High inter-observer reliability in standardized ultrasound measurements of subcutaneous adipose tissue in children aged three to six years

Abstract Background A procedure to measure subcutaneous adipose (SAT) using brightness-mode ultrasound has recently been standardized and applied to various groups of adults including underweight, overweight and obese adults. High reliability of this procedure was found in each of the examined groups. The purpose of this study was to determine inter-observer reliability of the standardized brightness-mode ultrasound measurement of uncompressed SAT in three to six-year-old children. Methods Three experienced observers independently captured the ultrasound images at the eight standardized measurement sites in each of the 20 children and evaluated their images using an interactive software that detects the SAT contour and automatically measures multiple thicknesses in each image; the mean of these represents SAT thickness at a given site. The children were aged 4.9 ± 1.0 years; their body mass index ranged from 13.6–17.7 kgm− 2. Sound speed was set to 1450 ms− 1 for SAT. Results SAT thickness sums with fibrous structures included (DI) ranged from 25.7–86.4 mm, mean DI was 48.1 ± 15.5 mm. For DI, resulting from 160 measurements by each observer, the intra-class correlation coefficient was 0.998 (95% confidence interval 0.980–0.999), standard error of the estimate was 1.1 mm, and 95% limits of agreement were within ±2.1 mm. The median difference in DI was 0.8 mm, i.e. about 1.9% of mean DI. Conclusions Inter-observer results in children are comparable to previously described high reliability in adults. This method, which provides a technical thickness measurement accuracy of about 0.1 to 0.2 mm, enables monitoring of subcutaneous adipose tissue in children with a similarly high reliability as was obtained in adults previously. Trial registration German Institute of Medical Documentation and Information, German Clinical Trials Register (DRKS) ID: DRKS00010089; Date 24/02/2016.