T2 mapping with 3.0 T MRI of the temporomandibular joint disc of patients with disc dislocation.

INTRODUCTION: T2 mapping, as a quantitative biochemical MRI-technique that provides information on water and collagen fiber content and composition, was shown to be clinically feasible for the evaluation of healthy temporomandibular joints.

OBJECTIVES: The aim of our study was to compare the T2 values of whole discs in patients with and without disc dislocation, to evaluate the possible influence of morphological findings on T2 values and to assess the interrater agreement.

METHODS: Sixty-six patients were included in the study. Three experienced examiners assessed the perceptibility of the morphological parameters and the position of the articular disc on the morphological MR images. On the T2 maps, the T2 values of the region-of-interest (ROI) were assessed.

RESULTS: The ICC (Intraclass Correlation Coefficient) for the reproducibility of the T2 values was 0.717. The assessment of the morphologic parameters was excellent or good in most of the discs. There was no significant difference in the T2 values based on disc position or signal intensity. But, a statistically significant moderation effect (p = .014) could be identified, indicating that the effect of disc position differs for different signal intensities. Condyle position, effusion, and degenerative changes showed pronounced moderation effects on the T2 values.

CONCLUSION: Due to the high sensitivity to effusion, T2 mapping currently seems to be unsuitable as a diagnostic tool for routine use in the temporomandibular joint. The moderation effect clearly shows the influence of factors such as signal intensity, effusion, arthrosis, and condyle position. Perhaps a solution for these problems could be the development of dedicated TMJ coils for higher field strengths at 7.0 T.