The purpose of the present study is to determine if a correlation exists between bone mineral density (BMD) obtained from dual energy X-ray absorptiometry (DXA) and Hounsfield unit (HU) from pelvic diagnostic computed tomography (dCT), and to evaluate whether HU could be used to identify osteoporosis. Seventy-nine patients were included in this study. HU values were measured in three different sections: the head-neck junction of the femur, the middle portion of the femoral neck, and the intertrochanter of the femur (IT). In each sectional image, HU values were measured at two regions of interest: cortical and cancellous bone (HU_t) and cancellous bone. The correlation between BMD and HU_t of IT was significant (r = 0.839, p < 0.01). In IT, the area under the curve value of HU_t was 0.875 (0.796-0.955). We found that a HU_t of IT <170 can be regarded as indicating osteoporosis: its positive predictive value is 96.9 %. A HU_t of IT >210 can be regarded as indicating an absence of osteoporosis: its negative predictive value is 84.6 %. In conclusion, we found that a significant correlation between HU of pelvic dCT and BMD of DXA, and HU potentially provided an alternative method for determining regional BMD. Therefore, pelvic dCT could possibly be a supplementary method for initial diagnosis of osteoporosis and for initiation of treatment.
Keywords: Bone mineral density; Hip; Hounsfield unit; Osteoporosis.