Sensitivity of dual-photon absorptiometry in spinal osteoporosis

Lumbar spine bone mass and density were measured with Dual photon absorptiometry (DPA) in 60 patients with crush fractures and 60 age-matched normal women. Short-term reproducibility of bone mineral density (BMD) was 1.3% in normal women and 2.5% in osteoporotic women; long-term reproducibility in normal women was 2.2%. The reproducibility of bone mineral content (BMC) seemed to be poorer than that of BMD. In this study, aortic calcifications had no effect on BMD, and one or two crush fractures in the L2-L4 region increased BMD by an average of 3% (0-10%). Lumbar spine DPA provided high sensitivity for these younger crush fracture osteoporotic patients (x = 65 years). The sensitivity at 95% specificity was 74% for BMD and 73% for BMC. This sensitivity is substantially better than that reported for DPA instruments giving higher variances or for quantitative computed tomography.