Correlation between signal intensity ratio of magnetic resonance imaging and arthroscopic findings in temporomandibular joint synovitis

/purpose : Temporomandibular joint (TMJ) disorders commonly involve intra-articular synovitis, which causes pain and limits function. This study investigated the associations of signal intensity ratios (SIRs) on T2-weighted magnetic resonance imaging (MRI) with the arthroscopic grading of synovitis for both anterior and posterior joint recesses. This study included 118 patients (131 joints) who presented with TMJ disorder symptoms and underwent both T2-weighted MRI and arthroscopic surgery. Regions of interest were identified on MRI by the same oral and maxillofacial surgeon, and SIRs were calculated for the anterior and posterior synovial spaces, with cerebral white and gray matter used as references. All surgical procedures were performed by the same oral and maxillofacial surgeon. Arthroscopic synovitis grading was independently conducted by two experienced oral and maxillofacial surgeons using McCain's classification system. The association between synovitis grade and SIRs in the anterior and posterior TMJ recesses was analyzed using the Kruskal–Wallis test followed by the Wilcoxon rank-sum post hoc test. For the 131 joints evaluated, the SIRs of the anterior and posterior joint recesses increased progressively with an increase in the synovitis grade. Significant positive correlations were discovered between synovitis grade and the SIRs in the two regions, indicating a strong association between T2-weighted MRI findings and arthroscopically observed severity of synovitis. T2-weighted MRI SIRs were strongly correlated with arthroscopic synovitis grading in the anterior and posterior TMJ recesses. These findings suggest that quantitative MRI evaluation can increase diagnostic accuracy in cases of TMJ synovitis.