Department of Biomedical Engineering, Amirkabir University of Technology (AUT), Tehran 15875-4413, Iran.
Faculty of Medical Sciences and Technologies, Science and Research Branch, Islamic Azad University, Tehran 1477893855, Iran.
Biomed Res Int. 2018 Nov 25;2018:3438470. doi: 10.1155/2018/3438470. eCollection 2018.
Hyperelastic models have been acknowledged as constitutive equations which reliably model the nonlinear behaviors observed from soft tissues under various loading conditions. Among them, the Mooney-Rivlin, Yeoh, and polynomial models have been proved capable of accurately modeling responses of breast tissues to applied compressions. Hyperelastic elastography technique takes advantage of the disparities between hyperelastic parameters of varied tissues and the change in hyperelastic parameters in pathological processes. The precise reconstruction of hyperelastic parameters of a completely unknown pathology in the breast in a noninvasive and nondestructive way using the ultrasound elastography has been scrutinized in this paper. In the ultrasound elastography, tissue displacement field is extracted from radio frequency signals or images recorded using the ultrasound medical imaging system; hence the exact displacement field might not be obtained. Our results indicate that the parameters estimated by manipulating the iterative sensitivity-matrix based method converge to tissue's real hyperelastic parameters providing appropriate parameters are assigned to the hypothetical hyperelastic and regularization parameters. Iterative methods have therefore been proposed to compute proper hypothetical hyperelastic and regularization parameters. Accurate estimates of hyperelastic parameters of obscure breast pathology have been achieved even from imprecise measurements of displacements induced in the tissue by the ramp excitation.
超弹性模型已被公认为本构方程，能够可靠地模拟各种加载条件下软组织的非线性行为。其中，Mooney-Rivlin、Yeoh 和多项式模型已被证明能够准确模拟乳房组织对施加压缩的响应。超弹性弹性成像技术利用不同组织的超弹性参数差异以及病理过程中超弹性参数的变化。本文研究了如何利用超声弹性成像技术以非侵入性和无损的方式精确重建乳房中完全未知病变的超弹性参数。在超声弹性成像中，从射频信号或使用超声医学成像系统记录的图像中提取组织位移场；因此，可能无法获得精确的位移场。我们的结果表明，通过操纵基于迭代灵敏度矩阵的方法估计的参数会收敛到组织的真实超弹性参数，只要为假设的超弹性和正则化参数分配适当的参数。因此，已经提出了迭代方法来计算适当的假设超弹性和正则化参数。即使在通过斜坡激励引起的组织位移的测量不精确的情况下，也可以实现对模糊性乳房病变的超弹性参数的准确估计。
