[Diagnosis of fever of unknown origin (FUO). Positron emission tomography/computed tomography (PET-CT)].

Nuclear medicine imaging is now well accepted for the localization of septic foci. But in patients the results of infection scintigraphy, radiology and ultrasound remain unsatisfactory in the diagnosis of fever of unknown origin (FUO). In contrast to septic infections, patients with FUO - mostly in elderly patients - tend to have such conditions as occult tumours, atypical pneumonia, hematoblastosis, malignant lymphomas. (18)F(Fluor-18)-Fluordeoxyglucose-PET ((18)F-FDG PET) has made it possible to localize symptomatically occult changes with a high diagnostic accuracy and to achieve differentiation between benign and malignant changes.