Cross-calibration of GE Lunar iDXA and Prodigy Densitometer for measurement of bone mineral density in young adults

Abstract

The assessment of bone mineral density (BMD) is essential to skeletal health, and dual-energy x-ray absorptiometry (DXA) is a type of bone densitometer that is extensively used in both clinical and research settings. When changing a DXA system during longitudinal monitoring or multicenter studies, it is important to conduct cross-calibration between the new and reference scanners to ensure that BMD values measured by the two systems are as close as possible. Purpose: To properly cross calibrate between the GE Lunar iDXA and Prodigy in healthy young adults. Methods: Thirty college students, ten males and twenty females, participated in the study. The BMD at the lumbar spine and dual femurs were measured using the GE iDXA and Prodigy by the same licensed technician on the same day. A paired sample t-test and linear regression analysis were utilized to compare the BMD values between the two systems. Limits of agreement were obtained by Bland-Altman analyses. Results: Although strong correlations were found between the two systems (r = 0.985 – 0.998), the iDXA had significantly higher lumbar spine (1.54%) and dual femur (1.28 - 1.56%) BMD values compared to the Prodigy. Conclusion: Our results suggest that calibration equations should be considered to examine data across densitometers to reduce system differences in the young adult population.