Comparison of Two DXA Systems, Hologic Horizon W and GE Lunar Prodigy, for Assessing Body Composition in Healthy Korean Adults

BACKGROUND: Dual-energy X-ray absorptiometry (DXA) is the most widely used method for evaluating muscle masses. The aim of this study was to investigate the agreement between muscle mass values assessed by two different DXA systems. METHODS: Forty healthy participants (20 men, 20 women; age range, 23 to 71 years) were enrolled. Total and regional body compositional values for fat and lean masses were measured consecutively with two DXA machines, Hologic Horizon and GE Lunar Prodigy. Appendicular lean mass (ALM) was calculated as the sum of the lean mass of four limbs. RESULTS: In both sexes, the ALM values measured by the GE Lunar Prodigy (24.8±4.3 kg in men, 15.8±2.9 kg in women) were significantly higher than those assessed by Hologic Horizon (23.0±4.0 kg in men, 14.8±3.2 kg in women). Furthermore, BMI values or body fat (%), either extremely higher or lower levels, contributed greater differences between two systems. Bland-Altman analyses revealed a significant bias between ALM values assessed by the two systems. Linear regression analyses were performed to develop equations to adjust for systematic differences (men: Horizon ALM [kg]=0.915×Lunar Prodigy ALM [kg]+0.322, R(2)=0.956; women: Horizon ALM [kg]=1.066×Lunar Prodigy ALM [kg]–2.064, R(2)=0.952). CONCLUSION: Although measurements of body composition including muscle mass by the two DXA systems correlated strongly, significant differences were observed. Calibration equations should enable mutual conversion between different DXA systems.