Assessment of trabecular bone strength at in vivo CT imaging with space-variant hysteresis and finite element modelling

Osteoporosis is a common bone disease associated with reduced bone strength and increased fracture risk. Finite element modelling (FEM) is a powerful tool to assess bone strength. Fast acquisition and highly reduced radiation in latest multi-row detector CT (MDCT) put it as a frontline imaging modality to assess in vivo trabecular bone (TB) microarchitecture and strength. In current CT image resolution, conventional segmentation methods fail to maintain TB network connectivity limiting reliable assessment of TB strength using FEM. In this paper, we present a new space-variant hysteresis approach to maintain TB connectivity while preserving marrow pores and a high quality mesh generator for FEM. We examine the effectiveness in estimating TB strength. The reproducibility and the ability to predict actual bone strength were examined on MDCT images of cadaveric ankle specimens under in vivo conditions. An intra-class correlation coefficient of 0.97 was observed in computed Young's modulus from repeat scans, and a high linear correlation (R2=0.92) were found between computed and experimental Young's modulus.