Repetitive 18F‐fluorodeoxyglucose positron emission tomography in giant cell arteritis: A prospective study of 35 patients

Abstract Objective To study fluorodeoxyglucose (FDG) uptake in the different vascular beds and in the large joints of patients with giant cell arteritis (GCA) at diagnosis, during steroid treatment, and at relapse. Methods All consecutive patients admitted to our department with a diagnosis of GCA underwent FDG–positron emission tomography (PET) scan before treatment with methylprednisolone was started. PET scans were repeated at 3 and 6 months, if the initial PET scans showed vascular FDG uptake. PET scans were scored at 7 different vascular areas and a total vascular score (TVS) was calculated, ranging from 0 to 21. Results A total of 35 patients entered the study. At diagnosis, vascular FDG uptake was noted in 29 patients (83%), especially in the subclavian arteries (74%), but also in the aorta (>50%) and up to the femoral arteries (37%). TVS decreased from a mean ± SD score of 7.9 ± 5.5 at baseline to 2.4 ± 3.5 on repeat PET scan at 3 months ( P < 0.0005), but did not further decrease at 6 months. The patients who relapsed had similar earlier decreases of TVS compared with those who did not relapse. FDG uptake in the shoulders at diagnosis correlated significantly with the presence of polymyalgia rheumatica ( P = 0.005). Conclusion FDG uptake in the large vessels is a sensitive marker for GCA, which can involve the larger thoracic, abdominal, and peripheral arteries. Polymyalgia rheumatica symptoms in patients with GCA correlate with (peri)synovitis of the shoulders. Relapses of GCA cannot be predicted by results of former PET scintigraphies.