STATIC AND REAL-TIME 3D SONOGRAPHY OF THE TEMPOROMANDIBULAR JOINT

Purpose: The specificity, sensitivity and accuracy of 2D temporomandibular joint (TMJ) sonography for the assessment of disk dislocation vary considerably in the literature. This difference may depend upon the quality of the ultrasound equipment, the frequency, observer experience and interpretation. Therefore static and real-time 3D sonography was introduced to assess additional information from a third dimension.

Methods and Materials: Sixty Eight patients, 136 TMJ, with different grades of clinical dysfunction were examined by 3D-scan (V530 static, V730 real-time, General Electric-Kretz, Solingen, Germany). A 8–12.5MHz transducer positioned parallel to the zygomatic arch, angulated by step-motor enabled 3D-imaging after defining a volume box on 2D-scan. Disc morphology and position was judged in occlusion and open mouth position. In order to compare the respective findings with those of a method offering high accuracy, coronal and sagittal magnetic resonance imaging was carried out immediately afterwards. Parasagittal, axial and – coronary MRI sequences followed (Magnetom Vision; Siemens, Tuttlingen, Germany).

Results: Sonographic examination on a comfortably erect sitting patient took 5 minutes average in maximum open and closed mouth position. The disc was seen overlying the condyle axial, frontal and sagittal with free transections and transparent hypoechogenic structures. Specificity was 75% determining partial dislocation, dislocation with repositioning and non-repositioning dislocation versus MRI, sensitivity 58%, accuracy 57%. Positive predictive value was 53%, negative predictive value 79%.

Conclusions: This study justifies further research on the diagnostic possibilities of 3D-sonography, with the advantage of multidimensional joint visualization at freely eligible angles. Although fair in specificity and negative predictive value, sensitivity and accuracy may ameliorate with future higher sound frequency and computed image enhancement.