MR imaging of the TMJ

High intensity spot of the anterior region with joint compartment by using “fast-scan” imaging

Abstract

In order to observe TMJ in a motion study, a protocol of 6 images was developed. MR images of the TMJ in multiple phases of opening were obtained by using the “fast scanning” capabilities of the GE RESONA MR system.
A short flip angle (gradient recalled acquisition in the steady state, or GRASS) “fast scanning” technique was used to assess functional TMJ dynamics.
GRASS is routinely used to image the joint from closed to maximally open position and back to closed again. While using the technique, areas of high intensity spot were noticed in the anterior of the upper and lower joint compartment. Blood vessels, synovia, effusion and fat artifacts were suspected as possible causes of the high intensity spot.
The flow compensation technique and method of changing the slice thickness in GRASS were used to examine these possible causes. We found that the intensity spot in the anterior joint compartment was probably a partial volume effect caused by synovia and effusion rather than blood vessels or fat artifact.