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Temporomandibular joint: morphology and signal intensity characteristics of the disk at MR imaging
C A Helms1, L B Kaban, C McNeill
1Department of Radiology, University of California, San Francisco 94143-0628.
Abstract:
Magnetic resonance (MR) imaging has been used in the temporomandibular joint (TMJ) primarily to define the disk position. This report examines altered morphology and signal intensity characteristics of the TMJ disk as they relate to the severity of internal derangement. Two hundred sixteen joints in 133 patients with a history of such derangement. were imaged with MR. Disk position, signal intensity, morphology, and the presence of osteoarthritis were determined for each joint. The normal disk was not anteriorly displaced and had a normal "bow-tie" shape. A grade 1 disk was anteriorly displaced and had a normal shape; a grade 2 disk was anteriorly displaced and had an abnormal shape. Forty (19%) joints were considered normal; none of these exhibited osteoarthritis. One hundred thirty-nine (64%) joints were grade 1; osteoarthritis was found in 17%. Thirty-seven (17%) were grade 2; osteoarthritis was found in 95%. All forty normal joints had high or intermediate signal intensity in the disk. Osteoarthritic joints had a higher percentage of disks with diminished intensity (P less than .0001). Severe or untreated osteoarthritis is known to be a complication of TMJ internal derangements; hence this grading system seems to correlate with the severity of internal derangement.
Insights
Magnetic resonance (MR) imaging reveals that temporomandibular joint (TMJ) disk changes correlate with internal derangement severity. Abnormal disk morphology and signal intensity on MR scans indicate increased likelihood of osteoarthritis.
Area of Science:
- Radiology
- Orthopedics
- Biomedical Imaging
Background:
- Temporomandibular joint (TMJ) internal derangement is a common condition.
- Magnetic resonance (MR) imaging is crucial for assessing TMJ disk position.
- Altered TMJ disk morphology and signal intensity may indicate disease severity.
Purpose of the Study:
- To investigate the relationship between TMJ disk morphology and signal intensity.
- To correlate MR imaging findings with the severity of TMJ internal derangement.
- To assess the presence of osteoarthritis in relation to TMJ disk characteristics.
Main Methods:
- MR imaging was performed on 216 TMJs in 133 patients with internal derangement.
- Disk position, signal intensity, and morphology were evaluated.
- The presence of osteoarthritis was recorded and correlated with disk findings.
Main Results:
- Normal disks were not anteriorly displaced and had a "bow-tie" shape.
- Grade 1 disks (anteriorly displaced, normal shape) showed 17% osteoarthritis.
- Grade 2 disks (anteriorly displaced, abnormal shape) showed 95% osteoarthritis.
- Osteoarthritic joints exhibited significantly diminished disk signal intensity (P < .0001).
Conclusions:
- A grading system for TMJ disk derangement based on MR imaging findings appears to correlate with disease severity.
- Abnormal disk morphology and reduced signal intensity on MR imaging are associated with a higher prevalence of osteoarthritis.
- MR imaging is valuable for assessing TMJ internal derangement severity and associated osteoarthritis.