Body composition in taller individuals using DXA: A validation study for athletic and non-athletic populations

Abstract

Dual energy X-ray absorptiometry (DXA) cannot be used to evaluate participants taller than the scan area. We aimed to analyse the accuracy of bone mineral content, fat mass, and lean mass assessed with DXA whole-body scan and from the sum of two scans (head and trunk plus limbs). Participants were 31 athletes (13 males and 18 females) and 65 non-athletes (34 males and 31 females), that fit within the DXA scan area. Three scans were performed using a Hologic Explorer-W fan-beam densitometer: a whole-body scan used as the reference; a head scan; and a trunk and limbs scan. The sum of the head scan and the trunk and limbs scan was used as the alternative procedure. Multiple regression and agreement analysis were performed. Non-significant differences between methods were observed for fat mass (0.06 kg) and lean mass (-0.07 kg) while bone mineral content from the alternative procedure differed from the reference scan (0.009 kg). The alternative procedure explained > 99% of the variance in the reference scan and low limits of agreement were observed. Precision analysis indicated low pure errors and the higher coefficients of variation were found for fat mass (whole-body: 3.70%; subtotal: 4.05%). The method proposed is a valid and simple solution to be used in individuals taller than the DXA scan area, including athletes engaged in sports recognised for including very tall competitors.

Reference Values for Body Composition and Anthropometric Measurements in Athletes

“…For athletes who were taller than the scan area, we used a validated procedure that consisted of the sum of a head and a trunk plus limbs scans. [24] The same technician positioned the participants, performed the scan, and executed the analysis (QDR for Windows software version 12.4; Hologic, Waltham, MA, USA) according to the operator's manual by using the standard analysis protocol.…”

Methodology Review: Using Dual-Energy X-Ray Absorptiometry (DXA) for the Assessment of Body Composition in Athletes and Active People

“…It is unclear if this error is limited to Lunar Prodigy scanners because it has not been reported in other studies using current models of Hologic scanners which scan "up and down" versus "transverse" in the Lunar Prodigy (Evans et al, 2005;Santos et al, 2012). Specifically, the technician should initiate a scan with one sweep to create an empty gap and pause, then reposition the subject on the scanning bed ensuring that their feet are within the scanning area before resuming the scan with the inclusion of the head region as much as possible.…”

“…Previous studies have examined scanning techniques to accommodate tall (Evans et al, 2005;Santos et al, 2012) or broad subjects (Rothney et al, 2009), including scanning tall subjects with the exclusion of the head or feet, or scanning with bent knees to allow both the head and feet to be included in the scan (Silva et al, 2004). Another alternative is to sum two partial scans, with preference given to dividing the body at the neck rather than at the hip (Evans et al, 2005).…”

Accuracy of a combined heart rate and motion sensor for assessing energy expenditure in free-living adults during a double-blind crossover caffeine trial using doubly labeled water as the reference method

“…Based on test-retest using ten subjects, the coefficient of variation (CV) for the FM and FFM are 1.7% and 0.8%, respectively 24 .…”