Reliability of imaging assessment of fatty infiltration in rotator cuff disorders: protocol for a systematic review and meta-analysis
Jinrong Lin, Zhenming Zhang, Shurong Zhang, Xiaoyu Tang, Cheng Chen, Hongyu Bai, Siyang Liu, Jeremy S Lewis, Jean-Sebastien Roy, Kat Steiner, Xin Ma, Shiyi Chen, Jiwu Chen, Jonathan Rees, Sally HopewellIntroduction
Fatty infiltration (FI) of the rotator cuff (RC) muscles reflects chronic deterioration in muscle quality associated with tendon injury, disuse, ageing and nerve injury. Accurate and reliable assessment of FI based on imaging interpretation is essential for evaluating muscle degeneration, guiding rehabilitation planning and enabling meaningful comparisons across clinical and research settings. Several semi-qualitative grading systems and quantitative measurement approaches across imaging modalities, including CT, MRI, ultrasound and advanced techniques such as Dixon MRI have been used to assess FI; however, the reproducibility of FI grading or quantification at the level of image interpretation varies widely. This protocol outlines a systematic review and meta-analysis designed to evaluate the inter-rater and intra-rater reliability of imaging-based FI assessment at the level of image interpretation in RC disorders.
Methods and analysis
The review will follow the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA-P) guidelines and is preregistered in PROSPERO (CRD420251242564). Searches will be conducted in MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library from inception to the search date. Two reviewers will independently screen, extract data and assess study quality using the Quality Appraisal of Reliability Studies (QAREL) checklist. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) framework will be used to guide interpretation of reliability-related measurement properties. The primary outcomes will be inter-rater and intra-rater reliability reflecting the consistency of image-based FI grading or quantification. Where appropriate, pooled reliability estimates will be calculated separately by imaging modality (eg, MRI, CT and US) and by type of reliability (inter-rater and intra-rater). When quantitative pooling is not feasible because of limited studies or substantial heterogeneity, findings will be synthesised narratively and presented in summary tables. These will be synthesised using a restricted maximum likelihood random-effects model in R software, version 4.3.2 (R Foundation for Statistical Computing, Vienna, Austria) with the metafor package.
Ethics and dissemination
Ethical approval is not required as the review will use only published data. The results will be disseminated through a peer-reviewed publication and conference presentations to inform research and clinical practice in musculoskeletal imaging.
PROSPERO registration number
CRD420251242564.