Shear wave elastography (SWE) has been used to measure viscoelastic properties for characterization of fibrotic livers. In this technique, external mechanical vibrations or acoustic radiation forces are first transmitted to the tissue being imaged to induce shear waves. Ultrasonically measured displacement/velocity is then utilized to obtain elastographic measurements related to shear wave propagation. Using an open-source wave simulator, k-Wave, we conducted a case study of the relationship between plane shear wave measurements and the microstructure of fibrotic liver tissues. Particularly, three different virtual tissue models (i.e., a histology-based model, a statistics-based model, and a simple inclusion model) were used to represent underlying microstructures of fibrotic liver tissues. We found underlying microstructures affected the estimated mean group shear wave speed (SWS) under the plane shear wave assumption by as much as 56%. Also, the elastic shear wave scattering resulted in frequency-dependent attenuation coefficients and introduced changes in the estimated group SWS. Similarly, the slope of group SWS changes with respect to the excitation frequency differed as much as 78% among three models investigated. This new finding may motivate further studies examining how elastic scattering may contribute to frequency-dependent shear wave dispersion and attenuation in biological tissues.

中文翻译：

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组织微观结构对平面剪切波弹性成像中剪切波速度测量的影响：无损纤维化肝介质的计算研究

剪切波弹性成像 (SWE) 已被用于测量粘弹性，以表征纤维化肝脏。在这种技术中，外部机械振动或声辐射力首先传输到被成像的组织以诱导剪切波。然后利用超声波测量的位移/速度来获得与剪切波传播相关的弹性测量。我们使用开源波模拟器 k-Wave 对平面剪切波测量与纤维化肝组织的微观结构之间的关系进行了案例研究。特别地，三种不同的虚拟组织模型（即基于组织学的模型、基于统计的模型和简单的包含模型）用于表示纤维化肝组织的潜在微观结构。我们发现，在平面剪切波假设下，底层微观结构对估计的平均群剪切波速度 (SWS) 的影响高达 56%。此外，弹性剪切波散射导致频率相关的衰减系数，并在估计的组 SWS 中引入了变化。同样，在研究的三个模型中，组 SWS 变化相对于激励频率的斜率差异高达 78%。这一新发现可能会激发进一步研究弹性散射如何导致生物组织中频率相关的剪切波色散和衰减。同样，在研究的三个模型中，组 SWS 变化相对于激励频率的斜率差异高达 78%。这一新发现可能会激发进一步研究弹性散射如何导致生物组织中频率相关的剪切波色散和衰减。同样，在研究的三个模型中，组 SWS 变化相对于激励频率的斜率差异高达 78%。这一新发现可能会激发进一步研究弹性散射如何导致生物组织中频率相关的剪切波色散和衰减。