Precision of the XCT 3000 and comparison of densitometric measurements in distal radius scans between XCT 3000 and XCT 2000 peripheral quantitative computed tomography scanners.

Researchers conducting longitudinal studies face challenges as technology evolves and data collection equipment is upgraded from older to newer models. In this study, we report precision error and associations from correlation, regression equations, and Bland-Altman plots that compare results of distal radius images from the XCT 2000 and XCT 3000 peripheral quantitative computed tomography densitometers at the 4% and 20% distal radius site. The mean difference expressed as a percent of the measurement's mean was approximately 5% for cortical thickness, periosteal and endosteal circumferences, and total bone size at the 20% site, and less than 2% for all other measures. There were strong associations between bone parameter measures from the XCT 3000 and XCT 2000 with correlation coefficients ranging from 0.92 to 1.0. Strong associations between the 2 machines allow for the comparison of results with minor adjustments.