Assessment of bone mineral content from 3D synchrotron radiation microtomography images

Synchrotron Radiation μCT (SR μCT) may provide 3D images with spatial resolution as high as one micrometer. The SR μCT system developed at ESRF was already used to quantify trabecular bone architecture in bone samples. In this work we propose for the first time to use SR μCT to assess the mineral content in bones. This quantification is possible thanks to the monochromaticity and high photon flux of the X-ray beam extracted from synchrotron radiation. For this purpose, we relate the reconstructed gray levels of the images to a degree of mineralization in bone. We propose a calibration method to estimate the 3D distribution of hydroxyapatite concentrations within the sample. This method if compared to a reference microradiography technique. Finally, we illustrate the possibilities of the method on 3D images of human biopsies from osteoporotic patients before and after a treatment with bisphosphonates