Evaluation of Noise Reduction in Acoustic Radiation Force Elastography

描述（由申请人提供）：超声跟踪剪切波在组织中的传播是几种超声弹性成像方法中估计组织剪切模量的关键步骤。对横波在多个位置的传播进行跟踪，以估计横波的速度或相位。我们已经表明，超声散斑可以贡献显著方差这些测量，作为独立的散射集在每个位置的结果。初步数据表明，依赖于单个空间位置跟踪的技术相对不受该噪声源的影响，并具有高空间和模量分辨率的潜力。最小化散斑噪声减少了对空间平均的需求，并允许在较小的样本量上以更好的精度估计剪切模量或速度。我们假设，对于给定的空间分辨率要求，在单个位置（STL）跟踪的方法比在多个位置（MTL）跟踪的方法产生更低的模量估计。我们提出在信噪比、超声参数和剪切模量相匹配的条件下，比较STL和MTL得到的模量估计的方差。将在组织模拟模型和肝纤维化大鼠模型中进行测量，以确定在组织异质性增加的体内条件下降噪的幅度。

DESCRIPTION (provided by applicant): Ultrasonic tracking of shear wave propagation in tissue is a key step in the estimation of tissue shear modulus in several methods of ultrasound elastography. Tracking of shear wave propagation at multiple locations is used to estimate shear wave velocity or phase. We have shown that ultrasound speckle can contribute a significant variance to these measurements, as a consequence of the independent scatterer sets at each location. Preliminary data indicates that techniques which rely on tracking at a single spatial location are relatively immune to this noise source and hold the potential for highe spatial and modulus resolution. Minimizing speckle noise reduces the need for spatial averaging and allows shear modulus or velocity to be estimated with better precision over a smaller sample volume. We hypothesize that, for a given spatial resolution requirement, methods that track at a single location (STL) produce lower modulus estimates than those that track at multiple locations (MTL). We propose experiments to compare the variance of modulus estimates obtained by STL and MTL under matched conditions of SNR, ultrasound parameters, and shear modulus. Measurements will be performed in tissue mimicking phantoms and in a rat model of liver fibrosis to establish the magnitude of noise reduction under in vivo conditions of increasing tissue heterogeneity.