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Diagnostic performance of magnetic resonance imaging for detecting osseous abnormalities of the temporomandibular joint and its correlation with cone beam computed tomography.

OBJECTIVE
With cone beam CT (CBCT) as the reference standard, the objective of this study was to determine the diagnostic accuracy of MRI for assessing osseous abnormalities of the temporomandibular joint (TMJ).


METHODS
106 TMJs from 55 patients with temporomandibular disorder were examined by CBCT and MRI. CBCT images were evaluated by two experienced oral radiologists with regard to the presence or absence of each of the following eight types of osseous abnormalities: Type 1, destructive and erosive osseous changes of the condyle; Type 2, flattening of the articular surface of the condyle; Type 3, deformity of the condyle; Type 4, sclerosis of the condyle; Type 5, osteophyte formation; Type 6, ankylosis; Type 7, erosion of the articular fossa and/or eminence; and Type 8, sclerosis of the articular fossa and/or eminence. For detection of these osseous abnormalities by MRI, proton density-weighted images and T(2) weighted images were evaluated independently by three observers. Using CBCT findings as the reference standard, the diagnostic performance of MRI for detecting various types of osseous abnormalities was evaluated by calculating its sensitivity and specificity.


RESULTS
Out of 106 joints, CBCT revealed Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities in 25, 19, 26, 20, 14, 5, 19 and 22 joints, respectively. The mean sensitivities of MRI among the three observers for detecting Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities were 61%, 30%, 82%, 40%, 48%, 34%, 61% and 41%, respectively, whereas the mean specificities were 86%, 92%, 91%, 95%, 84%, 98%, 89% and 91%, respectively.


CONCLUSIONS
Although high specificity (84-98%) was obtained with MRI, this modality showed relatively low sensitivity (30-82%) for detecting osseous abnormalities of the TMJ. The value of MRI for the detection of TMJ osseous abnormalities is considered to be limited.