In vivo assessment of trabecular and cortical bone microstructure

In addition to bone mineral density (BMD), bone microstructure is a major contributor to bone strength. With recently developed technologies we are able to assess bone microstructure in vivo . These technologies include high-resolution peripheral quantitative computed tomography (HR-pQCT), multi-detector computer tomography (MDCT), and high-resolution magnetic resonance imaging (HR-MRI). Using HR-pQCT both cortical and trabecular microstructure can be assessed with a voxel size of 82μm. While MDCT and HR-MRI have lower spatial resolution than HR-pQCT, they have the main advantage of imaging central sites such as the proximal femur. Using these technologies a variety of parameters can be measured including bone volume ratio, trabecular thickness and number, cortical thickness, and cortical porosity. In vivo microstructure measurements are associated with fracture risk and these measurements can be combined with finite element modeling to estimate bone strength. While limitations exist, such as measurement of only peripheral sites and motion artifacts, the assessment of microstructure is promising and provides clinically relevant information. The techniques may help to better predict fracture risk and determine the efficacy of treatments for metabolic bone diseases.