Histologic evaluation of computed tomographic TMJ articular disk visualization

The reliability of computed tomography (CT) for visualization of the temporomandibular joint (TMJ) articular disk has often been the subject of discussion. The success or failure of CT may be determined by different factors. This study was designed to evaluate the effect of these factors, such as type of equipment used, patient motion and artifacts on articular disk visualization, and also to assess the validity of the articular disk image in comparison with histological pictures. Ten TMJ autopsy specimens were collected after the teeth were placed in intercuspal position. The TMJ was deep frozen, dissected and kept frozen during subsequent CT scanning and histological processing. To study the influence of the specifications of the CT equipment on the visualization of the TMJ articular disk, two different CT units were used. The CT images were evaluated for interpretability and interpretation of articular disk position. The validity of the CT appearance of articular disk position and form was assessed by superposition of CT and histological pictures. The interpretability of the articular disk visualization in the CT images was very low. However, for CT images judged to be interpretable, there was a good degree of matching between the diagnosed articular disk position and form and the findings in the corresponding histological pictures. No significant differences between the two different CT units were noted. It is concluded that CT is inappropriate for TMJ articular disk visualization. Nevertheless, if the disk is visible on the CT image, its appearance represents the true position and form within the joint.