[The temporomandibular joint meniscus in MRI]

The continuing improvement of the MRI's equipment and software led us to a continuous adaptation of the exam technique. We use today a bilateral coil technique, 3 inches in diameter. Four slices are performed for each articulation (4 mm thick) in the true sagittal plane. A fast spin echo, balanced in proton density, for one minute, allows the study of 15 steps inside a full open/close cycle. Oblique coronal cuts are also performed parallel to the long axis of the condyle in a T1-weighted spin echo sequence in close and half-open positions. The analysis of 350 subjects allows to detail more precisely the meniscal displacement. Beside the classic anterior luxation, the meniscus slips medially, laterally and may rotate. These different situations may be isolated or combined. The dynamic study is specifically useful in the displacement with reduction exams. It enables permits to point out the timing of the disk disturbance: this information may be of great help in therapeutic decisions.