The accuracy of sonography for evaluation of internal derangement of the temporomandibular joint in asymptomatic elementary school children: Comparison with MR and CT

BACKGROUND AND PURPOSE: In order to clarify the incidence and evolution of disk displacement in the temporomandibular joint (TMJ) in children, we perf ormed a longitudinal analysis in 18 subjects. Some investigators have sugge sted that sonography can provide information about the articular disk posit ion of the TMJ, The purpose of this study was to determine the diagnostic a ccuracy of sonography for revealing internal derangement of the TMJ in elem entary school children compared with our standard of reference, MR imaging and helical CT. METHODS: Eighteen children were examined using both sonography and MR imagi ng or helical CT or both. The sonographically revealed distance between the articular capsule and the lateral surface of the mandibular condyle was me asured and compared with that obtained by MR or helical CT scanning. RESULTS: Compared,vith our MR/CT standard of reference, sonography revealed a sensitivity of 83%, a specificity of 96%, and an accuracy of 92% for ide ntifying disk displacement (defined as a distance of 4 mm or more between t he articular capsule and the lateral surface of the mandibular condyle), CONCLUSION: Although sonography's sensitivity, specificity, and accuracy fo r the diagnosis of disk displacement were slightly inferior to those of MR or helical CT, we assert it is a useful imaging method for longitudinal inv estigations of a large group of elementary school children, Internal derang ement of the TMJ should be suspected if sonography reveals a distance betwe en the articular capsule and the lateral surface of the mandibular condyle of 4 mm or more.