Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P30. Thoracic computed tomography Hounsfield unit measurement accurately predicts low bone mineral density of the femoral neck

Abstract

BACKGROUND CONTEXT Osteoporosis remains a major cause of morbidity and mortality, despite increasing efforts among provider organizations to promote awareness and screening. Recent attention has turned to the opportunistic utilization of Hounsfield unit (HU) measurements from computed tomography (CT) as a potential screening method for low bone mineral density (BMD). We hypothesized that thoracic spine CT HU measurements will correlate with BMD measurements conducted with dual X-ray absorptiometry (DXA) scans of the femoral neck. PURPOSE To compare thoracic spine HU and femoral neck T-scores determined by DXA, and determine the accuracy with which thoracic HU values estimate central BMD. STUDY DESIGN/SETTING Retrospective review of patients with applicable imaging. PATIENT SAMPLE Fifty-six patients with both computed tomography scans including the thoracic spine obtained for any indication, and dual X-ray absorptiometry T-scores of the femoral neck. METHODS Patients with thoracic CT and DXA scans at one institution were included in the study. Hounsfield units were manually measured from the cancellous bone in T4 vertebrae by one author blinded to DXA scans. HU measurements were compared with femoral neck DXA t-scores. A receiver operator characteristic curve (ROC) with associated dataset was utilized to aid in determining maximum screening HU values for sensitivity and specificity. RESULTS Fifty-six patients with 58 CT scans and femoral neck DXAs were included in the study. The average HU in the osteoporotic group was significantly lower than the normal group (148.89HU±56.53HU vs. 217.56HU±65.69HU, respectively; p CONCLUSIONS Thoracic vertebrae HU measurements correlate with low BMD of the femoral neck as determined by DXA scan T-score. Screening values of 218 HU captured over 95% of those with low BMD, with sensitivity of 90%. Opportunistic utilization of thoracic HU as a screening method provides a simple, quick, and easily assessable screening tool for assessing low BMD.