An evaluation of forearm bone mineral measurement with dual-energy X-ray absorptiometry.

Dual-energy x-ray absorptiometry (DEXA) has been reported to be a valuable means of bone mineral measurement of the lumbar spine and hip. In order to determine whether DEXA could be as useful for bone mineral analysis of the forearm, we compared its accuracy, precision and measurement performance to single-photon absorptiometry (SPA). There was high correlation between these techniques for integral bone mineral density in standard aluminum tubes (r = 0.99) and 30 adult volunteers or patients with osteoporosis (r = 0.95). The mean short-term precision of DEXA was 0.9% in vitro and about 1.5% in vivo. DEXA produced excellent bone images which enhance long-term in vivo precision. The measurement performance of both instruments was largely unaffected by localized fat deposits or increases in forearm thickness or proportion of fat subcutaneously. We conclude that DEXA is a clinically useful alternative to SPA for forearm bone mineral assessment.