Large vessel vasculitis, including giant cell arteritis and Takayasu arteritis, is traditionally diagnosed and classified according to the American College of Rheumatology criteria, which do not include findings on imaging modalities. We present a case in which non-invasive imaging with 18F-fluorodeoxyglucose positron emission tomography/computed tomography gave essential information in the diagnostic work-up of large vessel vasculitis in a female presenting with non-specific symptoms. We discuss the role of nuclear medicine imaging in early diagnosis and follow-up of this inflammatory disease, characterized by granulomatous panarteritis of the aorta and its major branches.