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Title High-Resolution Ultrasound Imaging Is an Accurate Diagnostic Modality for Disc Abnormalities of the Temporomandibular Joint
Clinical Question In adult patients with disc displacements of the temporomandibular joints, does ultrasound provide diagnostically accurate images?
Clinical Bottom Line High-resolution ultrasound imaging provides images of adequate diagnostic value when compared to the gold standard Magnetic Resonance Imaging (MRI). The evidence for this conclusion is provided by a systematic review and meta-analysis.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 29400370Talmaceanu/201874 patients with signs and symptoms of TMDs according the Research Diagnostic Criteria (RDC/TMD)Gold-standard controlled diagnostic accuracy study
Key results74 patients (148 TMJ sites) were clinically diagnosed according to RDC/TMD criteria and received subsequent ultrasound and MRI. Compared to MRI (which is widely considered to be the gold standard for soft tissue imaging of the TMJ) for the detection of disc displacements, high-resolution ultrasound imaging showed a high sensitivity (93%), specificity (87.8%), positive predictive value (87.1%), negative predictive value (93.5%), positive likelihood ratio (7.68), and accuracy (90.3%), Youden index (0.81) as well as a small negative likelihood ratio (0.03).
#2) 29455373Su/201816 studies including 1,747 TMJ sitesSystematic Review and Meta-Analysis
Key resultsSixteen studies were included for the meta-analysis based on defined inclusion criteria. Disc displacements with closed mouth were assessed in 14 studies while disc displacements with maximum mouth opening were assessed in 9 studies. For displacements with closed mouth, the pooled statistics were: sensitivity 78% (95% confidence interval [CI], 75% - 81%), specificity 77% (95% CI, 73% - 80%), positive likelihood ratio 3.02 (95% CI, 1.96 - 4.64), negative likelihood ratio 0.32 (95% CI, 0.23 - 0.45), diagnostic odds ratio 10.80 (95% CI, 5.46 - 21.38), AUC 0.8359. For disc displacements with maximum mouth opening, the pooled statistics were: sensitivity 70% (65% - 74%), specificity 88% (86% - 91%), positive likelihood ratio 5.08 (3.36 – 7.68), negative likelihood ratio 0.4 (0.26 – 0.63), diagnostic odds ratio 13.53 (6.27 - 29.18), AUC 0.95.
Evidence Search (“Ultrasonography” [Mesh] OR “ultrasonography” [All fields] OR “ultrasound” [All fields] OR “sonography” [All fields]) AND (“Temporomandibular joint disorders” [Mesh] OR “Temporomandibular joint disorders” [All Fields] OR “Temporomandibular joint disc” [Mesh] OR “Temporomandibular joint disc” [All Fields] OR “Temporomandibular joint dysfunction syndrome” [Mesh] OR “Temporomandibular joint dysfunction syndrome” [All Fields] OR “Temporomandibular joint” [Mesh] OR “Temporomandibular joint” [All Fields] OR “Craniomandibular disorders” [Mesh] OR “craniomandibular disorders” [All fields])
Comments on
The Evidence
Validity: The patient selection criteria in the clinical study by Talmaceanu et al. was homogenous; all the patients were selected according to RDC/TMD criteria. All the patients underwent both ultrasound and MRI, and examiners were blinded. According to this study, ultrasound has low sensitivity for degenerative changes as compared to MRI. It is also difficult to get superior quality ultrasound images of the TMJ, specifically at the open-mouth position due to superimposed hard tissues. The use of ultrasound is also not reliable in case of medial disc displacement because condyle interferes with the visualization of the disc. The reliability was not assessed in this study, and all the imaging examinations were done by a single radiologist. The most important limitation is that the accuracy of the gold standard (MRI) is not 100%, and the results of both ultrasound and MRI depend upon the examiner's skill. The systematic review by Su et al. clearly stated all the inclusion and exclusion criteria of an article to maintain homogeneity. The quality assessment was done using the QUADAS-2 tool based on four domains, including patient selection, index test, reference standard, and flow and timing. The author did a thorough search on PubMed and EMBASE using free text words and systematic vocabulary. Dental journals relevant to this topic as well as reference lists of the included studies were manually searched to avoid selection bias. Only the grey literature was not included in the systematic review. The systematic review listed a few limitations; for example, MRI was used as the gold standard, although it does not have perfect diagnostic accuracy for the diagnosis of disc derangement. For pragmatic reasons, however, MRI can be considered as a reference standard because comparison between ultrasound and autopsy is still not available to conduct a systematic review. The other limitation is exclusion of unpublished research because of the difficulty to recover this information. A third limitation was that, out of 16 included studies, 7 were from the same institution. Out of 7, 5 didn’t state the time limit of the study so repetition of the same subjects cannot be ruled out. This affects the result of meta-analysis. Despite of all the limitations mentioned, the role of ultrasound still be considered for the purpose of ruling in and ruling out disc derangement in dental practice. For further studies, a standardized protocol and well-trained operators are needed to reduce the variations in ultrasound results. The reference standard can also be improved by using latent class modeling by combining multiple diagnostic tests. Perspective: The limitations of MRI include high cost, slow scanning time, and contraindications for patients with pacemakers and other ferromagnetic devices; therefore, high-resolution ultrasound has the potential to be a very useful imaging modality to assess the soft tissue structures of the TMJ following a thorough clinical examination.
Applicability The low cost, lack of ionizing radiation, fast scan times, and dynamic imaging can make high-resolution ultrasound an adequate alternative screening modality for visualizing the soft tissue structures of the TMJ. However, there are certain limitations. The biggest limitation is the lack of a standardized protocol for acquisition and interpretation of the ultrasound images, making it highly operator-dependent, leading to subjective interpretation, and causing low interobserver reproducibility. Another limitation is that visualization of the joint structures is very technically challenging; thus further training and calibration are needed. The advantages of ultrasound over MRI should be emphasized, and further clinical research is needed to create standardized acquisition and interpretation protocols, which would help make ultrasound a universally accepted imaging modality for the temporomandibular joint soft tissue structures.
Specialty/Discipline (Oral Medicine/Pathology/Radiology) (Oral Surgery)
Keywords Ultrasonography, temporomandibular joint disorders, disc displacements
ID# 3345
Date of submission: 12/10/2018spacer
E-mail pahadia@uthscsa.edu
Author Mayank Pahadia
Co-author(s) e-mail
Faculty mentor/Co-author Dr. Hassem Geha
Faculty mentor/Co-author e-mail Geha@uthscsa.edu
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