Usefulness of proton density and T2-weighted vs. T1-weighted MRI in diagnoses of TMJ disk status.

The aim of this study was to test the hypothesis that proton density and T2-weighted magnetic resonance (MR) images are more useful than T1-weighted MR images in the diagnoses of disk displacement, disk reduction, and disk shape. The subject group consisted of 92 patients referred for bilateral MRI imaging because of diagnosed signs of temporomandibular disorders (TMD). In the experimental group (52 patients), both T2-weighted and proton density images were made. In the control group (40 patients), only T1-weighted images were taken. The images were evaluated by two oral radiologists relative to their usefulness as a diagnostic aid and rated as either good or fair in each diagnostic category. The percentages of ratings that were good were higher (p < 0.01) for T2-weighted and proton density images than for T1-weighted images in all three types of diagnoses (Fisher's Exact test). In conclusion, T2-weighted and proton density-weighted images were found to be more useful than T1-weighted images in the diagnoses of disk status.