Fast and precise noninvasive evaluation of tissue mechanical properties is of high importance in ultrasound shear wave elastography. In this study, we present an updated, faster version of the local phase velocity-based imaging (LPVI) method used to create images of local phase velocity in soft tissues. The updated LPVI implementation uses 1-D Fourier transforms in spatial dimensions separately in comparison to its original implementation. A directional filter is applied upon the shear wave field to extract the left-to-right (LR) and right-to-left (RL) propagating shear waves. A local shear wave phase velocity map is recovered based on both LR and RL waves. Finally, a 2-D shear wave velocity map is reconstructed by combining the LR and RL phase velocity maps. LPVI performance for shear wave displacement and velocity-wave motion data is examined. A study of LPVI used for only one data acquisition with multiple focused ultrasound push beams is presented. The lesion placement with respect to the pushes and whether two sequential pushes provided different results from two simultaneous radiation force pushes was investigated. The addition of white Gaussian noise to the wave motion data was also tested to examine the LPVI method's performance. Robust and accurate shear wave phase velocity maps are reconstructed using the proposed LPVI method using numerical tissue-mimicking phantoms with inclusions. Results from the numerical phantom study showed that the reconstructed, asymmetric inclusions, for various axial locations, are better preserved for shear wave particle velocity signals compared with particle displacement motion data.

中文翻译：

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基于快速局部相位速度的成像：剪切波粒子速度和位移运动研究。

在超声剪切波弹性成像中，快速准确的组织力学性能的无创评估非常重要。在这项研究中，我们提出了一种基于局部相速度的成像（LPVI）方法的更新，更快的版本，该方法用于在软组织中创建局部相速度的图像。与原始实现相比，更新后的LPVI实现在空间维度上分别使用了一维傅立叶变换。在剪切波场上应用定向滤波器，以提取从左向右（LR）和从右向左（RL）传播的剪切波。同时基于LR和RL波恢复局部剪切波相速度图。最后，通过组合LR和RL相速度图，重建了二维剪切波速度图。考察了LPVI在剪切波位移和速度波运动数据方面的性能。提出了一种LPVI的研究，该LPVI仅用于具有多个聚焦超声推力束的一个数据采集。研究了相对于推动的病变位置以及两次连续推动是否从两次同时辐射力推动提供了不同的结果。还测试了将白高斯噪声添加到波动数据中以检查LPVI方法的性能。鲁棒和准确的剪切波相速度图是使用拟议的LPVI方法使用数字化组织模拟体模（包含）重建的。数值幻象研究的结果表明，与粒子位移运动数据相比，对于剪切波粒子速度信号，在各个轴向位置重建的非对称夹杂物保留得更好。