Institute of Biomedical Engineering and Technology, Academy for Engineering and Technology, Fudan University, Shanghai, China.
Department of Medical Physics and Biomedical Engineering, University College London, London, UK.
Ultrason Imaging. 2021 May;43(3):157-163. doi: 10.1177/01617346211006660. Epub 2021 Apr 12.
Ultrasonic guided wave techniques have been applied to characterize cortical bone for osteoporosis assessment. Compared with the current gold-standard X-ray-based diagnostic methods, ultrasound-based techniques pose some advantages such as compactness, low cost, lack of ionizing radiation, and their ability to detect the mechanical properties of the cortex. Axial transmission technique with a source-receiver offset is employed to acquire the ultrasound data. The dispersion characteristics of the guided waves in bones are normally analyzed in the transformed domains using the dispersion curves. The transformed domain can be time-frequency map using a single channel or wavenumber-frequency (or phase velocity-frequency) map with multi-channels. In terms of acquisition effort, the first method is more cost- and time-effective than the latter. However, it remains unclear whether single-channel dispersion analysis can provide as much quantitative guided-wave information as the multi-channel analysis. The objective of this study is to compare the two methods using numerically simulated and ex vivo data of a simple bovine bone plate and explore their advantages and disadvantages. Both single- and multi-channel signal processing approaches are implemented using sparsity-constrained optimization algorithms to reinforce the focusing power. While the single-channel data acquisition and processing are much faster than those of the multi-channel, modal identification and analysis of the multi-channel data are straightforward and more convincing.
超声导波技术已被应用于皮质骨的特征化，以评估骨质疏松症。与目前基于 X 射线的金标准诊断方法相比，基于超声的技术具有一些优势，如紧凑、低成本、无电离辐射，以及能够检测皮质的机械性能。采用源-接收器偏移的轴向传输技术来获取超声数据。通常在变换域中使用频散曲线来分析骨骼中导波的频散特性。变换域可以是单通道的时频图，也可以是多通道的波数-频率（或相速度-频率）图。在采集工作量方面，第一种方法比第二种方法更具成本效益和时间效益。然而，目前尚不清楚单通道频散分析是否能像多通道分析那样提供更多的定量导波信息。本研究的目的是使用简单牛骨板的数值模拟和离体数据比较这两种方法，并探讨它们的优缺点。采用稀疏约束优化算法实现单通道和多通道信号处理方法，以增强聚焦能力。虽然单通道数据采集和处理比多通道快得多，但多通道数据的模态识别和分析简单明了，更有说服力。
