Is fluorine 18 fluorodeoxyglucose positron emission tomography scanning a suitable diagnostic test for histologically active large-vessel vasculitis?

Recent publications have highlighted the use of fluorine 18 fluorodeoxyglucose (F-FDG) positron emission tomography (PET) as a moderately sensitive, noninvasive diagnostic test for medium-and large-vessel vasculitis. We report the atypical case of a patient with biopsy-proven granulomatous vasculitis of the aorta in addition to a non-small cell lung cancer, whose whole-body F-FDG PET/computed tomography scan demonstrated metabolic activity within the lung malignancy but was metabolically inactive in the aorta. We submit that F-FDG PET may not be an accurate diagnostic test for histologically active large-vessel vasculitis and should be used with caution.