Osteonal mineralization patterns in cortical bone studied by synchrotron radiation-based computed microtomography and scanning acoustic microscopy

摘要

Osteons are longitudinally arranged cylindrical structures, which form the structural units of cortical bone. Cortical bone remodeling is closely related to the osteonal organization as newly formed osteons continuously replace older ones. The degree of mineralization in these new osteons is initially lower than in the existing bone as it takes time before osteons mature. Synchrotron radiation-based computed microtomography (μCT) and scanning acoustic microscopy (SAM) are two techniques, which have both sufficient spatial resolution and sensitivity to detect local variations in bone density. The aim of this study was therefore to compare both techniques for the analysis of osteonal mineralization. Eight human cortical bone samples were scanned with both techniques and the corresponding images were matched. Synchrotron-based μCT is not affected by beam hardening and the gray values in the reconstructed images are directly related to the local mineral density. For cortical bone this means that immature osteons appear darker than their surrounding. In SAM-images the gray values are a measure of the acoustic impedance, which is a function of the local stiffness and the density. Comparison of the μCT and the SAM images of the cortical samples shows a good correspondence in the gray values of the individual osteons.