Dual-circle: a new way of assessing temporomandibular joint disc position at coronal MRI

Temporomandibular disorders (TMDs) are frequently associated with internal derangement (ID) of the temporomandibular joint (TMJ), and MRI is the gold standard for diagnosis. However, most studies focus on sagittal disc position, neglecting coronal mediolateral displacement, while traditional quantitative methods have limitations. This study aimed to validate a novel dual-circle method for assessing coronal mediolateral disc displacement.

Thirty-eight asymptomatic volunteers (76 TMJs) underwent 3.0 T MRI. Two observers measured mediolateral displacement using both the classical Schmitter method and the dual-circle method. Inter-observer reliability was evaluated via intraclass correlation coefficient (ICC) and Cronbach's α, with correlation and diagnostic efficacy analyzed using Spearman's coefficient and McNemar's test.

Results showed the dual-circle method detected 15 (19.7%) disc displacements versus 7 (9.2%) via the conventional method, with significantly higher sensitivity (P < .05). Measurements of the 2 methods were strongly positively correlated (r = 0.868, P < .05). All dual-circle parameters achieved excellent inter-observer reliability (ICC = 0.715-0.965), markedly superior to the conventional method (partial ICC = 0.525) with better consistency.

The dual-circle method offers intuitive, accurate quantification of mediolateral disc displacement, reducing misdiagnoses. It is recommended as a practical option for coronal MRI analysis of TMJ disc position, with the potential to optimize TMD diagnosis and advance understanding of the morphological diversity of the TMJ disc.