Department of Electrical and Computer Engineering, University of Rochester, 724 Computer Studies Building, PO Box 270231, Rochester, NY 14627, United States of America.
Phys Med Biol. 2021 Aug 23;66(17). doi: 10.1088/1361-6560/ac1b37.
Reverberant shear wave fields are produced when multiple sources and multiple reflections establish a complex three-dimensional wave field within an organ. The expected values are assumed to be isotropic across all directions and the autocorrelation functions for velocity are expressed in terms of spherical Bessel functions. These results provide the basis for adroit implementations of elastography from imaging systems that can map out the internal velocity or displacement of tissues during reverberant field excitations. By examining the phase distribution of the reverberant field, additional estimators can be derived. In particular, we demonstrate that the reverberantis shown to be proportional to the local value of wavenumber. This phase estimator is less sensitive to imperfections in the reverberant field distribution and requires a smaller support window, relative to earlier estimators based on autocorrelation. Applications are shown in simulations, phantoms, andliver.
当多个声源和多次反射在器官内建立复杂的三维波场时，会产生混响剪切波场。假设各向同性的期望值在所有方向上都是各向同性的，并且速度的自相关函数用球贝塞尔函数表示。这些结果为能够在混响场激励期间绘制组织内部速度或位移的成像系统从弹性成像中提供了巧妙的实现基础。通过检查混响场的相位分布，可以推导出其他估计量。特别是，我们证明了混响与局部波数值成正比。与基于自相关的早期估计量相比，这个相位估计量对混响场分布的不完美性不太敏感，并且需要更小的支持窗口。在模拟、体模和肝脏中展示了应用。
