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.