High-frequency cortical backscatter reveals cortical microstructure - A simulation study

The role of quantitative ultrasound as a diagnostic and monitoring tool in bone pathologies has been widely investigated both experimentally and numerically. Recently, the numerical studies have focused on the exploitation of high-resolution imaging data of bone´s microarchitecture in order to develop more realistic computational models of osteoporotic bones. In this work, we present numerical simulations of high-frequency ultrasonic waves backscattered from the cortical microstructure, i.e. Haversian canals and large basic multicellular units BMUs. Two-dimensional computational academic models of cortical bone were developed to investigate the effects of cortical porosity, Haversian canal diameter and the occurrence of non-refilled large BMUs on the backscatter characteristics of high-frequency (5-MHz) waves. It was shown that the frequency dependence of cortical backscatter is strongly related to the size distribution of Haversian canals and the occurrence of large BMU´s can be detected. These findings may open a new path for the non-invasive monitoring of bone pathologies and response to treatments using conventional medical ultrasound scanners.