Whole-body composition analysis by dual-energy X-ray absorptiometry (DXA) requires subjects to fit within the width limits of the DXA bed. To overcome this limitation, the aim of this study was to validate a partial scanning technique at which the upper left limb is deliberately left unscanned and measurements are "reflected" from the right-side upper limb. A Hologic Explorer-W densitometer was used in a sample of 189 participants, including athletes and nonathletes, ranging from underweight to obese (body mass index: 17.0-40.1 kg/m2). A whole-body scan was analyzed as the reference procedure to determine bone mineral content (BMC), lean soft tissue (LST), and fat mass (FM), and reanalyzed using a partial reflection scanning (RS) technique. RS estimates of BMC were associated with athletic status and differed significantly from reference estimates (p < 0.05). Also, the RS estimates of LST and FM were different (p < 0.05) from those of the reference whole-body scan, although differences were small (0.17 kg, -0.02 kg, and -0.10% for BMC, LST, and FM, respectively). The alternative procedure explained more than 99% of the reference scan variance with low limits of agreement (BMC: -13.8 to 23.9 g [athletes] and -6.3 to 18.0 g [nonathletes]; LST: -0.11 to 0.45 kg; FM: -0.22 to 0.17 kg). Regardless of body mass index, athletic status, and gender, RS is a useful and simple solution to be used in individuals wider than the DXA scan area. However, individual errors for BMC may be higher in athletes engaged in lateral dominant sports practice.
Keywords: Body composition; DXA; dual-energy X-ray absorptiometry.
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