Determination and analysis of guided wave propagation using magnetic resonance elastography
Determination and analysis of guided wave propagation using magnetic resonance elastography
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DOI：
10.1002/mrm.20607
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发表时间：
2005-10-01
影响因子：
3.3
通讯作者：
Ehman, RL
中科院分区：
文献类型：
--
作者：
Romano, AJ;Abraham, PB;Ehman, RL
我们提出了标准磁共振弹性成像（MRE）测量和分析方法的新扩展，该方法适用于以波导或纤维束（即肌肉）为特征的介质导致弹性波受限传播的情况。作为这种新方法的演示，MRI被用来识别芹菜茎的单个纤维的路径，然后在包含芹菜纤维的整个体积中进行3D MRE，以测量位移。亥姆霍兹分解允许将位移分离为纵向和横向分量，混合Radon变换的应用允许沿光纤传播的波的光谱分解。在全局坐标系中测量的这些弹性位移与代表任何特定光纤方向的切线的三个Frenet矢量和两个相应的正交矢量之间的点积投影产生了沿光纤传播的位移贡献，就好像它是一个波导一样。然后沿着每根光纤的长度执行滑动窗口空间傅里叶变换，以获得描绘空间波数轮廓的色散图像。因此，这种方法可以允许局部跟踪和表征波的类型，速度和耦合沿任意取向的光纤。
We present a novel extension of standard magnetic resonance elastography (MRE) measurement and analysis methods, which is applicable in cases where the medium is characterized by waveguides or fiber bundles (i.e., muscle) leading to constrained propagation of elastic waves. As a demonstration of this new method, MRI is utilized to identify the pathways of the individual fibers of a stalk of celery, and 3D MRE is then performed throughout the volume containing the celery fibers for a measurement of the displacements. A Helmholtz decomposition is performed permitting a separation of the displacements into longitudinal and transverse components, and an application of a hybrid Radon transform permits a spectral decomposition of wave propagation along the fibers. Dot product projections between these elastic displacements measured in the global coordinate system and three Frenet vectors representing the tangent and two corresponding orthogonal vectors along any particular fiber orientation yield the displacement contributions to wave propagation along the fiber as if it were a waveguide. A sliding window spatial Fourier transform is then performed along the length of each fiber to obtain dispersion images that portray space-wavenumber profiles. Therefore, this method can permit localized tracking and characterization of wave types, velocities, and coupling along arbitrarily oriented fibers.