MR Imaging of the TMJ: A Pictorial Essay

Chris Roth, MD; Robert J. Ward, MD; Scott Tsai, MD; Wendy Zolotor, MD; Richard Tello, MD, MSME, MPH

Disclosures

Appl Radiol. 2005;34(5):9-16. 

In This Article

Arthropathies

The TMJ is susceptible to the same varieties of arthritis that involve other joints in the body. Inflammatory arthritis and degenerative arthritis are the most common offenders; however, other types of arthritis known to involve the TMJ include: Infectious, posttraumatic, and metabolic arthritis.2

Among the inflammatory arthritides affecting the TMJ, rheumatoid arthritis is the most common and has received the most coverage in the literature. The abnormalities described in the TMJ are similar to those in other synovial joints afflicted with rheumatoid arthritis (Figure 6). The advantage of MRI in evaluating involvement of the TMJ in rheumatoid arthritis is its ability to reveal the softtissue abnormalities. The inflammatory synovial pannus eventually destroys the disk and its supporting structures, resulting in abnormal disk position, abnormal morphology, and possibly complete destruction of the disk. The presence of a joint effusion can be depicted with T2- weighted images. Direct visualization of the synovial pannus with T1-weighted postgadolinium images has been reported with variable success.[1,8] In any event, synovial enhancement is nonspecific and may occur in any inflammatory process, including osteoarthritis.[10]

A 24-year-old man with rheumatoid arthritis. (A) Open-mouth and (B) closed-mouth sagittal T1-weighted images show irregularity and erosive changes of the mandibular condyle (black arrowheads) and articular eminence (white arrows) from rheumatoid arthritis.

Despite the superiority of CT in depicting osseous anatomy, the ability of MRI to depict the bony abnormalities of rheumatoid arthritis has been shown to equal CT.[5] Destruction of the condyle and articular eminence are typical findings, and marrow signal abnormalities may reflect edema or, occasionally, subchondral sclerosis. Eventually, bony apposition ensues with destruction of the intervening soft-tissue structures. Because the bony and soft-tissue findings in rheumatoid arthritis are frequently bilaterial, both TMJs should be imaged.

In degenerative arthritis of the TMJ, MRI initially reveals subchondral changes, such as increased T2 hyperintensity and cysts. These findings are shared by primary and secondary osteoarthritis. Secondary osteoarthritis can be associated with previous trauma, surgery, internal derangement, or congenital malformation. The common end point is subchondral sclerosis, marginal osteophytes, condylar flattening, occasional subchondral cysts, and distortion of the disk due to adhesions.[2,4] In advanced cases, fusion of the joint may occur (Figure 7).

A 32-year-old man with fused right temporomandibular joint. (A) Open-mouthed and (B) closed-mouth sagittal T1 images show minimal translation and rotation of the mandibular condyle (arrowhead) relative to the articular eminence (curved arrow) with condylar head flattening and distortion of the disk (arrow) due to a fused joint.

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