Repetitive 18-fluorodeoxyglucose positron emission tomography in isolated polymyalgia rheumatica: a prospective study in 35 patients

Objective. To study fluorodeoxyglucose (FDG) deposition in different vascular beds and in the large joints of patients with isolated polymyalgia rheumatica (PMR), and to investigate whether there is a relation between FDG-positron emission tomography (PET) results and risk of relapse. Methods. All consecutive patients with isolated PMR underwent a FDG-PET scan before treatment with steroids was started and-if logistics allowed-at 3 and 6 months. PET scans were scored at seven different vascular areas and a total vascular score (TVS) was calculated, ranging from 0 to 21. FDG uptake in the shoulders, the hips and the processi spinosi of the vertebrae was scored as 0 (no uptake), 1 (moderate uptake) or 2 (intense uptake). Results. Thirty-five patients entered the study. At diagnosis, vascular FDG uptake was noted in 11 patients (31%), predominantly at the subclavian arteries. Mean TVS was low. FDG uptake in the shoulders was noted in 94% of patients, in the hips in 89% and in the processi spinosi of the vertebrae in 51%. The intensity of FDG uptake in the large vessels or in the shoulders, hips or processi spinosi did not correlate with the risk of relapse. Conclusions. Only one in three patients has an (moderately) increased vascular FDG uptake, especially in the subclavian arteries. The vast majority has inflammation of shoulders and hips, and half of them have increased FDG-uptake at the processi spinosi. Results of FDG-PET scans in patients with PMR did not correlate with their risk of relapse.