Trabecular Bone Structure Analysis in the Osteoporotic Spine Using a Clinical In Vivo Setup for 64‐Slice MDCT Imaging: Comparison to μCT Imaging and μFE Modeling

Assessment of trabecular microarchitecture may improve estimation of biomechanical strength, but visualization of trabecular bone structure in vivo is challenging. We tested the feasibility of assessing trabecular microarchitecture in the spine using multidetector CT (MDCT) on intact human cadavers in an experimental in vivo–like setup. BMD, bone structure (e.g., bone volume/total volume = BV/TV; trabecular thickness = Tb.Th; structure model index = SMI) and bone texture parameters were evaluated in 45 lumbar vertebral bodies using MDCT (mean in‐plane pixel size, 274 μm²; slice thickness, 500 μm). These measures were correlated with structure measures assessed with μCT at an isotropic spatial resolution of 16 μm and to microfinite element models (μFE) of apparent modulus and stiffness. MDCT‐derived BMD and structure measures showed significant correlations to the density and structure obtained by μCT (BMD, R² = 0.86, p < 0.0001; BV/TV, R² = 0.64, p < 0.0001; Tb.Th, R² = 0.36, p < 0.01). When comparing μCT‐derived measures with μFE models, the following correlations (p < 0.001) were found for apparent modulus and stiffness, respectively: BMD (R² = 0.58 and 0.66), BV/TV (R² = 0.44 and 0.58), and SMI (R² = 0.44 and 0.49). However, the overall highest correlation (p < 0.001) with μFE app. modulus (R² = 0.75) and stiffness (R² = 0.76) was achieved by the combination of QCT‐derived BMD with the bone texture measure Minkowski Dimension. In summary, although still limited by its spatial resolution, trabecular bone structure assessment using MDCT is overall feasible. However, when comparing with μFE‐derived bone properties, BMD is superior compared with single parameters for microarchitecture, and correlations further improve when combining with texture measures.