Comparative Evaluation of MRI and Ultrasonography for Temporomandibular Joint Pathologies with Emphasis on Bone Marrow Edema

OBJECTIVES: This retrospective diagnostic accuracy study compared magnetic resonance imaging and ultrasonography in 98 temporomandibular joints from 49 patients for evaluating disc position, disc configuration, joint effusion, condylar degenerative changes, and bone marrow edema. METHODS: A total of 98 temporomandibular joints from 49 patients who underwent both modalities were retrospectively evaluated by two independent, blinded observers using established classification systems. All imaging was performed prior to the initiation of any specific TMJ treatment. Intra- and inter-observer agreement, the diagnostic accuracy of ultrasonography relative to the magnetic resonance imaging reference standard, diagnostic likelihood ratios, and associations between parameters were analysed statistically. RESULTS: Intra- and inter-observer agreement was good to excellent for both modalities (Kappa 0.71-0.91, p < 0.05). Ultrasonography showed high sensitivity and specificity for disc displacement (94.4-97.4% and 61.5-70.0%) and effusion (87.5-92.3% and 84.0-87.0%), but more limited performance for bone marrow edema, particularly in specificity (60.0-61.1%). On the left side, magnetic resonance imaging identified bone marrow edema in 63.3% of cases compared with 36.7% on ultrasonography (p = 0.015). Folded and convex disc configurations and marked or severe effusion were both associated with displacement without reduction (p ≤ 0.046). CONCLUSIONS: Ultrasonography appears suitable as a first-line screening modality for selected TMJ abnormalities, whereas magnetic resonance imaging remains indispensable whenever bone marrow pathology or complex internal derangement is suspected. ADVANCES IN KNOWLEDGE: This study provides direct, same-patient diagnostic accuracy data comparing ultrasonography with magnetic resonance imaging across multiple temporomandibular joint pathologies, including an indirect ultrasonographic assessment of bone marrow edema via cortical irregularity, clarifying which findings ultrasonography can reliably screen for and which still require magnetic resonance imaging confirmation.