TMJ Imaging: Bridging the Gap

Abstract

I read with concern the article by Moe et al, titled “Magnetic Resonance Imaging of Temporomandibular Joints of Children,” 1 Moe J, Desai N, Kang J, et al: Magnetic resonance imaging of temporomandibular joints of children [published online ahead of print March 8, 2016]. J Oral Maxillofac Surg. http://dx.doi.org/10.1016/j.joms.2016.03.022 Google Scholar published in the Journal of Oral and Maxillofacial Surgery. They evaluated magnetic resonance imaging (MRI) findings of temporomandibular joints (TMJs) in healthy children. The study's methods clearly lacked sufficient rigor. The investigators used pituitary MR images for the evaluation of TMJs. MRI of the pituitary gland uses a completely different protocol from that for TMJ, so it cannot be used for evaluation of the TMJ just because the latter is routinely captured in the field of view. The standard TMJ imaging protocol obtains T1 and T2 oblique sagittal and T1 oblique coronal images perpendicular and parallel to the long axis of the mandibular condylar head. Sagittal images should be obtained in closed- and open-mouth positions to determine the function of the disc. Coronal images are obtained in the closed-mouth position. The technique uses a dedicated circular-polarized transmit-and-receive dual-surface TMJ coil. This coil is considered an efficacious technique for evaluation of the TMJ for 2 reasons. First, there is a decrease in time of approximately 50% for the overall setup and data acquisition. Second, the use of dual-surface coils allows images to be obtained simultaneously from the right and left TMJs so that a direct comparison can be made between the 2 joints at the same degree of mouth opening. 2 Shellock F. Barry D. Pressman dual-surface-coil MR imaging of bilateral temporomandibular joints: Improvements in the imaging protocol. AJNR Am J Neuroradiol. 1989; 10: 595 PubMed Google Scholar Contrast-enhanced MRI studies are used only when evaluating a neoplasm. However, some investigators have found that gadolinium-enhanced MRI of the TMJ can allow clear differentiation between the proliferating synovium, which enhances, and joint effusion, which does not. 3 Tomas X. Pomes J. Berenguer J. et al. MR imaging of temporomandibular joint dysfunction: A pictorial review. Radiographics. 2006; 26: 765 Crossref PubMed Scopus (134) Google Scholar However, the additive value of contrast-enhanced MRI in standard TMJ evaluation has not been fully established. However, Moe et al did not clarify why they distinguished between glenoid margin and condylar margin synovial enhancement. In contrast, they stated that the image review was performed independently by 3 neuroradiologists, 2 subspecialized in pediatric neuroradiology and 1 in head and neck neuroradiology. However, when looking at their affiliations, only 1 co-author had a radiological background, and none of the image reviewers specialized in oral and maxillofacial radiology. Moe et al should note that a multiple disciplinary approach can be very effective from this perspective, because 1 specialist could offer expertise that others lack.