Correlation between Hounsfield units in lumbar spine and bone mineral density measured by dual-energy X-ray absorptiometry in Vietnamese people

Abstract

Background: Osteoporosis is a disease that increases the risk of fractures. Evaluation of the Hounsfield Unit in the lumbar spine on computed tomography for any reason has the potential to predict bone density abnormalities that contribute to the warning of osteoporosis.

Objective: The aim of this study was to evaluate the correlation between Hounsfield Units (HU) in Lumbar Spine (LS) and bone mineral density (BMD) measured by Dual-Energy X-Ray Absorptiometry (DEXA).

Method: Retrospective and cross-sectional study of 150 patients comprised CT-DXA pairs within a 6-month period performed for any indication. Measure HU at lumbar vertebrae from L1 to L4. Calculate Spearman correlation coeffificient between the mean HU at lumbar vertebrae and the BMD values from DEXA scan. Using area under the ROC Curve (AUC) and finding cut-off of HU for diferentiating normal BMD and abnormal BMD, osteopenia and osteoporosis.

Result: We noted correlations between the HU at LS and the BMD from DXA scan which is significant, the highest correlation at L2 (Spearman correlation coefficient = 0.68). At L2, normal BMD: ≥ 131 HU, osteopenia: 101 – 131 HU, osteoporosis: ≤ 131 HU, we also determined that threshold of 101 HU was more than 90 % sensitive, and a threshold of 171 HU was more than 90 % specific for distinguishing normal BMD. In addition, cut-off ≤ 132 HU was more than 90 % sensitive, and cut-off ≤ 62 HU was more than 90 % specific for distinguishing osteoporosis from osteopenia. Conclusion: The correlations between the HU at LS and the BMD from DXA scan is significant.