Eleonora Kruglenko, Ph.D.

Department of Ultrasound (ZU)
Division of Biomechanics (PB)
position: senior specialist
telephone: (+48) 22 826 12 81 ext.: 414
room: 509
e-mail: ekrug

Doctoral thesis
2007-10-25Analiza funkcjonałów niewypukłych charakteryzujących mikromagnetyki 
supervisor -- Kazimierz Piechór, Ph.D., Dr. Habil., IPPT PAN
606
 
Recent publications
1.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
Abstract:

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

Keywords:

Temperature monitoring, homodyned K distribution, focused ultrasound

Affiliations:
Byra M.-IPPT PAN
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
Nowicki A.-IPPT PAN
2.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

Affiliations:
Gambin B.-IPPT PAN
Byra M.-IPPT PAN
Kruglenko E.-IPPT PAN
Doubrovina O.-Belarussian State University (BY)
Nowicki A.-IPPT PAN
3.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
Abstract:

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.

Keywords:

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

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
4.Gambin B., Kruglenko E., Temperature Measurement by Statistical Parameters of Ultrasound Signal Backscattered from Tissue Samples, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.128.A-72, Vol.128, No.1-A, pp.A-72-78, 2015
Abstract:

A novel estimation of temperature changes inside soft tissues has been proposed in sub-ablation range, i.e. 20°C-48°C. This estimation has been obtained by studying statistical properties of backscattered ultrasonic signals. Two different procedures of heating/cooling have been performed in which the RF echoes have been registered from soft tissue phantom in the first procedure, and from soft tissue in vitro in the second one. Calculated envelopes of signals registered in time points during heating/cooling experiments have been treated as a statistical sample drawn from a random variable with three different distributions, namely the Rayleigh distribution, the Nakagami distribution, and the K-distribution. The histograms obtained in subsequent time moments have been fitted to the three distributions. Dependencies of their shape and scale parameters on temperature have been calculated. It is concluded that the shape parameter of the K-distribution can be chosen as the best marker of temperature changes in both experiments. The choice of the marker has been made by analysis of temperature dependencies of all calculated parameters and by comparing the quality of fitting all histograms to the considered distributions. Besides, the chosen marker as a function of temperature exhibits the closest shape to temperature/time function experimentally measured.

Keywords:

therapeutic applications, ultrasonics, medical imaging

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
5.Gambin B., Kruglenko E., Gałka A.A., Wojnar R., Macroscopic thermal properties of quasi-linear cellular medium on example of the liver tissue, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.22, No.4, pp.329-346, 2015
Abstract:

There are two main topics of this research: (i) one topic considers overall properties of a nonlinear cellular composite, treated as a model of the liver tissue, and (ii) the other topic concerns the propagation of heat in the nonlinear medium described by the homogenised coefficient of thermal conductivity.

For (i) we give a method and find the effective thermal conductivity for the model of the liver tissue, and for the point (ii) we present numerical and analytical treatment of the problem, and indicate the principal difference of heat propagation in linear and nonlinear media. In linear media, as it is well known, the range of the heat field is infinite for all times t > 0, and in nonlinear media it is finite.

Pennes’ equation, which should characterize the heat propagation in the living tissue, is in general a quasi-nonlinear partial differential equation, and consists of three terms, one of which describes Fourier’s heat diffusion with conductivity being a function of temperature T . This term is just a point of our analysis.

We show that a nonlinear character of the medium (heat conductivity dependent on the temperature) changes in qualitative manner the nature of heat transfer. It is proved that for the heat source concentrated initially (t = 0) at the space point, the range of heated region (for t > 0) is finite. The proof is analytical, and illustrated by a numerical experiment.

Keywords:

heat transport, asymptotic homogenisation, effective heat conductivity

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Gałka A.A.-other affiliation
Wojnar R.-IPPT PAN
6.Gambin B., Kruglenko E., Wójcik J., Relationship between thermal and ultrasound fields in breast tissue in vivo, HYDROACOUSTICS, ISSN: 1642-1817, Vol.18, pp.53-58, 2015
Abstract:

The study shows the direct relationship between the temperature field and the parallel changes that are taking place in backscattered ultrasonic signals from the breast tissue in vivo when heated to the temperature of approximately 42 o C. The non-uniform temperature field inside the heating tissue was determined by the numerical model using FEM. It is shown that the spatial distribution of intensities of the backscattered signals coincides with the temperature distribution field predicted by the numerical model in some areas. The result indicates the possibility of the indirect measurement of the temperature rise in the breast tissue in vivo by measuring the intensity variations of the ultrasound echo.

Keywords:

temperature field, backscattered ultrasonic signals, breast tissue in vivo, FEM model

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Wójcik J.-IPPT PAN
7.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

Affiliations:
Kujawska T.-IPPT PAN
Secomski W.-IPPT PAN
Kruglenko E.-IPPT PAN
Krawczyk K.-IPPT PAN
Nowicki A.-IPPT PAN
8.Doubrovina O., Gambin B., Kruglenko E., Temperature level and properties of wavelet approximations of back scattered ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.37-46, 2014
Abstract:

The aim of the paper is to find links between the dynamics of changes of statistical parameters and changes in spectral properties of the signal envelope of backscattered RF signals during the thermal process. We have shown previously that by using wavelet approximations these tendencies are better recognized in the case of the heating of a phantom sample than in the parallel analysis performed for a full signal envelope. Here we are currently expanding this statement to the case of heating a soft tissue sample in vitro. The shape parameter of the K- distributed random variable is considered as a statistical marker of temperature level changes. Additionally, the spectral properties of different levels of wavelet approximations are calculated and their sensitivity to temperature increase and decrease is demonstrated. Both approaches registering changes in temperature, are used in the case of the pork loin tissue sample in vitro, heated by an ultrasound beam with a different power.

Keywords:

ultrasound echoes, soft tissue sample in vitro, statistical marker of temperaturę rise

Affiliations:
Doubrovina O.-Belarussian State University (BY)
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
9.Kruglenko E., Gambin B., RF signal amplitude statistics during temperature changes in tissue phantoms, HYDROACOUSTICS, ISSN: 1642-1817, Vol.17, pp.115-122, 2014
Abstract:

Two heating protocols for soft tissue phantoms have been performed. An Agar-Gel-Oil (AGO) mixture has been heated locally by applying ultrasonic beams and a Poly Vinyl Alcohol-cryogel (PVA-c) has been heated “globally” by a water bath with a controlled temperature rise. The RF signals were collected during heating by an ultrasound transducer to ensure no interference from waves from the heating transducer. Independently, the thermocouples' measurement has been used to obtain temperature as a function of time in the AGO case. At first, a compensation of attenuation was performed and normalized envelopes of signals were used as data for statistical analysis. It is shown that random the values of the backscattered amplitude are close to Rayleigh and K-distributed random variables for AGO and PVA-c, respectively. Temperature is linked to the scale parameter of Rayleigh distribution for the AGO, and the shape parameter of K-distribution for PVA-c were calculated and discussed in the context of their suitability for the acoustic measurement of temperature.

Keywords:

Agar-Gel_Oil soft tissue phantom, K-distribution shape parameter, temperaturę measurements

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
10.Kruglenko E., Gambin B., Cieślik L., Soft Tissue-Mimicking Materials With Various Number of Scatterers and Their Acoustical Characteristics, HYDROACOUSTICS, ISSN: 1642-1817, Vol.16, pp.121-128, 2013
Abstract:

For the study of the temperature increase in the soft tissues irradiated by a low-power ultrasound [1], soft tissue-mimicking materials can be used. The phantoms have been produced based on an aqueous solution of agar, oil, and glass beads microparticles. The RF signals collected in the experiments enabled evaluation of the acoustic properties of phantoms with different number of strong scatterers (concentration varied from 0 to 30 pcs/mm3). Speed of sound (SOS) determined for the phantoms was similar to the value typical of soft tissue (about 1540 m/s). To determine attenuation coefficient the semi-transmission method has been used. Attenuation coefficient value varied from 0.5 to 1.1 dB/(MHz cm), depending on the number of scatterers. It was shown that the phantoms stored for 6 months preserved their acoustical properties and were usable for further experiments. It was found that within the total attenuation, the part corresponding to scattering can be distinguished.

Keywords:

acoustical characteristics, soft tissue mimicking material, scatterers number

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
Cieślik L.-IPPT PAN
11.Kruglenko E., Wpływ zmienności właściwości fizycznych tkanki na rozkład temperatury w tkance przy terapeutycznym oddziaływaniu ultradźwięków, INŻYNIERIA BIOMEDYCZNA/BIOMEDICAL ENGINEERING, ISSN: 1234-5563, Vol.18, No.4, pp.250-254, 2012
Abstract:

Artykuł dotyczy numerycznego wyznaczania in vivo przestrzennego i czasowego rozkładu temperatury po oddziaływaniu na tkankę zogniskowaną wiązką ultradźwiękową małej mocy. Celem pracy jest analiza wpływu parametrów fizycznych tkanki na rozkład temperatury oraz przedstawienie wyników obliczeń dla modelu wątroby szczura, w którym uwzględniono zależność parametrów fizycznych tkanki od temperatury. Wykazano, że przewidywana temperatura tkanki po 20-minutowym oddziaływaniu w większym stopniu zależy od zmiany przewodnictwa cieplnego tkanki niż od jej ciepła właściwego. Parametry materiałowe wody i tkanki wątroby przyjęto na podstawie danych z literatury. Założono, że geometria modelu numerycznego odpowiada rzeczywistemu położeniu obszaru oddziaływania względem głowicy emitującej zogniskowaną wiązkę ultradźwiękową.

Keywords:

wiązka ultradźwiękowa małej mocy, rozkład temperatury, tkanka miękka, przewodność cieplna, ciepło właściwe

Affiliations:
Kruglenko E.-IPPT PAN
12.Gambin B., Kruglenko E., Kujawska T., Michajłow M., Modeling of tissues in vivo heating induced by exposure to therapeutic ultrasound, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, Vol.119, pp.950-956, 2011
Abstract:

The aim of this work is mathematical modeling and numerical calculation in space and time of temperature fields induced by low power focused ultrasound beams in soft tissue in vivo after few minutes exposure time. These numerical predictions are indispensable for planning of various ultrasound therapeutic applications. Both, the acoustic pressure distribution and power density of heat sources induced in tissue, were calculated using the numerical solution to the second order nonlinear differential wave equation describing propagation of the high intensity acoustic wave in three-layer structure of nonlinear attenuating media. The problem of the heat transfer in living tissues is modelled by the Pennes equation, which accounts for the effects of heat diffusion, blood perfusion losses and metabolism rate. Boundary conditions and geometry are chosen according to the anatomical dimensions of a rat liver. The obtained results are compared with those calculated previously and verified experimentally for temperature elevations induced by ultrasound in liver samples in vitro. The analysis of the results emphasizes the value of the blood perfusion and the values of heat conductivity on the temperature growth rate. The numerical calculations of temperature fields were performed using the ABAQUS FEM software package. The thermal and acoustic properties of the liver and water being the input parameters to the numerical model were taken from the published data in cited references. The range of thermal conductivity coefficient of living tissue is obtained from the model of two-phase composite medium with given microstructure. The first component is a “solid” tissue and the second one corresponds to blood vessels area. The circular focused ultrasonic transducer with a diameter of 15 mm, focal length of 25 mm and resonance frequency of 2 MHz has been used to generate the pulsed ultrasonic beam in a very introductory experiment in vivo, which has been performed. Numerical prediction confirms qualitatively its results.

Keywords:

focused ultrasound, soft tissues, local thermal fields, numerical modelling

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Kujawska T.-IPPT PAN
Michajłow M.-IPPT PAN
13.Kruglenko E., Gambin B., Some aspects of numerical modeling of temperature increase due to ultrasound beam irradiation of rat liver, HYDROACOUSTICS, ISSN: 1642-1817, Vol.14, pp.99-110, 2011
Abstract:

Some aspects of FEM modeling of hyperthermia, the procedure of tissue temperature rise above 37 oC inside the living organism, as a treatment modality, are studied. Low intensity focused ultrasound (LIFU) beam has been used as a source of temperature rise in the liver tissue during performed experiments in vitro. The comparison of the FEM model of the corresponding heating process and the experimental results has been presented in [1]. In the paper, the FEM model of heating scheme of the rat liver tissue in vivo irradiated by the same ultrasound transducer is formulated. At first, the existence of blood perfusion is taken into account in the model equation. Secondly, the thermal and acoustical properties, which are the input parameters of the numerical model, are taken from the published data in literature. Here, the size and the intensity of heat sources are modeled in two ways on the basis of acoustic nonlinear equation solutions in 3 layers attenuating medium. We demonstrate how the results of FEM model in the case of in vitro and in vivo heating, depend on the assumed power density of heat sources, as well as on the size of the heated area. The results are compared and discussed. The influence of different models on temperature rise profiles are demonstrated.

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
14.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

Affiliations:
Gambin B.-IPPT PAN
Kujawska T.-IPPT PAN
Kruglenko E.-IPPT PAN
Mizera A.-IPPT PAN
Nowicki A.-IPPT PAN

List of chapters in recent monographs
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
2.
219
Kruglenko E., Gambin B., Bielski W.R., Elektromagnetyczne techniki w ochronie zdrowia, rozdział: Materiały nieściśliwe magnetosprężyste jako model tkanek z mikromagnetycznymi cząstkami, CIOP PIB (Warszawa), Krawczyk A., Duraj A. (Eds.), pp.96-109, 2007
3.
179
Bielski W., Gambin B., Kruglenko E., Nonsmooth/Nonconvex Mechanics with applications in Engineering II. NNMAE206, A volume dedicated to the memory of Professor P.D.Panagiotopoulos, rozdział: Selected problems of rigid and deformable micromagnetics, ZITI, Baniotopoulos C.C. (Ed.), pp.69-76, 2006
4.
213
Gałka A., Gambin B., Kruglenko E., Bioelektromagnetyzm: teoria i praktyka, rozdział: Zagadnienie minimalizacji w analizie mikro-magnetyków nieodkształcalnych, CIOP-PIB (Warszawa), Krawczyk A., Zyss T. (Eds.), 6, pp.101-119, 2006

Conference papers
1.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

Affiliations:
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
2.Kruglenko E., Gambin B., Statistical analysis of ultrasonic signals backscattered from heated tissue phantom and soft tissue samples in vitro, FA2014, 7th FORUM ACUSTICUM 2014, 2014-09-07/09-12, Kraków (PL), No.SS27_3, pp.1-9, 2014
Abstract:

The work concerns in finding the ultrasonic characteristics of temperature changes within the heated region of two types of samples: phantom sample made from PVA (Polyvinyl Alcohol Cryogel) and soft tissues sample in vitro. We are looking for changes in the statistical parameters of the backscattered signals registered during two different heating procedures for the two types of samples. We are looking for statistical distributions describing the statistics of the signal envelope received during the experiments heating/cooling. Matching of the histogram to the different probability density functions of Rayleigh, Gamma, Nakagami and K-distribution was analyzed by calculating the mean square error. Besides, the dependence on temperature changes of characteristic parameters for considered distributions have been calculated. We conclude that the shape parameter of K-distribution is the best statistical marker of a temperature level in the performed experiments.

Keywords:

therapeutic applications, ultrasonics, medical imaging

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
3.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

Affiliations:
Karwat P.-IPPT PAN
Litniewski J.-IPPT PAN
Secomski W.-IPPT PAN
Kujawska T.-IPPT PAN
Krawczyk K.-IPPT PAN
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
Nowicki A.-IPPT PAN
4.Kruglenko E., Mizera A., Gambin B., Tymkiewicz R., Zienkiewicz B., Litniewski J., Nagrzewanie ultradźwiękami tkanek miękkich in vitro i własności akustyczne wytworzonych wzorców tkanek miękkich, 59th Open Seminar on Acoustics, 2012-09-10/09-14, Boszkowo (PL), pp.129-132, 2012
Abstract:

W pracy przedstawiono wstępne wyniki pomiaru pola temperatury wewnątrz tkanki in vitro w czasie procesu nagrzewania wiązką ultradźwiękową o słabej mocy oraz pomiaru właściwości akustycznych wzorców tkanek miękkich. Wzorce te zbudowano w celu dalszych badań nad powiązaniem wzrostu temperatury z właściwościami akustycznymi, gdyż próbki tkankowe in vitro okazały się niepowtarzalne i nietrwałe. Na wykonanych 3 wzorcach tkankowych dokonano pomiaru sygnału przejścia i wyznaczono prędkość propagacji impulsu, współczynnik tłumienia oraz zbadano statystykę rozproszenia. Przedyskutowano wpływ liczby elementów rozpraszających na te wielkości.

Keywords:

wzorce tkanek, sygnał ultradźwiękowy, prędkość dźwięku, tłumienie, statystyka rozproszenia

Affiliations:
Kruglenko E.-IPPT PAN
Mizera A.-IPPT PAN
Gambin B.-IPPT PAN
Tymkiewicz R.-IPPT PAN
Zienkiewicz B.-IPPT PAN
Litniewski J.-IPPT PAN
5.Karwat P., Litniewski J., Secomski W., Kujawska T., Krawczyk K., Kruglenko E., Gambin B., Non-invasive imaging of thermal fields induced in soft tissues in vitro by focused ultrasound using analysis of ultrasonic echoes displacement, International Conference Biomedical Engineering, 2012-10-25/10-26, Kaunas (LT), pp.66-72, 2012
Abstract:

Therapeutic and surgical applications of focused ultrasound require monitoring of local temperature rises induced inside tissues. From an economic and practical point of view ultrasonic imaging techniques seem to be the best for a temperature control. In this work an attempt to apply the method of the ultrasonic echoes displacement estimation for monitoring local temperature rises in tissues during their heating by focused ultrasound is presented. The estimated temperature rise was compared with this measured by a thermocouple. The obtained results enable to evaluate the temperature fields induced in tissues by pulsed focused ultrasonic beams using non-invasive imaging ultrasound technique.

Keywords:

HIFU, therapeutic ultrasound, ultrasonic imaging, echo strain estimation

Affiliations:
Karwat P.-IPPT PAN
Litniewski J.-IPPT PAN
Secomski W.-IPPT PAN
Kujawska T.-IPPT PAN
Krawczyk K.-IPPT PAN
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
6.Kruglenko E., Gambin B., Modelowanie numeryczne obszaru nagrzewania oraz intensywności źródła ciepła w szczurzej wątróbce in vivo naświetlanej skoncentrowaną wiązką ultradźwiękową o niskiej mocy, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.103-106, 2010
Abstract:

W pracy rozpatrzono modelowanie hipertermii, to jest procedury podwyższania temperatury powyżej 37 oC w celach terapeutycznych. Skoncentrowana wiązka ultradźwiękowa niskiej mocy była poprzednio wykorzystywana jako źródło ciepła w tkance wątroby w doświadczeniach przeprowadzanych in vitro. Do generowania impulsu wiązki ultradźwiękowej został użyty okrągły skupiający przetwornik piezoelektryczny o średnicy 15 [mm], długości ogniskowej 25 [mm] i częstotliwości rezonansowej 2 [MHz]. Eksperymentalne dane wzrostu temperatury mierzone przez termopary, zostały porównane z wynikami obliczeniowymi otrzymanymi z modelu numerycznego bazującego się na metodzie elementów skończonych. W tej pracy użyto metody elementów skończonych do obliczenia procesu nagrzewania tkanek in vivo. Po pierwsze, w modelowaniu została uwzględniona perfuzja krwi, jako ujemne źródła ciepła zależne liniowo od przyrostu temperatury. Po drugie, właściwości termiczne i akustyczne tkanki używane w modelu numerycznym zastały przyjęte z opublikowanych danych, podczas gdy rozmiar i intensywność źródeł ciepła modelowane są w zgodzie z wynikami uzyskanymi z rozwiązań nieliniowego równania propagacji fali akustycznej w trójwarstwowym ośrodku stratnym. Pokazano, że wyniki modelu numerycznego procesu nagrzewania w tkance in vivo silnie zależą od gęstości mocy cieplnej źródeł oraz od rozmiaru obszaru nagrzewania. Źródła ciepła aproksymowano numeryczne na dwa różne sposoby. Pierwszy, polegał na modelowaniu źródeł ciepła, jako jednorodnego rozkładu gęstości mocy cieplnej rozłożonej w objętości 3 cylindrów imitujących kształt wiązki akustycznej. Drugi sposób przyjmuje ciągły, niejednorodny rozkład gęstości mocy uzyskany bezpośrednio z numerycznego rozwiązania przez odpowiednio dobrane aproksymanty Padé (funkcje wymierne). Wyniki są porównywane i omówione. Pokazano wpływ różnych modeli na profile wzrostu temperatury.

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN

Conference abstracts
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
Abstract:

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?

Keywords:

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

Affiliations:
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
Keywords:

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

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Byra M.-IPPT PAN
3.Gambin B., Kruglenko E., Wojnar R., Macroscopic thermal properties of quasi-linear cellular medium on example of the liver tissue, NHT 2015, Numerical Heat Transfer 2015 – Eurotherm Seminar No. 109, 2015-09-27/09-30, Warszawa (PL), pp.177-178, 2015
Abstract:

After discovery of strong sonar systems, it was realized that the high intensity ultrasound waves can be dangerous for biological organisms. This observation led to research in tissue heating effects. The liver tissue from mathematical point of view can be considered as a micro-periodic cellular medium, and in circumstances justified by biological reasons, the mathematical methods of homogenisation developed for micro-periodic media can be applied to determine some overall properties of the tissue. Fourier’s heat diffusion term in Pennes’ equation is the point of departure in our analysis, . The liver, the largest internal organ in the human body, is connected to two large blood vessels, the hepatic artery and the portal vein. The hepatic artery carries oxygen-rich blood from the aorta, whereas the portal vein carries blood rich in digested nutrients from the entire gastrointestinal tract and also from the spleen and pancreas. These blood vessels subdivide into small capillaries known as liver sinusoids, which then lead to a lobule. A hepatic lobule is a small division of the liver defined at the histological scale. The lobules are arranged into an hexagonal lattice.
We have evaluated the dependence of effective conductivity λeff for the composite consisting of the basic cells arranged in a two-dimensional periodic system and built of the collagen capillaries filled with the water. Analytical and numerical results are going to be verified by measurement of temperature using magnetic resonance imaging (MRI) and through measurement of backscattered ultrasound waves.

Keywords:

liver tissue, Pennes’ equation, heat transport, asymptotic homogenization, effective coefficients

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Wojnar R.-IPPT PAN
4.Gambin B., Kruglenko E., Secomski W., Karwat P., Temperature dependencies of ultrasound signals backscattered from an agar-oil soft-tissue mimicking material, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.215-216, 2015
Abstract:

Tissue mimicking materials for ultrasound research, phantoms, should be acousticaly similar to the tissues. Such requirements are filled by the AGO (agar-oil) phantoms. Here, they have been used in experiment of heating internal region of samples by the high intensity ultrasound (HIFU) transducer. During heating the RF (radio frequency) ultrasound signals have been collected. It is demonstrated that the temperature changes in AGO phantoms can be described by the special properties of the backscattered RF signals, namely the shape parameter of the Nakagami distribution and SNR (signal to noise ratio) of signal envelopes random distribution. Reveal of qualitative relationships between the temperature increase/decrease measured by thermocouples and the statistical parameters changes are the main result of the paper.

Keywords:

soft tissue phantom, absorption of acoustic energy, temperature marker, signal-to-noise ratio, Nakagami distribution

Affiliations:
Gambin B.-IPPT PAN
Kruglenko E.-IPPT PAN
Secomski W.-IPPT PAN
Karwat P.-IPPT PAN
5.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

Affiliations:
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
6.Kruglenko E., Gambin B., Cieślik L., Soft tissue phantoms and back-scattered signal analysis to determine their acoustical properties, XX Conference on Acoustic and Biomedical Engineering, 2013-04-15/04-19, Zakopane (PL), pp.37-38, 2013
Abstract:

For the study of the temperature increase in the soft tissues irradiated by a lowpower ultrasound, see [1], soft tissue phantoms can be used. They should exhibit acoustic properties similar to soft tissue and being sufficiently stable during the hyperthermia treatment. Such phantoms have been produced based on an aqueous solution of agar, oil, and glass microparticles. The FR signals collected in experiments provide to obtain the acoustic properties of phantoms with different numbers of scatterers, from 0-30/mm3. Measured ultrasonic wave velocity in the phantoms is similar to the typical velocity in soft tissues and is equal about 1540 m / s. Attenuation coefficient has been determined by two methods - the pulse method, and the spectral shift method. It is changed in the range of 0.5 to 1.1 dB / (MHz cm), depending on the number of scatterers. It was verified that the patterns do not alter the parameters during 6 months in suitable conditions of storage after production and can be used for further experiments. Besides, based on the analysis of the backscattered signal from pulse/echo ultrasound the statistical properties of the signal envelope and the attenuation coefficient have been studied. It was found that within the total attenuation, the part can be distinguished corresponding to the attenuation due to Rayleigh scattering.

Keywords:

lowpower ultrasound, scatterers number,attenuation, Rayleigh scattering

Affiliations:
Kruglenko E.-IPPT PAN
Gambin B.-IPPT PAN
Cieślik L.-IPPT PAN
7.Gambin B., Kruglenko E., Kujawska T., Modelowanie procesu nagrzewania tkanek in vivo wywołanego terapeutycznymi ultradźwiękami, XVII Konferencja Inzynierii Akustycznej i Biomedycznej, 2010-03-22/03-26, Zakopane (PL), pp.88-89, 2010