Temporomandibular joint (TMJ) pain revisited with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

PURPOSE: We aimed to assess the contrast enhancement patterns of the retrodiscal tissue with dynamic contrast-enhanced MR imaging (DCE-MRI) with respect to different temporomandibular joint disc pathologies. Additionally, we questioned the relationship between the temporomandibular joint (TMJ) pain and the contrast enhancement pattern of the retrodiscal tissue regardless of the TMJ disc position.

MATERIALS AND METHODS: 52 joints of 26 patients (4 males and 22 females) who have pain in at least at one of their TMJ were included in this study. For the qualitative analysis, the joints were divided into four groups in terms of their disc positions: normal (1), partially displaced with or without reduction (2), totally dislocated with reduction (3) and totally dislocated without reduction (4). Besides, two different joint groups were constituted, namely the painful group and painless group according to the clinical findings without taking the TMJ disc positions into account. Quantitative analyses were made by means of measuring signal intensity ratios (SI) ratio at the retrodiscal tissue (from internal side and external side of the each joint) using DCE-MRI and these measurements were analyzed with paired samples t test to define the difference between the measurements. At the second stage, the time-dependent arithmetical mean values of the SI ratios were calculated for each joint group and significant differences between the groups were questioned using analysis of variance (ANOVA) test. Besides, painful and painless groups which were classified on the basis of the clinical data were compared according to the mean SI ratios found for each joint and the significant differences between these two groups were assessed by means of Student's T test. The results were assessed in 95% confidence interval where the significance level was p<0.05.

RESULTS: A significant difference was observed between the internal and external contrast enhancement of the joints with partial displacement. Another significant difference was found between the average time versus SI ratio curves of the four groups. In consequence of the comparison made between the joints classified as painful and painless on the basis of the clinical data, one more significant difference was observed according to the mean SI ratios of the groups without taking the TMJ disc position into account.

CONCLUSION: The contrast enhancement patterns in the retrodiscal tissues of the painful joints showed significant differences in comparison with the painless joints. This result supports the hypothesis defending that inflammation and increased vascularity are responsible from the TMJ pain. Besides, the measurements from the retrodiscal tissues of the joints with partial displacement show significant difference between the signals of the displaced and non-displaced parts of the joints. Dynamic contrast-enhanced imaging revealed that different disc malpositions create different contrast enhancement patterns. On this basis, it is assessed that the types of the disc malpositions, which are believed to be acquired pathologies, are correlated with the retrodiscal inflammation degrees.