Analysis of Coherent and Diffuse Scattering Using a Reference Phantom.
Analysis of Coherent and Diffuse Scattering Using a Reference Phantom.
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DOI：
10.1109/tuffc.2016.2547341
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
Hall TJ
中科院分区：
文献类型：
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作者：
Rosado-Mendez IM;Drehfal LC;Zagzebski JA;Hall TJ
许多基于频谱的定量超声参数的估计假设后向散射回波信号来自静止的非相干散射过程。这些假设在真实的组织中的准确性可能限制这些参数的诊断价值以及它们可以传达的关于组织微观结构的物理洞察力。这项工作提出了一个经验的决策测试，以确定显着的相干贡献回波信号的存在，以及它们是否是由低散射体数密度或存在的镜面反射体或散射体与周期性间隔。这是通过从回波信号计算参数来实现的，所述参数量化与相干散射相关的静止或非静止特征，然后将它们的值与从提供漫散射的参考材料确定的阈值进行比较。本文首先提出了一些参数与相干散射的敏感性，并描述了标准，选择那些最高的敏感性，使用模拟和基于幻影的回波数据。结果表明，回波幅度信噪比和多锥度广义谱分别是对平稳和非平稳相干散射最敏感的参数。这些参数被纳入到基于参考的决策测试，成功地确定了不同的非相干和相干散射条件下，在模拟和组织模仿幻影的区域。当检测到具有周期性组织的散射体时，固定和非固定分析的组合允许估计低于和高于由脉冲大小施加的分辨率限制的平均间距。该算法的初步应用，人类宫颈组织离体显示的B-模式图像显示明亮的反射体，组织界面，和低回声区域与区域分类为镜面反射体和低散射体数密度的区域之间的对应关系。这些结果鼓励进一步应用的算法，以更复杂的结构幻影和组织。
The estimation of many spectral-based, Quantitative Ultrasound parameters assumes that backscattered echo signals are from a stationary, incoherent scattering process. The accuracy of these assumptions in real tissue can limit the diagnostic value of these parameters and the physical insight about tissue microstructure they can convey. This work presents an empirical decision test to determine the presence of significant coherent contributions to echo signals and whether they are caused by low scatterer number densities or the presence of specular reflectors or scatterers with periodic spacing. This is achieved by computing parameters from echo signals that quantify stationary or non-stationary features related to coherent scattering, and then comparing their values to thresholds determined from a reference material providing diffuse scattering. The paper first presents a number of parameters with demonstrated sensitivity to coherent scattering and describes criteria to select those with highest sensitivity using simulated and phantom-based echo data. Results showed that the echo amplitude signal-to-noise ratio and the multitaper generalized spectrum were the parameters with highest sensitivity to coherent scattering with stationary and non-stationary features, respectively. These parameters were incorporated into the reference-based decision test, which successfully identified regions in simulated and tissue-mimicking phantoms with different incoherent and coherent scattering conditions. When scatterers with periodic organization were detected, the combination of stationary and non-stationary analysis permitted the estimation of the mean spacing below and above the resolution limit imposed by the pulse size. Preliminary applications of this algorithm to human cervical tissue ex vivo showed correspondence between regions of B-mode images showing bright reflectors, tissue interfaces, and hypoechoic regions with regions classified as specular reflectors and low scatterer number density. These results encourage further application of the algorithm to more structurally complex phantoms and tissue.