Diagnostic contribution of (18)F-FDG-PET/CT in fever of unknown origin

Objectives: Fever of unknown origin (FUO) remains one of the most compelling diagnostic issues in medicine. We aimed to evaluate the potential clinical contribution of 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) in the identification of the underlying cause of FUO.

Methods: Fifty consecutive patients (27 men and 23 women; age range 16-88 years) with FUO based on the revised definition criteria were included in the study. A diagnostic protocol including biochemistry, histopathology, and microbiological tests was performed and the patients were followed up. FDG-PET was performed in 25 of the 50 patients (12 males and 13 females; age range 16-88 years) in order to determine the etiology of the patient's fever. PET-CT images were obtained with the Gemini Philips TF (18)F-FDG-PET/CT camera after a 60-min 'standard uptake' period following an injection of a mean 330 MBq (range 290-370 MBq) intravenous (18)F-FDG.

Results: A total of 21 patients were available for analysis of the diagnostic contribution of PET/CT (two patients were undiagnosed and two had non-contributory PET/CT findings). (18)F-FDG-PET/CT was able to precisely detect the cause of fever in 60% of the cases (n=15). The accuracy, sensitivity, and specificity of this imaging modality were 90.5%, 93.8%, and 80%, respectively. Among the cases with a true-positive (18)F-FDG-PET/CT finding (i.e., 15 cases), the identified underlying causes of FUO included localized infection (n=7), non-infective inflammatory process (n=5), and malignancy (n=3).

Conclusions: Further studies to confirm the high diagnostic yield of (18)F-FDG-PET/CT observed in the present study would lend support to the inclusion of this imaging modality in the initial diagnostic work-up of patients with suspected FUO.