18F-FDG uptake by prosthetic arterial grafts in large vessel vasculitis is not specific for active disease: results from a cohort study

Objectives: To investigate the incidence and clinical significance of arterial graft-associated uptake of fluorodeoxyglucose in large vessel vasculitis (LVV). Background: The role of [18F]-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) in the management of LVV remains to be defined. Although 18FFDG uptake at arterial graft sites raises concerns regarding active arteritis or infection, its clinical significance in LVV has never been formally studied. Methods: An observational prospective study sought to identify patients with Takayasu arteritis (TA) undergoing 18F-FDG-PET/CT more than 6 months after graft surgery, from a large cohort of patients from two tertiary referral centres. 18F-FDG uptake by the graft and native arteries was scored on a 0 to 3 scale against hepatic uptake, and peri-prosthetic maximum standardized uptake value (SUVmax) was calculated. Peri-prosthetic 18F-FDG uptake in active or inactive disease was compared and arterial progression was assessed by prospective magnetic resonance angiography (MRA). Results: Twenty-six subjects with TA were enrolled. All were afebrile with negative blood culture. Peri-prosthetic uptake was significant in 23/26 patients, with a mean SUVmax of 4.21±1.46. Median peri-prosthetic 18F-FDG uptake score (3, IQR 3-3) was higher than in the native aorta (1, IQR 0-1, p