Simplified MRI Scoring System for TMJ Assessment in Juvenile Idiopathic Arthritis

The temporomandibular joint (TMJ) is a small, yet complex joint. MRI interpretation of TMJ involvement in children with juvenile idiopathic arthritis (JIA) is challenging but essential for the diagnosis and treatment monitoring. We propose a simplified and reproducible MRI scoring system to facilitate both initial diagnosis as well as longitudinal follow-up. Two pediatric radiologists independently scored 139 TMJ MRIs from 66 children with JIA using a detailed literature-based score (Score A) and a newly developed simplified score (Score B). For all 278 TMJs, reading time was recorded, and interrater reliability was assessed using intraclass correlation coefficients (ICCs). The primary objective was to assess interrater reliability, with construct validity evaluated in an exploratory manner. The mean patient age was 12.0 years (SD: 3.7). For Score A, interrater agreement showed moderate agreement for the acute score with an ICC of 0.67–0.77 and good agreement for the chronic score (ICC: 0.75–0.86). In contrast, Score B demonstrated excellent agreement for the acute score (ICC: 0.94–0.99) and good agreement for the chronic score (ICC: 0.85–0.90). Both scores showed similar associations with relevant clinical criteria, including the decision to treat. Image interpretation using Score B required 83% less time than with Score A. These findings support the reproducibility and feasibility of the simplified score (Score B) for evaluating TMJ involvement in children with JIA, although further studies are required to evaluate its diagnostic performance, external validity, and impact on clinical decision-making.