper describes the use of synthetic transmit aperture (STA) imaging in medical ultrasound. The synthetic aperture (SA) imaging is a novel approach to today's commercial systems. In these systems the image is acquired sequentially one image line at a time that puts a strict limit on the frame rate and the possibility of acquiring a sufficient amount of data for high image quality. This limitation can be lifted by employing SA imaging where the data are acquired simultaneously from all directions over a number of emissions, and the full image can be reconstructed from those data. Due to the complete data set, it is possible to have full transmitting and receiving focusing at the entire image region to improve the contrast dynamic and spatial resolution. The paper describes the STA imaging with a single element transmitting and all elements receiving apertures. In experiments, 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100ns duration were used. The single element transmission aperture was used to generate a spherical wave covering the full image region. The 2D ultrasound images of wire phantom are presented to demonstrate the benefits of SA imaging.

Keywords:
ultrasound imaging, synthetic aperture, beamforming

9p.
80.Wójcik J., Litniewski J., Nowicki A., Multiple scattering contribution to trabecular bone backscatter, HYDROACOUSTICS, ISSN: 1642-1817, Vol.12, pp.227-236, 2009
Wójcik J., Litniewski J., Nowicki A., Multiple scattering contribution to trabecular bone backscatter, HYDROACOUSTICS, ISSN: 1642-1817, Vol.12, pp.227-236, 2009

Abstract:
Integral equations that describe scattering on the structure with step like abruptly changing physical parameters, have been numerically solved on example of the trabecular bone model. The model consists of several hundred elements with randomly selected parameters. The spectral distribution of scatter coefficients in subsequent orders - first second and third- of scattering has been presented.

Keywords:
Multiple scattering in absorbing medium, Complex random structure, Back scatter coefficients

6p.
81.Kujawska T., Wójcik J., Nowicki A., Numerical modeling of ultrasound-induced temperature fields in multilayer nonlinear attenuating media, HYDROACOUSTICS, ISSN: 1642-1817, Vol.12, pp.91-98, 2009
Kujawska T., Wójcik J., Nowicki A., Numerical modeling of ultrasound-induced temperature fields in multilayer nonlinear attenuating media, HYDROACOUSTICS, ISSN: 1642-1817, Vol.12, pp.91-98, 2009

Abstract:
Ultrasound is safe, convinient and inexpensive modality which may be useful for soft tissues treatment. A range of beneficial biological effects induced by ultrasound depends on the exposure level used during treatment. At high intensities instantaneous tissue necrosis is desired, whereas at lower intensities remedial reversible cellular effects may be produced. For example, increasing of cell immunity against stress can be obtained through the heat shock proteins (Hsp) expression enhancement. The possibility of the Hsp expression enhancement in soft tissues in vivo by means of controlled exposure to ultrasound would allow to evaluate the treatment efficiency. Ultrasonic regimes can be controlled by adjusting the ultrasound intensity, frequency, pulse duration, duty-cycle and exposure time. The goal of this work was to develop the numerical model capable of predicting in space and time the temperature fields induced by circular focused transducer generating tone bursts in multilayer nonlinear attenuating media, which is intended for the Hsp expression enhancement therapeutic applications. The acoustic pulsed pressure field generated by the transducer was calculated using our original 3D numerical solver [1]. For prediction of the temperature distributions in multilayer biological media the Pennes bio-heat transfer equation was solved numerically. The 3D thermal fields induced in a rat liver in vitro by a 2 MHz transducer of 15-mm diameter and 25-mm focal length during ultrasonic Hsp expression enhancement treatment using various acoustic beam intensities and exposure time was predicted.

Keywords:
multilayer biological media, ultrasound exposure parameters, local thermal fields, numerical prediction

6p.
82.Lewandowski M., Nowicki A., High frequency coded imaging system with RF software signal processing, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2008.871, Vol.55, No.8, pp.1878-1882, 2008
Lewandowski M., Nowicki A., High frequency coded imaging system with RF software signal processing, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2008.871, Vol.55, No.8, pp.1878-1882, 2008

Abstract:
Coded transmission is an approach to solve the inherent compromise between penetration and resolution required in ultrasound imaging. Our goal was to examine the applicability of the coded excitation to HF (20–35MHz) ultrasound imaging. A novel real-time imaging system for research and evaluation of the coded transmission was developed. The digital programmable coder-digitizer module based on the field programmable gate array (FPGA) chip supports arbitrary waveform coded transmission and RF echoes sampling up to 200MSPS, as well as real-time streaming of digitized RF data via a high speed USB interface to the PC. All RF and image data processing was implemented in the software. A novel balanced software architecture supports real-time processing and display at rates up to 30 frames/sec. The system was used to acquire quantitative data for sine burst and 16-bit Golay code excitation at 20MHz fundamental frequency. SNR gain close to 14 dB was obtained. The example of the skin scan clearly shows the extended penetration and improved contrast when 35MHz Golay code is used. The presented system is a practical and low cost implementation of coded excitation technique in HF ultrasound imaging that can be used as a research tool as well as to be introduced into production.

Keywords:
high frequency ultrasound, coded transmission, pulse compression, RF signal processing

83.Wójcik J., Kujawska T., Nowicki A., Lewin P.A., Fast prediction of pulsed nonlinear acoustic fields from clinically relevant sources using time averaged wave envelope approach: comparison of numerical simulations and experimental results, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2008.03.013, Vol.48, pp.707-715, 2008
Wójcik J., Kujawska T., Nowicki A., Lewin P.A., Fast prediction of pulsed nonlinear acoustic fields from clinically relevant sources using time averaged wave envelope approach: comparison of numerical simulations and experimental results, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2008.03.013, Vol.48, pp.707-715, 2008

Abstract:
The primary goal of this work was to verify experimentally the applicability of the recently introduced time-averaged wave envelope (TAWE) method as a tool for fast prediction of four dimensional (4D) pulsed nonlinear pressure fields from arbitrarily shaped acoustic sources in attenuating media. The experiments were performed in water at the fundamental frequency of 2.8 MHz for spherically focused (focal length F = 80 mm) square (20mm x 20 mm) and rectangular (10mm x 25 mm) sources similar to those used in the design of 1D linear arrays operating with ultrasonic imaging systems. The experimental results obtained with 10-cycle tone bursts at three different excitation levels corresponding to linear, moderately nonlinear and highly nonlinear propagation conditions (0.045, 0.225 and 0.45 MPa on-source pressure amplitude, respectively) were compared with those yielded using the TAWE approach. The comparison of the experimental results and numerical simulations has shown that the TAWE approach is well suited to predict (to within ± 1 dB) both, the spatial–temporal and spatial–spectral pressure variations in the pulsed nonlinear acoustic beams. The obtained results indicated that implementation of the TAWE approach enabled shortening of computation time in comparison with the time needed for prediction of the full 4D pulsed nonlinear acoustic fields using a conventional (Fourier-series) approach. The reduction in computation time depends on several parameters, including the source geometry, dimensions, fundamental resonance frequency, excitation level as well as the strength of the medium nonlinearity. For the non-axisymmetric focused transducers mentioned above and excited by a tone burst corresponding to moderately nonlinear and highly nonlinear conditions the execution time of computations was 3 and 12h, respectively, when using a 1.5 GHz clock frequency, 32-bit processor PC laptop with 2 GB RAM memory, only. Such prediction of the full 4D pulsed field is not possible when using conventional, Fourier-series scheme as it would require increasing the RAM memory by at least 2 orders of magnitude.

Keywords:
rectangular focused apertures, pulsed acoustic fields, nonlinear distortion, numerical modelling and experiments

84.Dynowski K., Litniewski J., Nowicki A., Scanning acoustic microscope for 3D imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.3, pp.293-302, 2008
Dynowski K., Litniewski J., Nowicki A., Scanning acoustic microscope for 3D imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.3, pp.293-302, 2008

Abstract:
A new Acoustic Microscope operating at the frequency up to 200 MHz and allowing for visualization of the internal structures of materials was developed. The system was built basing on the commercially available components and the self-designed acoustic lenses. The dedicated software was developed to control the process of 3D RF-data acquisition, processing and presenting in 2D cross-sections or 3D surface rendering mode. This article describes the technical principles of the constructed microscope and presents the reconstructed images of the designed test-probe and of the integrated circuit.

Keywords:
Acoustic Microscopy, SAM, 3D imaging, rendering, subsurface imaging

85.Wójcik J., Kujawska T., Nowicki A., Pulsed nonlinear acoustic fields from clinically relevant sources: numerical calculations and experiments results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.565-572, 2008
Wójcik J., Kujawska T., Nowicki A., Pulsed nonlinear acoustic fields from clinically relevant sources: numerical calculations and experiments results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.565-572, 2008

Abstract:
The goal of this work was to verify experimentally the applicability of the recently developed Time-Averaged Wave Envelope (TAWE) method [1] as a tool for fast prediction of pulsed nonlinear pressure fields from focused nonaxisymmetric acoustic sources in attenuating media. The experiments were performed in water at the fundamental frequency of 2.8 MHz for spherically focused (focal length F = 80 mm) square (20 x 20 mm) and rectangular (10 x 25 mm) sources similar to those used in the design of 1D linear arrays operating with ultrasonic imaging systems. The experimental results obtained with 10-cycle tone bursts at three different excitation levels corresponding to linear, moderately nonlinear and highly nonlinear propagation conditions (0.045, 0.225 and 0.45 MPa on-source pressure amplitude, respectively) were compared with those yielded using the TAWE approach. Comparison of the experimental and numerical calculations results has shown that the TAWE approach is well suited to predict (to within ± 1 dB) both the spatial-temporal and spatial-spectral pressure variations in the pulsed nonlinear acoustic beams.

Keywords:
rectangular focused apertures, pulsed acoustic fields, nonlinear distortion, numerical modelling

86.Trots I., Nowicki A., Lewandowski M., Laboratory setup for synthetic aperture ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.573-580, 2008
Trots I., Nowicki A., Lewandowski M., Laboratory setup for synthetic aperture ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.573-580, 2008

Abstract:
The paper describes the synthetic transmit aperture (STA) imaging system with a single element transmitting and multi-element reception in medical ultrasound. Synthetic aperture method allows to achieve high electronic signal-to-noise ratio and good contrast resolution. A laboratory setup for acquisition of RF signals from linear transducer array was built. Simulated multichannel acquisition by multiplexing individual transducer was performed. In experiments 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse with time duration 100 ns was used. Single element in the transducer transmitting aperture was used to generate a spherical wave covering the full image region. The echo signals were sampled independently by individual elements for each transmission. The comparison of 2D ultrasound images of wire phantom obtained using STA method and standard linear array scanning with commercial ultrasonograph is given. The results show excellent image resolution of the STA method and its robustness to refraction, attenuation and multiple reflection of ultrasound waves.

Keywords:
ultrasound imaging, synthetic aperture, contrast resolution

87.Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., Double pulse transmission - signal to noise ratio improvement in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.593-601, 2008
Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., Double pulse transmission - signal to noise ratio improvement in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.593-601, 2008

Abstract:
This study investigates a new composing method of double transmission of short coded sequences based on well-known Golay complementary codes, which allow to obtain the higher signal-to-noise ratio (SNR) and increase penetration depth. The proposed method can potentially find application in small parts ultrasonography and play important role in examination of superficial structures, e.g. in dermatology, ophthalmology, etc., where using longer coded sequences leads to increase of a dead zone and single pulse transmission of short sequences does not assure sufficient SNR. This paper discusses the comparison of results obtained during the examination of four different lengths pairs of Golay coded sequences excited at 3.7 MHz: the single 64-bits pair of Golay sequences and combined sequences consisting of two 8-, 16-, and 32-bits Golay codes separated in time. The experimental results have shown that using the double pulse transmission allows to suppress considerably the noise level, the SNR increases by 5.7 dB in comparison with the single pulse transmission of Golay sequences of the same length. The results of this work indicate that double pulse transmission enhances SNR while maintaining the dead zone short.

Keywords:
Golay complementary sequences, double pulse transmission, dead zone

88.Secomski W., Trots I., Nowicki A., Golay code excitation of ultrasonic transducers with different backing, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4S, pp.21-26, 2008
Secomski W., Trots I., Nowicki A., Golay code excitation of ultrasonic transducers with different backing, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4S, pp.21-26, 2008

Abstract:
Two 3.7 MHz focused ultrasonic transducers were built. One without backing and the second loaded on back. The primary application of the first transducer is Doppler blood flow measuring ultrasonic devices, the second is most useful for the B-mode imaging devices. The electrical and acoustical properties were tested and finally the results of the different Golay code excitations were compared. Efficiency of the not backed transducer was 4.1 dB higher. The not backed transducer performed maximum sensitivity for 8 bit two periods per bit code excitation. The backed transducer achieved maximum axial resolution for 16 bit one period per bit excitation.

Keywords:
ultrasonic transducers, imaging, backing, coded excitation, Golay codes

89.Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., The influence of the transducer bandwidth and double pulse transmission on the encoded imaging ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.11, pp.419-430, 2008
Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., The influence of the transducer bandwidth and double pulse transmission on the encoded imaging ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.11, pp.419-430, 2008

Abstract:
An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compressed echo signal being the complementary Golay sequences (CGS) with different spectral widths is studied in this paper. Also, a new composing transmission method of CGS is discussed together with compression technique applied in order to increase the signal-to-noise ratio (SNR) and penetration.
The CGS with two different bit lengths, one-cycle and two-cycles are investigated. Two transducers with fractional bandwidth of 25% and 80% at centre frequency 6 MHz are used. The experimental results are presented, clearly proofing that increasing of the code length leads to compressed echo amplitude enhancement. The smaller the bandwidth is the larger is this effect; the pulse-echo sensitivity of the echo amplitude increases by 1.88 for 25% fractional bandwidth and 1.47 for 80% while preserving time resolution. The presented results of double transmission of short codes show the penetration and SNR improvement while maintaining dead zone.

Keywords:
ultrasound, transducer, bandwidth, Golay code

90.Litniewski J., Nowicki A., Klimonda Z., Lewandowski M., Sound fields for coded excitations in water and tissue, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, Vol.33, No.4, pp.601-607, 2007
Litniewski J., Nowicki A., Klimonda Z., Lewandowski M., Sound fields for coded excitations in water and tissue, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, Vol.33, No.4, pp.601-607, 2007

Abstract:
Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties, particularly increased penetration depth and signal-to-noise ratio (SNR). However, no data on the spatial behavior of the pressure field generated by coded bursts transmissions in the tissue were yet reported. This paper reports the results of investigations of the field structure in water, in degassed beef liver and in pork tissue using four different excitations signals, two and 16 periods sine bursts and sinusoidal sequences with phase modulation using 13-bits Barker code and 16-bits Golay complementary codes. The results of measured pressure field distributions before and after compression were compared with those recorded using short pulse excitation.

Keywords:
Coded excitation, Ultrasound field distribution, Matching filtering

91.Nowicki A., Wójcik J., Secomski W., Harmonic imaging using multitone nonlinear coding, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2007.02.001, Vol.33, No.7, pp.1112-1122, 2007
Nowicki A., Wójcik J., Secomski W., Harmonic imaging using multitone nonlinear coding, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2007.02.001, Vol.33, No.7, pp.1112-1122, 2007

Abstract:
We present a new method that uses nonlinear properties of tissue to improve contrast-to-noise ratio.
In our novel method, the acoustic source is activated with two tone-bursts (2.2 and 4.4 MHz), with specially designed polarization of the individual tone-burst. This new approach is called multitone nonlinear coding (MNC) because the choice of polarization of both tones (and their amplitudes), allowing optimization of the receiving properties, depends on the nonlinear properties of tissue. The calculations were done for two tone-bursts propagating in the tissue-like glossy medium with absorption of 7 Np/m · MHz. The method was experimentally verified by scanning the incident pulses propagating in soft tissue and by scanning the thread phantom immersed in water. The concept of the virtual fields was introduced to explain abilities and properties of pulse inversion and MNC and to compare the two methods. Comparison of the spatial field distribution obtained using MNC with the conventional harmonic imaging approach, in which the second harmonic is used to reconstruct the image, is presented. It was shown that, for the same peak pressure amplitude, the resulting mechanical index was about 40% lower for MNC, lateral resolution was 10% to 30% better and, what seems to be the most encouraging, the signal gain was up to eight times higher than pulse inversion.

Keywords:
harmonic imaging, ultrasonography, nonlinear propagation

92.Nowicki A., Trots I., Lewin P.A., Secomski W., Tymkiewicz R., Influence of the ultrasound transducer bandwidth on selection of the complementary Golay bit code length, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2007.07.003, Vol.47, pp.64-73, 2007
Nowicki A., Trots I., Lewin P.A., Secomski W., Tymkiewicz R., Influence of the ultrasound transducer bandwidth on selection of the complementary Golay bit code length, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2007.07.003, Vol.47, pp.64-73, 2007

Abstract:
In contrast to previously published papers [A. Nowicki, Z. Klimonda, M. Lewandowski, J. Litniewski, P.A. Lewin, I. Trots, Comparison of sound fields generated by different coded excitations – Experimental results, Ultrasonics 44 (1) (2006) 121–129; J. Litniewski, A. Nowicki, Z. Klimonda, M. Lewandowski, Sound fields for coded excitations in water and tissue: experimental approach, Ultrasound Med. Biol. 33 (4) (2007) 601–607], which examined the factors influencing the spatial resolution of coded complementary Golay sequences (CGS), this paper investigates the effect of ultrasound imaging transducer’s fractional bandwidth on the gain of the compressed echo signal for different spectral widths of the CGS. Two different bit lengths were considered, specifically one and two cycles. Three transducers having fractional bandwidth of 25%, 58% and 80% and operating at frequencies 6, 4.4 and 6 MHz, respectively were examined (one of the 6 MHz sources was focused and made of composite material). The experimental results have shown that by increasing the code length, i.e. decreasing the bandwidth, the compressed echo amplitude could be enhanced. The smaller the bandwidth was the larger was the gain; the pulse-echo sensitivity of the echo amplitude increased by 1.88, 1.62 and 1.47, for 25%, 58% and 80% bandwidths, respectively. These results indicate that two cycles bit length excitation is more suitable for use with bandwidth limited commercially available imaging transducers. Further, the time resolution is retained for transducers with two cycles excitation providing the fractional bandwidth is lower than approximately 90%. The results of this work also show that adjusting the code length allows signal-to-noise-ratio (SNR) to be enhanced while using limited (less that 80%) bandwidth imaging transducers. Also, for such bandwidth limited transducers two cycles excitation would not decrease the time resolution, obtained with ‘‘conventional’’ spike excitation. Hence, CGS excitation could be successfully implemented with the existing, relatively narrow band imaging transducers without the need to use usually more expensive wideband, composite ones.

Keywords:
ultrasound imaging, transducer bandwidth, complementary Golay sequences

93.Trots I., Nowicki A., Secomski W., Tymkiewicz R., The influence of the transducer bandwidth on the efficient Golay codes compression, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.101-110, 2007
Trots I., Nowicki A., Secomski W., Tymkiewicz R., The influence of the transducer bandwidth on the efficient Golay codes compression, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.101-110, 2007

Abstract:
The maximization of penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. To solve this problem a pulse compression technique employing long coded sequences is now under intensive investigation and in fact some of the corresponding techniques were already implemented in commercial scanning machines. This paper investigates the influence of the effective bandwidth of the transducer on the behaviour of the encoding/compression technique and its potential influence on the axial resolution. We have investigated two different bits lengths – one and two periods – in the Golay sequences resulting in substantial difference of the bandwidth of the transmitted sequences. Three transducers with different fractional bandwidths were used in the experiments: 6 MHz focused transducer with 25% fractional bandwidth, 4.4 MHz flat transducer with 58% fractional bandwidth and 6 MHz flat, composite transducer with 80% fractional bandwidth. The experimental results are clearly showing that the elongation of the Golay single bit length (two cycles in our case) compensates for the limited transducer bandwidth. For 25% bandwidth peak-to-peak echo increased by 1.89 times; for 58% bandwidth peak-to-peak echo amplitude increased by 1.62 times, and for 80% bandwidth peak-to-peak echo increased by 1.47 times.

Keywords:
ultrasound imaging, transducer bandwidth, Golay complementary sequences

94.Dynowski K., Litniewski J., Nowicki A., Three-dimensional imaging in ultrasonic microscopy, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.71-77, 2007
Dynowski K., Litniewski J., Nowicki A., Three-dimensional imaging in ultrasonic microscopy, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.71-77, 2007

Abstract:
Advances in modern technology increases requirements for nondestructive characterization of material and biological properties in the μm range. The acoustic microscope presented in this paper combines C-scan and B-scan modes. The data collected during single XY scan allow to present transversal and horizontal crosssections of the sample as well as real three-dimensional images of the sample interior. The system consist of several components: step motor driven mechanical scanner, transmitter/ receiver device, ADC 1 GHz board, ultrasonic heads, PC-class computer and image processing and visualization software. Image processing software is used for initial 3D image analysis of the whole image or its fragments, and for preparing it this way for vectorization. To achieve vectorization we used VTK (Visualization Tool Kit) library from Kitware Inc., which is the open source software, designed for 3D graphics and image processing. Finally iso-surface is constructed and presented as 3D scene in interactive GUI (Graphical User Interface).

Keywords:
3D visualization, microscope, ultrasound

95.Klimonda Z., Nowicki A., Imaging of the mean frequency of the ultrasonic echoes, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.77-80, 2007
Klimonda Z., Nowicki A., Imaging of the mean frequency of the ultrasonic echoes, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.77-80, 2007

Abstract:
A standard USG image is in fact a visualization of a distribution of the reflexion coefficients. There is an increasing interest in imaging of the different parameters, which might characterize another physical properties of a tissue. The attenuation coefficient is one of such parameters and theoretically it can be estimated using frequency shift of the RF signal. The frequency shift results from dispersive character of the attenuation in tissue and is a function of attenuation along the propagate path. In this work authors use echo’s mean frequency as an imaging modality. The results of measurement of tissue phantom using 10 MHz linear array are presented. The preliminary results are encouraging being the first attempt towards mapping of the attenuation in tissue.

Keywords:
parametric visualization, mean frequency, attenuation estimation

96.Lewandowski M., Nowicki A., Universal coded ultrasound imaging system with software processing, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.81-86, 2007
Lewandowski M., Nowicki A., Universal coded ultrasound imaging system with software processing, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.81-86, 2007

Abstract:
Coded transmission is a technique to solve the inherent compromise between penetration and resolution required in ultrasound imaging. Our aim was to examine the performance of the coded excitation in HF (20–35 MHz) ultrasound imaging. For this purpose a novel realtime imaging system has been developed. The digital programmable coder-digitizer module supports arbitrary coded waveform generation and RF echoes sampling up to 200 MSPS. All digital RF and image processing was implemented in software. The system performance was evaluated with a single thick-film transducer (focused 25 MHz, 75% bandwidth) scanning head. The RF echoes were acquired from a perfect reflector located with 1 cm of tissue mimicking material. Single sinus burst and 16-bits Golay codes excitations were evaluated. SNR gain for the Golay codes (referenced to single burst) of 15 dB for 20 MHz and 16 dB for 35 MHz were obtained. The axial resolution measured at half maximum was 35 ns for 20 MHz and 25 ns for 35 MHz for both single burst and the Golay codes. It clearly shows that the Golay codes can perfectly restore the resolution while giving respectable SNR gain.

Keywords:
medical imaging, coded excitation, high frequency ultrasound, digital signal processing

97.Trots I., Nowicki A., Influence of transducer bandwidth on compressed ultrasonic echoes, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.903-915, 2007
Trots I., Nowicki A., Influence of transducer bandwidth on compressed ultrasonic echoes, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.903-915, 2007

Abstract:
The aim of this work is to explore and analyze the influence of the transducer bandwidth on the compressed echoes resulted from the Golay complementary codes transmission. For that reason, a computer simulation and experimental verification were performed that reflected the influence of the transducer bandwidth on the distortion of a signal. This study helps to elucidate why the echoes ringing is present for narrow bandwidth transducers. As known, the shape and symmetry of the pulse waveform and its interaction with the transducer bandwidth and its tuning circuitry have a profound effect on the pulse echo performance achievable from a medical scanning probe. The computer simulation was performed using the Matlab software for different fractional transducer bandwidths - from wideband transducers of 100% (ideal case), 90%, 75% to narrowband ones of 50% and 25%. The 16-bits Golay complementary sequences at nominal frequency of 1 MHz were used to illustrate the transducer bandwidth influence on the resulted signal. It was shown that the decreasing of the transducer bandwidth results in a considerable drop of the amplitude of the compressed echoes from 20.1 V for the 90% fractional bandwidth down to: 17.1 V, 12.5 V and 6.6 V for 75%, 50% and 25% bandwidths, respectively. The widths of the compressed echoes were widening at the same time from 708 ns up to 2.38 μs reducing the axial resolution from about 1 mm to over 3.6 mm. In the experiments, two transducers with different fractional bandwidths of 70% and 35% and nominal frequencies of 4.8 MHz and 6 MHz, respectively, were used.

Keywords:
transducer, signal analysis, distortion, filtering, Golay sequences

98.Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A., Trots I., Comparison of sound fields generated by different coded excitations experimental results, Ultrasonics, ISSN: 0041-624X, Vol.44, pp.121-129, 2006
Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A., Trots I., Comparison of sound fields generated by different coded excitations experimental results, Ultrasonics, ISSN: 0041-624X, Vol.44, pp.121-129, 2006

Abstract:
This work reports the results of measurements of spatial distributions of ultrasound fields obtained from five energizing schemes. Three different codes, namely, chirp signal and two sinusoidal sequences were investigated. The sequences were phase modulated with 13 bits Barker code and 16 bits Golay complementary codes. Moreover, two reference signals generated as two and sixteen cycle sine tone bursts were examined. Planar, 50% (fractional) bandwidth, 15 mm diameter source transducer operating at 2 MHz center frequency was used in all measurements. The experimental data were collected using computerized scanning system and recorded using wideband, PVDF membrane hydrophone (Sonora 804). The measured echoes were compressed, so the complete pressure field in the investigated location before and after compression could be compared. In addition to a priori anticipated increase in the signal to noise ratio (SNR) for the decoded pressure fields, the results indicated differences in the pressure amplitude levels, directivity patterns, and the axial distance at which the maximum pressure amplitude was recorded. It was found that the directivity patterns of non-compressed fields exhibited shapes similar to the patterns characteristic for sinusoidal excitation having relatively long time duration. In contrast, the patterns corresponding to compressed fields resembled those produced by brief, wideband pulses. This was particularly visible in the case of binary sequences. The location of the maximum pressure amplitude measured in the 2 MHz field shifted towards the source by 15 mm and 25 mm for Barker code and Golay code, respectively. The results of this work may be applicable in the development of new coded excitation schemes. They could also be helpful in optimizing the design of imaging transducers employed in ultrasound systems designed for coded excitation. Finally, they could shed additional light on the relationship between the spatial field distribution and achievable image quality and in this way facilitate optimization of the images obtained using coded systems.

Keywords:
coded excitation, sound fields

99.Wójcik J., Nowicki A., Lewin P.A., Bloomfield P.E., Kujawska T., Filipczyński L., Wave envelopes method for description of nonlinear acoustic wave propagation, Ultrasonics, ISSN: 0041-624X, Vol.44, pp.310-339, 2006
Wójcik J., Nowicki A., Lewin P.A., Bloomfield P.E., Kujawska T., Filipczyński L., Wave envelopes method for description of nonlinear acoustic wave propagation, Ultrasonics, ISSN: 0041-624X, Vol.44, pp.310-339, 2006

Abstract:
A novel, free from paraxial approximation and computationally efficient numerical algorithm capable of predicting 4D acoustic fields in lossy and nonlinear media from arbitrary shaped sources (relevant to probes used in medical ultrasonic imaging and therapeutic systems) is described. The new WE (wave envelopes) approach to nonlinear propagation modeling is based on the solution of the second order nonlinear differential wave equation reported in [J. Wojcik, J. Acoust. Soc. Am. 104 (1998) 2654-2663; V.P. Kuznetsov, Akust. Zh. 16 (1970) 548-553]. An incremental stepping scheme allows for forward wave propagation. The operator-splitting method accounts independently for the effects of full diffraction, absorption and nonlinear interactions of harmonics. The WE method represents the propagating pulsed acoustic wave as a superposition of wavelet-like sinusoidal pulses with carrier frequencies being the harmonics of the boundary tone burst disturbance. The model is valid for lossy media, arbitrarily shaped plane and focused sources, accounts for the effects of diffraction and can be applied to continuous as well as to pulsed waves. Depending on the source geometry, level of nonlinearity and frequency bandwidth, in comparison with the conventional approach the Time-Averaged Wave Envelopes (TAWE) method shortens computational time of the full 4D nonlinear field calculation by at least an order of magnitude; thus, predictions of nonlinear beam propagation from complex sources (such as phased arrays) can be available within 30-60 min using only a standard PC. The approximateratio between the computational time costs obtained by using the TAWE method and the conventional approach in calculations of the nonlinear interactions is proportional to (1/N)**2, and in memory consumption to 1/N where N is the average bandwidth of the individual wavelets. Numerical computations comparing the spatial field distributions obtained by using both the TAWE method and the conventional approach (based on a Fourier series representation of the propagating wave) are given for circular source geometry, which represents the most challenging case from the computational time point of view. For two cases, short (2 cycle) and long (8 cycle) 2 MHz bursts, the computational times were 10 min and 15 min versus 2 h and 8 h for the TAWE method versus the conventional method, respectively.

Keywords:
Nonliear propagation, Envelope waves, Fast calculations

100.Pong M., Umchid S., Guarino A.J., Lewin P.A., Litniewski J., Nowicki A., Wrenn S.P., In vitro ultrasound-mediated leakage from phospholipid vesicles, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2006.07.021, Vol.45, pp.133-145, 2006
Pong M., Umchid S., Guarino A.J., Lewin P.A., Litniewski J., Nowicki A., Wrenn S.P., In vitro ultrasound-mediated leakage from phospholipid vesicles, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2006.07.021, Vol.45, pp.133-145, 2006

Keywords:
ultrasound exposure, therapcutic ultrasound, membraue pcrmeability, giant vesicles

101.Trots I., Nowicki A., Lewandowski M., Litniewski J., Secomski W., Golay complementary codes, double pulse repetition frequency transmission, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.31, pp.35-40, 2006
Trots I., Nowicki A., Lewandowski M., Litniewski J., Secomski W., Golay complementary codes, double pulse repetition frequency transmission, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.31, pp.35-40, 2006

Abstract:
This study concerns the development and investigation of a new composing method of short coded sequences and their transmission based on well-known Golay complementary codes and applied compression technique allowing to increase the signal-to-noise ratio (SNR) and penetration. This new method can potentially play important role in examination of superficial structures, e.g. dermatology, ophthalmology, etc. This paper reports the results of examination of the two pairs 3.5 MHz coded sequences of the same duration: the single 32-bits pair Golay sequences and combined sequences consisting of two 16-bits Golay codes separated in time. The results clearly demonstrate the potential of the combined coded transmission obtaining the SNR = 22.6 dB that is 2.6 dB higher than for the traditional Golay sequences and it is in case when coded length is two times shorter. For obtaining the same SNR using traditional method the code length should be at least 64 bits long, resulting in the increased dead zone up to 1.4 cm.

Keywords:
Golay complementary sequences, double transmission, dead zone

102.Klimonda Z., Lewandowski M., Nowicki A., Trots I., Lewin P.A., Direct and post-compressed sound fields for different coded excitations - experimental results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.30, No.4, pp.507-514, 2005
Klimonda Z., Lewandowski M., Nowicki A., Trots I., Lewin P.A., Direct and post-compressed sound fields for different coded excitations - experimental results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.30, No.4, pp.507-514, 2005

Abstract:
Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties: increased depth penetration, signal-to-noise ratio (SNR) gain and improved axial resolution. However, no data concerning the spatial behavior of the pressure field generated by coded bursts transmissions were reported so far. Five different excitation schemes were investigated. Flat, circular transducer with 15 mm diameter, 2 MHz center frequency and 50% bandwidth was used. The experimental data was recorded using the PVDF membrane hydrophone and collected with computerized scanning system developed in our laboratory. The results of measured pressure fields before and after compression were then compared to those recorded using standard ultrasonographic short-pulse excitation. The increase in the SNR of the decoded pressure fields is observed. The modification of the spatial pressure field distribution, especially in the intensity and shape of the sidelobes is apparent. Coded sequences are relatively long and, intuitively, the beam shape could be expected to be very similar to the sound field of long-period sine burst. This is true for non-compressed distributions of examined signals. However, as will be shown, the compressed sound fields, especially for the measured binary sequences, are similar rather to field distributions of short, wideband bursts.

Keywords:
coded excitation, ultrasonic field distribution, pulse compression, matched filtration, medical imaging

103.Secomski W., Nowicki A., Guidi F., Tortoli P., Lewin P.A., Non-invasive measurement of blood hematocrit in artery, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, Vol.53, No.3, pp.245-250, 2005
Secomski W., Nowicki A., Guidi F., Tortoli P., Lewin P.A., Non-invasive measurement of blood hematocrit in artery, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, Vol.53, No.3, pp.245-250, 2005

Abstract:
Objective:
The goal of this work was to develop a clinically applicable method for non-invasive acoustic determination of hematocrit in vivo.

Methods:
The value of hematocrit (HCT) was determined initially in vitro from the pulse-echo measurements of acoustic attenuation. The testing was carried out using a laboratory setup with ultrasound transducer operating at 20 MHz and employing human blood samples at the temperature of 37C. The attenuation coefficient measurements in blood in vitro and in vivo were implemented using multi-gated (128-gates), 20 MHz pulse Doppler flow meter. The Doppler signal was recorded in the brachial artery. Both in vitro and in vivo HCT data were compared with those obtained using widely accepted, conventional centrifuge method.

Results:
The attenuation coefficient in vitro was determined from the measurements of 168 samples with hematocrit varying between 23.9 and 51.6%. Those experiments indicated that the coefficient increased linearly with hematocrit. The HCT value was obtained from the 20 MHz data using regression analysis. The attenuation (() was determined as a 42.14 + 1.02*HCT (Np/m). The corresponding standard deviation (SD), and the correlation coefficient were calculated as SD = 2.4 Np/m, and R = 0.9, (p<0.001), respectively The absolute accuracy of in vivo measurements in the brachial artery was determined to be within 5% HCT.

Conclusions:
The method proposed appears to be promising for in vivo determination of hematocrit as 5% error is adequate to monitor changes in patients in shock or during dialysis. It was found that the multigate system largely simplified the placement of an ultrasonic probing beam in the center of the blood vessel. Current work focuses on enhancing the method’s applicability to arbitrary selected vessels and reducing the HCT measurement error to well below 5%.

Keywords:
hematocrit, blood, Doppler, power Doppler, multigate Doppler

104.Kujawska T., Wójcik J., Nowicki A., Nonlinear ultrasound propagation in water from square focused transducer, HYDROACOUSTICS, ISSN: 1642-1817, Vol.8, pp.89-98, 2005
Kujawska T., Wójcik J., Nowicki A., Nonlinear ultrasound propagation in water from square focused transducer, HYDROACOUSTICS, ISSN: 1642-1817, Vol.8, pp.89-98, 2005

Abstract:
The nonlinear pulsed acoustic pressure field from a focused square aperture is considered. Experimental measurements in water of a 4D sound field radiated from a 2.8 MHz focused square transducer of a 20 mm side and a 80 mm focal distance for excitation level producing an average acoustic pressure P0 = 0.14 MPa at its surface are presented. The obtained results are compared with the numerical calculation results for the same boundary conditions. The novel, free from paraxial approximation and computationally efficient numerical algorithm was used to simulate the 4D nonlinear pulsed pressure field from the nonaxisymmetric acoustic source. Our theoretical model was based on the Time-Averaged Pressure Envelope (TAPE) method recently developed that enable to represent the propagated pulsed disturbance as a superposition of sinusoidal wavelets with carrier frequencies being the harmonics of the initial tone burst and with envelopes determined by the TAPE method. The novel approach to the solution of the nonlinear wave equation enabled to simulate full 4D nonlinear field for given boundary conditions in a dozen or so minutes utilizing the computational power of the standard PC.

Keywords:
square spherically focused transducer, pulsed waves, nonlinear propagation in water, sound fields, numerical modelling

105.Nowicki A., Litniewski J., Secomski W., Trots I., Lewandowski M., Tymkiewicz R., Coded ultrasonography, Annual Report - Polish Academy of Sciences, ISSN: 1640-3754, pp.56-57, 2005
106.Radulescu E.G., Lewin P.A., Wójcik J., Nowicki A., Berger W.A., The influence of finite aperture and frequency response of ultrasonic hydrophone probes On the determination of acoustic output, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2003.11.019, Vol.42, No.1-9, pp.367-372, 2004
Radulescu E.G., Lewin P.A., Wójcik J., Nowicki A., Berger W.A., The influence of finite aperture and frequency response of ultrasonic hydrophone probes On the determination of acoustic output, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2003.11.019, Vol.42, No.1-9, pp.367-372, 2004

Abstract:
The influence of finite aperture and frequency response of piezoelectric ultrasonic hydrophone probes on the Thermal and Mechanical Indices was investigated using a comprehensive acoustic wave propagation model. The experimental verification of the model was obtained using a commercially available, 8 MHz, dynamically focused linear array and a single element, 5 MHz, focused rectangular source. The pressure–time waveforms were recorded using piezoelectric polymer hydrophone probes of different active element diameters and bandwidths. The nominal diameters of the probes ranged from 50 to 500 μm and their usable bandwidths varied between 55 and 100 MHz. The Pulse Intensity Integral (PII), used to calculate the Thermal Index (TI), was found to increase with increasing bandwidth and decreasing effective aperture of the probes. The Mechanical Index (MI), another safety indicator, was also affected, but to a lesser extent. The corrections needed were predicted using the model and successfully reduced the discrepancy as large as 30% in the determination of PII. The results of this work indicate that by accounting for hydrophones' finite aperture and correcting the value of PII, all intensities derived from the PII can be corrected for spatial averaging error. The results also point out that a caution should be exercised when comparing acoustic output data. In particular, hydrophone's frequency characteristics of the effective diameter and sensitivity are needed to correctly determine the MI, TI, and the total acoustic output power produced by an imaging transducer.

Keywords:
Ultrasound imaging, Nonlinear propagation, Spatial averaging, Safety indices

107.Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003
Radulescu E., Wójcik J., Lewin P.A., Nowicki A., Nonlinear Propagation Model for Ultrasound Hydrophones Calibration in Frequency Range up to 100 MHz, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00124-0, Vol.41, No.4, pp.239-245, 2003

Abstract:
To facilitate the implementation and verification of the new ultrasound hydrophone calibration techniques described in the companion paper (somewhere in this issue) a nonlinear propagation model was developed. A brief outline of the theoretical considerations is presented and the model’s advantages and disadvantages are discussed. The results of simulations yielding spatial and temporal acoustic pressure amplitude are also presented and compared with those obtained using KZK and Field II models. Excellent agreement between all models is evidenced. The applicability of the model in discrete wideband calibration of hydrophones is documented in the companion paper somewhere in this volume.

Keywords:
Nonlinear propagation modeling, Nonlinear propagation, JW model

108.Radulescu E., Lewin P.A., Wójcik J., Nowicki A., Calibration of Ultrasonic Hydrophone Probes up to 100 MHz using Time Gating Frequency Analysis and Finite Amplitude Wave, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00123-9, Vol.41, No.4, pp.247-254, 2003
Radulescu E., Lewin P.A., Wójcik J., Nowicki A., Calibration of Ultrasonic Hydrophone Probes up to 100 MHz using Time Gating Frequency Analysis and Finite Amplitude Wave, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/S0041-624X(03)00123-9, Vol.41, No.4, pp.247-254, 2003

Abstract:
A number of ultrasound imaging systems employs harmonic imaging to optimize the trade off between resolution and penetration depth and center frequencies as high as 15 MHz are now used in clinical practice. However, currently available measurement tools are not fully adequate to characterize the acoustic output of such nonlinear systems primarily due to the limited knowledge of the frequency responses beyond 20 MHz of the available piezoelectric hydrophone probes. In addition, ultrasound hydrophone probes need to be calibrated to eight times the center frequency of the imaging transducer. Time delay spectrometry (TDS) is capable of providing transduction factor of the probes beyond 20 MHz, however its use is in practice limited to 40 MHz. This paper describes a novel approach termed time gating frequency analysis (TGFA) that provides the transduction factor of the hydrophone probes in the frequency domain and significantly extends the quasi-continuous calibration of the probes up to 60 MHz. The verification of the TGFA data was performed using TDS calibration technique (up to 40 MHz) and a nonlinear calibration method (up to 100 MHz). The nonlinear technique was based on a novel wave propagation model capable of predicting the true pressure–time waveforms at virtually any point in the field. The spatial averaging effects introduced by the finite aperture hydrophones were also accounted for. TGFA calibration results were obtained for different PVDF probes, including needle and membrane designs with nominal diameters from 50 to 500 μm. The results were compared with discrete calibration data obtained from an independent national laboratory and the overall uncertainty was determined to be ±1.5 dB in the frequency range 40–60 MHz and less than ±1 dB below 40 MHz.

Keywords:
Time gating frequency analysis (TGFA), Time delay spectrometry (TDS), High frequency hydrophone calibration, Nonlinear hydrophone calibration, High frequency ultrasound, Ultrasonic metrology

109.Wójcik J., Trots I., Lewandowski M., Nowicki A., Formulation of anisotropic failure criteria incorporating a microstructure tensor, COMPUTERS AND GEOTECHNICS, ISSN: 0266-352X, DOI: 10.1016/S0266-352X(99)00034-8, Vol.26, No.2, pp.105-112, 2000
Wójcik J., Trots I., Lewandowski M., Nowicki A., Formulation of anisotropic failure criteria incorporating a microstructure tensor, COMPUTERS AND GEOTECHNICS, ISSN: 0266-352X, DOI: 10.1016/S0266-352X(99)00034-8, Vol.26, No.2, pp.105-112, 2000

Abstract:
Anisotropy is inherently related to microstructural arrangement within a representative volume of material. The microstructure can be represented by a second order tensor whose eigenvectors specify the orientation of the axes of material symmetry. In this paper, failure criteria for geomaterials are formulated in terms of the stress state and a microstructure tensor. The classical criteria for isotropic materials are generalized for the case of orthotropy as well as transverse isotropy. The proposed approach is illustrated by a simple example demonstrating the sensitivity of the uniaxial strength of the material to the orientation of the sample relative to the loading direction.

110.Nowicki A., Secomski W., Wójcik J., Acoustic streaming: Comparison of low amplitude linear model with streaming velocities measured by means of 32 MHz doppler, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(97)00005-7, Vol.23, No.5, pp.783-791, 1997
Nowicki A., Secomski W., Wójcik J., Acoustic streaming: Comparison of low amplitude linear model with streaming velocities measured by means of 32 MHz doppler, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/S0301-5629(97)00005-7, Vol.23, No.5, pp.783-791, 1997

Abstract:
The pressure gradient along the ultrasonic beam results in medium streaming. Following Nyborg's analysis of the Navier-Stokes equation, Wu and Du developed an approximate solution for the streaming velocity generated by flat and weakly focused transducers. We have modified their solution of the Poisson equation by directly deriving the Dirichlet boundary conditions to be applied for this type of equation. Our numerical results (for the linear case) were about one half smaller for flat and weakly focused Gaussian beam transducers compared to the results by Wu and Du. The theoretical calculations were verified using a purpose-designed 32-MHz pulsed Doppler unit. The applied average acoustic power was changed from 1 μW to 6 mW, the burst width was 0.5 μs and the pulse repetition frequency was 32 kHz. The experiments were done on 4-mm-diameter flat and focused (focal distance = 8 and 12 mm) transducers. The streaming was measured along the ultrasonic beam from 0–20 mm; at all positions, the maximum Doppler frequency was estimated from the recorded spectra. Streaming was induced in a solution of water and corn starch. The experimental results showed that, for a given acoustic power, the streaming velocity was independent of the starch density in water changed from 0.3–40 g of starch in 1 l of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2–40 mm/s. Both the theoretical solutions for plane and focused waves and the experimental results were in good agreement.

Keywords:
Ultrasound, Streaming, Nonlinear ultrasound effects, Doppler

111.Nowicki A., Echografia dopplerowska, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.17, pp.1-186, 1985
112.Nowicki A., Ultradźwiękowe metody wizualizacji naczyń krwionośnych i przepływów krwi (Praca habilitacyjna), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.65, pp.1-89, 1979
113.Nowicki A., Borodziński K., Powałowski T., Impulsowy dopplerowski miernik przepływu krwi, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.72, pp.1-9, 1974
114.Powałowski T., Borodziński K., Nowicki A., Ocena pomiaru przepływu ciągłą metodą dopplerowską, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.72, pp.11-22, 1974
115.Borodziński K., Filipczyński L., Nowicki A., Powałowski T., Badania prędkości przepływu ultradźwiękową metodą wykorzystującą zjawisko Dopplera, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.40, pp.1-16, 1972
116.Filipczyński L., Nowicki A., Powałowski T., Kretowicz J., Starzyńska J., Badanie wpływu ultradźwięków promieniowanych przez detektor tętna na chromosomy człowieka w hodowli limfocytów, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.46, pp.1-24, 1972
117.Etienne J., Filipczyński L., Nowicki A., Powałowski T., Ultradźwiękowa metoda badania tętna na zasadzie zjawiska Dopplera, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.51, pp.1-17, 1970

Lista ostatnich monografii
1.
505
Nowicki A., ULTRASONOGRAFIA Wprowadzenie do obrazowania i metod dopplerowskich, Wydawnictwo Instytutu Podstawowych Problemów Techniki, PAN, Warszawa, pp.1-517, 2016
2.
15
Nowicki A., Ultradźwięki w medycynie, wprowadzenie do współczesnej ultrasonografii, IPPT PAN, Warszawa, pp.1-303, 2010
3.
120
Kotulski Z.A., Nowicki A., Szczepiński W., Wprowadzenie do teorii fal naprężeń i deformacji w zastosowaniach technicznych i do diagnostyki ultradźwiękowej, BEL Studio (Warszawa), pp.1-271, 2008
Lista rozdziałów w ostatnich monografiach
1.
352
Nowicki A., 50 lat Komitetu Akustyki Polskiej Akademii Nauk 1964-2014. Osiągnięcia i wydarzenia, rozdział: Polska szkoła ultrasonografii Zakładu Ultradźwięków IPPT PAN, Polska Akademia Nauk, Polskie Towarzystwo Akustyczne, Warszawa , pp.203-213, 2014
2.
320
Lewin P.A., Nowicki A., Ultrasonic transducers. Materials and design for sensors,actuators and medical applications, rozdział: Nonlinear acoustics and its application to biomedical ultrasonics, Woodhead Publishing Limited, 29, pp.517-544, 2013
3.
328
Lewandowski M., Walczak M., Karwat P., Nowicki A., Karłowicz P., Polskie protezy serca, opracowanie konstrukcji, badania kwalifikacyjne, przedkliniczne i kliniczne., rozdział: Wykonanie modelu i implementacja oprogramowania do ultradźwiękowego pomiaru przepływu krwi, FRK, Zabrze. Praca zbiorowa pod redakcją: Kustosz R., Gonsior M., Jarosz A., pp.3-21, 2013
4.
326
Nowicki A., Litniewski J., Trots I., Lewandowski M., Hydroacoustics of shallow water, rozdział: Encoded Ultrasound, Wydawnictwo Instytutu Podstawowych Problemów Techniki PAN, Warszawa, pp.181-208, 2013
5.
248
Piotrzkowska H., Litniewski J., Nowicki A., Szymańska E., Acoustical Imaging, rozdział: STATISTICAL PROPERTIES OF ECHOSIGNAL OBTAINED FROM HUMAN DERMIS IN VIVO, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.123-133, 2012
6.
261
Klimonda Z., Litniewski J., Nowicki A., Acoustical Imaging, rozdział: Enhancing tissue attenuation estimation from backscattered ultrasound using spatial compounding and synthetic aperture techniques, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.181-190, 2012
7.
263
Trots I., Tasinkevych Y., Nowicki A., Acoustical Imaging, rozdział: Coded Excitation with Directivity Correction in Synthetic Aperture Imaging System, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.157-167, 2012
8.
306
Tasinkevych Y., Klimonda Z., Lewandowski M., Nowicki A., Acoustical Imaging, rozdział: Sound Field Directivity Correction in Synthetic Aperture Algorithm for Medical Ultrasound, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.169-179, 2012
9.
308
Tasinkevych Y., Trots I., Nowicki A., Acoustical Imaging, rozdział: Optimization in the multi-element synthetic transmit aperture method for ultrasound imaging, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), pp.147-156, 2012
10.
62
Kujawska T., Wójcik J., Nowicki A., Acoustical Imaging, rozdział: Determination of B/A of Biological Media by Measuring and Modeling Nonlinear Distortion of Pulsed AcousticWave in Two-Layer System of Media, Springer, Michael P. André, Joie P. Jones and Hua Lee (Eds.), 30, pp.295-303, 2011
11.
254
Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Ultrasound Imaging, rozdział: Synthetic Aperture Method in Ultrasound Imaging, Masayuki Tanabe, pp.37-56, 2011
12.
307
Wójcik J., Litniewski J., Nowicki A., Acoustical Imaging, rozdział: Multiple Scattering Contribution to Trabecular Bone Backscatter, Springer, 30, pp.69-77, 2011
13.
311
Litniewski J., Klimonda Z., Nowicki A., Acoustical Imaging, rozdział: Applying Echoes Mean Frequency Shift for Attenuation Imaging in Tissue, Springer, 30, pp.97-103, 2011
14.
20
Nowicki A., Etienne J., Deputat J., Gubrynowicz R., Motylewski J., Ranachowski Z., Akustyka polska-wczoraj i dziś, rozdział: Instytut Podstawowych Problemów Techniki Polskiej Akademii Nauk, Centralny Instytut Ochrony Pracy-Państwowy Instytut Badawczy, pp.216-245, 2010
15.
21
Nowicki A., Akustyka polska-wczoraj i dziś, rozdział: Akustyka medyczna, Centralny Instytut Ochrony Pracy-Państwowy Instytut Badawczy, pp.379-386, 2010
16.
332
Kowalewski T.A., Nowicki A., Nauka Polska, jej potrzeby, organizacja i rozwój, rozdział: Instytut Podstawowych Problemów Techniki PAN. Główne kierunki badań i perspektywy rozwoju, Rocznik Kasy im. J. Mianowskiego, Fundacja Popierania Nauki, XIX (XLIV), pp.151-176, 2010
17.
126
Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A., Trots I., Acoustical imaging, rozdział: Direct and post-compressed sound fields for different coded excitations, Springer, André M.P. et al (Eds.), 28, pp.399-407, 2007
18.
135
Secomski W., Nowicki A., Tortoli P., Blood flow modelling and diagnostics, ABIOMED Lecture Notes 6, rozdział: Ultrasonic Doppler measurement of the attenuation, scattering and blood hematocrit in the human artery, IPPT PAN, ABIOMED (Warszawa), Kowalewski T.A. (Ed.), pp.427-438, 2005
19.
207
Litniewski J., Nowicki A., Dynowski K., Secomski W., Tissue remodelling, ABIOMED Lecture Notes 3, rozdział: Assessment of a trabecular bone status with high and low frequency ultrasounds, IPPT PAN, ABIOMED (Warszawa), Piekarski J. (Ed.), pp.173-188, 2005
Redaktor monografii
1.
266
Nowicki A., Litniewski J., Kujawska T., Acoustical Imaging, Springer, 31, pp.1-400, 2012

Prace konferencyjne
1.Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Olszewski R., Estimation of Flow Mediated Vasodilation of the Radial Artery, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0392, pp.1-4, 2015
Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Olszewski R., Estimation of Flow Mediated Vasodilation of the Radial Artery, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0392, pp.1-4, 2015

Abstract:
Preceding atherosclerosis is endothelial dysfunction. There is therefore interest in the application of non-invasive clinical tools to assess endothelial function. There are commercially available ultrasound scanners to measure flow-mediated vasodilatation (FMD) of the brachial artery using 10-12 MHz linear array probes, however the attainable precision in estimating the changes in artery dilation does not exceeds 0.2 mm, far beyond the required one. We have introduced a high frequency scanning schemes 25-35MHz encoded (Golay) wobbling type imaging without Doppler (uScan developed in our lab, thick film wide bandwidth transducer, 50 microns axial resolution) and 20 MHz ultrasound (Ultrasonix) with 20 MHz pulsed Doppler attached to the linear array. The FMD results were normalized using AUC of shear rate at the radial artery wall.

Keywords:
thick-film transducers, flow-mediated vasolidation, radial artery, shear rate

2.Byra M., Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Litniewski J., Correcting the influence of tissue attenuation on Nakagami distribution shape parameter estimation, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0408, pp.P1B6-3-4, 2015
Byra M., Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Litniewski J., Correcting the influence of tissue attenuation on Nakagami distribution shape parameter estimation, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0408, pp.P1B6-3-4, 2015

Abstract:
Nakagami distribution is used to model the statistical properties of backscattered echoes in tissue. The proper estimate requires the compensation of attenuation along each scanning line. Attenuation of the wave results in decreasing of the envelope mean intensity with depth what modifies the Nakagami scale parameter. This phenomenon violates the assumption that envelope samples within region of interest are identically distributed and disrupts estimation. Here, we investigate the influence of wave attenuation on Nakagami shape parameter estimators for various scattering scenarios, attenuation coefficients and region of interest size. Three methods are proposed to solve this issue. Scans of a thyroid and of a breast lesion are analyzed. It was found that proposed methods improved the estimation, especially when larger regions were used to collect envelope samples.

Keywords:
ultrasound, breast cancer, Nakagami distribution

3.Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Litniewski J., Byra M., Gambin B., Kruglenko E., Differentiation of normal tissue and tissue lesions using statistical properties of backscattered ultrasound in breast, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0417, pp.P1B6-15-4, 2015
Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Litniewski J., Byra M., Gambin B., Kruglenko E., Differentiation of normal tissue and tissue lesions using statistical properties of backscattered ultrasound in breast, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0417, pp.P1B6-15-4, 2015

Abstract:
The aim of the study was finding the relationship between BIRADS classification combined with envelope K and Nakagami statistics of the echoes backscattered in the breast tissue in vivo and the histological data. 107 breast lesions were examined. Both, the RF echo-signal and B-mode images from the lesions and surrounding tissue were recorded. The analysis method was based on the combining data from BIRADS classifications and both distributions parameters. 107 breasts lesions - 32 malignant and 75 benign - were examined. When only BIRADS classification was used all malignant lesions were diagnosed correctly, however 34 benign lesions were sent for the biopsy unnecessarily. For K distribution the sensitivity and specificity were 78.13%, and 86.67% while for Nakagami statistics the sensitivity and specificity were 62.50% and 93.33%, respectively. Combined K and BIRADS resulted in sensitivity of 96.67% and specificity 60%. Combined BIRADS (3/4a cut-off) plus Nakagami statistics showed 100% of sensitivity with specificity equal 57.33%, decreasing the number of lesions which were biopsied from 34 to 28.

Keywords:
breast cancer, quantitative ultrasound, BIRADS

4.Litniewski J., Piotrzkowska H., Nowicki A., Szymańska E., Statistics of envelope of Ultrasonic Backscatter from Basal Cell Carcinoma and Actinic Keratosis lesion, IUS 15, IEEE International Ultrasonics Symposium, 2014-09-03/09-06, Chicago (US), DOI: 10.1109/ULTSYM.2014.0474, pp.1908-1911, 2014
Litniewski J., Piotrzkowska H., Nowicki A., Szymańska E., Statistics of envelope of Ultrasonic Backscatter from Basal Cell Carcinoma and Actinic Keratosis lesion, IUS 15, IEEE International Ultrasonics Symposium, 2014-09-03/09-06, Chicago (US), DOI: 10.1109/ULTSYM.2014.0474, pp.1908-1911, 2014

Abstract:
Basal cell carcinoma is the most common cutaneous malignancy, representing 80% of all skin cancer cases. The quantitative ultrasound can provide information potentially helpful in diagnosing. The goal of this study was to find the quantitative measure of the skin tissue backscattering properties that could be used for differentiating the changes of tissue structure induced by Basal Cell Carcinoma (BCC) and precancerous lesions - Actinic Keratosis (AK). The study presents the results concerning the statistical properties of ultrasonic echoes scattered in cancer lesions and attenuation coefficient determined from the backscatter.

Keywords:
tissue characterization, quantitative ultrasound,skin lesions, statistical distribution, attenuation coefficient

5.Nowicki A., Byra M., Litniewski J., Wójcik J., Two Frequencies Push-Pull Differential Imaging, IUS 15, IEEE International Ultrasonics Symposium, 2014-09-03/09-06, Chicago (US), DOI: 10.1109/ULTSYM.2014.0175, pp.710-713, 2014
Nowicki A., Byra M., Litniewski J., Wójcik J., Two Frequencies Push-Pull Differential Imaging, IUS 15, IEEE International Ultrasonics Symposium, 2014-09-03/09-06, Chicago (US), DOI: 10.1109/ULTSYM.2014.0175, pp.710-713, 2014

Abstract:
Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing an approach based on simultaneous propagation of two waves being a combination of two pulses differing in pressure and frequency: a low frequency pulse is expected to change the local scattering properties of the tissue due to compression/rarefaction while a high frequency pulse is used for imaging. Two transmissions are performed for each scanning line. First, with the imaging pulse that propagates on maximum compression caused by a low frequency wave. Next, the low frequency wave is inverted and the imaging pulse propagates over the maximum rarefaction. After the processing of the subtracted echoes from subsequent transmissions including wavelet transform and band-pass filtering, differential images were reconstructed. The low frequency wave has a visible impact on the scattering properties of the tissue which can be observed on a differential image.

6.Klimonda Z., Litniewski J., Nowicki A., Compounded plane wave technique applied to imaging attenuation of ultrasound in tissue structures, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.SS27_1, pp.1-5, 2014
Klimonda Z., Litniewski J., Nowicki A., Compounded plane wave technique applied to imaging attenuation of ultrasound in tissue structures, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.SS27_1, pp.1-5, 2014

Abstract:
The parametric imaging can enhance ultrasonic examinations that are widely used in medical diagnostics. Attenuation of the wave propagating through the soft tissue reflects the state of the tissue, what is clearly demonstrated in literature. The visualization of the spatial distribution of attenuation may support the diagnosis by accurate discrimination of the lesions from normal tissue at the early stage of the disease. This research is focused on the developing of the method of attenuation estimation from ultrasonic backscatter. It would allow to produce the parametric images from the same data as the standard B-mode images. The attenuation estimation method bases on the spectral mean frequency (fm) downshift of the propagating pulse, that results from the frequency dependence of attenuation. The fm was determined (using fm correlation estimator and trend extraction with Single Spectrum Analysis algorithm) from the ultrasonic echoes scattered in the tissue mimicking phantom which contained a cylinder with the attenuation coefficient higher than in the background. The data acquisition were performed using ultrasonic scanner. The earlier research indicated the effectiveness of attenuation estimation method using the synthetic aperture technique to collect the data. The use of the synthetic transmit aperture scheme to acquire the data results in better attenuation imaging comparing to standard beamforming, however it lower the penetration depth. In this research the compounded plane wave transmit-receiving scheme was used, to improve the penetration range. Compensation for the diffraction effects was included in the data processing. The results indicate suitability of this approach for attenuation imaging. We can measure attenuation in the tissue mimicking materials with the spatial resolution of approximately 10mm and accuracy of 0.2dB/(MHz·cm). In the presentation, the attenuation images of tissue mimicking phantoms and the images of human liver, obtained in vivo, will be presented.

Keywords:
attenuation imaging, plane wave imaging

7.Piotrzkowska H., Nowicki A., Litniewski J., Gambin B., Dobruch-Sobczak K., Breast carcinoma tissues characterization using statistics of ultrasonic backscatter, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.SS27_7, pp.1-9, 2014
Piotrzkowska H., Nowicki A., Litniewski J., Gambin B., Dobruch-Sobczak K., Breast carcinoma tissues characterization using statistics of ultrasonic backscatter, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.SS27_7, pp.1-9, 2014

Abstract:
The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images together with appropriate RF echoes from the pathological and healthy breasts regions of patients with diagnosed malignant and benign breast lesions. The RF data were processed for the statistics of the backscattered echo signals assessment (K distribution and effective density of scatterers – M and Nakagami distribution and its shape parameter m). The comparison of signals recorded from malignant and healthy tissues showed, that in 80% of examined cases the values of the statistical parameters M were higher for carcinomas tissues than for healthy tissue. Beside of that in the case of benign lesions obtained results was able to distinguish the fibroadenoma from the other with probability of 75%.

Keywords:
quantitative ultrasound, breast cancer, statistics

8.Trawiński Z., Wójcik J., Nowicki A., Balcerzak A., Olszewski R., Frankowska E., Zegadło A., Rydzyński P., Evaluation of Left Ventricle Phantom by Ultrasound and Multislices Computer Tomography Imaging, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.R24_4, pp.1-5, 2014
Trawiński Z., Wójcik J., Nowicki A., Balcerzak A., Olszewski R., Frankowska E., Zegadło A., Rydzyński P., Evaluation of Left Ventricle Phantom by Ultrasound and Multislices Computer Tomography Imaging, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.R24_4, pp.1-5, 2014

Abstract:
The main goal of this study was to verify the suitability of sonographic model of the left ventricle (LV) in Computed Tomography (CT) environment and compare radial strain calculations obtained by two different techniques: speckle tracking ultrasonography and Multislices Computed Tomography (MSCT). The Left Ventricular (LF) phantom was fabricate from 10% solution of the poly(vinyl alcohol) (PVA). Our model of the LV was driven by the computer-controlled hydraulic piston Super-Pump (Vivitro Inc., Canada) with adjustable fluid volumes. During cycle of the pump, the Stroke Volume (SV) of water was pumped into the LV phantom and returned to the pump, resulting in changing the inner and outer diameters of the phantom. The stroke volume was set at of 24ml. The fluid pressure was changed within range of 0-60 mmHg, and the pulse rate was equal 60 cycles/per minute. The relationships between computer controlled left ventricular wall deformations and its visualizations of the echocardiographic and CT imaging, both in the normal and pathological conditions were examined. The difference of assessment the Radial Strain between two methods was not exceeding 1.1%.

9.Wójcik J., Trots I., Nowicki A., Lewandowski M., Cumulative method of image reconstruction in synthetic aperture - theory and experimental results, IUS 2013, IEEE International Ultrasonics Symposium, 2013-07-21/07-25, Praga (CZ), DOI: 10.1109/ULTSYM.2013.0528, Vol.1, pp.2068-2071, 2013
Wójcik J., Trots I., Nowicki A., Lewandowski M., Cumulative method of image reconstruction in synthetic aperture - theory and experimental results, IUS 2013, IEEE International Ultrasonics Symposium, 2013-07-21/07-25, Praga (CZ), DOI: 10.1109/ULTSYM.2013.0528, Vol.1, pp.2068-2071, 2013

Abstract:
The Synthetic Aperture (SA) method provides a new solution in ultrasound diagnostics. It has particular importance in applications where frame rate and image resolution are crucial. Our new approach named Cumulative Synthetic Transmit Aperture (CSTA) allows optimizing SA in terms of memory size and computational power. The proposed CSTA algorithm requires 25 times less memory than a reference STA method for 64 elements transducer. This makes feasible implementation of CSTA on a low-power embedded GPU.

Keywords:
ultrasonic imaging, synthetic aperture, GPU

10.Tasinkevych Y., Klimonda Z., Lewandowski M., Trots I., Nowicki A., Sound field directivity in multi-element synthetic transmit aperture method for ultrasound imaging, Conference on Medical Imaging - Physics of Medical Imaging, 2012-02-05/02-08, San Diego (US), DOI: 10.1117/12.910584, Vol.8313, pp.831369-1, 2012
Tasinkevych Y., Klimonda Z., Lewandowski M., Trots I., Nowicki A., Sound field directivity in multi-element synthetic transmit aperture method for ultrasound imaging, Conference on Medical Imaging - Physics of Medical Imaging, 2012-02-05/02-08, San Diego (US), DOI: 10.1117/12.910584, Vol.8313, pp.831369-1, 2012

Abstract:
A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity is presented. The property is significant as the element width becomes commensurable with the wavelength of the emitted signal. The angular dependence of the radiation efficiency of the transmit/receive aperture is obtained from exact solution of the corresponding mixed boundary-value problem for periodic baffle system, modeling the transducer array. It is evaluated at the nominal frequency of the excitation signal and is implemented in the developed MSTA algorithm as apodization weights calculated for each imaging point and all combinations of the transmit/receive apertures. The performance of developed method is tested using FIELDII simulated synthetic aperture data of the point reflectors to estimate the visualization depth and lateral resolution. Besides, a FIELDII simulated and measurement data of cyst phantom are used for qualitative assessment of the imaging contrast. Comparison of the results obtained by the modified and conventional MSTA algorithms is given which reveals considerable improvement of the image quality in the area neighboring to the transducer’s aperture, and increase of the visualization depth at the cost of slight degradation of lateral resolution near the transducer face.

Keywords:
synthetic aperture, ultrasound imaging, beamforming

11.Piotrzkowska H., Litniewski J., Nowicki A., Szymańska E., Basal Cell Carcinoma Lesions Characterization With Ultrasound, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0596, pp.1-6, 2012
Piotrzkowska H., Litniewski J., Nowicki A., Szymańska E., Basal Cell Carcinoma Lesions Characterization With Ultrasound, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0596, pp.1-6, 2012

Abstract:
Quantitative ultrasounds were applied for the detection and assessment of skin lesions. 30MHz ultrasonic scanner was used to collect B-scan images together with appropriate RF echoes from the pathological and healthy skin regions of skin of patients with diagnosed Basal Cell Carcinoma and precancerous states. The RF data were processed for the attenuation coefficient and statistics assessment (K distribution and effective number of scatterers – M). For patients with BCC the attenuation coefficient was significantly higher than for the healthy skin ones. Also, precancerous skin lesions revealed increased attenuation. The averaged M parameter for cancer lesions was significantly lower than for precancerous states and healthy skin. Similar results were obtained from numerical simulations of the ultrasonic echoes scattered in skin and skin lesions.

Keywords:
skin cancer, K distribution, effective number of scatterers, high frequency ultrasound

12.Litniewski J., Wójcik J., Nowicki A., Contribution of multiple scattering to the trabecular bone backscatter - dependence on porosity and frequency, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0650, pp.1-4, 2012
Litniewski J., Wójcik J., Nowicki A., Contribution of multiple scattering to the trabecular bone backscatter - dependence on porosity and frequency, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0650, pp.1-4, 2012

Abstract:
Scattering-based ultrasonic methods potentially enable assessment of microscopic structure of bone. In our previous study we have shown how to account the higher orders of scattering in the backscatter evaluation. Here, the role of multiple scattering in bone backscatter is assessed for the varying bone porosity. The set of integral equations corresponding to the singular Sturm–Liouville equation was solved numerically allowing for the calculation of the field scattered forward and backward in the bone model. The results indicate that for the porosities below 85% the approximation of the first order scattering is not valid for all considered frequencies. The Laue’s equations were applied to explain considerable increase of the scattering at some frequencies. It was shown that the deformation of trabecular mesh results in flattening of the scattering peaks

Keywords:
trabecular bone, ultrasounds scattering, multiple scattering

13.Klimonda Z., Litniewski J., Nowicki A., Correcting for bounded bandwidth when estimating tissue attenuation from mean frequency downshift, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0413, pp.1647-1650, 2012
Klimonda Z., Litniewski J., Nowicki A., Correcting for bounded bandwidth when estimating tissue attenuation from mean frequency downshift, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0413, pp.1647-1650, 2012

Abstract:
The attenuation of tissue can be estimated utilizing the downshift of the center frequency of a propagating pulse. In general it is assumed that the shape of the emitted pulse can be approximated by a Gaussian function and attenuation is assumed to change linearly with frequency. At this conditions the downshift of the mean frequency of pulse spectrum depends linearly on attenuation coefficient, pulse bandwidth and propagation distance. This is a good approximation for relatively narrowband pulses and small penetration depth. But for short pulses and deep penetration the frequency downshift is large and the ultrasonic pulse is no more Gaussian, thus the previous assumption is no longer correct. The closer is the mean frequency of the pulse to the lower frequency bound of the receiving system the bigger deformation of the pulse spectrum occurs and consequently the attenuation is determined with bigger error. The following paper presents how to correct the experimentally determined mean frequency and to obtain reliable results when investigating tissue attenuation with wideband pulses. We propose a new formula for the dependence between pulse mean frequency, tissue attenuation, pulse bandwidth and traveled distance. The formula was derived from the mean frequency of Gaussian pulse spectrum determined in the limited frequency band. The formula was applied to simulate variation of mean frequency MF of the pulse propagating in the medium with attenuation coefficient corresponding to the attenuation in the tissue mimicking phantom. The MF was also determined (using the correlation estimator of MF and next trend extraction using Single Spectrum Analysis) from the simulated ultrasonic echoes and echoes scattered in the tissue phantom. The corrected nonlinear formula describes well MF variation along the pulse propagation path. The departure from the linear dependence increases with large MF shift, thus it is well pronounced for highly attenuating tissue, the wideband pulses and deep penetration.

Keywords:
attenuation estimation, frequency downshift

14.Klimonda Z., Litniewski J., Karwat P., Secomski W., Nowicki A., Tissue attenuation imaging - Synthetic Aperture Focusing versus Spatial Compounding, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0590, pp.2361-2363, 2012
Klimonda Z., Litniewski J., Karwat P., Secomski W., Nowicki A., Tissue attenuation imaging - Synthetic Aperture Focusing versus Spatial Compounding, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0590, pp.2361-2363, 2012

Abstract:
The long term goal of this research is to develop the system enabling the imaging and quantitative measure of ultrasonic attenuation in tissue. It may support the diagnosis by accurate discrimination of the lesions from normal tissue at the early stage of the disease. The attenuation is estimated from the stochastic ultrasonic backscatter and time/spatial averaging is necessary to achieve reasonable accuracy. However the averaging worsens the spatial resolution. Two techniques of ultrasonic imaging, the Synthetic Aperture Focusing technique (SAFT) and Spatial Compounding (SC), were applied and compared with respect to the quality of attenuation estimation. The ultrasonic RF data were collected from a tissue mimicking phantom using ultrasonic scanner (Ultrasonix SonixTOUCH). Both acquired echoes-sets were processed in the same way in order to calculate the downshift in a mean frequency fm of the backscatter signal and resulting spatial distribution of attenuation coefficient. Compensation for the diffraction effects was included in the data processing. The RF data obtained with use of the SAFT proved to be more suitable for attenuation estimation.

Keywords:
tissue attenuation imaging, synthetic aperture, spatial compounding

15.Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Imaging Quality of the Classical Beamforming, SAFT and Plane Wave Imaging – Experimental Results, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0320, pp.1283-1286, 2012
Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Imaging Quality of the Classical Beamforming, SAFT and Plane Wave Imaging – Experimental Results, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0320, pp.1283-1286, 2012

Abstract:
The synthetic aperture focusing techniques (SAFT) are well known and widely deployed in radar techniques. Increasing processing power of modern computers allows effective implementation of various SAFT schemes in medical ultrasound systems with multi-element probes. The advance of the SAFT over the classical beamforming (BFR) is dynamic focusing in receive and transmit as well, which brings high resolution on every imaging point. We intend to develop the ultrasound imaging platform with some of the SAFT schemes implemented. The choice of the scheme must be preceded by examination of the imaging quality parameters. The results of the comparison of different SAFT schemes with conventional beamforming are presented in the paper. The results indicate that SAFT schemes can work better than BFR scheme. For example, for some point located near the center of the image the full width at half maximum (FWHM) was equal approximately 0.5, 0.4 and 0.3 mm, while the contrast-to-noise ratio (CNR) was equal 18, 19, and 19 dB for BFR, STA and PWI respectively.

Keywords:
Ultrasonic imaging, SAFT, Plane Wave Imaging

16.Karwat P., Litniewski J., Secomski W., Kujawska T., Krawczyk K., Kruglenko E., Gambin B., Nowicki A., Nieinwazyjne obrazowanie temperatury tkanki miękkiej in vitro metodą analizy przemieszczenia ech ultradźwiękowych, 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), pp.101-104, 2012
Karwat P., Litniewski J., Secomski W., Kujawska T., Krawczyk K., Kruglenko E., Gambin B., Nowicki A., Nieinwazyjne obrazowanie temperatury tkanki miękkiej in vitro metodą analizy przemieszczenia ech ultradźwiękowych, 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), pp.101-104, 2012

Abstract:
Terapeutyczne i chirurgiczne zastosowania ogniskowych ultradźwięków wymagają monitorowania lokalnych zmian temperatury w tkance. Najkorzystniejsze z punktu widzenia użytkowego i ekonomicznego byłoby zastosowanie do tych celów technik ultradźwiękowych.
Praca przedstawia próbę zastosowania metody estymacji przemieszczenia ech do monitorowania zmian temperatury podczas ultradźwiękowego nagrzewania tkanki in vitro. Dane uzyskane drogą pomiarów ultradźwiękowych zostały przetworzone w celu wyznaczenia mapy przemieszczeń ech i odniesione do pomiarów rozkładu temperatury przeprowadzonych za pomocą termopar. Uzyskane wyniki umożliwiają ocenę pola temperatury i pozytywnie rokują połączeniu ultradźwiękowych technik nagrzewania i szacowania lokalnej temperatury tkanki.

Keywords:
obrazowanie temperatury, prędkość akustyczna

17.Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Niszczenie komórek nowotworowych glejaka C6 za pomocą fali ultradźwiękowej i kwasu aminolewulinowego (ALA), 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), pp.225-228, 2012
Secomski W., Bilmin K., Kujawska T., Nowicki A., Grieb P., Niszczenie komórek nowotworowych glejaka C6 za pomocą fali ultradźwiękowej i kwasu aminolewulinowego (ALA), 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), pp.225-228, 2012

Abstract:
Nową metodą terapii antynowotworowej glejaków jest sonoterapia polegająca na jednoczesnym podawaniu leku kumulującego się w tkankach nowotworowych i napromieniowanie falą akustyczną. Skuteczność metody została sprawdzona na komórkach glejaka C6, poddanych działaniu kwasu aminolewulinowego (ALA) i fali ultradźwiękowej 1MHz o natężeniu 0.94, 1.88 i 3.77W/cm2 przez 3 min. Jednoczesne działanie fali akustycznej i ALA było skuteczniejsze (pozostało 15%-13% żywych komórek) niż samej fali akustycznej (41%-27%) dla natężeń 0.94 i 1.88W/cm2. Natężenie 3.77W/cm2 było wystarczające do zniszczenia większości komórek niezależnie od obecności ALA. Podczas eksperymentu zaobserwowano powstawanie fali stojącej, zwiększającej natężenie 7x-10x. Otrzymane wyniki wskazują na przydatność nowej techniki sonodynamicznej do terapii nowotworów.

Keywords:
ultradźwięki, sonoterapia, terapia antynowotworowa, glejaki

18.Klimonda Z., Litniewski J., Nowicki A., Zastosowanie uśredniania częstotliwościowego i przestrzennego przy estymacji tłumienia w tkance miękkiej, 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), Vol.1, pp.1-4, 2012
Klimonda Z., Litniewski J., Nowicki A., Zastosowanie uśredniania częstotliwościowego i przestrzennego przy estymacji tłumienia w tkance miękkiej, 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), Vol.1, pp.1-4, 2012

Abstract:
Standardowe obrazy ultrasonograficzne przestawiają rozkład zmian impedancji akustycznej wewnątrz tkanki. Możliwe jest jednak obrazowanie innych parametrów akustycznych. Takie parametryczne obrazy dostarczałyby dodatkowych informacji o stanie tkanki, przydatnych w diagnostyce. Zmiany wartości współczynnika tłumienia fali ultradźwiękowej często towarzyszą patologicznym zmianom struktury tkanki, np. nowotworom. Jedną z metod estymacji tłumienia jest metoda bazująca na przesunięciu częstotliwości średniej widma sygnału w czasie jego propagacji w tkance. Główną niedogodnością metody jest duża wariancja otrzymywanych estymat. W niniejszej pracy przedstawiono rezultaty zastosowania metod uśredniania przestrzennego i częstotliwościowego w celu polepszenia jakości otrzymywanych obrazów rozkładu tłumienia. Weryfikacje metod przeprowadzono w oparciu o dane symulacyjne i dane z fantomu tkankowego o stałej echogeniczności i zmiennym tłumieniu.

Keywords:
estymacja tłumienia, uśrednianie przestrzenne, uśrednianie częstotliwościowe

19.Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Skin lesions assessment using attenuating and statistical properties of the backscattered ultrasound, IUS 2011, IEEE International Ultrasonics Symposium, 2011-10-18/10-21, Orlando (US), DOI: 10.1109/ULTSYM.2011.0338, pp.1368-1371, 2011
Piotrzkowska H., Litniewski J., Szymańska E., Nowicki A., Skin lesions assessment using attenuating and statistical properties of the backscattered ultrasound, IUS 2011, IEEE International Ultrasonics Symposium, 2011-10-18/10-21, Orlando (US), DOI: 10.1109/ULTSYM.2011.0338, pp.1368-1371, 2011

Abstract:
While the needles biopsy is still the gold standard in skin cancer diagnosis there is a growing interest in application of the high frequency ultrasound for the skin lesions detection and their thickness assessment. The quantitative ultrasound can provide additional information, potentially helpful in diagnosis. The purpose of this study was to assess the usefulness of the attenuating and statistical properties of the backscattered ultrasounds for the skin tissues characterization. The paper presents the classification of the healthy skin and skin lesions (BCC-basal cell carcinoma and AK-actinic keratosis). For patients with BCC the attenuation coefficient was significantly higher than for the healthy ones. Also, precancerous skin lesions revealed increased attenuation. The statistical properties were different for BCC comparing to AK lesions and healthy skin.

Keywords:
basal cell carcinoma, actinic keratosis, attenuation coefficient, statistical properties, high frequency ultrasound

20.Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Bone scanner for examination of deeply located trabecular bones, IUS 2011, IEEE International Ultrasonics Symposium, 2011-10-18/10-21, Orlando (US), DOI: 10.1109/ULTSYM.2011.0117, pp.486-489, 2011
Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Bone scanner for examination of deeply located trabecular bones, IUS 2011, IEEE International Ultrasonics Symposium, 2011-10-18/10-21, Orlando (US), DOI: 10.1109/ULTSYM.2011.0117, pp.486-489, 2011

Abstract:
The paper presents a new yield criterion for the transversal isotropy of metal sheets under plane-stress conditions which is an extension of the isotropic yield function proposed by Burzynski (Burzynski W. l928). Studium nad hipotezami Burzynski's doctoral dissertation "Study on material effort hypotheses”, Engng. Trans., 2009, t. 57, nr 3-4, s. l85-2l5). Two additional coefficients have been introduced in order to allow a better representation of plastic behavior of metal sheets. The proposed yield condition includes the influence of first invariant of the stress tensor and also the strength differential effect. The system of equations describing the sheet metal forming process is solved by algorithm using the return mapping procedure. PIane stress constraint is incorporated into the Newton-Raphson iteration loop. The proposed algorithm is verified by performing a numerical test using shell elements in commercial FEM software ABAQUS/EXPLICIT with a developed VUMAT subroutine. It is shown that the proposed approach provides the satisfactory prediction of material behavior, at least in the cases when anisotropy effects are not advanced. To perform FE simulations of cup deep drawing processes, three independent yield stresses are required. Those yield stresses can be obtained from: directional uniaxial tensile test, directional uniaxial compression test and equibiaxial compression tests. In the paper the formability of two metal sheets are analysed. First the influence of strength differential effect on the cup height profile is shown. Then the comparison between the Huber-Mises-Hencky yield condition and the proposed yield condition is presented.

Keywords:
bone scanner, trabecular bone, osteoporosis

21.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay coded sequences in synthetic aperture imaging systems, 58 Otwarte Seminarium z Akustyki, 2011-08-13/08-16, Jurata (PL), pp.347-357, 2011
Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay coded sequences in synthetic aperture imaging systems, 58 Otwarte Seminarium z Akustyki, 2011-08-13/08-16, Jurata (PL), pp.347-357, 2011

Abstract:
The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:
Golay codes, coded sequences, synthetic aperture, ultrasound imaging

22.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Optimal aperture in MSTA method for medical ultrasound imaging applications, 58 Otwarte Seminarium z Akustyki, 2011-08-13/08-16, Jurata (PL), pp.323-334, 2011
23.Kujawska T., Secomski W., Krawczyk K., Nowicki A., Thermal effects induced in tissues by pulsed focused ultrasonic beams from annular transducer, International Conference Biomedical Engineering, 2011-10-27/10-28, Kaunas (LT), pp.144-150, 2011
Kujawska T., Secomski W., Krawczyk K., Nowicki A., Thermal effects induced in tissues by pulsed focused ultrasonic beams from annular transducer, International Conference Biomedical Engineering, 2011-10-27/10-28, Kaunas (LT), pp.144-150, 2011

Abstract:
Many therapeutic applications of focused ultrasound are based on heating of a detected lesion which may be located inside tissues at different depths under a skin. In order to raise the tumor temperature the focal spot of the ultrasonic beam is guided to it. The focusing of acoustic energy in tissues at the desired depth can be achieved using single-element circular concave piezoelectric transducers with the selected diameters and radii of curvature. This solution is inefficient because it requires as many transducers as there are depths at which tumors are localized. In order to solve this problem a new approach, allowing to concentrate the acoustic energy at different depths inside tissues using a planar multi-element phased annular array with electronically steered focus, was proposed in this work. The main purpose of this study was to investigate the thermal fields induced in bovine liver in vitro by the pulsed focused ultrasound beam with various acoustic properties generated from the planar multi-element phased annular array with electronically steered focal spot. The array with 20 mm outer diameter and 2.4 MHz centre frequency has 7 elements with the same radiating surface. The electronic steering of the time-delay of excitation of each array element allowed to obtain the focal spot of the beam at any distance from the transducer surface. This paper presents measurement results performed for the beam focused at 20 mm distance. In order to maximize nonlinear propagation effects being one of the reason of the local temperature rise induced in tissues by focused ultrasound the measurements have been performed in two-layer parallel media of propagation comprising of a water layer, whose thickness was specific for the transducer used and equal to 13 mm, and of a bovine liver in vitro layer with a thickness of 27 mm. It was determined numerically as the axial distance at which the second harmonics amplitude for the tone burst generated by the transducer used in water starts to increase rapidly. The measurements of temperature rise versus time were performed using a thermocouple placed inside the liver at the beam focus. The temperature rises induced in the bovine liver in vitro for beams with the average acoustic power of 1W, 2W and 3W and duty cycle of 1/5, 1/15 and 1/30 have been measured. For each beam the exposure time needed for local heating of the liver to a temperature of 43 °C (used in therapies based on ultrasonic enhancement of drug delivery or therapies involving stimulation of immune system by enhancement of the heat shock proteins expression) and to a temperature of 56 °C (used in HIFU therapies) was determined. In each sample of liver for each considered beam at first, the measurement of temperature rise (with thermocouple) was carried out, and then, exposing the sample (without thermocouple) to the same beam the real-time monitoring of dynamics of the thermo ablation area growth was performed using the ultrasonic imaging technique. The necrosis spot becomes visible in the ultrasonic image only when the beam has sufficient acoustic power. The quantitative analysis of the obtained results allowed to determine the beam acoustic power and exposure time that are sufficient to visualize necrosis spot in the ultrasonic image.

Keywords:
phased annular array, pulsed focused nonlinear ultrasound beams, electronically movable focus, tissue heating, biological effects, tissue necrosis

24.Kujawska T., Wójcik J., Nowicki A., Heating of tissues in vivo by pulsed focused ultrasound to stimulate enhanced HSP expression, 10th International Symposium on Therapeutic Ultrasound, 2010-06-09/06-12, Tokyo (JP), DOI: 10.1063/1.3607877, pp.24-29, 2010
Kujawska T., Wójcik J., Nowicki A., Heating of tissues in vivo by pulsed focused ultrasound to stimulate enhanced HSP expression, 10th International Symposium on Therapeutic Ultrasound, 2010-06-09/06-12, Tokyo (JP), DOI: 10.1063/1.3607877, pp.24-29, 2010

Abstract:
The main aim of this work was numerical modeling of temperature fields induced in soft tissues in vivo by pulsed focused ultrasound during neurodegenerative disease treatment and experimental verification of the proposed model for a rat liver. The new therapeutic approach to neurodegenerative diseases consists of stimulation of enhanced expression of the Heat Shock Proteins (HSP) which are responsible for immunity of cells to stress. During therapy the temperature rise in tissues in vivo should not exceed 6 oC above level of the thermal norm (37 oC). First, the 3D acoustic pressure field, and the rate of heat production per unit volume due to that field, were calculated using our 3D numerical solver capable of predicting nonlinear propagation of pulsed high intensity waves generated from circular focused acoustic sources in multilayer configuration of attenuating media. The two-layer configuration of media (water - rat liver) assumed in calculations fairly well approximated both the real anatomic dimensions of rat liver and the geometric scheme of our experimental set-up. A numerical solution of the Pennes bio-heat transfer equation which accounted for the effects of heat diffusion, blood perfusion and metabolism rates, was employed to calculate the temperature fields induced in the rat liver by the ultrasonic beam. The numerical simulation results were verified experimentally using a thermocouple inserted in the liver of a rat under anesthesia at the beam focus. The quantitative analysis of the obtained results enabled estimation of the effects of several acoustic and thermal parameters of the rat liver in vivo on the temperature rise, as well as determination of exposure time for ultrasonic beams with varied acoustic power generated by a 2-MHz circular transducer of 15-mm diameter and 25-mm focal length, in order to avoid the tissue overheating that leads to cells necrosis, which would be unacceptable in neurodegenerative disease treatment.

Keywords:
low power ultrasound, tissue heating, HSP expression enhancement, cell immunity, degenerative deceases treatment

25.Litniewski J., Cieslik L., Wójcik J., Nowicki A., Statistical properties of trabecular bone backscatter: experimental and simulations results, IUS 2010, IEEE International Ultrasonics Symposium, 2010-10-11/10-14, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935557, Vol.1, pp.2155-2158, 2010
Litniewski J., Cieslik L., Wójcik J., Nowicki A., Statistical properties of trabecular bone backscatter: experimental and simulations results, IUS 2010, IEEE International Ultrasonics Symposium, 2010-10-11/10-14, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935557, Vol.1, pp.2155-2158, 2010

Abstract:
The presented investigations were intended to compare the experimental results obtained from the heel bones in vivo with the results of simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 MHz and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in water. For each measured or simulated RF backscatter statistical properties of the signal envelope was determined. Experimental results suggest deviations from the Rayleigh distribution. Simulation results suggest that deviations from Rayleigh distribution depend on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well with the deviations calculated from simulated echoes assuming trabeculae thickness variation equal to published histomorphometric study results.

Keywords:
trabecular bone, scattering, statistical properties

26.Wójcik J., Litniewski J., Nowicki A., Multiple Scattering Contribution to Trabecular Bone Backscatter, 10ème Congrès Français d'Acoustique, 2010-04-12/04-16, Lyon (FR), Vol.1, No.CD file: 000361.pdf, pp.1-6, 2010
Wójcik J., Litniewski J., Nowicki A., Multiple Scattering Contribution to Trabecular Bone Backscatter, 10ème Congrès Français d'Acoustique, 2010-04-12/04-16, Lyon (FR), Vol.1, No.CD file: 000361.pdf, pp.1-6, 2010

Abstract:
Trabecular bone consists of trabeculae which mechanical properties differ significantly from the surrounding marrow and therefore the ultrasonic wave is strongly scattered within the bone structure. The aim of the presented paper was the evaluation of the contribution of the first, second and higher order scattering (multiple scattering) into total scattering of ultrasounds in the trabecular bone. The scattering due to interconnections between thick trabeculae, usually neglected in trabecular bone models, has been also studied. The basic element in our model of trabecular bone was an elastic cylinder with finite-length and varying diameter and orientation. The applied model was taking into account variation of elements size and spatial configuration. The field scattered on the bone model was evaluated by solving numerically the integral form of the Sturm-Liouville equation that describes scalar wave in inhomogeneous media. For the calculated scattered fields the effective cross-sections as well as the Broadband Ultrasonic Backscatter (BUB) were determined. The influence of the absorption on scattering coefficients was demonstrate. The results allowed to conclude that within the frequency range from 0.5 to 1.5 MHz the contribution of the second order scattering to the effective backscattering cross-section is at least 500 times lower than the one due to the first order scattering. BUB, calculated under the same assumptions, is 20 times lower. Above the 1.5 MHz the fast growth of the BUB, calculated for the second order scattering, occurs.

Keywords:
Complex media, Modeling, Multiple scattering, Trabecular bone,Ultrasound

27.Secomski W., Nowicki A., Święszkowski W., Controlled ultrasonic destruction of the polycaprolactone shell microcapsules based on resonance scattering theory, 10th Polish - Japanese Seminar on Biomedical Engineering - "New Trends in Biomedical and Clinical Engineering", 2009-09-14/09-16, Warszawa (PL), pp.80-84, 2010
Secomski W., Nowicki A., Święszkowski W., Controlled ultrasonic destruction of the polycaprolactone shell microcapsules based on resonance scattering theory, 10th Polish - Japanese Seminar on Biomedical Engineering - "New Trends in Biomedical and Clinical Engineering", 2009-09-14/09-16, Warszawa (PL), pp.80-84, 2010

Abstract:
The use of the ultrasonically destructible microcapsules as local drug delivery systems continues to grow. Microbubble destruction requires correct ultrasonic frequency equal to its resonance. This frequency depends on the bubble size and polymer shell stiffness. Measurements of the ultrasonic signal, backscattered from microspheres gives practical information of the bubble resonance and nonlinearity.
In experiment, the backscattered power spectrum of measured sample was recorded by an ultrasonic scanner. Radio frequency (RF) data was recorded at 2.0 – 6.6 MHz. The mean particle diameter in the measured sample was 21 μm. The resonance frequency, measured under the microscope, was 0.60 MHz for 43 μm diameter microsphere. The sample volume was 10cm³ and the mean quantity of scatterers was 6•103/cm³.
The simulated power spectrum of the ultrasonic backscattered signal was calculated from the resonance scattering theory for the gas bubbles surrounded by elastic shell.
In conclusion, the measured spectra matched those calculated from the theory. The use of the ultrasonic scanner with RF data output and the high sensitivity, wide bandwidth ultrasonic transducer allows to measure the backscattered signal from the very small quantity of resonance scatterers with satisfactory results at 40 dB signal to noise ratio.

Keywords:
ultrasound, microcapsules, controlled drug delivery, backscattering

28.Kujawska T., Wójcik J., Nowicki A., Heating of tissues by pulsed focused ultrasound to stimulate enhanced HSPs expression, 14th International Conference on Biomedical Engineering, , Kaunas (LT), Vol.I, pp.4-9, 2010
Kujawska T., Wójcik J., Nowicki A., Heating of tissues by pulsed focused ultrasound to stimulate enhanced HSPs expression, 14th International Conference on Biomedical Engineering, , Kaunas (LT), Vol.I, pp.4-9, 2010

Abstract:
The new therapeutic approach to neurodegenerative diseases consisting in stimulation of enhanced expression of the Heat Shock Proteins (HSPs) responsible for immunity of cells to stress is proposed. During such therapy local temperature rises in tissues should not exceed 6 oC above the thermal norm (37 oC). Tissue heating at temperatures higher than 43 oC may lead to an inability of cells to divide or to their death. The main aim of this work is numerical modeling of temperature rises induced locally in soft tissues in vivo by pulsed focused ultrasound during neurodegenerative diseases therapy and experimental verification of correctness and accuracy of the proposed model in a rat liver. Both the pulsed acoustic fields and power density of heat sources produced locally in tissues due to those fields were calculated using our 3D numerical solver capable of predicting nonlinear propagation of pulsed finite-amplitude acoustic waves generated from circular focused sources in multilayer configuration of attenuating media with arbitrary attenuation law. The two-layer configuration of media (water - rat liver) assumed in calculations fairly well approximated both the real anatomic dimensions of the rat liver and geometric scheme of our experimental set-up. The Pennes bio-heat transfer equation accounting for the effects of heat diffusion, blood perfusion and metabolism rates was employed to calculate the temperature fields. The numerical simulation results were verified experimentally using a thermocouple positioned in the rat liver at the acoustic beam focus. The quantitative analysis of the obtained results enabled estimation of the effects of the source acoustic power, blood perfusion and metabolism rates on the temperature rises in the rat liver as well as determination of the level and time of exposure to ultrasound in order to avoid the tissue overheating above 43 oC that leads to cells necrosis. The ultrasonic 20-cycle tone bursts with 20 % duty cycle and initial acoustic pressure amplitude varied from 0.131 to 0.226 MPa were generated from a 2-MHz circular transducer with a 15-mm diameter and 25-mm focal length during 10-min exposure time. It was shown that for the 0.226-MPa source pressure the exposure time should not exceed 5 minutes in order to avoid the rat liver overheating. The thermal conductivity coefficient for the rat liver in vivo was determined to be 0.47.

Keywords:
pulsed focused ultrasound, tissues heating, HSPs expression enhancement, cells immunity, neurodegenerative diseases treatment

29.Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of cancellous bone using three models of trabecular structure, 159th Meeting of the Acoustical Society of America and NOISE-CON 2010, 2010-04-19/04-23, Baltimore (US), Vol.9, No.020002, pp.1-9, 2010
Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of cancellous bone using three models of trabecular structure, 159th Meeting of the Acoustical Society of America and NOISE-CON 2010, 2010-04-19/04-23, Baltimore (US), Vol.9, No.020002, pp.1-9, 2010

Abstract:
The semi-empirical scattering models of trabecular bone were developed and examined for their abilities to mimic the frequency dependent backscattering coefficient measured in the cancellous bone. In the simulation of the bone RF echoes the real properties of the bone and experimental conditions were taken into account. Three types of trabeculae mimicking scatterers were considered. First, the bone consisted of cylinders with varying thickness (Gamma distributed) within the population, was assumed. The next two cases accounted for the contribution of thick and thin trabeculae to the total backscattered signal. The second model assumed existence of two populations of the cylindrical scatterers significantly differing in the average value of Gamma distributed diameters. Finally, the mixed model composed of thick and thin trabeculae modeled respectively by cylindrical and spherical scatterers was examined. The last selection resulted from the similarity found between scattering on small sphere and finite cylinder. Calculated echoes demonstrated the usefulness of the mixed model. Frequency dependence of backscattering coefficient agreed well with the experimentally determined dependences. The study showed also that the amplitude histograms calculated using demodulated RF echoes deviate from the Rayleigh distribution when the variation of scatterers’ diameters increases.

Keywords:
trabecular bone structure, modeling, backscatter

30.Litniewski J., Wójcik J., Nowicki A., Scattering model of trabecular bone, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.117-120, 2010
Litniewski J., Wójcik J., Nowicki A., Scattering model of trabecular bone, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.117-120, 2010

Abstract:
In our previous study we have developed the simulation technique that enables determination of the ultrasound signal received at the pulse-echo transducer surface after interrogation of cancellous bone. The simulation can be applied for different scattering models of a trabecular structure. In this study we examined newly developed scattering models of the trabecular bone for their abilities to mimic the frequency dependent backscattering coefficient measured in the cancellous bone. Three types of trabeculae mimicking scatterers were considered. First the bone consisted of cylinders with varying thickness (Gamma distributed) within the population, was assumed. The next two cases accounted for the contribution of thick and thin trabeculae to the total backscattered signal. The second model assumed existence of two populations of the cylindrical scatterers significantly differing in the average value of Gamma distributed diameters. Finally, the mixed model composed of thick and thin trabeculae modeled respectively by cylindrical and spherical scatterers was examined. The last selection resulted from the similarity found between scattering on small sphere and finite cylinder. Calculated echoes demonstrated the usefulness of the mixed model. Frequency dependence of backscattering coefficient agreed well with the experimentally determined dependences.

Keywords:
trabecular bone, scattering, bone model

31.Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Bone ultrasonic scanner, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.49-52, 2010
Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Bone ultrasonic scanner, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.49-52, 2010

Abstract:
Acoustical waves scattered in trabecular bone contain information about its microstructural properties. These properties may change on course of a disease. Standard ultrasonic examinations of bone (densitometry) are performed in transmission and does not provide complete information about bone strength. We have developed the bone ultrasonic scanner that enables measurements of the physical properties of trabecular bone microstructure. Thus the evaluation of bone properties using ultrasonic scanner may be essential for bone diseases diagnosis and treatment monitoring. This study presents application of the scanner operating at 1,5 MHz frequency for examination of trabecular bone (calcaneus) . Backscattered data were collected and processed in order to obtain power backscattering coefficient (PBSC). Calculated values were compared to these published by several authors in order to verify ultrasonic scanner application as a tool for trabecular bone examination. This study is an approach towards developing a method for the investigation of scattering in trabecular bone that can potentially provide clinically useful information about bone strength and condition.

Keywords:
trabecular bone, bone scanner, osteoporosis

32.Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique - preliminary results, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.95-98, 2010
Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique - preliminary results, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.95-98, 2010

Abstract:
The pathological states of biological tissues are often connected with attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency hanges due to tissue attenuation dispersion is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the mean frequency trends extraction. These trends were converted into attenuation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom with uniform echogenicity but varying attenuation coefficient (DFS, Denmark).

Keywords:
tissue attenuation estimation, spatial compounding

33.Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multielement synthetic transmit aperture in medical ultrasound imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.205-208, 2010
Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multielement synthetic transmit aperture in medical ultrasound imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.205-208, 2010

Abstract:
Synthetic aperture (SA) technique is a novel approach to today's commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data.
The paper describes the multielement STA method in medical ultrasound imaging with a small number of elements transmitting and all elements receiving apertures. Compared to other methods the multielement STA allows to increase the system frame rate and provides the best compromise between penetration depth and lateral resolution. In the experiments a 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of tissue mimicking phantom obtained using STA and multielement STA methods are presented to demonstrate the benefits of the second method.

Keywords:
synthetic aperture, ultrasound imaging

34.Karwat P., Klimonda Z., Sęklewski M., Lewandowski M., Nowicki A., Metoda przerzedzania danych dla algorytmu syntetycznej apertury nadawczej, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.91-94, 2010
Karwat P., Klimonda Z., Sęklewski M., Lewandowski M., Nowicki A., Metoda przerzedzania danych dla algorytmu syntetycznej apertury nadawczej, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.91-94, 2010

Abstract:
Metody ultradźwiękowego obrazowania struktur wewnętrznych człowieka są nieustannie ulepszane. Opracowywane są nowe algorytmy umożliwiające poprawę niektórych parametrów wynikowych. Przykładem jest metoda syntetycznej apertury (SA), która pozwala wyświetlać obrazy o wysokiej rozdzielczości z większą częstotliwością niż standardowa metoda formowania wiązki.
Ograniczeniem metody SA jest większa złożoność obliczeniowa, która przy znacznej ilości danych może uniemożliwić osiągnięcie pożądanej szybkości rekonstrukcji. Problem ten można ominąć rezygnując z części zarejestrowanych sygnałów. Wiąże się to oczywiście z pogorszeniem jakości obrazowania, jednak przy odpowiedniej technice przerzedzania danych degradacja obrazu jest niewielka. Proponowany sposób przerzedzania ma zastosowanie w metodzie syntetycznej apertury nadawczej (STA) i opiera się na założeniu, że sygnał uzyskany za pomocą dowolnej pary przetworników jest taki sam niezależnie od tego, który z przetworników nadawał, a który odbierał. W tej sytuacji można pominąć blisko połowę zapisanych danych i wciąż
możliwe będzie zrekonstruowanie obrazu w poprzedniej jakości. Na podstawie prezentowanych wyników symulacji oraz pomiarów na fantomach nitkowym i tkankowym wykazano, że stosując opisaną technikę przerzedzania można zmniejszyć o połowę ilość danych przy zachowaniu rozdzielczości i nieznacznym spadku parametru SNR oraz kontrastu rekonstruowanych obrazów.

Keywords:
metody syntetycznej apertury, przerzedzanie danych

35.Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: analysis of Synthetic Transmit Aperture technique in ultrasonic imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.173-176, 2010
Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: analysis of Synthetic Transmit Aperture technique in ultrasonic imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.173-176, 2010

Abstract:
The Synthetic Aperture (SA) methods are widespread and successfully used in radar technology, as well as in the sonar systems. The advantages of relatively good resolution in the whole area of scanning without decrease of framerate, make this technique an object of interest in medical imaging methods such as ultrasonography (US).This paper describes the possible usage of the SA method in ultrasound imaging. The measurements of different SA schemes were conducted using the set-up consisting of the research ultrasonograph module, the PC and the special wire phantom. The results for different schemes of image reconstruction are presented. Particularly the Synthetic Transmit Aperture (STA) technique was concerned. Results of the STA method are discussed in this paper.

Keywords:
ultrasonic imaging, synthetic aperture focusing technique

36.Tasinkevych Y., Nowicki A., Trots I., Element directivity influence in the synthetic focusing algorithm for ultrasound imaginig, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.197-200, 2010
37.Lewandowski M., Klimonda Z., Karwat P., Sęklewski M., Nowicki A., Bassi L., Tortoli P., Comparison of different schemes of synthetic transmit aperture using an ultrasound advanced open platform (ULA-OP), IUS 2010, IEEE International Ultrasonics Symposium, 2010-10-11/10-14, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935656, pp.1988-1991, 2010
Lewandowski M., Klimonda Z., Karwat P., Sęklewski M., Nowicki A., Bassi L., Tortoli P., Comparison of different schemes of synthetic transmit aperture using an ultrasound advanced open platform (ULA-OP), IUS 2010, IEEE International Ultrasonics Symposium, 2010-10-11/10-14, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935656, pp.1988-1991, 2010

Abstract:
Increasing efforts are currently dedicated to incorporate the Synthetic Transmit Aperture (STA) method in ultrasound imaging systems. The STA technique can provide a pixel-like focusing (dynamic focusing at both transmit and receive) without impairment of the frame rate. This goal can only be achieved by a careful design of the transmission and reception schemes. In this paper, the preliminary results of resolution, Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) measurements for a specific SA scheme with different transmit apertures are presented. The measurements were made using a novel ultrasound advanced open platform (ULA-OP) developed at the University of Florence. The ULA-OP is fully programmable and enables access to the RF echo-data from each transducer element.

Keywords:
synthetic aperture, ultrasound open platform

38.Nowicki A., Wójcik J., Lewandowski M., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick film transducers for high frequency coded ultrasonography, 9th International Conference on Information Technology and Applications in Biomedicine, 2009-11-04/11-07, Larnaka (CY), DOI: 10.1109/ITAB.2009.5394411, pp.1-4, 2009
Nowicki A., Wójcik J., Lewandowski M., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick film transducers for high frequency coded ultrasonography, 9th International Conference on Information Technology and Applications in Biomedicine, 2009-11-04/11-07, Larnaka (CY), DOI: 10.1109/ITAB.2009.5394411, pp.1-4, 2009

Abstract:
Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature - 11 mm, 12 mm, 15 mm, 16 mm.
All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35-40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4-1.5 and finally resulting in a SNR gain of the same order. Examples of skin scans obtained with the new thick-film transducers are presented.

Keywords:
transducers, thick film, high frequency ultrasound, pulse compression, Golay code

39.Lewandowski M., Walczak M., Nowicki A., Compact modular Doppler system with digital RF processing, IUS 2009, IEEE International Ultrasonics Symposium, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441933, pp.1848-1851, 2009
Lewandowski M., Walczak M., Nowicki A., Compact modular Doppler system with digital RF processing, IUS 2009, IEEE International Ultrasonics Symposium, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441933, pp.1848-1851, 2009

Abstract:
Doppler instruments are widely used for evaluation of the hemodynamic of vascular circulation. The objective of the work was to develop a modular acquisition and processing system to enable the construction of various ultrasound instruments. The developed system consists of two electronic boards with dimensions of 130x82mm in sandwich configuration. Digital signal processing was based on an efficient DSP (Blackfin BF537, Analog Devices, USA) with 128MB RAM and an FPGA (Cyclone III EP3C25, Altera, USA). The system can work as a standalone device with the limited user interface or as a PC peripheral under the control of the application software. The dual channel transcranial PW Doppler flowmeter with multigate processing has been the first application of the developed platform. The acquisition module provides the A/D sampling at 64 MSPS rate with 14-bits resolution and supports ultrasonic transducers within the range of 1–16 MHz. The PC software performs signal processing and visualization of color Doppler, spectrum, flow profile and audio. The developed system is a modern technical solution which enables to build portable Doppler instruments of different classes. The developed prototype of transcranial Doppler will be introduced into production soon.

Keywords:
ultrasound Doppler systems, transcranial aplications, digital RF processing, DSP, FPGA

40.Litniewski J., Klimonda Z., Lewandowski M., Nowicki A., Szymańska E., Correcting for focusing when estimating tissue attenuation from mean frequency shift, IUS 2009, IEEE International Ultrasonics Symposium, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441930, pp.2383-2385, 2009
Litniewski J., Klimonda Z., Lewandowski M., Nowicki A., Szymańska E., Correcting for focusing when estimating tissue attenuation from mean frequency shift, IUS 2009, IEEE International Ultrasonics Symposium, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441930, pp.2383-2385, 2009

Abstract:
Determination of attenuating properties of the tissue from the echoes of waves emitted by the focused transducer requires to compensate the echo signal for the effects of focusing. We propose the diffraction/focusing effects correcting (FC) technique that compensates focusing-induced mean frequency
shift (MFS) of the propagating pulse. The method corrects mean frequency estimates derived from echo pulses propagating in attenuating tissue with locally varying attenuation coefficient. The FC algorithm applies the diffraction correcting coefficients obtained experimentally from the probing pulses focused in water for assessing the expected values of MFS of pulses focused in attenuating tissue. The calculations involves the pulse ‘history’ that due to overall attenuation along the traveled path downshifts the pulse spectrum resulting in variation of the focusinginduced MFS obtained in water.

Keywords:
attenuation estimation, difraction correction, parametric imaging

41.Trots I., Nowicki A., Secomski W., Litniewski J., Lewandowski M., Transducer Bandwidth Influence on the Golay Encoded Ultrasound Echoes, IUS, IEEE Ultrasonics Symposium, 2007-10-28/10-31, New York (US), DOI: 10.1109/ULTSYM.2007.320, pp.1274-1277, 2007
Trots I., Nowicki A., Secomski W., Litniewski J., Lewandowski M., Transducer Bandwidth Influence on the Golay Encoded Ultrasound Echoes, IUS, IEEE Ultrasonics Symposium, 2007-10-28/10-31, New York (US), DOI: 10.1109/ULTSYM.2007.320, pp.1274-1277, 2007

Abstract:
This paper investigates the effect of ultrasound imaging transducer’s fractional bandwidth on the gain of the compressed echo signal for different spectral widths of the complementary Golay sequences (CGS). Two different bit lengths were investigated, specifically one and two cycles. Three transducers having fractional bandwidth of 25%, 58% and 80% and operating at frequencies 6 MHz, 4.4 MHz and 6 MHz, respectively were examined (one of the 6 MHz sources was made of composite material). The experimental results have shown that by increasing the code length, i.e. decreasing the bandwidth, the compressed echo amplitude could be enhanced. The smaller the bandwidth was the larger was the gain; the pulse-echo sensitivity of the echo amplitude increased by 1.88, 1.62 and 1.47, for 25%, 58% and 80% bandwidths, respectively. These results indicate that two cycles bit length excitation is more suitable for use with bandwidth limited commercially available imaging transducers. Further, the time resolution is retained for transducers with two cycles excitation providing the fractional bandwidth is lower than approximately 90%. The results of this work indicate that adjusting the code length allows signal-to-noise-ratio (SNR) to be enhanced while using limited (less that 80%) bandwidth imaging transducers. Also, for such transducers two cycles excitation would not decrease the time resolution, obtained with ’conventional’ spike excitation. These results also indicate that CGS excitation could be successfully implemented with the existing, relatively narrow band imaging transducers without the need to use usually more expensive wide-band, composite ones.

Keywords:
ultrasound imaging, coded transmission, transducer badnwidth, Golay codes

42.Nowicki A., Wójcik J., Secomski W., Multitone nonlinear coding, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603121, pp.1420-1423, 2005
Nowicki A., Wójcik J., Secomski W., Multitone nonlinear coding, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603121, pp.1420-1423, 2005

Abstract:
Tissue Harmonic Imaging (THI) was introduced in 1997 [1] and is today routinely used in diagnostic ultrasound. The benefits of harmonic imaging in many clinical situations have been proved. However, it has to be stressed that it is away from optimal because only half of the available transducer bandwidth is used for image formation - lower half for transmission and upper half during reception.

Keywords:
Ultrasonic imaging, Image resolution, Polarization, Absorption, Image coding, Pulse inverters, Dynamic range, Nonlinear equations, Boundary conditions, Propagation losses

43.Kujawska T., Wójcik J., Nowicki A., Nonlinear pulsed pressure field from focused rectangular apertures: experimental and numerical simulation results, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603267, pp.1992-1995, 2005
Kujawska T., Wójcik J., Nowicki A., Nonlinear pulsed pressure field from focused rectangular apertures: experimental and numerical simulation results, IUS 2005, IEEE International Ultrasonics Symposium, 2005-09-18/09-21, Rotterdam (NL), DOI: 10.1109/ULTSYM.2005.1603267, pp.1992-1995, 2005

Abstract:
The theoretical and experimental studies of the finite amplitude acoustic waves propagation in attenuating media from nonaxisymmetric sources rather rarely can be found in literature in spite of the fact that probes of the rectangular geometry (such as linear phased arrays) are commonly used in clinical practice for medical ultrasonic imaging purposes. The main reason of such situation is a lack in simpler theoretical models and in computationally efficient numerical algorithms that are able to predict accurately the nonlinear effects in 4D ultrasound fields from pulsed, arbitrarily shaped sources (plane and focused) in biological media with arbitrary frequency-dependent absorption. In recent years the only study describing the computationally efficient numerical model that is able to simulate accurately the 4D nonlinear ultrasound field in water and in biological tissues from pulsed nonaxisymmetric sources was developed by Zemp et al. [1]. Their model is based on the second order operator-splitting method, proposed by Tavakkoli et al., with the modified fractional step scheme whereby the combined effects of diffraction and absorption are accounted for over half-steps and the effects of nonlinear harmonic interactions over full incremental steps. The computation of diffraction and absorption sub-steps was based on the angular spectrum technique with modified sampling method (to obtain computational savings due to larger axial propagation steps) while the computation of nonlinear steps was based on the time-domain solution to Burgers' equation. There are not reports yet describing an experimental confirmation of an agreement between the simulated nonlinear acoustic pulsed fields in water or in soft tissues from nonaxisymmetric focused sources (obtained by using the numerical model proposed) and nonlinear field from realistic probes.

Keywords:
Apertures, Numerical simulation, Acoustic pulses, Absorption, Ultrasonic imaging, Computational modeling, Acoustic propagation, Focusing, Phased arrays, Nonlinear acoustics

44.Radulescu E.G., Wójcik J., Lewin P.A., Nowicki A., A Novel Method for Characterization of Nonlinear Propagation and Spatial Averaging Effects for Ultrasound Imaging Systems, IEEE Ultrasonics Symposium, 2002-10-08/10-11, Monachium (DE), DOI: 10.1109/ULTSYM.2002.1192498, pp.1153-1156, 2002
Radulescu E.G., Wójcik J., Lewin P.A., Nowicki A., A Novel Method for Characterization of Nonlinear Propagation and Spatial Averaging Effects for Ultrasound Imaging Systems, IEEE Ultrasonics Symposium, 2002-10-08/10-11, Monachium (DE), DOI: 10.1109/ULTSYM.2002.1192498, pp.1153-1156, 2002

Abstract:
Harmonic imaging at frequencies up to 15 MHz is now routinely used in clinical practice and frequencies well beyond 20 MHz are considered for diagnostic ultrasound imaging applications. However, currently available measurement tools are not fully adequate to characterize such high frequency systems, primarily due to the combined effects of limited frequency responses and spatial averaging effects. To alleviate this problems, a comprehensive wave propagation model has been developed and tested. The model can predict the linear and nonlinear acoustic wave propagation generated by differently shaped acoustic radiators at virtually any point in the field and takes into account spatial averaging effects introduced by hydrophone probes and their associated frequency responses. The applicability of the model in hydrophone probe calibration up to 100 MHz is demonstrated. Also, a novel calibration technique termed Time-Gating Frequency Analysis (TGFA) is briefly described and calibration results in the frequency range up to 60 MHz for hydrophones having effective diameters between 150 and 500 /spl mu/m are presented. Also presented are the results of the investigation that determined the effect of using hydrophone probes of different diameters and bandwidth on Spatial-Peak Pulse-Average Intensity (I/sub SPPA/). It was found that the values of I/sub SPPA/ increased with decreasing effective aperture of the hydrophone probe and its bandwidth.

Keywords:
Ultrasonic imaging, Frequency, Sonar equipment, Probes, Calibration, Acoustic propagation, Nonlinear acoustics, Bandwidth, Acoustic measurements, Current measurement

45.Nowicki A., Secomski W., Wójcik J., 32 MHz Doppler assessment for streaming measurements, IEEE Ultrasonics Symposium, 1996-11-03/11-06, San Antonio, Texas (US), DOI: 10.1109/ULTSYM.1996.584158, pp.995-998, 1996
Nowicki A., Secomski W., Wójcik J., 32 MHz Doppler assessment for streaming measurements, IEEE Ultrasonics Symposium, 1996-11-03/11-06, San Antonio, Texas (US), DOI: 10.1109/ULTSYM.1996.584158, pp.995-998, 1996

Abstract:
An approximate solution for the streaming velocity generated by flat and weakly focused transducers was derived by directly solving the Dirichlet boundary conditions for the Poisson equation. The theoretical calculations were verified using a purpose-designed 32 MHz pulsed Doppler unit. The applied average acoustic power was changed from 1 /spl mu/W to 6 mW. The experiments were done on 4 mm diameter flat and focused transducers. The streaming velocity was measured along the ultrasonic beam from O to 20 mm. Streaming was induced in a solution of water and corn starch. The experimental results showed that for a given acoustic power the streaming velocity was independent of the starch density in water changed from 0.3 grams to 40 grams of starch in 1 litre of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2 to 40 mm/s. Theoretical solutions for both plane and focused waves agreed with experimental results.

Keywords:
Acoustic beams, Poisson equations, Acoustic transducers, Ultrasonic transducers, Differential equations, Ultrasonic variables measurement, Acoustic waves, Impedance, Navier-Stokes equations, Boundary conditions


Abstrakty konferencyjne
1.Nowicki A., Dobruch-Sobczak K., Piotrzkowska H., Litniewski J., Gambin B., Roszkowska K., Chrapowicki E., Clinical Validation of the Statistical Analysis of US RF Signals in Differentiation of the Breast Lesions, AIUM 2015, Ultrasound in Medicine and Biology Annual Convention, 2015-03-21/03-25, Lake Buena Vista (US), DOI: 10.1016/j.ultrasmedbio.2014.12.403, Vol.41, No.4S, Special issue: 2015 AIUM Annual Convention and Preconvention Program Hosting WFUMB Congress, ABSTRACT 2088809, pp.S98-S99, 2015
Nowicki A., Dobruch-Sobczak K., Piotrzkowska H., Litniewski J., Gambin B., Roszkowska K., Chrapowicki E., Clinical Validation of the Statistical Analysis of US RF Signals in Differentiation of the Breast Lesions, AIUM 2015, Ultrasound in Medicine and Biology Annual Convention, 2015-03-21/03-25, Lake Buena Vista (US), DOI: 10.1016/j.ultrasmedbio.2014.12.403, Vol.41, No.4S, Special issue: 2015 AIUM Annual Convention and Preconvention Program Hosting WFUMB Congress, ABSTRACT 2088809, pp.S98-S99, 2015

Abstract:
The scattering is the fundamental phenomena used for US imaging of specific organs. In this study the method searching for best fitted statistical distribution of the acquired echoes from the breast tissue is discussed, especially addressing the ‘‘effective’’ number of scatterers. The aim of the study was finding the relationship between the specific properties of statistics of envelope of the ultrasonic echoes backscattered in the breast tissue in vivo, and its morphological properties for normal tissue and the pathological lesions.
Methods: 72 patients with 83 suspicious breast lesions (BIRADS 3, 4, 5) were examined. The analysis method was based on the parametric imaging representing a map of local statistical properties of the scattering of ultrasound waves in normal and pathological tissues. Both, the RF echo-signal and B-mode images from the lesions and surrounding tissue were recorded. The statistics of backscattered speckle-like echoes envelopes were modelled using K and Nakagami distributions. For all lesions the set of sub-ROIs covering full lesion was chosen. The statistical analysis was done for every sub-ROI separately. The shape parameters were calculated including the compensation for TGC applied and for the attenuation.
Results: The evaluation of all 83 breasts lesions revealed 23 malignant and 60 benign lesions. Typically, both, shape parameters for malignant lesions were statistically larger than for surrounding tissue. On the other hand, the benign lesions revealed much larger variance of the parameters comparing to the surrounding and malignant tissue. The sensitivity and specificity of B-mode imaging with the cut-off points BIRADS-4a/4b were 93%, 86%. For K and Nakagami distributions obtained sensitivity and specificity were respectively 85% and 91%.
Conclusions: The quantitative measurements of the breast tissue backscattering statistical properties improve the specificity of B-mode examinations and can be helpful in the differentiation the character of the breast lesions. It was proved that the range of the shape parameters appears to be rather large and can not be interpreted without taking into account the corresponding values in the surrounding ‘‘normal’’ tissue.

Keywords:
breast cancer, ultrasound, RF echo-signal

2.Gambin B., Kruglenko E., Byra M., Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Changes in ultrasound echoes of a breast tissue in vivo after exposure to heat - a case study, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.217-218, 2015
Gambin B., Kruglenko E., Byra M., Nowicki A., Piotrzkowska H., Dobruch-Sobczak K., Changes in ultrasound echoes of a breast tissue in vivo after exposure to heat - a case study, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.217-218, 2015

Abstract:
A B-mode ultrasonography provides structural information on the tissue under investigation encoding the echo strength in gray scale in a two-dimensional image. Interpretation of the B-mode image of breast tissue is done by a physician. The analysis of statistical properties of backscattered RF signal has been recently applied successfully to distinct healthy tissue from tissue lesions regions as a new method of quantitative ultrasound (QUS). Up till now, the most reliable results were obtained for liver and renal tissue lesions, because their normal, healthy structures are nearly homogeneous while a heterogeneous breast tissue classification is still an open issue. The recent study revealed that the medium contraction and expansion induced by a temperature change may cause variations in the relative position of scatterers in a tissue. We have developed a new procedure of heating the patient breast and allowing to observe and record in vivo the influence of temperature changes on a B-mode image and properties of unprocessed radio frequency (RF) backscattered echoes. The initial, feasibility studies of influence of the temperature increase in breast tissue on the intensity, spectrum and statistics of ultrasonic echoes will be discussed.

Keywords:
breast tissue, RF signal, backscattered signal amplitude statistics, spectral properties

3.Nowicki A., Lewandowski M., Trots I., Olszewski R., High Frequency Thick Film Ultrasonic Transducers Used for Estimation of Flow-Mediated Vasodilation of the Radial Artery, SENSORDEVICES 2015, 6th International Conference on Sensor Device Technologies and Applications, 2015-08-23/08-28, Wenecja (IT), pp.99-100, 2015
Nowicki A., Lewandowski M., Trots I., Olszewski R., High Frequency Thick Film Ultrasonic Transducers Used for Estimation of Flow-Mediated Vasodilation of the Radial Artery, SENSORDEVICES 2015, 6th International Conference on Sensor Device Technologies and Applications, 2015-08-23/08-28, Wenecja (IT), pp.99-100, 2015

Abstract:
Preceding atherosclerosis is an endothelial dysfunction. Therefore there is a growing interest in the application of non - invasive clinical tools to assess endothelial function. Commercially available ultrasound machines can measure flow - mediated vasodilatation of the brachial artery using maximum 10-12 MH z linear probes. The higher the probe frequency, the better the axial resolution. Recently, a new technology of piezoelectric transducers based on PZT thick film technology has been developed in Meggitt (Denmark) as a response to a call for devices working at higher frequencies. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducers, resulting in an increase in match filtering encoding output by a factor of 1.4 - 1.5 and finally resulting in a signal to noise gain of the same order. The introduction of a high frequency 25 - 30 MHz ultrasound scanner to measure radial artery diameter after reactive hyperemia open s a new window for more precise imaging of endothelial function.

Keywords:
thick film transducers, atherosclerosis, flow mediated vaso dilation

4.Dobruch-Sobczak K., Gumińska A., Bakuła-Zalewska E., Piotrzkowska H., Mlosek R.K., Słapa R.Z., Wareluk P., Migda B., Olszewski W., Jakubowski W., Nowicki A., Dedecjus M., Wartość sonoelastografii fali poprzecznej (SWE) w szacowaniu ryzyka złośliwości zmian ogniskowych tarczycy, V Konferencja Rak Tarczycy i inne nowotwory zlośliwe układu wydzielania wewnętrznego, 2015-11-14/11-17, Wisła (PL), Vol.66, pp.1, 2015
5.Dobruch-Sobczak K., Gumińska A., Bakuła-Zalewska E., Kaczor A., Piotrzkowska H., Jakubowski W., Nowicki A., Dedecjus M., Zastosowanie elastografii fali poprzecznej w diagnostyce raka rdzeniastego tarczycy, V Konferencja Rak Tarczycy i inne nowotwory zlośliwe układu wydzielania wewnętrznego, 2015-11-14/11-17, Wisła (PL), DOI: 10.15557/JoU.2015.003, Vol.66, No.15, pp.358-367, 2015
Dobruch-Sobczak K., Gumińska A., Bakuła-Zalewska E., Kaczor A., Piotrzkowska H., Jakubowski W., Nowicki A., Dedecjus M., Zastosowanie elastografii fali poprzecznej w diagnostyce raka rdzeniastego tarczycy, V Konferencja Rak Tarczycy i inne nowotwory zlośliwe układu wydzielania wewnętrznego, 2015-11-14/11-17, Wisła (PL), DOI: 10.15557/JoU.2015.003, Vol.66, No.15, pp.358-367, 2015

Abstract:
Elastografia fali poprzecznej jest nowoczesną metodą oceny sztywności tkanek. Obserwuje się wzrost zainteresowania tą techniką w różnicowaniu charakteru zmian ogniskowych w tarczycy również w diagnostyce przedoperacyjnej. Cel pracy: Celem niniejszej pracy była ocena klinicznej przydatności elastografi i fali poprzecznej w diagnostyce raka rdzeniastego tarczycy (RRT). Materiał i metoda: W badanej grupie 139 pacjentów stwierdzono 169 zmian ogniskowych, a u 4 pacjentów (średni wiek: 45 lat) rozpoznano 6 RRT. Wykonano USG B-mode oraz elastografię fali poprzecznej aparatem Aixplorer (Super-Sonic, Aix-en-Provence), głowicą liniową o częstotliwości 4–15 MHz. W USG oceniano echogeniczność i echo strukturę zmian, ich brzegi, objaw „halo”, stosunek wysokości dogłębokości (W/G), obecność zwapnień oraz wzorzec unaczynienia. Następnie analizowano: maksymalne i średnie wartości modułu Younga (E) dla największego ROI dla RRT (EmaxLR, EmeanLR ) oraz dla otaczających tkanek w miąższu gruczołu (EmaxSR , EmeanSR), a także średnie wartości E (EmeanLRz) dla 2 mm obszaru zainteresowania z najsztywniejszej części zmiany. Zmiany zweryfikowano histopatologicznie i/lub cytologicznie. Wyniki: W ocenie B-mode wszystkie RRT były hipoechogeniczne, bez obecności objawu „halo”, oraz zawierał y mikro- i/lub makrozwapnienia. Nieostre granice zmiany obecne były w 4 z 6 raków. Wartość ilorazu WG >1 dotyczył a 4 na 6 zmian. Niejednorodną echo strukturę oraz typ III unaczynienia stwierdzono w 5 na 6 zmian. W SWE średnia wartość E maxLR w obrębie RRT wynosił a 89,5 kPa, w otoczeniu – 39,7 kPa. Średnie wartości E meanLR , E meanSR wynosił y odpowiednio: 34,6 kPa i 24,4 kPa. Wartość średnia E meanLRz=49,2 kPa. Wnioski: W SWE RRT przedstawiały się jako zmiany sztywniejsze w porównaniu z otaczającymi tkankami. W ocenie B-mode spełniały wskazania do biopsji spiracyjnej cienkoigłowej. Jednak algorytm diagnostyczny RRT opiera się na pomiarze stężenia kalcytoniny w surowicy krwi, ocenie USG B-mode oraz biopsji.

Keywords:
rak rdzeniasty, tarczyca, badanie USG, sonoelastografia fali poprzecznej

6.Secomski W., Olszewski R., Bilmin K., Nowicki A., Kujawska T., Grieb P., Terapeutyczne wykorzystanie ultradźwięków – wspomaganie procesu rozpuszczania skrzeplin oraz stymulacja apoptozy komórek nowotworowych, XIX Krajowa Konferencja Biocybernetyka i Inżynieria Biomedyczna, 2015-10-14/10-16, Warszawa (PL), pp.59, 2015
Secomski W., Olszewski R., Bilmin K., Nowicki A., Kujawska T., Grieb P., Terapeutyczne wykorzystanie ultradźwięków – wspomaganie procesu rozpuszczania skrzeplin oraz stymulacja apoptozy komórek nowotworowych, XIX Krajowa Konferencja Biocybernetyka i Inżynieria Biomedyczna, 2015-10-14/10-16, Warszawa (PL), pp.59, 2015

Abstract:
Ultradźwięki są stosowane w medycynie zarówno w diagnostyce - ultrasonografii jak i w terapii. Działanie terapeutyczne sprowadza się do efektów termicznych, uśmiercania komórek przez apoptozę oraz efektów sonomechanicznych. Terapie in-vivo są poprzedzane testami in-vitro komórek umieszczonych na szalce Petriego. W tej pracy zostaną przedstawione dwa efekty oddziaływania fali akustycznej na komórki: wspomaganie rozpuszczania skrzepliny oraz apoptoza komórek nowotworowych.
Do badań przygotowano zbiornik wypełniony odgazowaną wodą destylowaną z termostatem i mieszadłem elektromagnetycznym. W zbiorniku umieszczono płaski przetwornik ultradźwiękowy, promieniujący do góry, w kierunku zanurzonej w wodzie szalki Petriego ze skrzepliną lub komórkami.
W pierwszej części oddziaływano falą ultradźwiękową o częstotliwości 1.0 MHz i natężeniu Isata = 0.2 W/cm2 na skrzeplinę uzyskaną z kropli krwi 30 min po pobraniu. Skrzeplinę umieszczono w roztworze soli fizjologicznej z dodatkiem leku rozpuszczającego skrzeplinę tPA typu Actilyse 50 w stężeniu 10μg/ml i nadźwiękawiano przez 20 min. Eksperyment powtórzono z kolejnymi skrzeplinami stosując same ultradźwięki oraz sam lek Actilyse. Współdziałanie leku i fali ultradźwiękowej w ciągu 20 min spowodowało całkowite rozpuszczenie skrzepliny. W pozostałych przypadkach skrzeplina pozostała zmniejszając swoją objętość o 10-20%.
W drugiej części badano wpływ fali ultradźwiękowej 1.0 MHz na komórki nowotworowe szczurzego glejaka C6. Komórki wysiano na dnie szalki i hodowano w pożywce DMEM w temperaturze 37ºC. Następnie do pożywki dodano 1mM kwasu 5-aminolewulinowego ALA. Po 24h inkubacji, komórki poddano działaniu ultradźwięków o natężeniu Isata = 0.4, 0.8 oraz 1.2 W/cm2 przez 3 min. Po kolejnych 24h, żywotność komórek zbadano spektrofotometrem po dodaniu do pożywki odczynnika MTT assay. Badania powtórzono dla komórek bez ALA oraz bez ultradźwięków. Dla natężenia Isata = 1.2 W/cm2, żywotność komórek wynosiła 39% dla współdziałania ALA i ultradźwięków, 78% dla ALA oraz 99% dla ultradźwięków.
Przygotowane przez autorów stanowisko pomiarowe umożliwia prowadzenie badań in-vitro nad terapeutycznym oddziaływaniu ultradźwięków na komórki. Uzyskano pozytywne rezultaty w wykorzystaniu ultradźwięków zarówno do rozpuszczania skrzeplin – sonotrombolizy jak i uśmiercania komórek nowotworowych – terapii sonodynamicznej. Stosowano ultradźwięki małej mocy, niepowodujące zniszczenia komórek przez przegrzanie lub kawitację.

Keywords:
ultradźwięki terapeutyczne, sonotromboliza, tromboliza, leczenie nowotworów

7.Frankowska E., Trawiński Z., Zegadło A., Olszewski R., Nowicki A., Bogusławska R., Assessment of radial strain in ultrasonographic model of left ventricle using speckle tracking ultrasound technique and multislice computed tomography, ECR 2014, European Congress of Radiology, 2014-03-06/03-10, Wiedeń (AT), DOI: 10.1594/ecr2014/C-0473, Vol.C-0473, pp.1-7, 2014
Frankowska E., Trawiński Z., Zegadło A., Olszewski R., Nowicki A., Bogusławska R., Assessment of radial strain in ultrasonographic model of left ventricle using speckle tracking ultrasound technique and multislice computed tomography, ECR 2014, European Congress of Radiology, 2014-03-06/03-10, Wiedeń (AT), DOI: 10.1594/ecr2014/C-0473, Vol.C-0473, pp.1-7, 2014

Abstract:
The aim of this study was to verify suitability of sonographic model of LV (left ventricle) in CT (computed tomography) environment and to compare in vitro radial strain calculations obtained by two different techniques: speckle tracking ultrasonography and multislice CT.

8.Kujawska T., Secomski W., Byra M., Nowicki A., Controlling the depth of local tissue necrosis induced by pulsed nonlinear focused ultrasonic beam with electronically sliding focus, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), pp.381, 2014
Kujawska T., Secomski W., Byra M., Nowicki A., Controlling the depth of local tissue necrosis induced by pulsed nonlinear focused ultrasonic beam with electronically sliding focus, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), pp.381, 2014

Abstract:
To target a focal spot of an ultrasound beam on a tumor located deep inside tissues during thermo-ablative treatment by HIFU technique, beams with different focal distances are required. To be able to control a depth of local thermal fields induced in tissues by a single beam, both, the planar and concave 7-element annular phased array transducers with a 2 MHz frequency and 29 mm diameter generating beams with electronically controlled focal length were designed and produced. The radius of curvature (ROC) for the concave transducer was equal to 60 mm. Elements of each transducer had the same area to provide uniform pressure distribution on the radiating surface due to the same impedance and were excited by pulses with time delays providing the beam focusing in water at three different depths (25 mm, 30 mm, and 35 mm). To select sets of time delays for each focal depth the measurements of pressure waveforms on the axis of each beam generated in water were performed using a needle hydrophone. For these measurements 10-cycle tone bursts with 1 kHz PRF were used. In order to induce local thermo-ablative necrosis inside a tissue at three different depths (10mm, 15mm, and 20mm) a two-layer media of propagation comprising of 15-mm layer of water and 25-mm layer of pork loin was used. To heat the pork loin locally 20-cycle tone bursts with 0.2 duty-cycle and average acoustic power varied between12W and 18W (initial intensity ISATA varied between 2W/cm2 and 3W/cm2) was applied. In order to determine the exposure time required to induce necrosis (rise in temperature to 56 °C) inside the pork loin sample at the selected depth the thermocouples placed on the acoustic beam axis were used. After exposure to focused ultrasound three necrotic lesions were observed after cutting the tested tissue sample along the axes of the beams used. The obtained results proved the feasibility of controlling the depth of local tissue necrosis using pulsed focused ultrasound beams with electronically movable focal spot generated by the annular phased array transducer designed.

Keywords:
annular phased array transducer, pulsed High Intensity Focused Ultrasound, electronically movable focus, local tissue heating, thermal ablation, tissue necrosis

9.Lewandowski M., Walczak M., Karwat P., Witek B., Nowicki A., Karłowicz P., Research & Medical Doppler platform, 11th Congrès Français d'Acoustique, 2012 IOA annual meeting, 2012-04-23/04-27, Nantes (FR), pp.x1-x6, 2012
Lewandowski M., Walczak M., Karwat P., Witek B., Nowicki A., Karłowicz P., Research & Medical Doppler platform, 11th Congrès Français d'Acoustique, 2012 IOA annual meeting, 2012-04-23/04-27, Nantes (FR), pp.x1-x6, 2012

Abstract:
A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are difficult to penetrate for standard systems. The device can display a color map of flow velocities in time-depth domain and a spectrogram of a Doppler signal received from a particular depth. The system offers a multigate processing that allows to display simultaneously a number of spectrograms and to reconstruct a flow velocity profile. The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost. The digiTDS design fulfills all necessary medical standards being a new useful tool in transcranial field as well as in heart velocimetry research.

Keywords:
ultrasound transcranial Doppler, RF signal processing, DSP, FPGA


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pdf
390405
2010-02-09
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Kujawska T., Nowicki A.
Sposób i urządzenie pomiarowe do wyznaczania akustycznego parametru nieliniowości B/A biologicznych cieczy i tkanek
PL, Instytut Podstawowych Problemów Techniki PAN
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284663
1990-04-06
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Nowicki A., Liwski J.
Sposób wyznaczania widma dopplerowskich sygnałów przepływu krwi
PL, Nowicki A., Liwski J.
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277279
1989-01-20
BUP 15/90
1990-07-23 BUP 15/90
Marciniak A., Nowicki A., Secomski W., Karłowicz P., Piechocki M., Liwski J.
Ultradźwiękowa głowica sektorowa
PL, Instytut Podstawowych Problemów Techniki PAN
157977
WUP 07/92
1992-07-31
277279
1989-01-20
-
1992-07-31
Marciniak A., Nowicki A., Secomski W., Karłowicz P., Piechocki M., Liwski J.
Ultradźwiękowa głowica sektorowa
PL, Instytut Podstawowych Problemów Techniki PAN
157977
-
1990-07-23
255681
1985-10-08
-
1990-07-31
Karłowicz P., Liwski J., Nowicki A.
Sposób określania kierunku przepływu w cyfrowym pomiarze prędkości przepływu z zastosowaniem impulsowego przepływomierza dopplerowskiego
PL, Instytut Podstawowych Problemów Techniki PAN
149954
-
1987-05-18
253467
1985-05-17
-
1990-04-30
Łowicki J., Nowicki A., Szygendowski S.
Sposób i urządzenie do pomiaru momentu wtrysku paliwa z pompy wtryskowej do cylindra pracującego silnika wysokoprężnego, wykonywanego za pomocą ultradźwiękowego układu rejestrującego zjawisko Dopplera
PL, Łowicki J., Nowicki A., Szygendowski S.
149018
-
1987-07-13
247801
1984-05-23
-
1989-04-29
Karłowicz P., Nowicki A., Piechocki M., Secomski W.
Ultradźwiękowy przepływomierz dopplerowski do rejestracji maksymalnej prędkości cieczy
PL, Instytut Podstawowych Problemów Techniki PAN
144601
-
1985-12-03
239097
1982-11-18
-
1986-11-15
Filipczyński L., Karłowicz P., Nowicki A.
Sposób i urządzenie do rozpoznania zaburzenia przepływu cieczy, zwłaszcza krwi
PL, Instytut Podstawowych Problemów Techniki PAN
136932
-
1984-12-03
206955
1978-05-20
-
1983-03-15
Etienne J., Filipczyński L., Nowicki A., Powałowski T.
Ultradźwiękowe urządzenie dopplerowskie zwłaszcza do pomiaru przepływu krwi
PL, Instytut Podstawowych Problemów Techniki PAN
117416
-
1980-01-28
196471
1977-03-07
-
1979-08-30
Filipczyński L., Nowicki A.
Sposób oraz urządzenie do wizualizacji naczynia krwionośnego i wyznaczania kąta nachylenia wiązki ultradźwiękowej względem naczynia krwionośnego
PL, Instytut Podstawowych Problemów Techniki PAN
103608
-
1978-01-16
194133
1976-12-03
-
1981-01-31
Nowicki A.
Urządzenie do rejestracji ech ultradźwiękowych
PL, Instytut Podstawowych Problemów Techniki PAN
108773
-
1978-06-05
179156
1975-03-28
-
1976-10-23
Filipczyński L., Nowicki A., Borodziński K.
Impulsowy ultradźwiękowy miernik przepływu i profilu prędkości cieczy zwłaszcza krwi płynącej w naczyniach krwionośnych
PL, Instytut Podstawowych Problemów Techniki PAN
99449
-
1978-11-15
178139
1975-02-18
-
1976-03-13
Nowicki A.
Sposób wyznaczania kąta nachylenia wiązki ultradźwiękowej względem naczynia krwionośnego oraz urządzenie do realizacji tego sposobu
PL, Instytut Podstawowych Problemów Techniki PAN
97775
-
1980-01-31
162550
1973-05-15
-
1975-04-01
Borodziński K., Etienne J., Nowicki A., Powałowski T.
Ultradźwiękowy sposób i urządzenie do badania tętna płodu z wykorzystaniem zjawiska Dopplera
PL, Instytut Podstawowych Problemów Techniki PAN
89237
-
1977-06-20