The Analysis of Incidental Findings on Temporomandibular Joint Magnetic Resonance Imaging

Purpose: The aim of this study was to investigate the types and frequency of the various incidental findings (IFs) on magnetic resonance images (MRI) taken from the patients with temporomandibular disorder (TMD) symptoms. Materials and Methods: Temporomandibular joint (TMJ) MRI taken from 1,013 patients with TMD symptoms were evaluated retrospectively. IF was defined as imaging features that were accidentally or unexpectedly found, rather than degenerative bony changes of TMJ complex or disc derangement. They were classified into two groups as TMJ site-specific findings and unexpected findings at other regions. The frequency of the sub groups was analyzed. Result: A total of 26 (2.57%) cases with IFs were classified into 13 cases with TMJ site-specific findings and 13 cases with unexpected findings at other region. TMJ site-specific findings included synovial chondromatosis in 6 cases, synovial cyst in 6 cases and osteochondroma in one case. Unexpected findings included salivary gland tumor in 3 cases, developmental cyst in 3 cases, vascular malformation in 2 cases, mastoiditis in 4 cases and sialadenitis on parotid gland in one case. Conclusion: When diagnosing TMD through TMJ MRI, clinicians should carefully read the image, considering the possibility of IFs because TMJ MRI can provide pathologic information in TMJ region and other oral and maxillofacial region.