Value of FDG PET in patients with fever of unknown origin

Fever of unknown origin (FUO) is a diagnostic challenge, because the cause of such fer er may be manifold. Studies on the use of positron emission tom ography (PET) using F-18-fluorodeoxyglucose (F-18-FDG), for the diagnosis o f inflammation in patients with osteomyelitis or HIV have been promising an d suggest its use in patients with FUO. In this study, we used FDG PET in 1 6 patients with FUO in whom conventional diagnostics had not been conclusiv e. In 12 patients, (75%) non-physiological accumulations of FDG were found which led to the final diagnosis in 11 patients (69%). FDG PET was negative in four patients (25%). Two of these patients had rheumatic fever, while i n the other two patients the origin of fever could not be detected within 3 months after PET by any other laboratory or imaging means. These findings point to the high sensitivity of FDG whole-body PET for the detection of mo rphologically assessable foci as an origin of FUO. Moreover, they suggest a high negative predictive value of FDG PET in the setting of FUO, since in no patient with a negative FDG PET could a morphological origin of the feve r be determined. In conclusion, FDG whole-body PET appears to be a promisin g diagnostic tool in patients with FUO, in whom conventional diagnostics ha d been unsuccessful. ((C) 2001 Lippincott Williams & Wilkins).