Evaluation of total-body-less-head dual energy X-ray absorptiometry for the assessment of lean, fat and bone mass in athletes

Abstract Introduction: The routine assessment of body composition is common practice in athletic populations, particularly at the elite level. DXA is a criterion method of body composition assessment, providing precise measurements of bone mineral content (BMC), lean mass (LM) and fat mass (FM) from the standard total-body scan. More recently, a new scan application has been introduced, which measures body composition excluding the head region. The aim of this study was to investigate the precision of the new total-body less head (TBLH) application for the measurement of total body composition in athletes and compare precision with that of the standard total-body scan. The second aim was to compare the differences in total body composition outcomes between standard DXA total-body scans and TBLH scans. Methods: This study compared in-vivo precision and total body composition outcomes from the standard total-body scan and the new TBLH scan (Lunar iDXA, GE Healthcare, Madison, WI). A total of 95 athletes (mixed sports) received repeated TBLH scans and 58 of these athletes also received standard total-body scans (overall mean age: 26.3 ± 8.8 years; male n = 63, female n=41). Participants ranged in body mass (42.7 to 129.1 kg), stature (1.55 to 2.04 m) and BMI (16.4 to 46.9 kg/m2). Precision was derived from repeat scans with re-positioning, and precision error was reported as the root mean square standard deviation (RMS±SD) and percentage co-efficient of variation (%CV). Results: Precision error ranged from 0.38 % to 1.15 % (%CV) for standard total-body and 0.39 % to 1.28 % (%CV) for the TBLH application, depending on the body composition compartment. Body composition outcomes for the TBLH were significant lower than for the standard total body for BMC (2,865 g v 2,308 g), LM (50,276 g v 46,954 g) and FM (15,888 g v 15,183 g) , all p