Evaluation of Temporomandibular Joint Shape by MR Imaging Analysis

Magnetic resonance (MR) imaging is useful for the medical diagnosis of temporomandibular joint (TMJ) syndrome. However, the signal intensities of MR image from condyle, glenoid fossa and articular disk in TMJ are low and the difference of intensities among them is small. It is difficult to separate each structure of TMJ from their signal intensities by the computer detection system completely. In this paper, the method of separation for the closed-mouth MR image was newly developed by using the information of the image analysis of tomography and the open-mouth MR image. Three normal samples and three abnormal ones were examined practically and the method for evaluation of TMJ shape was studied. The area of TMJ space was available to distinguish an abnormal sample from a normal one. The area of articular disk and the center of gravity on it were also useful and the anterior displacement of articular disk was found in abnormal samples.