Current trends in temporomandibular joint imaging.

Diagnostic imaging of the temporomandibular joint has undergone a revolutionary development during the last two decades. With advanced modalities we have been able to differentiate between different articular entities in patients with temporomandibular joint disorders. The purpose of this article is to review and discuss these modalities and their contribution to our present knowledge, with emphasis made on current trends in diagnostic temporomandibular joint imaging. The main section deals with diagnostic imaging of the subgroup of disorders with internal derangement caused by disk displacement including posttreatment imaging. Imaging of pathologic entities characterized by chronic inflammation such as rheumatoid arthritis are discussed in the second section. Finally, the potential of diagnostic imaging of infrequent conditions such as tumors is briefly reviewed. Magnetic resonance imaging has surpassed arthrography and computed tomography for the evaluation of most patients in these three subgroups. In patients who have various forms of disk displacements with or without accompanying bone abnormalities, a diagnostic accuracy of at least 90% may be achieved by oblique sagittal and coronal magnetic resonance imaging. In addition, alterations in the condylar marrow may be detected. T2-weighted magnetic resonance imaging can make a significant diagnostic contribution by demonstrating inflammatory reactions such as joint effusion and marrow edema. In the subgroup of patients with chronic inflammatory diseases, magnetic resonance imaging may also demonstrate abnormalities not shown with other imaging modalities. Disk deformation, fragmentation, and destruction may indirectly suggest the presence of synovial proliferation/pannus formation, which in selected cases may be directly depicted with intravenous gadopentetate dimeglumine. For more detailed evaluation of the bone condition and of soft tissue calcifications in joints with inflammatory diseases, tumors, or other disorders, computed tomography is the preferable imaging modality.