Diagnosis of retrodiscal tissue in painful temporomandibular joint (TMJ) by fluid-attenuated inversion recovery (FLAIR) signal intensity

The purpose of the present study is to analyze the fluid-attenuated inversion recovery (FLAIR) signal intensity of the retrodiscal tissue in a painful temporomandibular joint (TMJ), and to develop a diagnostic system based on FLAIR data.The study was based on 33 joints of 17 patients referred for MR imaging of the TMJ. Regions of interest were placed over retrodiscal tissue and gray matter (GM) on FLAIR images. Using signal intensities of GM as reference points, signal intensity ratios (SIR) of retrodiscal tissue were calculated. SIRs in painful TMJ were compared with those in painless TMJ. Wilcoxon's Rank Sum Test was used to analyze the difference in SIRs between the painful and painless groups (P<0·05).The SIRs of retrodiscal tissue were significantly higher in painful joints than in painless joints.FLAIR sequences provide a high signal in patients having painful TMJ, and it suggests that retrodiscal tissue in painful TMJ contains elements such as protein.