Medical UltraSound Imaging Center (MUSIC), Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands.
Medical UltraSound Imaging Center (MUSIC), Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, the Netherlands.
J Biomech. 2014 Mar 3;47(4):815-23. doi: 10.1016/j.jbiomech.2014.01.015. Epub 2014 Jan 13.
Deformations of the atherosclerotic vascular wall induced by the pulsating blood can be estimated using ultrasound strain imaging. Because these deformations indirectly provide information on mechanical plaque composition, strain imaging is a promising technique for differentiating between stable and vulnerable atherosclerotic plaques. This paper first explains 1-D radial strain estimation as applied intravascularly in coronary arteries. Next, recent methods for noninvasive vascular strain estimation in a transverse imaging plane are discussed. Finally, a compounding technique that our group recently developed is explained. This technique combines motion estimates of subsequently acquired focused ultrasound images obtained at various insonification angles. However, because the artery moves and deforms during the multi-angle acquisition, errors are introduced when compounding. Recent advances in computational power have enabled plane wave ultrasound acquisition, which allows 100 times faster image acquisition and thus might resolve the motion artifacts. In this paper the performance of strain imaging using plane wave compounding is investigated using simulations of an artery with a vulnerable plaque and experimental data of a two-layered vessel phantom. The results show that plane wave compounding outperforms 0° focused strain imaging. For the simulations, the root mean squared error reduced by 66% and 50% for radial and circumferential strain, respectively. For the experiments, the elastographic signal-to-noise and contrast-to-noise ratio (SNR(e) and CNR(e)) increased with 2.1 dB and 3.7 dB radially, and 5.6 dB and 16.2dB circumferentially. Because of the high frame rate, the plane wave compounding technique can even be further optimized and extended to 3D in future.
超声应变成像可用于估计脉动血流引起的动脉粥样硬化血管壁变形。由于这些变形间接提供了关于机械斑块组成的信息，因此应变成像是区分稳定和易损斑块的有前途的技术。本文首先解释了应用于冠状动脉内的 1-D 径向应变估计。接下来，讨论了最近在横向成像平面上进行无创血管应变估计的方法。最后，解释了我们小组最近开发的一种组合技术。该技术结合了在不同照射角度下获得的随后获取的聚焦超声图像的运动估计。然而，由于动脉在多角采集期间移动和变形，因此在组合时会引入误差。计算能力的最新进展使得平面波超声采集成为可能，这使得图像采集速度快 100 倍，从而可能解决运动伪影问题。本文使用具有易损斑块的动脉的模拟和两层血管体模的实验数据研究了使用平面波复合的应变成像的性能。结果表明，平面波复合优于 0°聚焦应变成像。对于模拟，径向和周向应变的均方根误差分别降低了 66%和 50%。对于实验，弹性成像的信噪比和对比噪声比（SNR(e)和 CNR(e))径向增加了 2.1dB 和 3.7dB，周向增加了 5.6dB 和 16.2dB。由于帧率高，平面波复合技术甚至可以在未来进一步优化和扩展到 3D。
