Digital anthropometry via three-dimensional optical scanning: evaluation of four commercially available systems

Background Digital anthropometry is increasingly accessible due to commercial availability of three-dimensional optical scanners (3DO). Methods One hundred and seventy-nine participants were assessed by four 3DO systems (FIT3D (R), Size Stream (R), Styku (R), and Naked Labs (R)) in duplicate, air displacement plethysmography (ADP), and dual-energy x-ray absorptiometry (DXA). Test-retest precision was evaluated, and validity of total and regional volumes was established. Results All scanners produced precise estimates, with root mean square coefficient of variation (RMS-%CV) of 1.1-1.3% when averaged across circumferences and 1.9-2.3% when averaged across volumes. Precision for circumferences generally decreased in the order of: hip, waist and thigh, chest, neck, and arms. Precision for volumes generally decreased in the order of: total body volume (BV), torso, legs, and arms. Total BV was significantly underestimated by Styku (R) (constant error [CE]: -10.1 L; root mean square error [RMSE]: 10.5 L) and overestimated by Size Stream (R) (CE: 8.0 L; RMSE: 8.3 L). Total BV did not differ between ADP and FIT3D (R) (CE: -3.9 L; RMSE: 4.2 L) or DXA BV equations (CE: 0-1.4 L; RMSE: 0.7-1.5 L). Torso volume was overestimated and leg and arm volumes were underestimated by all 3DO. No total or regional 3DO volume estimates exhibited equivalence with reference methods using 5% equivalence regions, and proportional bias of varying magnitudes was observed. Conclusions All 3DO produced precise anthropometric estimates, although variability in specific precision estimates was observed. 3DO BV estimates did not exhibit equivalence with reference methods. Conversely, DXA-derived total BV exhibited superior validity and equivalence with ADP.