Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925819
R. Jalbout, G. Cloutier, Marie-Hélène Roy-Cardinal, M. Henderson, E. Levy, C. Lapierre, G. Soulez, J. Dubois
Increased arterial stiffness is one of the first signs of atherosclerosis. The objective of this study was to use non-invasive elastography (NIVE) to detect early changes in vascular biomechanics associated with obesity in children. The NIVE algorithm also measured the intimamedia thickness (IMT) for comparison.NIVE was applied in 120 children, 60 with elevated body mass index (BMI) (≥ 85th percentile for age and sex) and 60 non-overweight (BMI < 85th percentile). Participants were randomly selected from a longitudinal cohort, evaluating consequences of obesity in healthy children with one obese parent. The carotid wall was automatically segmented and elastograms were computed to measure the cumulated axial strain (CAS), cumulated axial translation (CAT), and maximal shear strain (Max |SSE|); IMT was also computed from segmented contours. Elastogram features were compared between groups with multivariate analyses to control for age, sex, Tanner stage, blood pressure, and lowdensity lipoprotein cholesterol (LDL).After Bonferroni correction, CAT was significantly higher in the elevated BMI group (0.68 ± 0.24 mm vs. 0.52 ± 0.18 mm), p < 0.001. CAS/CAT was significantly lower in the elevated BMI group (9.54 ± 4.8 %/mm vs. 13.34 ± 6.46 %/mm), p = 0.001; the lower CAS/CAT ratio suggests stiffer arteries with less deformation for a similar translation.Before Bonferroni correction, IMT was significantly higher in the elevated BMI group (0.36 ± 0.05 mm vs. 0.32 ± 0.05 mm), p = 0.013. IMT statistical difference was no longer significant after Bonferroni correction.After Bonferroni correction, NIVE detected differences in CAT and CAS/CAT biomarkers in elevated BMI children, whereas IMT failed to show a difference. NIVE is a promising technique to monitor radiological biomarkers of subclinical atherosclerosis in the pediatric population.
动脉硬化增加是动脉粥样硬化的最初迹象之一。本研究的目的是使用无创弹性成像(NIVE)来检测儿童肥胖相关血管生物力学的早期变化。NIVE算法还测量了内膜厚度(IMT)进行比较。NIVE应用于120名儿童，其中60名体重指数(BMI)升高(年龄和性别≥85百分位数)，60名非超重(BMI < 85百分位数)。参与者从纵向队列中随机选择，评估父母一方肥胖的健康儿童的肥胖后果。自动分割颈动脉壁，计算弹性图，测量累积轴向应变(CAS)、累积轴向平移(CAT)和最大剪切应变(Max |SSE|);IMT也从分割的轮廓计算。通过多变量分析比较各组之间的弹性图特征，以控制年龄、性别、Tanner分期、血压和低密度脂蛋白胆固醇(LDL)。经Bonferroni校正后，BMI升高组CAT显著升高(0.68±0.24 mm vs 0.52±0.18 mm)， p < 0.001。BMI升高组CAS/CAT显著降低(9.54±4.8% /mm vs. 13.34±6.46% /mm)， p = 0.001;较低的CAS/CAT比值表明动脉较硬，变形较少。Bonferroni矫正前，BMI升高组IMT显著增高(0.36±0.05 mm vs. 0.32±0.05 mm)， p = 0.013。经Bonferroni校正后，IMT统计差异不再显著。在Bonferroni校正后，NIVE检测到BMI升高儿童的CAT和CAS/CAT生物标志物的差异，而IMT没有显示出差异。NIVE是一种很有前途的技术，用于监测儿童亚临床动脉粥样硬化的放射学生物标志物。
{"title":"Carotid artery non invasive elastography (NIVE) to detect early changes of cardiovascular diseases in overweight and obese children","authors":"R. Jalbout, G. Cloutier, Marie-Hélène Roy-Cardinal, M. Henderson, E. Levy, C. Lapierre, G. Soulez, J. Dubois","doi":"10.1109/ULTSYM.2019.8925819","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925819","url":null,"abstract":"Increased arterial stiffness is one of the first signs of atherosclerosis. The objective of this study was to use non-invasive elastography (NIVE) to detect early changes in vascular biomechanics associated with obesity in children. The NIVE algorithm also measured the intimamedia thickness (IMT) for comparison.NIVE was applied in 120 children, 60 with elevated body mass index (BMI) (≥ 85th percentile for age and sex) and 60 non-overweight (BMI < 85th percentile). Participants were randomly selected from a longitudinal cohort, evaluating consequences of obesity in healthy children with one obese parent. The carotid wall was automatically segmented and elastograms were computed to measure the cumulated axial strain (CAS), cumulated axial translation (CAT), and maximal shear strain (Max |SSE|); IMT was also computed from segmented contours. Elastogram features were compared between groups with multivariate analyses to control for age, sex, Tanner stage, blood pressure, and lowdensity lipoprotein cholesterol (LDL).After Bonferroni correction, CAT was significantly higher in the elevated BMI group (0.68 ± 0.24 mm vs. 0.52 ± 0.18 mm), p < 0.001. CAS/CAT was significantly lower in the elevated BMI group (9.54 ± 4.8 %/mm vs. 13.34 ± 6.46 %/mm), p = 0.001; the lower CAS/CAT ratio suggests stiffer arteries with less deformation for a similar translation.Before Bonferroni correction, IMT was significantly higher in the elevated BMI group (0.36 ± 0.05 mm vs. 0.32 ± 0.05 mm), p = 0.013. IMT statistical difference was no longer significant after Bonferroni correction.After Bonferroni correction, NIVE detected differences in CAT and CAS/CAT biomarkers in elevated BMI children, whereas IMT failed to show a difference. NIVE is a promising technique to monitor radiological biomarkers of subclinical atherosclerosis in the pediatric population.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"23 1","pages":"2214-2216"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85368652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926147
Alexander Alvarez, Cameron Wilhite, Chet Preston, Teodoro Trujillo, Alice McArthur, D. Mustacich, R. Witte
Though atrial fibrillation (AF) is a growing public health problem, electrical characterization of the disease with electrocardiography (ECG) is inadequate due to poor spatial resolution. The goal of this study was to investigate propagation of the cardiac activation wave in a healthy swine model using acoustoelectric cardiac imaging (ACI), a noninvasive mapping technology that combines ultrasound with electrical recording to overcome limitations with standard ECG. Real-time 4D ACI with a custom 2D 0.6 MHz matrix US array demonstrated conduction velocities of 2.21 m/s, validated with standard epicardial recording. ACI FWHM at a single timepoint, a measure related to the resolution of ACI in imaging the volume of activation at peak ECG signal, was 7.31 mm, 7.63 mm, and 6.23 mm in the depth, lateral, and elevational directions, respectively. SNR of ACI was 21dB at peak activation. ACI signals tracked through a 4D volume demonstrated appropriate propagation of the signal from base to apex and from endocardium to epicardium. This study demonstrated the potential for this technology to noninvasively map arrhythmias, such as AF, at high resolution.
{"title":"4D Cardiac Activation Wave Mapping in In Vivo Swine Model using Acoustoelectric Imaging","authors":"Alexander Alvarez, Cameron Wilhite, Chet Preston, Teodoro Trujillo, Alice McArthur, D. Mustacich, R. Witte","doi":"10.1109/ULTSYM.2019.8926147","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926147","url":null,"abstract":"Though atrial fibrillation (AF) is a growing public health problem, electrical characterization of the disease with electrocardiography (ECG) is inadequate due to poor spatial resolution. The goal of this study was to investigate propagation of the cardiac activation wave in a healthy swine model using acoustoelectric cardiac imaging (ACI), a noninvasive mapping technology that combines ultrasound with electrical recording to overcome limitations with standard ECG. Real-time 4D ACI with a custom 2D 0.6 MHz matrix US array demonstrated conduction velocities of 2.21 m/s, validated with standard epicardial recording. ACI FWHM at a single timepoint, a measure related to the resolution of ACI in imaging the volume of activation at peak ECG signal, was 7.31 mm, 7.63 mm, and 6.23 mm in the depth, lateral, and elevational directions, respectively. SNR of ACI was 21dB at peak activation. ACI signals tracked through a 4D volume demonstrated appropriate propagation of the signal from base to apex and from endocardium to epicardium. This study demonstrated the potential for this technology to noninvasively map arrhythmias, such as AF, at high resolution.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"93 6 1","pages":"1414-1417"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83692424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925614
Adarsh Ravi, M. Abdelmejeed, J. Kuo, A. Lal
Acousto-optic modulation at GHz frequencies is demonstrated in water in a microfluidic channel. The photoelastic effect in water is induced by a silicon based GHz bulk acoustic wave aluminum nitride transducer placed in a Fresnel lens configuration. The planar GHz ultrasonic transducer is fabricated with a CMOS compatible process with no thin-film release step enabling easier integration with CMOS and microfluidics. A UHF vibrometer which is sensitive to changes in the refractive index along the laser path is used to measure the peak surface displacement. The peak refractive index change was determined to be O(10-6), when 1.08GHz RF drive voltages between 1Vp and 5Vp were applied to the focusing transducer. Peak phase modulation of 6mrad was determined from the experimental results for 5Vp RF drive signal. The total modulator area of such a system is 0.086 mm2. This result provides a framework to implement CMOS integrated acousto-optic modulator arrays.
{"title":"Acousto-Optic Modulation of Water in a Microfluidic Channel Using Planar Fresnel Type GHz Ultrasonic Transducer","authors":"Adarsh Ravi, M. Abdelmejeed, J. Kuo, A. Lal","doi":"10.1109/ULTSYM.2019.8925614","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925614","url":null,"abstract":"Acousto-optic modulation at GHz frequencies is demonstrated in water in a microfluidic channel. The photoelastic effect in water is induced by a silicon based GHz bulk acoustic wave aluminum nitride transducer placed in a Fresnel lens configuration. The planar GHz ultrasonic transducer is fabricated with a CMOS compatible process with no thin-film release step enabling easier integration with CMOS and microfluidics. A UHF vibrometer which is sensitive to changes in the refractive index along the laser path is used to measure the peak surface displacement. The peak refractive index change was determined to be O(10-6), when 1.08GHz RF drive voltages between 1Vp and 5Vp were applied to the focusing transducer. Peak phase modulation of 6mrad was determined from the experimental results for 5Vp RF drive signal. The total modulator area of such a system is 0.086 mm2. This result provides a framework to implement CMOS integrated acousto-optic modulator arrays.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"44 1","pages":"1025-1028"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90759715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925693
L. Kang, A. Feeney, W. Somerset, Ri-liang Su, D. Lines, S. Ramadas, S. Dixon
The calculation of the averaged flow velocity along an ultrasonic path is the core step in ultrasonic transit-time flow measurement. The conventional model for calculating the path-averaged velocity does not consider the influence of the flow velocity on the propagation direction of the ultrasonic wave and can introduce error when the sound speed is not much greater than the flow velocity. To solve this problem, a new mathematical model covering the influence of the flow velocity is proposed. It has been found that the same mathematical expressions of the path-averaged flow velocity, as a function of the absolute time-of-flight (ToFs) of ultrasonic waves travelling upstream and downstream, can be derived based on either of the models. However, the expressions as a function of the time difference (the relative ToF) between the ultrasonic waves travelling upstream and downstream derived by the two models are completely different. Flow tests are conducted in a calibrated flow rig utilising air as flowing medium. Experimental results demonstrate that the path-averaged flow velocities, calculated using either the relative or the absolute ToFs based on the new model, are much more consistent and stable, whereas those calculated based on the conventional model have shown evident and increasing discrepancy when the flow velocity exceeds 15 m/s. When the flow velocity is around 39.45 m/s, the discrepancy is as high as 0.38 m/s. As the relative ToF can be more accurately, reliably and conveniently measured in real applications, the proposed mathematical model has a great potential for the increase of the accuracy of the ultrasonic transit-time flowmeters, especially for the applications such as the measurement of fluids with high flow velocities.
{"title":"A Novel Mathematical Model for Transit-time Ultrasonic Flow Measurement","authors":"L. Kang, A. Feeney, W. Somerset, Ri-liang Su, D. Lines, S. Ramadas, S. Dixon","doi":"10.1109/ULTSYM.2019.8925693","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925693","url":null,"abstract":"The calculation of the averaged flow velocity along an ultrasonic path is the core step in ultrasonic transit-time flow measurement. The conventional model for calculating the path-averaged velocity does not consider the influence of the flow velocity on the propagation direction of the ultrasonic wave and can introduce error when the sound speed is not much greater than the flow velocity. To solve this problem, a new mathematical model covering the influence of the flow velocity is proposed. It has been found that the same mathematical expressions of the path-averaged flow velocity, as a function of the absolute time-of-flight (ToFs) of ultrasonic waves travelling upstream and downstream, can be derived based on either of the models. However, the expressions as a function of the time difference (the relative ToF) between the ultrasonic waves travelling upstream and downstream derived by the two models are completely different. Flow tests are conducted in a calibrated flow rig utilising air as flowing medium. Experimental results demonstrate that the path-averaged flow velocities, calculated using either the relative or the absolute ToFs based on the new model, are much more consistent and stable, whereas those calculated based on the conventional model have shown evident and increasing discrepancy when the flow velocity exceeds 15 m/s. When the flow velocity is around 39.45 m/s, the discrepancy is as high as 0.38 m/s. As the relative ToF can be more accurately, reliably and conveniently measured in real applications, the proposed mathematical model has a great potential for the increase of the accuracy of the ultrasonic transit-time flowmeters, especially for the applications such as the measurement of fluids with high flow velocities.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"78 1","pages":"1590-1593"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91070679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926165
F. Varray, Sébastien Salles, L. Petrusca, H. Liebgott
Blood flow evaluation with ultrasound is an extremely usefull tool in the clinics in many different situations. The evaluation of the real 2D or 3D flow direction and amplitude remains an unsolved issue and a challenge to access to the full and correct flow characteristic. In this paper, an advanced 3D ultrasound system is used to estimate the 3D blood flow in an home made phantom with a laminar flow. After the acquisitions, the 3D processing of the beamformed volumes allow the creation of transverse oscillations and motion estimation in several direction to create a complex vector flow map in 3D. The obtained streamlines are coherent through the cycle and the qualitative evaluation of the flow is possible, even in direction perpendicular to the US beam axis. The proposed setup and method must be evaluated more deeply in more complex geometries, but this work demonstrates the feasibility to use such advanced system in 3D+t flow evaluation.
{"title":"3D+t Vector Flow Imaging with Transverse Oscillations and Doppler Estimator","authors":"F. Varray, Sébastien Salles, L. Petrusca, H. Liebgott","doi":"10.1109/ULTSYM.2019.8926165","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926165","url":null,"abstract":"Blood flow evaluation with ultrasound is an extremely usefull tool in the clinics in many different situations. The evaluation of the real 2D or 3D flow direction and amplitude remains an unsolved issue and a challenge to access to the full and correct flow characteristic. In this paper, an advanced 3D ultrasound system is used to estimate the 3D blood flow in an home made phantom with a laminar flow. After the acquisitions, the 3D processing of the beamformed volumes allow the creation of transverse oscillations and motion estimation in several direction to create a complex vector flow map in 3D. The obtained streamlines are coherent through the cycle and the qualitative evaluation of the flow is possible, even in direction perpendicular to the US beam axis. The proposed setup and method must be evaluated more deeply in more complex geometries, but this work demonstrates the feasibility to use such advanced system in 3D+t flow evaluation.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"34 1","pages":"344-347"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91108433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925954
Jesse Heikkilä, E. Lampsijärvi, Antti Kontiola, A. Salmi, E. Hæggström
Non-linear acoustic waves were used to excite propagating waves on a curved biological membrane. A non-contact method was used to measure the displacement of the membrane at the pickup point. The frequency content, time-of-flight, and amplitude of the wave travelling across the membrane at the measurement location were studied as a function of incidence angle of the shockwave for different pressures inside a vessel bounded by the membrane. Detecting the peak frequency of the pickup signal provided the most accurate estimate of the pressure inside the vessel.
{"title":"Non-linear-wave-based excitation of waves on a membrane","authors":"Jesse Heikkilä, E. Lampsijärvi, Antti Kontiola, A. Salmi, E. Hæggström","doi":"10.1109/ULTSYM.2019.8925954","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925954","url":null,"abstract":"Non-linear acoustic waves were used to excite propagating waves on a curved biological membrane. A non-contact method was used to measure the displacement of the membrane at the pickup point. The frequency content, time-of-flight, and amplitude of the wave travelling across the membrane at the measurement location were studied as a function of incidence angle of the shockwave for different pressures inside a vessel bounded by the membrane. Detecting the peak frequency of the pickup signal provided the most accurate estimate of the pressure inside the vessel.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"107 6 1","pages":"166-169"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89706493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926143
C. Seok, Ziad Ali, F. Y. Yamaner, Ömer Oralkan
Interconnecting the inner elements of a densely populated ultrasonic transducer array with electronics poses a great challenge when pads are located in the inner area such that they are not easily accessible or wire bonding is not a viable solution. To tackle that challenge, we propose the technique of front-side flip-chip bonding capacitive micromachined ultrasonic transducer (CMUT) arrays to flexible printed circuit boards (FPCBs). As the propagation through the flex material can cause signal attenuation, we measured the pressure reduction for a reference transducer and an experimental CMUT and observed that the reference underwent a 19% pressure reduction while the experimental CMUT experienced a 33% pressure reduction after transmission through the flex. We argue that the difference can be partly attributed to inappropriate underfill in the interface between the CMUT and the FPCB. The proposed packaging approach can potentially provide a versatile interconnecting scheme for densely populated small transducers required in applications such as ultrasound neuromodulation.
{"title":"Ultrasound Transmission through a Flexible Printed Circuit Board Bonded to the Front Side of a Capacitive Micromachined Ultrasonic Transducer Array: Feasibility Study","authors":"C. Seok, Ziad Ali, F. Y. Yamaner, Ömer Oralkan","doi":"10.1109/ULTSYM.2019.8926143","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926143","url":null,"abstract":"Interconnecting the inner elements of a densely populated ultrasonic transducer array with electronics poses a great challenge when pads are located in the inner area such that they are not easily accessible or wire bonding is not a viable solution. To tackle that challenge, we propose the technique of front-side flip-chip bonding capacitive micromachined ultrasonic transducer (CMUT) arrays to flexible printed circuit boards (FPCBs). As the propagation through the flex material can cause signal attenuation, we measured the pressure reduction for a reference transducer and an experimental CMUT and observed that the reference underwent a 19% pressure reduction while the experimental CMUT experienced a 33% pressure reduction after transmission through the flex. We argue that the difference can be partly attributed to inappropriate underfill in the interface between the CMUT and the FPCB. The proposed packaging approach can potentially provide a versatile interconnecting scheme for densely populated small transducers required in applications such as ultrasound neuromodulation.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"34 1","pages":"853-856"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89760850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8925571
Andres Coila, M. Oelze
The attenuation coefficient (AC) has demonstrated the ability to classify tissue state. Linear acoustic propagation is assumed when estimating the AC using spectral-based methods from the ultrasonic backscatter. However, the effects of acoustic nonlinearities can distort the backscattered power spectra versus depth. The distortion of the power spectra could result in a bias in the estimation of the AC. The goal of the study was to quantify the effects of nonlinear distortion on the estimation of AC from ultrasonic backscatter using spectral methods. We computed the AC from backscattered signals using the spectral log difference method and a reference phantom to account for diffraction effects. Computational simulations and experiments in phantoms were performed. In the experiments, three tissue-mimicking phantoms, named A, B and C having estimated AC values of 0.60, 0.90, and 0.20 dB/cm/MHz, respectively, and B/A ≈ 6.6 for each phantom were scanned using a single-element focused transducer (f/2) having a 0.5" diameter and 5-MHz center frequency. The phantoms were scanned using six excitation levels from a high-power (HP) pulsing apparatus (RAM-5000, Ritec, USA). The AC was estimated from phantom A using either phantom B (high attenuation) or phantom C (low attenuation) as the reference. The AC was estimated at each excitation level over the analysis bandwidth (− 6-dB criterion) to determine the effects of acoustic nonlinearity on estimation of AC. The presence of nonlinear distortion can be quantified through the Gol’dberg number, which is inversely proportional to the product of the nonlinearity coefficient and attenuation. We hypothesized that because the B/A values were approximately the same for each phantom, the effects of nonlinear distortion would be more pronounced when using phantom C, which had much lower attenuation. Specifically, increased excess attenuation due to transfer of energy from the fundamental to the harmonics would be observed more in phantom C. The AC estimate increased from 0.57 to 0.67 dB/cm/MHz as the excitation levels increased from level one to six when using phantom B as a reference. In contrast, when using phantom C as reference, the estimated AC slope of phantom A decreased from 0.57 to 0.43 dB/cm/MHz as the excitation levels increased from level one to six. Therefore, use of a reference with different attenuation resulted in increased bias of AC estimates due to nonlinear distortion being this deviation larger when using low attenuating media.
{"title":"Effects of Acoustic Nonlinearities on the Estimation of Attenuation from Ultrasonic Backscatter","authors":"Andres Coila, M. Oelze","doi":"10.1109/ULTSYM.2019.8925571","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8925571","url":null,"abstract":"The attenuation coefficient (AC) has demonstrated the ability to classify tissue state. Linear acoustic propagation is assumed when estimating the AC using spectral-based methods from the ultrasonic backscatter. However, the effects of acoustic nonlinearities can distort the backscattered power spectra versus depth. The distortion of the power spectra could result in a bias in the estimation of the AC. The goal of the study was to quantify the effects of nonlinear distortion on the estimation of AC from ultrasonic backscatter using spectral methods. We computed the AC from backscattered signals using the spectral log difference method and a reference phantom to account for diffraction effects. Computational simulations and experiments in phantoms were performed. In the experiments, three tissue-mimicking phantoms, named A, B and C having estimated AC values of 0.60, 0.90, and 0.20 dB/cm/MHz, respectively, and B/A ≈ 6.6 for each phantom were scanned using a single-element focused transducer (f/2) having a 0.5\" diameter and 5-MHz center frequency. The phantoms were scanned using six excitation levels from a high-power (HP) pulsing apparatus (RAM-5000, Ritec, USA). The AC was estimated from phantom A using either phantom B (high attenuation) or phantom C (low attenuation) as the reference. The AC was estimated at each excitation level over the analysis bandwidth (− 6-dB criterion) to determine the effects of acoustic nonlinearity on estimation of AC. The presence of nonlinear distortion can be quantified through the Gol’dberg number, which is inversely proportional to the product of the nonlinearity coefficient and attenuation. We hypothesized that because the B/A values were approximately the same for each phantom, the effects of nonlinear distortion would be more pronounced when using phantom C, which had much lower attenuation. Specifically, increased excess attenuation due to transfer of energy from the fundamental to the harmonics would be observed more in phantom C. The AC estimate increased from 0.57 to 0.67 dB/cm/MHz as the excitation levels increased from level one to six when using phantom B as a reference. In contrast, when using phantom C as reference, the estimated AC slope of phantom A decreased from 0.57 to 0.43 dB/cm/MHz as the excitation levels increased from level one to six. Therefore, use of a reference with different attenuation resulted in increased bias of AC estimates due to nonlinear distortion being this deviation larger when using low attenuating media.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"15 1","pages":"2416-2419"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90527012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926164
A. Demčenko, C. Witte, J. Reboud, J. Cooper
In this study we show that nonlinear ultrasonics, based on nonlinear wave mixing, can enable the measurement of the interactions between acoustic waves and a microliter liquid sample in a glass capillary microchannel. This has the potential to deliver new techniques with a high sensitivity to acoustic material properties.
{"title":"Ultrasonic Wave Mixing for Nonlinear Ultrasonics in a Microfluidic Capillary","authors":"A. Demčenko, C. Witte, J. Reboud, J. Cooper","doi":"10.1109/ULTSYM.2019.8926164","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926164","url":null,"abstract":"In this study we show that nonlinear ultrasonics, based on nonlinear wave mixing, can enable the measurement of the interactions between acoustic waves and a microliter liquid sample in a glass capillary microchannel. This has the potential to deliver new techniques with a high sensitivity to acoustic material properties.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"21 1","pages":"284-286"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73548007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ULTSYM.2019.8926267
Akiyo Fukase, Kanta Nagasawa, Shohei Mori, M. Arakawa, S. Yashiro, Yasushi Ishigaki, H. Kanai
High blood glucose level (BGL) is related to the high viscosity of blood. Red blood cells (RBCs) tend to gather each other in the condition of high viscosity. Backscattered echoes become high as RBCs aggregate. Therefore, the intensity of backscattered echo is anticipated to be high as the BGL increases. In the present study, we investigated the relationship between RBC aggregations by ultrasound and the BGL for the development of non-invasive BGL measurement methods. Ultrasonic backscattering echoes for dorsal hand vein and BGLs were repeatedly measured from fasting to 190 min after injecting 40-g glucose for a healthy subject. The brightness of the B-mode image increased as the BGL increased. The brightnesses of B-mode image and the BGLs after 160-190 min were less than those at fasting. The relationship between the brightness of the B-mode image and BGL was almost linear, although the hysteresis characteristic was observed. This is because multiple factors other than BGL are closely related to the RBC aggregations.
{"title":"Correlation between Red Blood Cell Aggregation and Blood Glucose Level","authors":"Akiyo Fukase, Kanta Nagasawa, Shohei Mori, M. Arakawa, S. Yashiro, Yasushi Ishigaki, H. Kanai","doi":"10.1109/ULTSYM.2019.8926267","DOIUrl":"https://doi.org/10.1109/ULTSYM.2019.8926267","url":null,"abstract":"High blood glucose level (BGL) is related to the high viscosity of blood. Red blood cells (RBCs) tend to gather each other in the condition of high viscosity. Backscattered echoes become high as RBCs aggregate. Therefore, the intensity of backscattered echo is anticipated to be high as the BGL increases. In the present study, we investigated the relationship between RBC aggregations by ultrasound and the BGL for the development of non-invasive BGL measurement methods. Ultrasonic backscattering echoes for dorsal hand vein and BGLs were repeatedly measured from fasting to 190 min after injecting 40-g glucose for a healthy subject. The brightness of the B-mode image increased as the BGL increased. The brightnesses of B-mode image and the BGLs after 160-190 min were less than those at fasting. The relationship between the brightness of the B-mode image and BGL was almost linear, although the hysteresis characteristic was observed. This is because multiple factors other than BGL are closely related to the RBC aggregations.","PeriodicalId":6759,"journal":{"name":"2019 IEEE International Ultrasonics Symposium (IUS)","volume":"192 1","pages":"45-47"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75072637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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