Methods: The study group consisted of 30 volunteers (23 female and 7 male) with a mean age of 25 years. Prior to the MRI examinations, the subjects underwent clinical investigation according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Subsequently, continuous movements of the TMJ during voluntary mouth opening and closing at high spatial resolution (0.75 x 0.75 mm2) were monitored on a clinical 3 T MRI system in real-time based on FLASH acquisition with radial encoding. The data were evaluated by three TMJ experts independently without knowledge of the results of the clinical investigation. Consecutively, the clinical and MRI diagnoses and findings were compared.
Results: In general, the disc shape, the anterior and posterior border of the disc as well as the range of motion of the condyle head were illustrated in good condition during jaw opening and closing using real-time radial FLASH MRI. Particularly, various types of internal derangements were observed, which corresponded to the results of the clinical investigation. In case of distinct disc dislocations with reduction, information about both motion and anatomical relation of the TMJ at and around the position where the disc moved back onto the condyle were clearly presented. In case of limited mouth opening due to disc displacement without reduction, it was easily recognizable, that the disc stays anterior to the condylar head upon opening.
Conclusion: The preliminary data confirm the advances of real-time radial FLASH MRI to be an effective and versatile tool for the evaluation of the TMJ during motion. In particular cases, the additional information provided by this procedure might be useful in deciding more precisely whether and which therapeutic intervention is recommendable.