The value of [18F]FDG PET/CT in fever of unknown origin (FUO): an update and future aspects.

Fever of unknown origin (FUO) is a clinical diagnostic challenge because its symptoms are often vague and its causes varied. Although the use of 2-deoxy-2-[18F]-fluoro-d-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) is on the rise to help solve these cases, the optimal timing and strategy for its application remains under debate. As a comprehensive whole-body imaging modality, [18F]FDG PET/CT reveals areas of increased uptake and it is highly effective for detecting active oncological diseases, infectious or inflammatory foci that might be missed by radiological imaging. In FUO, [18F]FDG PET/CT presents good diagnostic performances with a clinical impact in more than half of cases, also in special populations like pediatrics and critically ill patients. It may help to identify underlying causes of fever and to modify treatment and management procedures. Also a negative [18F]FDG PET scan may help to exclude potential diseases and is associated with a good prognosis. And the future looks even more bright with huge developments in both camera systems (LAFOV PET/CT) and in specific infection and inflammation radiotracers.