Contribution of PET/CT imaging to differential diagnosis of fever of unknown origin

Abstract

Vasculitis is a collective title for a heterogeneous group of diseases with common signs of inflammation, leukocytic infiltration and necrosis of the vessel wall leading to regional perfusion disturbances. There are many ways to classify vasculitis. Into the group of large-vessel vasculitis we include Takayasu´s arteritis as well as temporal arteritis (giant-cell arteritis) affecting also the aorta and its major branches. FDG PET/CT is a hybrid imaging method combining spatial imaging of metabolic activity obtained by the detection of 18-fluorodeoxyglucose (FDG) with positron emission tomography (PET) and X-ray computed tomography (CT). While carried out together with PET imaging in the same session, CT imaging is helpful in identifying precisely the anatomical identification of hypermetabolic lesions detected via PET. In this case report we refer to the key contribution of PET/CT imaging to concluding successfully a diagnostic process lasting for a few months and leading to a revelation of large-vessel vasculitis manifesting itself only with systemic inflammation symptoms, i.e. without any clinical signs of specific organ damage. In conclusion, FDG PET/CT scan is a combined imaging technique which has a remarkable potential in the diagnosis of large-vessel vasculitis. This potential is particularly valued in cases when symptoms of vasculitis are clinically nonspecific and when other non-invasive methods are failing (Fig. 2, Ref. 20).