Statistical properties of estimates of signal-to-noise ratio and number of scatterers per resolution cell.
Statistical properties of estimates of signal-to-noise ratio and number of scatterers per resolution cell.
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DOI：
10.1121/1.419738
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发表时间：
1997-07
期刊：
影响因子：
--
通讯作者：
K. Wear;Robert F. Wagner;David G. Brown;Michael F. Insana
中科院分区：
文献类型：
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作者：
K. Wear;Robert F. Wagner;David G. Brown;Michael F. Insana
回顾了每个分辨率单元的散射体数目(N)与回波强度信噪比(SNR)之间关系的基本理论。导出了N和SNR2估计的概率密度函数之间的关系。这种关系是用计算机模拟来验证的。描述了体模实验和体外实验。在一组关于模体的实验中，测量了N和SNR2估计的经验分布，并与理论预测进行了比较。使用接收器工作特性(ROC)分析来评估SNR2在区分具有不同N值的模体方面的有效性。在另一组实验中，研究了双组分体模和切除狗肾的SNR2估计的频率依赖性。结果表明，信噪比的频率依赖性有助于识别空间混合的两个或多个散射分量的存在。关于肾脏数据，报告了与主要肾单位方向平行和垂直的测量结果。将观测到的各向异性与以前研究中遇到的后向散射系数的各向异性进行了比较。
Elementary theory underlying the relationship between the number of scatterers per resolution cell (N) and echo intensity signal-to-noise ratio (SNR) is reviewed. A relationship between the probability density functions for estimates of N and SNR2 is derived. This relationship is validated using a computer simulation. Phantom and in vitro experiments are described. In one set of experiments on phantoms, empirical distributions of estimates of N and SNR2 are measured and compared to theoretical predictions. The utility of SNR2 for discrimination of phantoms with different values for N is assessed using receiver operating characteristic (ROC) analysis. In another set of experiments, the frequency dependence of the SNR2 estimate is investigated for a two-component phantom and for excised dog kidney. It is shown that the frequency dependence of the SNR can help to identify the presence of two or more scattering components that are spatially mixed. With regard to kidney data, measurements performed both parallel and perpendicular to the predominant nephron orientation are reported. The observed anisotropy is compared to the anisotropy of backscatter coefficient encountered in previous investigations.