Hyperintensity signal in the joint space of the temporomandibular joint on fat-saturated T2-weighted magnetic resonance imaging.

Our aim was to investigate the incidence of a hyperintense signal in the joint space of the temporomandibular joint (TMJ) on fat-saturated T2-weighted magnetic resonance images (MRIs). We studied 112 patients (224 joints) with disorders of the TMJ who were examined by T2-weighted MRI, and recorded the association between displacement of the disc and the hyperintense signal using the κ coefficient. A hyperintense signal was found in 4 of 91 joints (4%) when the disc was in the normal position, in all 19 joints with anterior disc displacement with reduction, and in 108 of the 114 joints (95%) with anterior disc displacement without reduction. There was a significant correlation between displacement of the disc and the hyperintense signal (p<0.001). The κ coefficient was 0.91. Such a signal in the joint space of the TMJ on fat-saturated T2-weighted MRI may indicate the presence of synovial fluid in the joint space with displacement of the disc.