Jerzy Litniewski | Polish Academy of Sciences (original) (raw)

Papers by Jerzy Litniewski

The parametric imaging can enhance ultrasonic examinations that are widely used in medical diagno... more 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 ...

Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitor... more Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitoring of local temperature rises induced inside tissues. It is needed to appropriately target the focal plane, and hence the whole focal volume inside the tumor tissue, prior to thermo-ablative treatment, and the beginning of tissue necrosis. In this study we present an ultrasound method, which calculates the variations of the speed of sound in the locally heated tissue. Changes in velocity correspond to temperature change. The method calculates a 2D distribution of changes in the sound velocity, by estimation of the local phase shifts of RF echo-signals backscattered from the heated tissue volume (the focal volume of the HIFU beam), and received by an ultrasound scanner (23). The technique enabled temperature imaging of the heated tissue volume from the very inception of heating. The results indicated that the contrast sensitivity for imaging of relative changes in the sound speed was on the order of 0.06%; corresponding to an increase in the tissue temperature by about 2 °C.

Ultrasonic imaging and tissue characterization is a noninvasive technique widely used in medicine... more Ultrasonic imaging and tissue characterization is a noninvasive technique widely used in medicine for many years to assess body conditions. However, the expertise required to operate the equipment and interpret the results is not always available. The medical ultrasonography project is developing a system concept for a remotely steerable, multibeam ultrasonic scanner that can be operated by skilled medical personnel. The properly chosen ultrasonic sensor and duration of signal play an important role in ultrasonography. The choice of the ultrasonic sensor is influenced by a variety of parameters among which are: type and frequency of the signal, spectrum width of the signal, which in turn depend on the environment and object under consideration. The most frequently used signals are short sine burst, Barker code, chirp signal and Golay sequences. Each signal has its own IHDWXUHV DQG SHFXOLDULWLHV WKDW GLVWLQJXLVK LW IURP WKH RWKHUV DQG FRQVLGHUDEO\ GHWHUPLQH WKH VHQVRU¶V properties.

The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images toge... more The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images together with appropriate RF echoes fro m the pathological and healthy breasts regions of patients with diagnosed malignan t and benign breast lesions. The RF data were processed for the statistics of the backs c ttered 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 maligna nt and healthy tissues showed, that in 80% of examined cases the v alu s 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 disting uish the fibroadenoma from the other with probability of 75%.

The purpose of this study was to evaluate the accuracy of statistical properties of the backscatt... more The purpose of this study was to evaluate the accuracy of statistical properties of the backscattered 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 was 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 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, quantitative sonography is a method which has potential to be a complementary tool for classification of the breast lesions.

Archives of Acoustics, 2008

This study investigates a new composing method of double transmission of short coded sequences ba... more 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.

Archives of Acoustics, 2009

The attenuating properties of biological tissue are of great importance in ultrasonic examination... more 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.

An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compr... more 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.

The issue of maximizing penetration depth with concurrent retaining or enhancement of image resol... more The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Code (CGS) was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Computer simulation results for CGS pulse compression are presented. Next three different methods and algorithms used to calculate the pairs of Golay sequences of the different length are described. Experimental results are presented in the form, which in clear way illustrates the resolution, signal...

This study concerns the development and investigation of a new composing method of short coded se... more 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 de...

Bulletin of the Polish Academy of Sciences, Technical Sciences

The issue of maximizing penetration depth with concurrent retaining or enhancement of image resol... more The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Sequences (CGS) Code was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Experimental data indicate that the quality — resolution, signal penetration and contrast dynamics — of CGS images is better than the one obtain for standard ultrasonography using short burst excitation.

Ultrasonography (USG) is a widespread and powerful tool used successfully in modern diagnostics. ... more 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 com...

Signals scattered in trabecular bone contain information about properties of the bone structure. ... more 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 f...

Acoustical waves scattered in trabecular bone contain information about its microstructural prope... more 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) in vivo. 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 a...

Archives of Acoustics, 2015

Therapeutic and surgical applications of focused ultrasound require monitoring of local temperatu... more 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 most suitable for the temperature control. This paper presents an implementation of the ultrasonic echoes displacement estimation technique for monitoring of local temperature rise in tissue during its heating by focused ultrasound The results of the estimation were compared to the temperature measured with thermocouple. The obtained results enable to evaluate the temperature fields induced in tissues by pulsed focused ultrasonic beams using non-invasive imaging ultrasound technique

Archives of Acoustics, 2010

A trabecular bone consists of trabeculae whose mechanical properties differ significantly from th... more 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.

Physics Procedia, 2010

The paper describes the computer simulations allowing investigating the properties of the ultraso... more 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.

Acoustical Imaging, 2012

The paper presents the classification of the healthy skin and the skin lesions (basal cell carcin... more The paper presents the classification of the healthy skin and the skin lesions (basal cell carcinoma and actinic keratosis), basing on the statistical parameters of the envelope of ultrasonic echoes. The envelope was modeled using Rayleigh and non-Rayleigh (K-distribution) statistics. Furthermore, the characteristic parameter of the K-distribution, the effective number of scaterrers was investigated. Also the attenuation coefficient was used for the skin lesion assessment. The comparison of the results obtained for the region of skin where the pathological states were diagnosed with the results obtained for healthy skin has shown differences in the values of attenuation coefficient and effective number of scatterers (M). The attenuation coefficient was higher in the case of pathological state of the skin. The effective number of scatterers, obtained for the skin cancer was lower comparing to the value obtained for healthy skin. No differences were found in the values of M parameters calculated for healthy skin and precancerous state. The results, indicate that the combination of quantitative ultrasound parameters, has the potential for extracting information useful for the skin conditions characterization.

Acoustical Imaging, 2007

Coded ultrasonography is intensively studied in many laboratories due to its remarkable propertie... more Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties; increased penetration depth, signal to noise (SNR) gain and improved axial resolution. However, no data concerning the spatial behavior of the pressure field generated by coded bursts transmissions were yet reported. This work reports the results of investigations using five different excitations schemes: two and sixteen periods

IEEE Symposium on Ultrasonics, 2003

The use of coded signals in medical ultrasound allows both frequency and penetration depth to be ... more The use of coded signals in medical ultrasound allows both frequency and penetration depth to be increased while retaining image resolution and avoiding the need to augment the transmitted peak pressure amplitude. Such approach minimizes the potential for bioeffects even if the average transmitted energy is increased. The goal of this work was to examine noise immunity and the bandwidth requirements of Golay coded waves used to determine frequency dependent attenuation of highly absorbing and scattering biological tissues such as bones.

The parametric imaging can enhance ultrasonic examinations that are widely used in medical diagno... more 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 ...

Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitor... more Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitoring of local temperature rises induced inside tissues. It is needed to appropriately target the focal plane, and hence the whole focal volume inside the tumor tissue, prior to thermo-ablative treatment, and the beginning of tissue necrosis. In this study we present an ultrasound method, which calculates the variations of the speed of sound in the locally heated tissue. Changes in velocity correspond to temperature change. The method calculates a 2D distribution of changes in the sound velocity, by estimation of the local phase shifts of RF echo-signals backscattered from the heated tissue volume (the focal volume of the HIFU beam), and received by an ultrasound scanner (23). The technique enabled temperature imaging of the heated tissue volume from the very inception of heating. The results indicated that the contrast sensitivity for imaging of relative changes in the sound speed was on the order of 0.06%; corresponding to an increase in the tissue temperature by about 2 °C.

Ultrasonic imaging and tissue characterization is a noninvasive technique widely used in medicine... more Ultrasonic imaging and tissue characterization is a noninvasive technique widely used in medicine for many years to assess body conditions. However, the expertise required to operate the equipment and interpret the results is not always available. The medical ultrasonography project is developing a system concept for a remotely steerable, multibeam ultrasonic scanner that can be operated by skilled medical personnel. The properly chosen ultrasonic sensor and duration of signal play an important role in ultrasonography. The choice of the ultrasonic sensor is influenced by a variety of parameters among which are: type and frequency of the signal, spectrum width of the signal, which in turn depend on the environment and object under consideration. The most frequently used signals are short sine burst, Barker code, chirp signal and Golay sequences. Each signal has its own IHDWXUHV DQG SHFXOLDULWLHV WKDW GLVWLQJXLVK LW IURP WKH RWKHUV DQG FRQVLGHUDEO\ GHWHUPLQH WKH VHQVRU¶V properties.

The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images toge... more The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images together with appropriate RF echoes fro m the pathological and healthy breasts regions of patients with diagnosed malignan t and benign breast lesions. The RF data were processed for the statistics of the backs c ttered 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 maligna nt and healthy tissues showed, that in 80% of examined cases the v alu s 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 disting uish the fibroadenoma from the other with probability of 75%.

The purpose of this study was to evaluate the accuracy of statistical properties of the backscatt... more The purpose of this study was to evaluate the accuracy of statistical properties of the backscattered 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 was 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 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, quantitative sonography is a method which has potential to be a complementary tool for classification of the breast lesions.

Archives of Acoustics, 2008

This study investigates a new composing method of double transmission of short coded sequences ba... more 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.

Archives of Acoustics, 2009

The attenuating properties of biological tissue are of great importance in ultrasonic examination... more 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.

An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compr... more 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.

The issue of maximizing penetration depth with concurrent retaining or enhancement of image resol... more The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Code (CGS) was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Computer simulation results for CGS pulse compression are presented. Next three different methods and algorithms used to calculate the pairs of Golay sequences of the different length are described. Experimental results are presented in the form, which in clear way illustrates the resolution, signal...

This study concerns the development and investigation of a new composing method of short coded se... more 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 de...

Bulletin of the Polish Academy of Sciences, Technical Sciences

The issue of maximizing penetration depth with concurrent retaining or enhancement of image resol... more The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Sequences (CGS) Code was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Experimental data indicate that the quality — resolution, signal penetration and contrast dynamics — of CGS images is better than the one obtain for standard ultrasonography using short burst excitation.

Ultrasonography (USG) is a widespread and powerful tool used successfully in modern diagnostics. ... more 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 com...

Signals scattered in trabecular bone contain information about properties of the bone structure. ... more 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 f...

Acoustical waves scattered in trabecular bone contain information about its microstructural prope... more 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) in vivo. 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 a...

Archives of Acoustics, 2015

Therapeutic and surgical applications of focused ultrasound require monitoring of local temperatu... more 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 most suitable for the temperature control. This paper presents an implementation of the ultrasonic echoes displacement estimation technique for monitoring of local temperature rise in tissue during its heating by focused ultrasound The results of the estimation were compared to the temperature measured with thermocouple. The obtained results enable to evaluate the temperature fields induced in tissues by pulsed focused ultrasonic beams using non-invasive imaging ultrasound technique

Archives of Acoustics, 2010

A trabecular bone consists of trabeculae whose mechanical properties differ significantly from th... more 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.

Physics Procedia, 2010

The paper describes the computer simulations allowing investigating the properties of the ultraso... more 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.

Acoustical Imaging, 2012

The paper presents the classification of the healthy skin and the skin lesions (basal cell carcin... more The paper presents the classification of the healthy skin and the skin lesions (basal cell carcinoma and actinic keratosis), basing on the statistical parameters of the envelope of ultrasonic echoes. The envelope was modeled using Rayleigh and non-Rayleigh (K-distribution) statistics. Furthermore, the characteristic parameter of the K-distribution, the effective number of scaterrers was investigated. Also the attenuation coefficient was used for the skin lesion assessment. The comparison of the results obtained for the region of skin where the pathological states were diagnosed with the results obtained for healthy skin has shown differences in the values of attenuation coefficient and effective number of scatterers (M). The attenuation coefficient was higher in the case of pathological state of the skin. The effective number of scatterers, obtained for the skin cancer was lower comparing to the value obtained for healthy skin. No differences were found in the values of M parameters calculated for healthy skin and precancerous state. The results, indicate that the combination of quantitative ultrasound parameters, has the potential for extracting information useful for the skin conditions characterization.

Acoustical Imaging, 2007

Coded ultrasonography is intensively studied in many laboratories due to its remarkable propertie... more Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties; increased penetration depth, signal to noise (SNR) gain and improved axial resolution. However, no data concerning the spatial behavior of the pressure field generated by coded bursts transmissions were yet reported. This work reports the results of investigations using five different excitations schemes: two and sixteen periods

IEEE Symposium on Ultrasonics, 2003

The use of coded signals in medical ultrasound allows both frequency and penetration depth to be ... more The use of coded signals in medical ultrasound allows both frequency and penetration depth to be increased while retaining image resolution and avoiding the need to augment the transmitted peak pressure amplitude. Such approach minimizes the potential for bioeffects even if the average transmitted energy is increased. The goal of this work was to examine noise immunity and the bandwidth requirements of Golay coded waves used to determine frequency dependent attenuation of highly absorbing and scattering biological tissues such as bones.