Evaluation of Noise Reduction in Acoustic Radiation Force Elastography

描述(申请人提供)：在几种超声弹性成像方法中，对组织中剪切波传播的超声跟踪是估计组织剪切模数的关键步骤。多个位置的横波传播轨迹被用来估计横波的速度或相位。我们已经证明，由于每个位置的独立散射体集合，超声散斑可以对这些测量结果做出显著的贡献。初步数据表明，依赖于单一空间位置跟踪的技术相对不受这种噪声源的影响，并具有高空间和模数分辨率的潜力。斑点噪声的最小化减少了对空间平均的需要，并允许在较小的样本体积上以更高的精度估计剪切模数或速度。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估计。我们提出了实验来比较STL和MTL在信噪比、超声参数和剪切模数匹配的条件下所获得的模数估计的方差。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活体条件下噪音降低的幅度。

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.