Bone Mineral Density in Dual Energy X-Ray Absorptiometry and Hounsfield Units on Diagnostic Computed Tomography Scan:...

Previous studies have demonstrated a moderate correlation between bone mineral density (BMD) measured by dual energy X-ray absorptiometry (DXA) and Hounsfield units (HU) assessed on diagnostic computed tomography (CT), primarily in the lumbar spine. However, the correlation between HU values and DXA scores in other bones and at different anatomical landmarks remains underexplored. This study aimed to evaluate the relationship between HU values at various cortical and medullary regions and DXA-derived T-scores across multiple skeletal sites.

In this retrospective cross-sectional study, 214 patients who underwent both DXA and diagnostic CT imaging were included. The bones analyzed included the proximal humerus (N=96), distal tibia (N=56), distal femur (N=34), and proximal tibia (N=28). HU measurements were taken at five anatomic landmarks: the medullary center, anteromedial cortex, anterolateral cortex, posteromedial cortex, and posterolateral cortex. Correlations were analyzed between these HU values and the lowest T-score from the DXA scan.

Significant moderate correlations were found between medullary HU values and the lowest T-scores in the proximal tibia (r=0.486, P=0.04) and distal tibia (r=0.458, P=0.01). In the proximal humerus, the anteromedial cortex HU also correlated with the lowest T-score (r=0.353, P=0.01). Mean HU values at several cortical and medullary regions significantly differed between osteoporotic and normal BMD groups.

There is a moderate correlation between HU values at specific anatomical landmarks and DXA T-scores. These findings suggest that diagnostic CT scans may serve as a supplementary tool in assessing bone quality, especially when DXA is not available.