Reliability of ultrasound measurements of muscle thickness and echointensity in older adults with type 2 diabetes

Ultrasound is an emerging tool for muscle-based measurements. However, the analysis of hyperechoic images (high muscle fat infiltration, as in type 2 diabetes [T2D]) can be challenging. Objective To evaluate the reliability of ultrasound image analysis of muscle thickness and echointensity in older adults with T2D and non-diabetic controls by experienced and novice analysts. We hypothesized that reliability would be high for the experienced analysts, and lower, but acceptable, for a novice analyst. Methods We recruited three groups: 1) adults >60 years with T2D; 2) age- and sex-matched normoglycemic controls; and 3) healthy adults 18–35 years. All participants underwent ultrasound imaging of the abdomen and anterior thigh. Ultrasound images were de-identified, randomized, and separately analyzed by two expert analysts (>3 years experience each). A subset of images was also analyzed by a novice analyst with no prior experience. Inter- and intra-rater reliability was assessed using coefficients of variation (CVs), intraclass correlation coefficients (ICCs), and Bland-Altman analysis. Results For the expert analysts, ICCs were >0.90 and CVs were <10 % for all measurements, regardless of participant group. For the novice analyst, all ICCs were >0.90, except for rectus abdominus thickness measurements in the T2D group (ICC: 0.659 [95%CI: -0.134, 0.911]). CVs were <10 % for all measurements, except for rectus abdominus thickness in the T2D group (CV: 12.7 %). Ultrasound image analysis of muscle thickness and echointensity by experienced analysts was highly reliable. Conclusion Novice and expert analysts produced comparable measurements, except for rectus abdominus thickness in images obtained from older adults with T2D.