Correlation Between Hounsfield Units Measured by Diagnostic Noncontrast Enhanced CT in Lumbar Spine and Femoral Neck With Bone Mineral Density Measured by Dual-Energy X-Ray Absorptiometry

Abstract

Background: Computed tomography (CT) is widely available and measurement of Hounsfield unit (HU) is easy and reproducible. Can this measurement predict osteoporosis?

Objective: To evaluate correlation between HU of the lumbar spine and femoral neck and bone mineral density T-score (BMD T-score), and to assess the cutoff HU values at the lumbar spine and femoral neck to predict osteoporosis.

Methods: This retrospective study reviewed 237 patients who underwent both dual-energy x-ray absorptiometry (DXA) and CT within an interval of 1 year from January 2014 to August 2022. HU at the L1-L4 lumbar spine and femoral neck, as well as BMD T-score for the same regions were determined. Correlation of BMD T-score and HU was evaluated using Pearson correlation. Receiver operating characteristic (ROC) curves were generated to determine the cutoff HU values for predicting osteoporosis and its sensitivity, specificity, positive, and negative predictive values.

Results: Among 205 patients included, 64 (31.2%) had osteoporosis. At the lumbar spine, the average HU was moderately correlated with the BMD T-score (r = 0.639; 95% CI, 0.550 - 0.714), whereas at the femoral neck, the average HU had a good correlation with BMD T-score (r = 0.756; 95% CI, 0.691 - 0.809). Cutoff values for predicting osteoporosis were 155 HU at the lumbar spine and 130 HU at the femoral neck.

Conclusions: HU and BMD T-score were more strongly correlated at the femoral neck than at the lumbar spine. A cutoff HU value of 130 at the femoral neck was used for predicting osteoporosis in Thai people.