Ultrasound grayscale histogram analysis for early rheumatoid arthritis cartilage assessment

OBJECTIVE: To evaluate the feasibility of ultrasound grayscale histogram analysis in detecting metacarpal head (MH) cartilage damage in rheumatoid arthritis (RA) and its correlation with clinical parameters. METHODS: This cross-sectional study enrolled 50 RA patients and 50 healthy controls (HCs). Bilateral MH2-5 cartilages were scanned using a Mindray Resona R9 ultrasound system. Grayscale values were quantified via histogram analysis in standardized regions of interest. Intraclass correlation coefficients (ICC) assessed reliability. Mann-Whitney U tests compared groups; Spearman correlation analyzed associations with disease duration and body mass index (BMI). RESULTS: RA patients exhibited significantly higher grayscale values in total MH (median: 48.6 vs. 44.8, P < 0.001), MH2 (46.4 vs. 42.7, P = 0.015), and MH3 (48.6 vs. 43.4, P = 0.006) compared to HCs. ICC demonstrated excellent intra- (0.905–0.945) and inter-observer (0.861–0.908) reliability. Weak correlations were observed between grayscale values and disease duration (r = 0.120, P = 0.001) or BMI (r = − 0.136, P < 0.001). CONCLUSION: Quantitative grayscale histogram analysis of the metacarpal head cartilage demonstrates promising feasibility and provides valuable imaging evidence to support the early diagnosis of rheumatoid arthritis. CLINICAL TRIAL NUMBER: Not applicable.