Comparison of Bone Mineral Density Measured by Dual X-ray, Axial Dual-energy Photon X-ray Absorptiometry and Laser Absorptiometry of Calcaneus

The objective of this study was to validate the use of bone mineral measurements of the calcaneus bone by dual X-ray and laser (DXL) in a cross-sectional study carried out in an osteoporosis clinic. Measurements of bone mineral density (BMD) at proximal femur and spine were obtained by dual-energy photon X-ray absorptiometry (DEXA). Osteoporosis was defined by a DEXA T-score <-2.5 at the femoral neck or lumbar spine. Sensitivity, specificity and kappa statistics for DXL were calculated, assuming the DEXA measurement as the gold-standard.  The study included 475 women with a mean age of 54±11.9 years. 15% had osteoporosis while 39% were osteopenic (-2.5<T-score between<-1) at the femoral neck or spine. A significant correlation (p<0.001) was found between BMD values as measured by DXL at femoral neck and DEXA at the lumbar spine. Assuming the same T-score cut-off value for the diagnosis osteoporosis and a modified cut-off value for the diagnosis of osteopenia (-2.5<T-score<-1.5), yields a sensitivity of 83% and a specificity of 74% to 86% for the DXL device. In conclusion, BMD measured at the calcaneal bone by DXL, has a good correlation with that measured by axial DEXA.Iran J Med Sci 2005; 30(1): 34-37. Keywords ● Bone mineral densitometry ● Calcaneus ● Osteoporesis