New arguments for a vasculitic nature of polymyalgia rheumatica using positron emission tomography

Objective. To study the possible contribution of fluorodeoxyglucose (FDG)-p ositron emission tomography (PET) in the diagnosis of giant cell arteritis and polymyalgia rheumatica. Methods. A consecutive case series consisting of five patients with polymya lgia rheumatica, six patients with temporal arteritis and 23 age-matched pa tients with ether inflammatory conditions were evaluated with FDG-PET. Stud ies were performed before therapy with steroids was started. Results. A total of 4/6 patients with giant cell arteritis and 4/5 patients with polymyalgia had increased FDG uptake in their thoracic vessels, compa red to 1/23 controls (P < 0.001). Increased vascular FDG uptake in the uppe r legs was seen in 8/11 patients with giant cell arteritis or polymyalgia c ompared to 8/23 control patients (P < 0.05), and in the lower legs in 6/11 patients compared to 6/23 controls (P = not significant). Conclusions. FDG-PET scan is the first non-invasive technique which may ind icate large-vessel vasculitis and which ran show its extension throughout t he body. It strongly suggests that polymyalgia rheumatica is a form of vasc ulitis.