Characterization of Transverse Isotropy in Compressed Tissue-Mimicking Phantoms
Characterization of Transverse Isotropy in Compressed Tissue-Mimicking Phantoms
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DOI：
10.1109/tuffc.2014.006847
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发表时间：
2015-06-01
影响因子：
3.6
通讯作者：
Greenleaf, James F.
中科院分区：
文献类型：
--
作者：
Urban, Matthew W.;Lopera, Manuela;Greenleaf, James F.
骨骼肌和肾脏等组织具有明确的结构，会影响机械性能的测量。作为表征这些组织材料特性的一种方法，不同的研究小组假设它们是横向各向同性（TI）的，并测量剪切波速度随相对于器官结构结构的角度变化的情况。为了完善这些器官的测量，需要具有表现出类似各向异性特征的模仿组织的模型。一些方法涉及将纤维嵌入材料基体中。然而，如果均匀固体由于静态应力而受到压缩，则可能会出现声弹性效应，使测量的波速随压缩应力而变化。我们建议利用这一特性来证明受压组织模拟体模可以被表征为 TI 材料。我们测试了用不同浓度的明胶和琼脂制成的六个模型。压力是通过位于模型顶部的板顶部中心的水容器的重量施加的。使用线性阵列换能器和 V-1 Verasonics 系统来感应和测量体模中的剪切波。使用复合平面波成像技术测量剪切波运动。将自相关应用于接收到的同相/正交数据。使用氡变换方法估计剪切波速度 c。传感器安装在旋转台上，因此在 0 度到 360 度的范围内每 10 度进行一次测量，其中应力沿着 0 度到 180 度的方向施加。估计剪切模量。 TI 模型适合数据并评估分数各向异性。这种方法可用于探索具有相同体模的横向各向同性的多种配置，只需对模拟组织的体模施加应力即可。
Tissues such as skeletal muscle and kidneys have well-defined structure that affects the measurements of mechanical properties. As an approach to characterize the material properties of these tissues, different groups have assumed that they are transversely isotropic (TI) and measure the shear wave velocity as it varies with angle with respect to the structural architecture of the organ. To refine measurements in these organs, it is desirable to have tissue-mimicking phantoms that exhibit similar anisotropic characteristics. Some approaches involve embedding fibers into a material matrix. However, if a homogeneous solid is under compression due to a static stress, an acoustoelastic effect can manifest that makes the measured wave velocities change with the compression stress. We propose to exploit this characteristic to demonstrate that stressed tissue mimicking phantoms can be characterized as a TI material. We tested six phantoms made with different concentrations of gelatin and agar. Stress was applied by the weight of a water container centered on top of a plate on top of the phantom. A linear array transducer and a V-1 Verasonics system were used to induce and measure shear waves in the phantoms. The shear wave motion was measured using a compound plane wave imaging technique. Autocorrelation was applied to the received in-phase/quadrature data. The shear wave velocity, c, was estimated using a Radon transform method. The transducer was mounted on a rotating stage so measurements were made every 10 degrees over a range of 0 degrees to 360 degrees, where the stress is applied along 0 degrees to 180 degrees direction. The shear moduli were estimated. A TI model was fit to the data and the fractional anisotropy was evaluated. This approach can be used to explore many configurations of transverse isotropy with the same phantom, simply by applying stress to the tissue-mimicking phantom.