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OBJECTIVE: To define the proportions of agreement between fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), clinical diagnosis, and temporal artery biopsy (TAB) in patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). Furthermore, the association of 18F-FDG PET/CT uptake patterns and clinical presentation of newly diagnosed PMR and GCA was investigated. METHODS: Eighty patients newly suspected of having PMR, GCA, or concomitant PMR and GCA were included and followed for 40 weeks. Every patient underwent an 18F-FDG PET/CT scan before or within 3 days of initiation of steroids in case of GCA. FDG uptakes in 8 paired articular/periarticular sites and 14 arterial segments were evaluated based on a 4-point visual grading scale. RESULTS: Of the 80 patients (female: 50 [62.5%]; mean age ± SD: 72.0 ± 7.9), 64 (80.0%) patients were diagnosed with pure PMR, 3 (3.7%) with pure GCA, and 10 (12.5%) with concomitant PMR and GCA. Additionally, three (3.7%) patients were diagnosed with seronegative rheumatoid arthritis during the follow-up period. For the diagnosis of PMR, 18F-FDG PET/CT had a proportion of agreement of 75.3 (64.2-84.4), compared with clinical diagnosis. When comparing findings of 18F-FDG PET/CT with TAB, 18F-FDG PET/CT had a proportion of agreement of 93.0 (84.3-97.7) in all included patients and 69.2 (38.6-90.9) in the subgroup of patients with vasculitis. C-reactive protein was significantly higher in patients with PMR activity on 18F-FDG PET/CT compared with those without 18F-FDG PET/CT activity (P value = 0.006). CONCLUSIONS: 18F-FDG PET/CT is a powerful imaging technique in PMR and GCA that was in good agreement with clinical diagnosis and TAB.
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INTRODUCTION: Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are common inflammatory conditions. The diagnosis of PMR/GCA poses many challenges since there are no specific diagnostic tests. Recent literature emphasizes the ability of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to assess global disease activity in inflammatory diseases. 18F-FDG PET/CT may lead to the diagnosis at an earlier stage than conventional imaging and may also assess response to therapy. With respect to the management of PMR/GCA, there are 3 significant areas of concern as follows: vasculitis process/vascular stiffness, malignancy, and osteoporosis. METHODS AND ANALYSIS: All patients with suspected PMR/GCR referred to the Rheumatology section of Medicine Department at Svendborg Hospital, Denmark. The 4 separate studies in the current protocol focus on: the association of clinical picture of PMR/GCA with PET findings; the validity of 18F-FDG PET/CT scan for diagnosis of PMR/GCA compared with temporal artery biopsy; the prevalence of newly diagnosed malignancies in patients with PMR/GCA, or PMR-like syndrome, with the focus on diagnostic accuracy of 18F-FDG PET/CT scan compared with conventional workup (ie, chest X-ray/abdominal ultrasound); and the impact of disease process, and also steroid treatment on bone mineral density, body composition, and vasculitis/vascular stiffness in PMR/GCA patients. ETHICS AND DISSEMINATION: The study has been approved by the Regional Ethics Committee of the Region of Southern Denmark (identification number: S-20160098) and Danish Data Protection Agency (J.nr 16/40522). Results of the study will be disseminated via publications in peer-reviewed journals, and presentation at national and international conferences.