OP0001 [18F]Fdg PET in Giant-Cell Arteritis: A Prognostic Tool for Aortic Complications

Background Extracranial involvement of large vessels in giant-cell arteritis (GCA) is probably underdiagnosed. Aortic complications (dilatation and dissection) are a prominent cause of death. [18]F-fluorodeoxyglucose positron-emission tomography ([18F]FDG-PET) is an imaging tool that can demonstrate the inflammation of large vessels. Objectives To assess the value of PET in the diagnosis, the extent of disease's activity and the follow-up of patients with GCA. Methods Patients were enrolled if they satisfied two criteria: (1) diagnosis of GCA was established fulfilling the American College of Rheumatology criteria (including patients with two criteria and extra-temporal biopsy-proven giant-cell vasculitis); and (2) at least one PET had been performed, at diagnosis (before or in the first 10 days of corticosteroid treatment) or during the follow-up. Patients' charts were retrospectively reviewed. Clinical symptoms were divided into cephalic and extra-cephalic manifestations. Positivity of PET was defined as a FDG vascular uptake superior to the liver on at least one of the eight following vascular segments: thoracic, abdominal aorta, subclavian, axillary, carotidian, iliac/femoral, and upper and lower limb arteries. Isolated uptakes from the iliac/femoral arteries were not considered as a positive PET. Results 133 patients were enrolled (88 women [66%], median age 70 [50–86]). GCA was biopsy-proven in 78 patients (59%), including 14 positive temporal-artery biopsies (TAB) in patients without any cephalic symptoms. PET was performed at diagnosis in 67 patients and during the follow-up in 66 patients. PET results were positive in 68 (51%) patients and a median of 4 [1–8] vascular areas were involved. The thoracic aorta was involved in 79% of cases. Patients with a positive PET had significantly more extra-cephalic manifestations (59% vs. 37%, p=0.001) and less cephalic symptoms (71% vs. 94%, p=0.0005) than patients with a negative PET. No difference was noted between the 2 groups regarding the TAB status, inflammatory parameters, or cardiovascular risk factors. With a median follow-up of 35 months [6–263], 76 (57%) patients relapsed, and PET results were not clinically useful in 24/26 patients in whom another PET was performed. Aortic dilatation occurred in 14 (11%) patients (of which, 11 [16%] had a positive PET, p=0.03) and aortic dissection in three patients with a positive PET (all with a known dilatation). In univariable analyses, occurrence of aortic co