Opportunistic osteoporosis screening via the measurement of frontal skull Hounsfield units derived from brain computed tomography images

Background and purpose Osteoporosis is one of the most common chronic metabolic diseases, but detection and treatment rates are low. The aim of the current study was to evaluate the correlation between frontal skull Hounsfield unit (HU) values from brain computed tomography (CT) scans and T-scores of the lumbar spine and femoral neck from dual-energy X-ray absorptiometry (DXA) scans. Methods Patients with < 1 year between brain CT and DXA scans were included in the study. The average frontal skull HU value used for analysis was defined as the average of four HU values of the frontal bone. A receiver operating characteristic curve was generated, and area under the curve (AUC) was used to determine the HU values of the frontal skull for predicting osteoporosis. The frontal skull HU value with the highest sensitivity and specificity was considered the optimal cutoff value. Results In total, 899 patients who underwent both brain CT and DXA scans at a single institution were enrolled. Average skull HU values differed significantly among patients in different bone mineral density categories (p < 0.001). There was a positive correlation between skull HU value and T-score (beta = 105.06, p < 0.001, R-2 = 0.343). The mean HU value in subjects with osteoporosis was 515, and the optimal cutoff value for the prediction of osteoporosis was 610 HU (AUC = 0.775, 95% CI 0.744-0.806, p < 0.001). Conclusions Clinical brain CT scans can assist in the detection of osteoporosis, and patients with an HU value < 610 as determined via brain CT may be considered for further evaluation for possible osteoporosis.