Pub Date : 2024-06-19DOI: 10.1109/TUFFC.2024.3416512
Mostafa Amin Naji, Iman Taghavi, Erik Vilain Thomsen, Niels Bent Larsen, Jorgen Arendt Jensen
Velocity estimation in ultrasound imaging is a technique to measure the speed and direction of blood flow. The flow velocity in small blood vessels, i.e., arterioles, venules, and capillaries, can be estimated using super-resolution ultrasound imaging (SRUS). However, the vessel width in SRUS is relatively small compared with the full-width-half-maximum of the ultrasound beam in the elevation direction (FWHMy), which directly impacts the velocity estimation. By taking into consideration the small vessel widths in SRUS, it is hypothesized that the velocity is underestimated in 2-D super-resolution ultrasound imaging when the vessel diameter is smaller than the FWHMy. A theoretical model is introduced to show that the velocity of a 3-D parabolic velocity profile is underestimated by up to 33% in 2-D SRUS, if the width of the vessel is smaller than the FWHMy. This model was tested using Field II simulations and 3-D printed micro-flow hydrogel phantom measurements. A Verasonics Vantage 256™ scanner and a GE L8-18i-D linear array transducer with FWHMy of approximately 770 μm at the elevation focus were used in the simulations and measurements. Simulations of different parabolic velocity profiles showed that the velocity underestimation was 36.8%±1.5% (mean±standard deviation). The measurements showed that the velocity was underestimated by 30%±6.9%. Moreover, the results of vessel diameters, ranging from 0.125×FWHMy to 3×FWHMy, indicate that velocities are estimated according to the theoretical model. The theoretical model can, therefore, be used for the compensation of velocity estimates under these circumstances.
超声成像中的速度估算是一种测量血流速度和方向的技术。超分辨率超声成像(SRUS)可估算小血管(即动脉、静脉和毛细血管)中的流速。然而,与超声波束在仰角方向的全宽-半最大值(FWHMy)相比,SRUS 中的血管宽度相对较小,这直接影响了流速的估算。考虑到 SRUS 中的血管宽度较小,假设当血管直径小于 FWHMy 时,二维超分辨率超声成像中的速度会被低估。引入的理论模型表明,如果血管宽度小于 FWHMy,二维 SRUS 中三维抛物线速度曲线的速度会被低估 33%。该模型通过 Field II 仿真和三维打印微流水凝胶模型测量进行了测试。模拟和测量中使用了 Verasonics Vantage 256™ 扫描仪和 GE L8-18i-D 线性阵列换能器,在仰角焦点处的 FWHMy 约为 770 μm。对不同抛物线速度剖面的模拟显示,速度低估率为 36.8%±1.5%(平均值±标准偏差)。测量结果显示,速度被低估了 30%±6.9%。此外,血管直径从 0.125×FWHMy 到 3×FWHMy 的结果表明,速度是根据理论模型估算的。因此,在这种情况下,理论模型可用于补偿速度估计值。
{"title":"Underestimation of Flow Velocity in 2-D Super-Resolution Ultrasound Imaging.","authors":"Mostafa Amin Naji, Iman Taghavi, Erik Vilain Thomsen, Niels Bent Larsen, Jorgen Arendt Jensen","doi":"10.1109/TUFFC.2024.3416512","DOIUrl":"10.1109/TUFFC.2024.3416512","url":null,"abstract":"<p><p>Velocity estimation in ultrasound imaging is a technique to measure the speed and direction of blood flow. The flow velocity in small blood vessels, i.e., arterioles, venules, and capillaries, can be estimated using super-resolution ultrasound imaging (SRUS). However, the vessel width in SRUS is relatively small compared with the full-width-half-maximum of the ultrasound beam in the elevation direction (FWHM<sub>y</sub>), which directly impacts the velocity estimation. By taking into consideration the small vessel widths in SRUS, it is hypothesized that the velocity is underestimated in 2-D super-resolution ultrasound imaging when the vessel diameter is smaller than the FWHM<sub>y</sub>. A theoretical model is introduced to show that the velocity of a 3-D parabolic velocity profile is underestimated by up to 33% in 2-D SRUS, if the width of the vessel is smaller than the FWHM<sub>y</sub>. This model was tested using Field II simulations and 3-D printed micro-flow hydrogel phantom measurements. A Verasonics Vantage 256™ scanner and a GE L8-18i-D linear array transducer with FWHM<sub>y</sub> of approximately 770 μm at the elevation focus were used in the simulations and measurements. Simulations of different parabolic velocity profiles showed that the velocity underestimation was 36.8%±1.5% (mean±standard deviation). The measurements showed that the velocity was underestimated by 30%±6.9%. Moreover, the results of vessel diameters, ranging from 0.125×FWHM<sub>y</sub> to 3×FWHM<sub>y</sub>, indicate that velocities are estimated according to the theoretical model. The theoretical model can, therefore, be used for the compensation of velocity estimates under these circumstances.</p>","PeriodicalId":13322,"journal":{"name":"IEEE transactions on ultrasonics, ferroelectrics, and frequency control","volume":"PP ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141426796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zebrafish has been considered as an essential small-animal model for investigating the mechanism of heart regeneration. Due to the small size of zebrafish heart, high-frequency ultrasound (HFUS) imaging is often required for in vivo evaluations of its dynamic functions. Although commercial HFUS systems are available for myocardial velocity and strain measurement, only the outer myocardial region can be quantified due to the complex structure of zebrafish heart. In this study, a high-resolution 2-D myocardial tissue Doppler and strain imaging based on ultrafast HFUS imaging was developed for zebrafish heart imaging during heart regeneration. The cardiac flow region was first extracted to recognize the myocardial region, and the myocardial velocity and strain were then determined through vector Doppler estimation. Adult AB-line zebrafish was used for in vivo experiments, and cryoinjury was induced in the apical region of the heart. Both the myocardial velocity and strain of the whole ventricle after cryoinjury were directly visualized over 28 days. Myocardial velocity (during later diastolic motion) and strain, respectively, were significantly decreased (anterior wall: −2.0 mm/s and −3.3%; apical region: −2.0 mm/s and −4.5%; and posterior wall (PW): −1.7 mm/s and −4.3%) at the first three days after cryoinjury, which indicates weak myocardial beating due to heart injury. However, these all returned to the baseline values at 14 days after cryoinjury. All of the experimental results indicate that the proposed method is a useful tool for heart regeneration studies in adult zebrafish. In particular, it allows for the noninvasive evaluation of regional dynamic heart function.
{"title":"High-Resolution Tissue Doppler and Strain Imaging for Adult Zebrafish Myocardial Tissue Through Ultrafast High-Frequency Ultrasound Vector Doppler Estimation","authors":"Hsin Huang;Alexander Machikhin;De-Quan Chen;Chih-Chung Huang","doi":"10.1109/TUFFC.2024.3414856","DOIUrl":"10.1109/TUFFC.2024.3414856","url":null,"abstract":"Zebrafish has been considered as an essential small-animal model for investigating the mechanism of heart regeneration. Due to the small size of zebrafish heart, high-frequency ultrasound (HFUS) imaging is often required for in vivo evaluations of its dynamic functions. Although commercial HFUS systems are available for myocardial velocity and strain measurement, only the outer myocardial region can be quantified due to the complex structure of zebrafish heart. In this study, a high-resolution 2-D myocardial tissue Doppler and strain imaging based on ultrafast HFUS imaging was developed for zebrafish heart imaging during heart regeneration. The cardiac flow region was first extracted to recognize the myocardial region, and the myocardial velocity and strain were then determined through vector Doppler estimation. Adult AB-line zebrafish was used for in vivo experiments, and cryoinjury was induced in the apical region of the heart. Both the myocardial velocity and strain of the whole ventricle after cryoinjury were directly visualized over 28 days. Myocardial velocity (during later diastolic motion) and strain, respectively, were significantly decreased (anterior wall: −2.0 mm/s and −3.3%; apical region: −2.0 mm/s and −4.5%; and posterior wall (PW): −1.7 mm/s and −4.3%) at the first three days after cryoinjury, which indicates weak myocardial beating due to heart injury. However, these all returned to the baseline values at 14 days after cryoinjury. All of the experimental results indicate that the proposed method is a useful tool for heart regeneration studies in adult zebrafish. In particular, it allows for the noninvasive evaluation of regional dynamic heart function.","PeriodicalId":13322,"journal":{"name":"IEEE transactions on ultrasonics, ferroelectrics, and frequency control","volume":"71 8","pages":"1006-1018"},"PeriodicalIF":3.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141320779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-10DOI: 10.1109/TUFFC.2024.3411718
Hang Jung Ling, Salome Bru, Julia Puig, Florian Vixege, Simon Mendez, Franck Nicoud, Pierre-Yves Courand, Olivier Bernard, Damien Garcia
Intraventricular vector flow mapping (iVFM) seeks to enhance and quantify color Doppler in cardiac imaging. In this study, we propose novel alternatives to the traditional iVFM optimization scheme by utilizing physics-informed neural networks (PINNs) and a physics-guided nnU-Net-based supervised approach. When evaluated on simulated color Doppler images derived from a patient-specific computational fluid dynamics model and in vivo Doppler acquisitions, both approaches demonstrate comparable reconstruction performance to the original iVFM algorithm. The efficiency of PINNs is boosted through dual-stage optimization and pre-optimized weights. On the other hand, the nnU-Net method excels in generalizability and real-time capabilities. Notably, nnU-Net shows superior robustness on sparse and truncated Doppler data while maintaining independence from explicit boundary conditions. Overall, our results highlight the effectiveness of these methods in reconstructing intraventricular vector blood flow. The study also suggests potential applications of PINNs in ultrafast color Doppler imaging and the incorporation of fluid dynamics equations to derive biomarkers for cardiovascular diseases based on blood flow.
{"title":"Physics-Guided Neural Networks for Intraventricular Vector Flow Mapping.","authors":"Hang Jung Ling, Salome Bru, Julia Puig, Florian Vixege, Simon Mendez, Franck Nicoud, Pierre-Yves Courand, Olivier Bernard, Damien Garcia","doi":"10.1109/TUFFC.2024.3411718","DOIUrl":"10.1109/TUFFC.2024.3411718","url":null,"abstract":"<p><p>Intraventricular vector flow mapping (iVFM) seeks to enhance and quantify color Doppler in cardiac imaging. In this study, we propose novel alternatives to the traditional iVFM optimization scheme by utilizing physics-informed neural networks (PINNs) and a physics-guided nnU-Net-based supervised approach. When evaluated on simulated color Doppler images derived from a patient-specific computational fluid dynamics model and in vivo Doppler acquisitions, both approaches demonstrate comparable reconstruction performance to the original iVFM algorithm. The efficiency of PINNs is boosted through dual-stage optimization and pre-optimized weights. On the other hand, the nnU-Net method excels in generalizability and real-time capabilities. Notably, nnU-Net shows superior robustness on sparse and truncated Doppler data while maintaining independence from explicit boundary conditions. Overall, our results highlight the effectiveness of these methods in reconstructing intraventricular vector blood flow. The study also suggests potential applications of PINNs in ultrafast color Doppler imaging and the incorporation of fluid dynamics equations to derive biomarkers for cardiovascular diseases based on blood flow.</p>","PeriodicalId":13322,"journal":{"name":"IEEE transactions on ultrasonics, ferroelectrics, and frequency control","volume":"PP ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141300544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Super-resolution ultrasound imaging using the erythrocytes (SURE) has recently been introduced. The method uses erythrocytes as targets instead of fragile microbubbles (MBs). The abundance of erythrocyte scatterers makes it possible to acquire SURE data in just a few seconds compared with several minutes in ultrasound localization microscopy (ULM) using MBs. A high number of scatterers can reduce the acquisition time; however, the tracking of uncorrelated and high-density scatterers is quite challenging. This article hypothesizes that it is possible to detect and track erythrocytes as targets to obtain vascular flow images. A SURE tracking pipeline is used with modules for beamforming, recursive synthetic aperture (SA) imaging, motion estimation, echo canceling, peak detection, and recursive nearest-neighbor (NN) tracker. The SURE tracking pipeline is capable of distinguishing the flow direction and separating tubes of a simulated Field II phantom with 125–25- $mu text { m}$