Visualization of the articular disk of the temporomandibular joint in near-real-time MRI: feasibility study

While static MRI of the TMJ is the method of choice to evaluate the articular disk (AD), dynamic MRI so far has failed to display the AD. The capability of a modified True-FISP sequence to visualize the AD in dynamic near-real-time imaging (NRTI) was evaluated. Twelve healthy subjects and 17 patients were investigated. Besides static routine imaging, sagittal NRTI of both TMJs was performed with a True-FISP sequence at 1.5 T with TE/TR=1.84/3.68 ms. Two temporal resolutions (250/500 ms) were tested. The quality of the visualization of the AD was rated on a four-point scale (1= very good to 4= poor visualization) by two observers in consensus. ADs of the volunteers were visualized with high quality in all stages of movement (score: 1.69). In patients with internal derangement, disk-motion was clearly depicted, including fast reposition movements. Due to degenerative changes of the AD, the quality of the depiction in patients was slightly lower (score: 2.4). According to the preliminary results of this feasibility study, the suggested NRTI True-FISP sequence is capable of visualizing the entire motion of the AD of the TMJ in normal and pathologic stages with high quality. Further studies are needed to prove the clinical usefulness of this new technique.