dr inż. Michał Byra

Zakład Ultradźwięków (ZU)
Pracownia Biomechaniki (PB)
stanowisko: starszy specjalista
telefon: (+48) 22 826 12 81 wew.: 414
pokój: 509
e-mail: mbyra

Doktorat
2017-09-28Klasyfikacja zmian nowotworowych piersi na podstawie własności statystycznych ech ultradźwiękowych 
promotor -- prof. dr hab. inż. Andrzej Nowicki, IPPT PAN
1254
 
Ostatnie publikacje
1.Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Byra M., Nowicki A., Open access database of raw ultrasonic signals acquired from malignant and benign breast lesions, Medical Physics, ISSN: 0094-2405, DOI: 10.1002/mp.12538, Vol.44, No.9, pp.1-5, 2017

Streszczenie:

Purpose: The aim of this paper is to provide access to a database consisting of the raw radio-frequency ultrasonic echoes acquired from malignant and benign breast lesions. The database is freely available for study and signal analysis.
Acquisition and validation methods: The ultrasonic radio-frequency echoes were recorded from breast focal lesions of patients of the Institute of Oncology in Warsaw. The data were collected between 11/2013 and 10/2015. Patients were examined by a radiologist with 18 yr’ experience in the ultrasonic examination of breast lesions. The set of data includes scans from 52 malignant and 48 benign breast lesions recorded in a group of 78 women. For each lesion, two individual orthogonal scans from the pathological region were acquired with the Ultrasonix SonixTouch Research ultrasound scanner using the L14-5/38 linear array transducer. All malignant lesions were histologically assessed by core needle biopsy. In the case of benign lesions, part of them was histologically assessed and another part was observed over a 2-year period. Data format and usage notes: The radio-frequency echoes were stored in Matlab file format. For each scan, the region of interest was provided to correctly indicate the lesion area. Moreover, for each lesion, the BI-RADS category and the lesion class were included. Two code examples of data manipulation are presented. The data can be downloaded via the Zenodo repository (https://doi.org/10.5281/zenodo.545928) or the website http ://bluebox.ippt.gov.pl/~hpiotrzk.
Potential applications: The database can be used to test quantitative ultrasound techniques and ultrasound image processing algorithms, or to develop computer-aided diagno sis systems.

Słowa kluczowe:

breast lesions, dataset, ultrasonic signals, ultrasonography

Afiliacje autorów:

Piotrzkowska-Wróblewska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
Byra M.-IPPT PAN
Nowicki A.-IPPT PAN
35p.
2.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

Streszczenie:

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.

Słowa kluczowe:

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

Afiliacje autorów:

Kujawska T.-IPPT PAN
Secomski W.-IPPT PAN
Byra M.-IPPT PAN
Postema M.-IPPT PAN
Nowicki A.-IPPT PAN
30p.
3.Byra M., Kruglenko E., Gambin B., Nowicki A., Temperature Monitoring during Focused Ultrasound Treatment by Means of the Homodyned K Distribution, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.131.1525, Vol.131, No.6, pp.1525-1528, 2017

Streszczenie:

Temperature monitoring is essential for various medical treatments. In this work, we investigate the impact of temperature on backscattered ultrasound echo statistics during a high intensity focused ultrasound treatment. A tissue mimicking phantom was heated with a spherical ultrasonic transducer up to 56 _C in order to imitate tissue necrosis. During the heating, an imaging scanner was used to acquire backscattered echoes from the heated region. These data was then modeled with the homodyned K distribution. We found that the best temperature indicator can be obtained by combining two parameters of the model, namely the backscattered echo mean intensity and the effective number of scatterers per resolution cell. Next, ultrasonic thermometer was designed and used to create a map of the temperature induced within the tissue phantom during the treatment

Słowa kluczowe:

Temperature monitoring, homodyned K distribution, focused ultrasound

Afiliacje autorów:

Byra M.-IPPT PAN
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
Nowicki A.-IPPT PAN
15p.
4.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

Streszczenie:

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.

Słowa kluczowe:

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

Afiliacje autorów:

Byra M.-IPPT PAN
Nowicki A.-IPPT PAN
Piotrzkowska-Wróblewska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
35p.
5.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

Streszczenie:

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.

Słowa kluczowe:

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

Afiliacje autorów:

Gambin B.-IPPT PAN
Byra M.-IPPT PAN
Kruglenko E.-IPPT PAN
Doubrovina O.-Belarussian State University (BY)
Nowicki A.-IPPT PAN
15p.
6.Gambin B., Kruglenko E., Byra M., Relationships between Acoustical Properties and Stiffness of Soft Tissue Phantoms, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.111-120, 2016

Streszczenie:

Polyvinyl-alcohol cryogel is commonly used for soft tissue phantom manufacture. The gel formation from an aqueous solution of polyvinyl-alcohol takes place during the freezing and thawing cycle. The aim of this work was to assess the degree of gel solidification, hence the material stiffness, by means of quantitative ultrasound. We manufactured three phantoms which differed in the number of freezing/thawing cycles. First, tissue phantoms were examined with an elastography technique. Next, we measured the speed of sound and the attenuation coefficient. What is more, the inter structure variations in phantoms were assessed with the Nakagami imaging which quantifies the scattering properties of the backscattered ultrasound echo. Obtained results confirmed the connection between the number of freezing/thawing cycles and the solidification process. We defined the boundary layer as a region which has a different structure than the sample interior. Next, for each phantom this layer was extracted based on a Nakagami parameter map. We calculated that the thickness of the boundary layer was lower in samples which were subjected to a larger number of freezing/thawing cycles.

Słowa kluczowe:

soft tissue phantoms, elastography, ultrasound attenuation, speed of sound, Nakagami maps, stiffness

Afiliacje autorów:

Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
6p.
7.Wójcik J., Byra M., Nowicki A., A spectral-based method for tissue characterization, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.369-375, 2016

Streszczenie:

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.

Słowa kluczowe:

quantitative ultrasound, signal analysis, wave scattering

Afiliacje autorów:

Wójcik J.-IPPT PAN
Byra M.-IPPT PAN
Nowicki A.-IPPT PAN
6p.
8.Byra M., Gambin B., Temperature detection based on nonparametric statistics of ultrasound echoes, HYDROACOUSTICS, ISSN: 1642-1817, Vol.18, pp.17-23, 2015

Streszczenie:

Different ultrasound echoes properties have been used for the noninvasive temperature monitoring. Temperature variations that occur during heating/cooling process induce changes in a random process of ultrasound backscattering. It was already proved that the probability distribution of the backscattered RF (radio frequency) signals is sensitive to the temperature variations. Contrary to previously used methods which explored models of scattering and involved techniques of fitting histograms to a special probability distribution two more direct measures of changes in statistics are proposed in this paper as temperature markers. They measure the ”distance” between the probability distributions. The markers are the Kolmogorov Smirnov distance and Kulback-Leiber divergence. The feasibility of using such nonparametric statistics for noninvasive ultrasound temperature estimation is demonstrated on the ultrasounds data collected during series of heating experiments in which the temperature was independently registered by the classical thermometer or thermocouples.

Słowa kluczowe:

ultrasoud echoes, non-invasive temperaturę monitoring, Kolmogorov Smirnov distance, Kulback-Leiber divergence

Afiliacje autorów:

Byra M.-IPPT PAN
Gambin B.-IPPT PAN
6p.
9.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

Streszczenie:

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.

Afiliacje autorów:

Nowicki A.-IPPT PAN
Byra M.-IPPT PAN
Litniewski J.-IPPT PAN
Wójcik J.-IPPT PAN
7p.

Lista rozdziałów w ostatnich monografiach
1.
489
Gambin B., Kruglenko E., Byra M., Postępy Akustyki , rozdział: Pomiary zmian temperatury we wzorcach tkanki miękkiej przez termopary i wstecznie rozproszone sygnały ultradźwiękowe, Polskie Towarzystwo Akustyczne, Oddział Warszawski, Warszawa, Poland, 1, pp.15-26, 2016

Prace konferencyjne
1.Byra M., Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Nowicki A., Combining Nakagami imaging and convolutional neural network for breast lesion classification, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092154, pp.1-4, 2017

Streszczenie:

In this paper we propose a computer-aided diagnosis system for the breast lesion classification. Our approach is based on quantitative ultrasound and deep learning. We used the Nakagami imaging to create parametric maps of breast lesions that illustrate tissue scattering properties. For this task the sliding window technique was applied. The Nakagami parameter was calculated using the maximum likelihood estimator. Next, we used the Nakagami parameter maps to train a convolutional neural network. Classification performance was evaluated by 5-fold cross-validation. We obtained the area under the receiver operating characteristic curve equal to 0.91. The results showed that our approach is useful to distinguishing between malignant and benign breast lesions. The proposed method serves as a general approach for tissue characterization and differentiation. The Nakagami parameter used in this study can be replaced with other QUS parameters and the neural network can be trained in a similar fashion.

Słowa kluczowe:

Nakagami imaging, quantitative ultrasound, convolutional neural networks, breast lesion classification, deep learning

Afiliacje autorów:

Byra M.-IPPT PAN
Piotrzkowska-Wróblewska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
Nowicki A.-IPPT PAN
2.Byra M., Wójcik J., Nowicki A., Ultrasound nonlinearity parameter assessment using plane wave imaging, 2017 IEEE, 2017 IEEE International Ultrasonics Symposium, 2017-09-06/09-09, Washington, DC (US), DOI: 10.1109/ULTSYM.2017.8092733, pp.1-4, 2017

Streszczenie:

In this paper we investigate how to assess the ultrasound nonlinearity coefficient using plane wave imaging. We employ the technique based on excitation of the medium with ultrasonic pulses of increasing amplitude level. As the pulse pressure is increased, due to medium nonlinearity, higher fraction of energy is transferred from the fundamental to higher harmonics during the propagation. In this case the amplitude of the backscattered echo is not linear in respect to the initial pulse amplitude at source. This phenomenon can be used for the nonlinearity coefficient assessment and show its implementation for the plane wave imaging. The method was validated experimentally using a wire phantom immersed in water and scanned using the Verasonics scanner. We discuss the usefulness of the proposed technique and its shortcomings. In comparison to other nonlinearity coefficient assessment methods, the presented technique works in the pulse-echo mode and it doesn't require information on second harmonic or using a special wide-band transducer. The method can be implemented directly into a medical scanner.

Słowa kluczowe:

Plane wave imaging, nonlinear ultrasound, quantitative ultrasound, coefficient of nonlinearity

Afiliacje autorów:

Byra M.-IPPT PAN
Wójcik J.-IPPT PAN
Nowicki A.-IPPT PAN
3.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

Streszczenie:

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.

Słowa kluczowe:

ultrasound, breast cancer, Nakagami distribution

Afiliacje autorów:

Byra M.-IPPT PAN
Nowicki A.-IPPT PAN
Piotrzkowska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
Litniewski J.-IPPT PAN
4.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

Streszczenie:

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.

Słowa kluczowe:

breast cancer, quantitative ultrasound, BIRADS

Afiliacje autorów:

Nowicki A.-IPPT PAN
Piotrzkowska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
Litniewski J.-IPPT PAN
Byra M.-IPPT PAN
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
5.Ramalli A., Byra M., Dallai A., Palombo C., Aizawa K., Sbragi S., Shore S., Portoli P., A Multiparametric Approach Integrating Vessel Diameter, Wall Shear Rate and Physiologic Signals for Optimized Flow Mediated Dilation Studies, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0326, pp.1-4, 2015

Streszczenie:

Flow Mediated Dilation (FMD) is a technique widely used to assess the endothelial function by ultrasound. Ideally, both the brachial artery wall shear stress (stimulus) and the diameter change (effect) shall be estimated and monitored for up to 10 minutes, while blood flow is restricted by a cuff and then suddenly released. An inherent method's difficulty is maintaining the linear array probe aligned with the artery for such a long time. The problem is here faced by an integrated hardware/software approach that displays in real-time both the spatial velocity profiles and the diameter changes, and acquires raw data all over the exam.

Słowa kluczowe:

component, Flow mediated dilation, FMD, wall shear stress, wall shear rate, diameter distension, ULA-OP

Afiliacje autorów:

Ramalli A.-University of Florence (IT)
Byra M.-IPPT PAN
Dallai A.-University of Florence (IT)
Palombo C.-University of Pisa (IT)
Aizawa K.-University of Exeter Medical School (GB)
Sbragi S.-University of Pisa (IT)
Shore S.-University of Exeter Medical School (GB)
Portoli P.-University of Florence (IT)
6.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

Streszczenie:

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.

Afiliacje autorów:

Nowicki A.-IPPT PAN
Byra M.-IPPT PAN
Litniewski J.-IPPT PAN
Wójcik J.-IPPT PAN

Abstrakty konferencyjne
1.Gambin B., Kruglenko E., Byra M., Acoustical Properties of Tissue Phantoms with Different Stiffness and Water-Like Absorption, 10th EAA International Symposium on Hydroacoustics, 2016-05-17/05-16, Jastrzębia Góra (PL), DOI: 10.1515/aoa-2016-0038, pp.361, 2016

Streszczenie:

Poly(vinyl alcohol) cryogel, PVA-C, is produced as a soft tissue-mimicking material, suitable for application in ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze–thaw process. The number of freeze–thaw cycles affects the properties of the material, particularly the mechanical stiffness. The ultrasound characteristics were investigated using 3 different cylindrical samples of PVA-C produced by 1, 2 and 3 cycles of freezing-thawing process. The speed of sound was found to range from 1502 to 1522 m s−1, and the attenuation coefficients were in the range of 0.085–0.124 dB/(cm MHz). The structural eterogeneities are visualized by Nakagami maps and it is shown that the range of Nakagami parameter characterize the differences between samples. The samples are structurally different in the regions close to the surface from the internal regions. This is probably caused by the spatial heterogeneity of the solidification process. The thickness of the boundary layer is also measured from Nakagami maps and it is shown that it is also linked to the type of samples. The elastography maps (measured by the commercial quasistatic strain imaging system . . . ) are compared with Nakagami maps. The question arises, in what circumstances parametric estimation of spatial structure variations by Nakagami maps are linked to the spatial variations of local stiffness?

Słowa kluczowe:

soft tissue phantoms, elastography, ultrasound attenuation, speed of sound, Nakagami maps, stiffness

Afiliacje autorów:

Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
2.Gambin B., Kruglenko E., Byra M., Thermocouple measurement of temperature variations in soft tissue phantoms versus backscattered ultrasonic signals properties, OSA 16, LXIII Otwarte Seminarium z Akustyki, 2016-09-13/09-16, Białowieża (PL), DOI: 10.1515/aoa-2016-0059, pp.617, 2016

Słowa kluczowe:

soft tissue phantoms, backscattered ultrasonic signal, changes in the backscattered energy

Afiliacje autorów:

Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
3.Gambin B., Byra M., Doubrovina O., Nonparametric statistics indirect temperature estimation by ultrasound imaging, 8th International Scientific Seminar on Analytic Methods of Analysis and Differential Equations, 2015-09-14/09-18, Mińsk (BY), Vol.1, pp.26, 2015

Streszczenie:

The practical aim of this research is to detect the temperature by the selected properties of the backscattered ultrasound signals collected during heating/cooling of the soft tissue sample. The initial data are the raw backscattered signals, RF (radio frequency) signals, which form the two-dimensional matrix. These data are divided according to the regions of interest (ROI) analyzed piece-wise in the following way:
• absolute value of Hilbert transform in each time sample is calculated,
• the approximations with Daubeschies 6 wavelets is performed,
• Kolmogorov-Smirnov distance and Kullback-Laibler divergence between initial ROI statistics and the statistics of the ROI in succesive temperature level are used to visualization of the dynamic temperature changes on the map of the sample volume.

Słowa kluczowe:

temperaturę detection, non-parametric statistics, backscattered ultrasound, wavelet

Afiliacje autorów:

Gambin B.-IPPT PAN
Byra M.-IPPT PAN
Doubrovina O.-Belarussian State University (BY)
4.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

Streszczenie:

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.

Słowa kluczowe:

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

Afiliacje autorów:

Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
Nowicki A.-IPPT PAN
Piotrzkowska H.-IPPT PAN
Dobruch-Sobczak K.-IPPT PAN
5.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

Streszczenie:

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.

Słowa kluczowe:

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

Afiliacje autorów:

Kujawska T.-IPPT PAN
Secomski W.-IPPT PAN
Byra M.-IPPT PAN
Nowicki A.-IPPT PAN