DUAL-ENERGY X-RAY ABSORPTIOMETRY OF THE SPINE DECUBITUS LATERAL VERSUS ANTEROPOSTERIOR PROJECTION IN OSTEOPOROTIC WOMEN - COMPARISON TO SINGLE-ENERGY X-RAY ABSORPTIOMETRY OF THE FOREARM

We investigated the discriminatory ability of dual energy X-ray absorp tiometry (DXA) of the lumbar spine in the anteroposterior vs, decubitu s lateral projection in 53 elderly women with at least one vertebral f racture and 63 age-matched women without fracture, Twenty-three premen opausal healthy women served as a reference group. Spine measurements were compared to forearm measurements by single energy X-ray absorptio metry (SXA), Bone mineral density (BMD) of the women with fractures wa s 16% lower in the AP projection and 17% lower in the decubitus latera l projection compared to age-matched women without fractures. t-Scores (deviation from normal premenopausal values in SDs) were -2.1 to -2.3 in the women without fractures, and -3.9 (AP projection), -3.1 (later al projection) and -3.8 (forearm) in the women with vertebral fracture s, t-Scores as well as z-scores for bone mineral content of the verteb ral body and the vertebral posterior elements (both measured with the lateral projection) were similar, ROC analysis showed no significant d ifference between the AP and the lateral projection of the spine, When subjects with vertebral endplate sclerosis (about 25% in each group, with considerably elevated spinal BMD) were excluded, it did not signi ficantly change the diagnostic abilities for fractures, We found no di agnostic advantage of the lateral projection as compared to the AP pro jection or forearm measurement, Future studies will reveal whether abs orptiometry in the lateral projection can be improved by supine latera l scanning.