Assessment of EchoMRI-AH versus dual-energy X-ray absorptiometry to measure human body composition

Abstract

Background:

The sensitivity to detect small changes in body composition (fat mass and fat-free mass) largely depends on the precision of the instrument. We compared EchoMRI-AH and dual-energy X-ray absorptiometry (DXA) (Hologic QDR-4500A) for estimating fat mass in 301 volunteers.

Methods:

Body composition was evaluated in 136 males and 165 females with a large range of body mass index (BMI) (19−49 kg m⁻²) and age (19−91 years old) using DXA and EchoMRI-AH. In a subsample of 13 lean (BMI=19–25 kg m⁻²) and 21 overweight/obese (BMI>25 kg m⁻²) individuals, within-subject precision was evaluated from repeated measurements taken within 1 h (n=3) and 1 week apart (mean of three measurements taken on each day).

Results:

Using Bland–Altman analysis, we compared the mean of the fat mass measurements versus the difference in fat mass measured by both instruments. We found that EchoMRI-AH quantified larger amount of fat versus DXA in non-obese (BMI<30 kg m⁻² (1.1 kg, 95% confidence interval (CI₉₅):−3.7 to 6.0)) and obese (BMI⩾30 kg m⁻² (4.2 kg, CI₉₅:−1.4 to 9.8)) participants. Within-subject precision (coefficient of variation, %) in fat mass measured within 1 h was remarkably better when measured by EchoMRI-AH than DXA (<0.5 versus <1.5%, respectively; P<0.001). However, 1-week apart within-subject variability showed similar values for both instruments (<2.2%; P=0.15).

Conclusions:

EchoMRI-AH yielded greater fat mass values when compared with DXA (Hologic QDR-4500A), particularly in fatter subjects. EchoMRI-AH and DXA showed similar 1-week apart precision when fat mass was measured both in lean and overweight/obese individuals.