Multiple-echo recombined gradient echo MR imaging of the temporomandibular joint

The purpose of this study was to compare images generated by a multiple-echo recombined gradient echo (MERGE) with the proton density-weighted fast spin-echo (PD-weighted FSE) sequence, T1-weighted fast spin-echo sequence (T1-weighted FSE), and T2-weighted fast spin-echo sequence (T2-weighted FSE) for the diagnostic imaging of the temporomandibular joint (TMJ).

Twenty-three patients with signs and symptoms of TMJ dysfunction were enrolled in this study. The four imaging modalities were used to examine the TMJ. Three images (lateral, middle, and medial parts of the condylar head) were reviewed by two radiologists, who rated the visibility of the disk and cortex of the condylar head.

For the medial part of the TMJ, in cases with a normally positioned disk, the results of the MERGE and PD-weighted FSE techniques were significantly better than those of the T1-weighted FSE and T2-weighted FSE. For visibility of the cortex in the normally positioned disk, MERGE was significantly better than PD-weighted FSE [P < 0.0125 (0.05/4)] at the middle and medial parts of the TMJ. MERGE was also significantly better than T1-weighted FSE [P < 0.0125 (0.05/4)] and T2-weighted FSE [P < 0.0125 (0.05/4)].

MERGE is better for visualizing the condylar only at the middle and the medial aspects of the TMJ in a normally positioned disk.