الفهرس 
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Abstract
RA is a systemic chronic inflammatory disease of which the etiology is not fully known and that affects joints dominantly. TMJ involvement in patients with RA is a common condition.
The aim of this study was to evaluate the temporomandibular joint abnormalities in patients with RA using Cone Beam Computed Tomography scanning and Magnetic Resonance Imaging.
40 TMJs from 20 RA patients were examined by CBCT and MRI. All CBCT and MRI images were evaluated separately by two experienced oral radiologists with regard to the presence or absence of soft tissue and/or osseous abnormalities, the radiologists were blinded to the clinical symptoms and prior TMJ disease.
The following joint abnormalities were noted, soft tissue abnormalities, which include synovial membrane thickening, pannus formation, bone marrow edema, disk distortion and disk displacement. where the osseous abnormalities were include: bone erosion, flattening of the articular surfaces, sub-cortical and generalized sclerosis, sub-cortical cyst, osteophyte, joint space reduction and abnormal position of the condyle head within the temporal fossa.
The collected data were coded, tabulated, and statistically analyzed using IBM SPSS statistics (Statistical Package for Social Sciences) software version 22.0, IBM Corp., Chicago, USA, 2013.
We found that CBCT was clearly depicted the morphology of the condyle and the surrounding bone structure in all of the cases. Based on CBCT images, the frequency of each osseous abnormality ranged from 72.5% for condylar head erosion to 10% for loose joint body. On the other hand MRI clearly detected all soft tissue abnormalities with the most frequent abnormality was synovial membrane thickening 85% and the least frequent abnormality was disk distortion 15%, MRI could also detect all osseous abnormalities with the most frequent abnormality was condylar head erosion 52.5% and the least frequent was loose joint body 5%.
By 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. Sensitivity test was used to measure the agreement between CBCT and MRI in detecting the probability of radiographic signs of osseous deformities in patients with RA.
MRI had low sensitivity, but high specificity in diagnosis of most of the osseous abnormalities, the mean sensitivity of MRI was 25%-90.9%, and the mean specificity was 70.8%-97.2%. MRI was most sensitive for detecting condyle abnormal position, and least sensitive for detecting loose joint body.