Reliability and accuracy of rectus femoris muscle measurements by dietitians using ultrasound, compared to sonographers.

Abstract

Background & aims Point-of-care (POCUS) ultrasound measurement of the rectus femoris is a useful tool for diagnosing myopenia. Current literature indicates Dietitians are completing these measurements in research settings with high methodological heterogeneity. We aim to determine the reliability and accuracy of dietitians using ultrasound to measure rectus femoris muscle, after rapid training, compared to sonographers. Methods A training program was designed by sonographers and completed by two study dietitians in 12 h. In this prospective cohort study, patients with a diagnosis of chronic liver disease (CLD) were recruited from the outpatient clinics and heathy participants (HP) were opportunistically recruited on-site. Two dietitians and two sonographers marked the ultrasound picture. Thickness, width, circumference and surface area were measured. Inter-rater reliability was presented as an intra class correlation (ICC, 95%CI) for reliability, and Bland-Altman assessment for bias and accuracy. Results 42 HP and 18 patients with CLD were recruited. ICC across the four raters, four ultrasound measurements and across BMI and sex ranged from minimum 0.73 (good) to 0.96 (excellent) in accuracy. For rectus femoris thickness, ICC was similar across both groups: 0.88 (95 % CI: 0.82-0.93) in HP and CLD patients 0.86 (95%CI: 0.71-0.94). Bland-Altman for thickness systematic error of differences between dietitians and sonographers was not statistically significant (0.032 cm, p = 0.554). Conclusion With a standardised training protocol, ultrasound-naive dietitians achieved both reliable and accurate ultrasound measurements when compared to sonographers in both healthy participants and patients with CLD. Future research should determine the scalability and generalisability of this training protocol.Copyright © 2026. Published by Elsevier Ltd.