TECHNICAL CONSIDERATIONS OF DUAL-ENERGY X-RAY ABSORPTIOMETRY-BASED BONE-MINERAL MEASUREMENTS FOR PEDIATRIC STUDIES

Dual-energy X-ray absorptiometry (DXA) measurements have been shown to provide useful information on bone mineral status in young pediatric subjects. The purpose of this study was to challenge this system under various conditions to determine the clinical and experimental paramet ers that may be encountered,which could interfere with DXA-based bone mineral content (BMC) and bone mineral density (BMD) measurements. Var iations in data acquisition, including the covering of step phantom (e xternal calibration standard) with a cotton blanket or partial exclusi on of step phantom in the scan field, tissue freezing, or the presence of small nonmetallic objects, did not significantly alter DXA BMC or BMD measurements. By contrast, the presence of movement artifact, radi ographic contrast media, and nonmetallic orthopedic casts significantl y interfered with DXA BMC and BMD measurements. Variability in operato r-dependent analysis of DXA scans occurred with regional analysis of w hole body scans for DXA BMC and BMD measurements (average coefficient of variation was 2.9% and 1%, respectively, depending on the region an alyzed) but did not affect the total (whole body) result. A minor adju stment in the manual delineation of the step phantom during data analy sis may result in almost a 30% difference in DXA BMC and BMD. We concl ude that movement artifact, radiographic contrast media, nonmetallic o rthopedic cast, and variations in operator-dependent data analysis may interfere with DXA BMC and BMD measurement in young pediatric subject s. Therefore, appropriate care should be taken to reduce or eliminate such interference.