PET imaging of inflammation.

Inflammatory diseases are common place and often chronic. Most inflammatory cells have increased uptake of glucose which is enhanced in the presence of local cytokines. Therefore, imaging glucose metabolism by the means of 18F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) holds significant promise in imaging focal inflammation. Most of the work published involved small series of patients with either vasculitis, sarcoid or rheumatoid arthritis. It would appear that FDG PET is a simple and effective technique to identify inflammatory tissue in these conditions. There is even some work to suggest that by comparing baseline and early post therapy scans clinical outcome can be predicted. This would appear to be true with vasculitis as well as retroperitoneal fibrosis. The number of patients in each study is small but the evidence is compelling enough to recommend FDG PET imaging in the routine care of these patients.