Wireless detector-based magnetic resonance imaging for grading assessment of the peridiscal attachments in temporomandibular joint internal derangement.

BACKGROUND: The relationship between the peridiscal attachments and temporomandibular joint (TMJ) internal derangement (ID) remains poorly understood. This study aimed to investigate the association between graded imaging features of the peridiscal attachments and disc displacement using wireless detector-based magnetic resonance imaging (WD-MRI). METHODS: This retrospective study included 61 patients (122 TMJs) diagnosed with TMD according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). All patients underwent oblique sagittal proton density-weighted imaging in both closed- and open-mouth positions using WD-MRI. Two radiologists independently assessed disc position [normal, disc displacement with reduction (DDWR), or disc displacement without reduction (DDWOR)] and performed ordinal grading (1-3 points: clearly, indistinctly, or non-visualized) of four peridiscal attachments: the anterior attachment superior (AAS), anterior attachment inferior (AAI), posterior attachment superior (PAS), and posterior attachment inferior (PAI). Inter-observer reliability between the two radiologists was evaluated using the weighted kappa coefficient. Group differences and correlations between attachment scores and disc position were analyzed using the Kruskal-Wallis H test, Mann-Whitney U test, and Spearman correlation analysis. RESULTS: A total of 122 TMJs (12 normal, 37 DDWR, and 73 DDWOR) were evaluated using WD-MRI. Peridiscal attachment scores differed significantly among the three groups (all P<0.05). The inter-observer reliability for AAS, AAI, PAS, and PAI demonstrated substantial to almost perfect agreement, with weighted kappa values of 0.838 [95% confidence interval (CI): 0.746-0.930], 0.896 (0.825-0.967), 0.852 (0.774-0.930), and 0.799 (0.705-0.893), respectively. Mann-Whitney U tests revealed that peridiscal attachment grades in the DDWOR group were significantly higher than those in both the normal and DDWR groups across all four attachments (Z=2.571-6.572, r=0.279-0.738, all P<0.05). However, when comparing the DDWR and normal groups, a significant difference was observed only for PAI (Z=2.653, P<0.05), with no significant differences for AAS, AAI, or PAS (P>0.05). The grading of the peridiscal attachments showed significant positive correlations with disc reducibility. Specifically, the positive correlations were strong for PAS (r=0.720) and PAI (r=0.630), and moderate for AAS (r=0.467) and AAI (r=0.356). CONCLUSIONS: This study demonstrated that structural alterations in the peridiscal attachments, particularly the posterior attachment, are significantly correlated with TMJ ID severity on WD-MRI, suggesting their potential value in TMD assessment.