Short-Term Precision and Least Significant Change of 3D-DXA Cortical and Trabecular Proximal Femur Measurements Across Hologic DXA Scanner Models
3D-DXA provides volumetric and compartment-specific hip measurements from standard DXA scans. However, for reliable longitudinal interpretation, establishing scanner-specific short-term precision data is essential. This study assessed the short-term precision of 3D-DXA-derived parameters using repeated acquisitions from five clinical Hologic DXA scanner datasets. Duplicate hip DXA acquisitions were collected at five clinical centers using two Horizon Wi scanners, two Horizon A scanners, and one Discovery W scanner. Each subject was scanned twice with complete repositioning between acquisitions. Conventional total hip and femoral neck aBMD were obtained using APEX software, and 3D-Shaper software was used to derive integral vBMD, trabecular vBMD, and cortical sBMD. Precision error was expressed as RMS-SD and RMS-CV, and LSC was calculated at the 95% confidence level. For total hip aBMD, absolute LSC values ranged from 0.018 to 0.037 g/cm$^2$. Femoral neck aBMD showed higher error, with LSC values ranging from 0.031 to 0.049 g/cm$^2$. For 3D-DXA parameters, absolute LSC values ranged from 9.955 to 17.859 mg/cm$^2$ for integral vBMD, 8.662 to 18.487 mg/cm$^2$ for trabecular vBMD, and 4.444 to 8.875 mg/cm$^2$ for cortical sBMD. Precision errors for 3D-Shaper parameters varied moderately across the five clinical datasets. Short-term precision of 3D-Shaper-derived measurements was broadly comparable with previously published precision data. The LSC values reported here can support interpretation of longitudinal changes in integral vBMD, trabecular vBMD, and cortical sBMD on Hologic scanners.