Estimation of polyvinyl alcohol cryogel mechanical properties with four ultrasound elastography methods and comparison with gold standard testings
Estimation of polyvinyl alcohol cryogel mechanical properties with four ultrasound elastography methods and comparison with gold standard testings
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DOI：
10.1109/tuffc.2007.273
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发表时间：
2007-03-01
影响因子：
3.6
通讯作者：
Cloutier, Guy
中科院分区：
文献类型：
--
作者：
Fromageau, Jeremie;Gennisson, Jean-Luc;Cloutier, Guy
仿组织体模在组织定征领域非常有用，在弹性成像中用于验证运动估计器的目的是必不可少的。本研究致力于表征聚乙烯醇冻凝胶（PVA-C）的这些类型的应用。一个严格的制造程序被定义为优化具有类似弹性的体模的再现性。在机械拉伸试验后，使用体模比较四种不同弹性成像方法的准确性。这四种方法分别基于一维（I-D）比例因子估计、2-D拉格朗日散斑模型估计器（准静态弹性成像方法）的两种不同实现以及I-D剪切波瞬态弹性成像技术（动态方法）。杨氏模量作为PVA-C的冻融循环次数的函数，和声散射体的浓度进行了研究。其他机械和声学参数，如声速，剪切波速度，质量密度，泊松比也进行了评估。泊松比估计具有良好的精度在0.499的所有样品，和杨氏模量变化的范围为20 kPa的一个冻融循环到600 kPa的10个周期。然而，超过6次冻融循环后，由于样品几何结构伪影，结果不太可靠。然而，对于经历了少于7次冻融循环的样品，用四种弹性成像方法估计的杨氏模量显示出与机械拉伸试验的良好匹配，回归系数从0.97变化到1.07，相关性R-2从0.93变化到0.99，取决于方法。
Tissue-mimicking phantoms are very useful in the field of tissue characterization and essential in elastography for the purpose of validating motion estimators. This study is dedicated to the characterization of polyvinyl alcohol cryogel (PVA-C) for these types of applications. A strict fabrication procedure was defined to optimize the reproducibility of phantoms having a similar elasticity. Following mechanical stretching tests, the phantoms were used to compare the accuracy of four different elastography methods. The four methods were based on a one-dimensional (I-D) scaling factor estimation, on two different implementations of a 2-D Lagrangian speckle model estimator (quasistatic elastography methods), and on a I-D shear wave transient elastography technique (dynamic method). Young's modulus was investigated as a function of the number of freeze-thaw cycles of PVA-C, and of the concentration of acoustic scatterers. Other mechanical and acoustic parameters-such as the speed of sound, shear wave velocity, mass density, and Poisson's ratio-also were assessed. The Poisson's ratio was estimated with good precision at 0.499 for all samples, and the Young's moduli varied in a range of 20 kPa for one freeze-thaw cycle to 600 kPa for 10 cycles. Nevertheless, above six freeze-thaw cycles, the results were less reliable because of sample geometry artifacts. However, for the samples that underwent less than seven freeze-thaw cycles, the Young's moduli estimated with the four elastography methods showed good matching with the mechanical tensile tests with a regression coefficient varying from 0.97 to 1.07, and correlations R-2 varying from 0.93 to 0.99, depending on the method.