Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada.
Ultrasound Med Biol. 2013 Dec;39(12):2422-30. doi: 10.1016/j.ultrasmedbio.2013.06.007. Epub 2013 Sep 12.
Recent in vitro studies have shown that guided waves can characterize bone properties. However, for clinical applications to be viable, the soft-tissue layer should be considered. This study examined the effect of soft tissue on guided waves using a bovine bone plate over a water half-space and overlaid by a 4-mm gelatin-based soft-tissue mimic. The data (with and without soft tissue) clearly show a high-frequency, fast-propagating wave packet and a low-frequency, delayed phase group. The presence of soft tissue attenuates the signals significantly and increases mode density and number as predicted by theory. The data retain higher frequency content than the bone-plate data at large offsets. Using theoretical dispersion curves, the guided modes can be identified with mode 1 (similar to the A0 Lamb mode) minimally affected by the addition of soft tissue. There is infiltration of high-frequency, late-arriving energy within the low-velocity guided-wave regime. Results of travel-time calculation suggest that P-wave and PP-reflections/multiples within the soft tissue may be responsible for the high-frequency oscillations.
最近的体外研究表明，导波可用于描述骨骼特性。然而，为了使临床应用可行，还应考虑软组织层。本研究使用牛骨板覆盖在水半空间上，并在其上覆盖 4 毫米厚的基于明胶的软组织模拟物，研究了软组织对导波的影响。数据（有和没有软组织）清楚地显示出高频、快速传播的波包和低频、延迟的相群。软组织的存在显著衰减了信号，并如理论预测的那样增加了模式密度和数量。与大偏移量的骨板数据相比，数据保留了更高的频率内容。使用理论色散曲线，可以识别出导波模式 1（类似于 A0 Lamb 模式），受软组织添加的影响最小。在低速导波范围内存在高频、迟来能量的渗透。传播时间计算结果表明，软组织中的 P 波和 PP 反射/多次反射可能是高频振荡的原因。
