[MRI of the temporomandibular joint. Demonstrability and significance of the retro-articular vascular plexus].

The retro-articular vascular plexus of the temporomandibular joint (TMJ) is of great importance for the function of this joint. Aim of this study was to determine the amount of increase of signal intensity in the retro-articular vascular plexus after intravenous injection of contrast medium and to figure out potential advantages of this procedure. The posterior band of the articular disc--a landmark in the diagnosis of disc dislocations--becomes prominent after injection of contrast medium. Forty-five temporomandibular joints were studied before, and after intravenous injection of contrast medium with magnetic resonance imaging (MRI) using T1-weighted images in parasagittal plane. In all cases a measurable increase of signal intensity was demonstrable in healthy volunteers as well as in patients with normal or pathological TMJ findings. In 53.3% of cases the posterior band was better differentiable after administration of contrast medium. In patients with suspicion of pathological features in series without contrast medium, in 27.3% of those cases administration of contrast medium led to a more precise--"diagnostic"--evaluation of disc location. The study emphasizes the use of contrasts medium for evaluations of disc dislocation with MRI in cases of pathological or unclear findings in precontrast MRI series.