Comparison of absorptiometric evaluations from total-body and local-regionskeletal scans

The most common measurement sites for dual-energy X-ray absorptiometry (DXA ) in clinical practice are the posteroanterior (PA) spine and femur. Howeve r, other skeletal regions may provide different bone density information. T he purpose of this study was to establish the least number of DXA measureme nts needed to obtain complete information about bone status. A total of 262 normal female subjects, ages 8-50, were measured on a Lunar DPX-L scanner under total body, PA spine, lateral spine, and femur protocol. Forearm meas urements were performed with a Lunar SP2 single-photon absorptiometry scann er. The various measurements were compared based on a linear regression mod el. The correlation coefficients for bone mineral density (BMD) between adj acent vertebrae were 0.92-0.95, and the associated standard errors of the e stimate (SEE) were 4.5-5.5%. Total-body BMD call best predict BMD of the tr unk, arms, and legs (SEE <4.3%), but least that of the lateral view of the spine (SEE >13.9%). BMD values of the leg from total-body scans pre diet th ose from the femoral neck with an error of 9.0%, and those of the trochante ric region with 11.1%. If the error between adjacent vertebrae (6%) is cons idered acceptable, then a total-body measurement combined with a lateral vi ew of the spine and a femur scan are adequate.