Semiquantitative SPECT imaging for assessment of bone reactions in internal derangements of the temporomandibular joint.

The temporomandibular joints (TMJs) of 60 patients with arthrographically confirmed internal derangements and 30 volunteers were examined with single photon emission computed tomography (SPECT). Semiquantitative evaluation was done by forming a quotient from the counts of a constantly sized TMJ-ROI relative to the overall counts of the cranium. The TMJ/cranium quotient depended on the age of the subject, with younger patients showing a larger quotient than older ones. Normal joints were separated from the afflicted ones by means of a discriminant analysis. Sensitivity of semiquantitative evaluation was 78% (disc displacements with reduction) and 89% (disc displacements without reduction). Correct visual evaluation was made in 53% of the reducing and 75% of the nonreducing discs. Semiquantitative SPECT of the TMJs provides important information on the extent of osseous changes in afflicted joints and is suitable for follow-up of splint therapy. It may also be helpful as a screening method in detecting clinically normal joints before arthrography is carried out and in assessing the presumptive response to treatment with a splint.