AbstractObjectiveTo evaluate the presence and extent of large‐vessel inflammation in patients with chronic periaortitis (CP) using 18F‐fluorodeoxyglucose‐positron emission tomography (FDG‐PET).MethodsA consecutive case series consisting of 7 patients with CP seen over a 3‐year period and a control group of 14 patients with malignancy were evaluated with FDG‐PET. For every case we selected 2 age‐ and sex‐matched controls who underwent PET imaging for malignancy. The diagnosis of CP was made by means of computed tomography. PET imaging was performed at diagnosis before therapy was started. Measurement of vascular uptake was graded using a 4‐point semiquantitative scale.ResultsAll patients had evidence of grade 2+ or 3+ vascular uptake in the abdominal aorta and/or iliac artery. No controls showed vascular uptake greater than 1+. Vascular uptake in the thoracic aorta and/or in its branches was seen in 3 (43%) of 7 patients. Vascular uptake in abdominal aorta and/or iliac artery was observed in patients with CP but not in controls (100% versus 0%). There was also a significantly more frequent FDG uptake in the large thoracic arteries in case‐patients compared with controls (43% versus 0%; P = 0.03).ConclusionFDG‐PET scan shows in patients with CP the presence of a large‐vessel vasculitis involving abdominal aorta and common iliac arteries, which in some patients is also extended to thoracic aorta and/or its branches.