论文标题
与剪切波的大声弹性衰减的组织粘弹性的非线性表征
Nonlinear Characterization of Tissue Viscoelasticity with Acoustoelastic Attenuation of Shear-Waves
论文作者
论文摘要
剪切波弹性图（SWE）测量剪切波速度（SWS），该速度与软组织的基础剪切模量有关。 SWE方法通常假定软组织粘弹性与机械载荷无关，但是，已知软组织具有粘弹性，并且随着预压缩而非线性地改变。因此，仅通过SWS的表征是不足的，可以将非线性特性视为混杂因素，但也可以用作附加的生物标志物。培养基的粘弹性具有其储存和损失模量，与SWS和剪切波衰减有关（SWA）。在这项工作中，我们研究了SWA特性是应用应变的函数，以测量软组织中的非线性粘弹性参数。为此，我们在测量SWS和SWA的同时，在样品上应用递增的准静态压缩，我们从中得出存储和损耗模量来估算非线性粘弹性参数，该参数是使用Acoustoytoyalastic（AE）理论的施加菌株的函数。模拟组织的幻象具有不同的油百分比和前体猪肝实验的结果证明了所提出的方法的可行性。在这两个实验中，都观察到SWA随着施加的应变而降低。对于10％的前体肝压缩，剪切波衰减平均下降了28％（93 NP/m），而SWS平均增加了20％（0.26 m/s）。
Shear-wave elastography (SWE) measures shear-wave speed (SWS), which is related to the underlying shear modulus of soft tissue. SWE methods generally assume that soft tissue viscoelasticity is independent of mechanical loading, however, soft tissues are known to have viscoelasticity changing nonlinearly with pre-compression. Hence, characterization by SWS alone is insufficient, where nonlinear properties can be seen as confounders but may also be utilized as additional bio-markers. The viscoelastic nature of a medium is fully characterized by its storage and loss moduli, which are related to SWS and shear-wave attenuation (SWA). In this work, we study SWA characteristics as a function of applied strain to measure nonlinear viscoelastic parameters in soft tissues. For this purpose, we apply incremental quasi-static compression on the samples while measuring SWS and SWA, from which we derive storage and loss moduli to estimate nonlinear viscoelastic parameters as a function of applied strain using acoustoelasticity (AE) theory. Results from tissue-mimicking phantoms with varying oil percentages and ex-vivo porcine liver experiments demonstrate the feasibility of the proposed approach. In both these experiments, SWA was observed to decrease with applied strain. For 10 % compression in ex-vivo livers, shear-wave attenuation decreased on average by 28 % (93 Np/m), while SWS increased on average by 20 % (0.26 m/s).
