Department of Electrical and Computer Engineering, Akashi National College of Technology, Akashi, Hyogo, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2011 Jul;58(7):1389-96. doi: 10.1109/TUFFC.2011.1958.
Ultrasound propagation through cancellous bone can be greatly affected by the trabecular structure. In the present study, the ultrasound propagation for the oblique orientation of the trabecular network was numerically investigated using 3-D finite-difference time-domain (FDTD) simulations. The models of cancellous bone were reconstructed from X-ray microcomputed tomographic (μCT) images of a bovine bone. Cancellous bone models with various orientations of the trabecular network were realized by cutting the μCT images rotated from 0 to 90°. Ultrasound waveforms propagating through these cancellous bone models were simulated while changing the receiving position. The refraction of the ultrasound wave for the oblique angle of the main orientation was investigated on the basis of the variation in the arrival time and peak amplitude. As the propagation direction approached the direction parallel to the main orientation, the arrival time of the first peak became less and the peak amplitude became smaller. This means that the wave of the first peak, which corresponded to a fast wave, propagated in the direction perpendicular to the main orientation. In addition, a strong correlation between the first-peak amplitude and the arrival time was observed in the porosity range of 0.68 to 0.85, in which the slope of the amplitude with respect to time increased linearly with porosity.
超声在松质骨中的传播会受到骨小梁结构的极大影响。在本研究中，使用三维有限差分时间域（FDTD）模拟对小梁网络倾斜方向的超声传播进行了数值研究。从牛骨的 X 射线微计算机断层扫描（μCT）图像中重建了松质骨模型。通过将 μCT 图像旋转 0 到 90°，实现了具有不同小梁网络方向的松质骨模型。通过改变接收位置，模拟了穿过这些松质骨模型的超声波形的传播。基于到达时间和峰值幅度的变化，研究了超声在主取向斜角的折射情况。随着传播方向接近与主取向平行的方向，第一峰值的到达时间减少，峰值幅度变小。这意味着与快波相对应的第一峰值的波在垂直于主取向的方向上传播。此外，在孔隙率为 0.68 至 0.85 的范围内，观察到第一峰值幅度与到达时间之间存在很强的相关性，其中幅度随时间的斜率随孔隙率呈线性增加。
