Comparison of the T2 relaxation time of the temporomandibular joint articular disk between patients with temporomandibular disorders and asymptomatic volunteers.

BACKGROUND AND PURPOSE: T2 relaxation time is a quantitative MR imaging parameter used to detect degenerated cartilage in the knee and lumbar intervertebral disks. We measured the T2 relaxation time of the articular disk of the temporomandibular joint in patients with temporomandibular disorders and asymptomatic volunteers to demonstrate an association between T2 relaxation time and temporomandibular disorder MR imaging findings. MATERIALS AND METHODS: One hundred forty-four patients with temporomandibular disorders and 17 volunteers were enrolled in this study. An 8-echo spin-echo sequence for measuring the T2 relaxation times was performed in the closed mouth position, and the T2 relaxation time of the entire articular disk was measured. Patients were classified according to the articular disk location and function, articular disk configuration, presence of joint effusion, osteoarthritis, and bone marrow abnormalities. RESULTS: The T2 relaxation time of the entire articular disk was 29.3 ± 3.8 ms in the volunteer group and 30.7 ± 5.1 ms in the patient group (P = .177). When subgroups were analyzed, however, the T2 relaxation times of the entire articular disk in the anterior disk displacement without reduction group, the marked or extensive joint effusion group, the osteoarthritis-positive group, and the bone marrow abnormality-positive group were significantly longer than those in the volunteer group (P < .05). CONCLUSIONS: The T2 relaxation times of the articular disk of the temporomandibular joint in patients with progressive temporomandibular disorders were longer than those of healthy volunteers.

Perineural spread of adenoid cystic carcinoma in the oral and maxillofacial regions: evaluation with contrast-enhanced CT and MRI.

OBJECTIVES: The objective of this study was to compare the accuracy of contrast-enhanced CT (CECT) and contrast-enhanced MRI (CEMRI) in the detection of perineural spread (PNS) of adenoid cystic carcinoma (ACC) in the oral and maxillofacial regions. METHODS: This study consisted of 13 ACCs from 13 patients, all of which were histopathologically diagnosed. Both CECT and CEMRI were performed in all patients before the treatment. The images of each patient were retrospectively evaluated for the detection of PNS. The definitions of PNS included abnormal density/signal intensity, contrast enhancement or widening of the pterygopalatine fossa, palatine foramen, incisive canal, mandibular foramen and mandibular canal, and enlargement or excessive contrast enhancement of a nerve. RESULTS: 11 out of 13 cases were proven to exhibit PNS histopathologically. 8 of the 11 cases for which PNS was histopathologically proven exhibited PNS on MR images. Six of the eight cases for which PNS was exhibited on MR images also exhibited PNS on CT images. The sensitivity, specificity and accuracy for the detection of PNS were 55%, 100% and 62% on CT images and 73%, 100% and 77% on MR images, respectively. Although the accuracy of PNS on MR images was slightly superior to that on CT images, there were no statistically significant differences between the detection of PNS on CT images and on MR images. CONCLUSIONS: CT and MR images are equally useful for the detection of PNS of ACC in the oral and maxillofacial regions.