Intra- and inter-rater reliability of skeletal muscle mass MRI assessment among adults: a systematic review.

BACKGROUND

Progressive and generalized loss of skeletal muscle mass (SMM) can lead to reduced physical performance, poor quality of life, increased mortality, fall-related fractures, cardiopulmonary ailments, cancers, cachexia, and sarcopenia. While computed tomography (CT) and magnetic resonance imaging (MRI) are considered gold standards for non-invasive SMM assessment, MRI offers advantages such as superior tissue contrast and a lack of radiation exposure. This systematic review synthesizes evidence on the reliability of measuring SMM with MRI and addresses gaps related to differences in segmentation methods and reliability across body regions.

METHODS

This review evaluates the reliability of measuring regional and total body SMM with MRI among adults. The databases PubMed, PsycINFO, Web of Science, and Embase were searched until September 2025. Studies assessing the intra- and inter-rater reliability of SMM using MRI in adults were included. The quality of the studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool.

RESULTS

Forty studies were included, with mostly healthy participants and others with musculoskeletal conditions such as osteoarthritis, low back pain, and rotator cuff tears. All participants were aged 18 to 87 years. Overall, twenty studies demonstrated a low risk of bias, fourteen a moderate risk, and six an unclear risk, reflecting generally adequate methodological quality. The majority reported excellent intra- and inter-rater reliability [intraclass correlation coefficient (ICC) >0.9] of MRI in assessing SMM across various muscle groups, with no significant differences observed between them. Segmentation methods included manual, semi-automatic, and automatic scan analyses, each presenting distinct advantages and limitations. Twenty studies focused on the leg, sixteen on the trunk, neck and head region, one on the arm, and two on total body SMM.

CONCLUSIONS

MRI shows mostly excellent reliability in assessing SMM. However, limited research on total body muscle mass and automatic segmentation methods highlights the need for further investigation. These approaches could improve efficiency and diagnostic precision in clinical practice.