Determinants of diagnostic performance of 18F-FDG PET/CT in patients with fever of unknown origin

Abstract

OBJECTIVES There is uncertainty about patient selection and the adequate timing at which fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) is indicated in the diagnostic work-up of fever of unknown origin (FUO). The aim of this study was to determine the diagnostic performance of F-FDG PET/CT in patients with FUO. METHODS All consecutive patients who underwent F-FDG PET/CT at the University Hospital Zurich because of FUO between 2006 and 2012 were included in this retrospective, observational study. RESULTS A total of 76 patients [70% men, median (interquartile range) age 60 (47-67) years] were included. F-FDG PET/CT showed characteristically increased F-FDG activity in 56 patients (74%), leading to confirmation of or change in the suspected cause of FUO in 57 and 17%, respectively. The final diagnosis after F-FDG PET/CT included infection (21%), malignancy (22%), noninfectious inflammatory disease (12%), others (5%), or an unknown cause (40%). The success rate, sensitivity, and specificity of F-FDG PET/CT were 60, 77, and 31%, respectively. Sensitivity was highest in patients with suspected malignancy (100%, 95% confidence interval 79-100%). Diagnostic performance was independent of the investigated variables other than suspected infection as a cause of FUO (odds ratio 0.1, 95% confidence interval 0.01-0.8, P=0.033). CONCLUSION The diagnostic performance of F-FDG PET/CT was significantly higher in patients with suspected malignancy causing a FUO compared with suspected infection or noninfectious inflammatory disease. However, it was independent of the baseline characteristics and duration of fever. This supports the recommendation to perform F-FDG PET/CT early in the diagnostic work-up of FUO, which may shorten disease duration and lower health costs, particularly when infection or malignancy is suspected.

Role of bone marrow biopsy for fever of unknown origin in the contemporary Australian context

“…[3][4][5]11 There is increasing evidence in the literature on the utility of FDG-PET with or without CT in investigations for FUO, due to its effectiveness in identifying sites of lymphoma and potential in diagnosing infections, hence contributing to the eventual diagnosis or exclusion of diagnosis in 46-75% of cases. [12][13][14][15][16][17][18][19][20][21] FDG-PET/CT is found to be better than FDG-PET alone due to better anatomic information obtained from CT. In our cohort, FDG-PET contributed to making the diagnosis in eight patients (25%), a much lower rate than that reported in the literature.…”

“…There is increasing evidence in the literature on the utility of FDG‐PET with or without CT in investigations for FUO, due to its effectiveness in identifying sites of lymphoma and potential in diagnosing infections, hence contributing to the eventual diagnosis or exclusion of diagnosis in 46–75% of cases . FDG‐PET/CT is found to be better than FDG‐PET alone due to better anatomic information obtained from CT.…”

Misleading Radiological Appearances for Fever of Unknown Origin: Beyond Terminal Ileitis

“…Patient history, physical examination, imaging methods and invasive procedures are the steps to diagnosis. Improved radiological and nuclear techniques may provide important clues for diagnosis [2] . Nevertheless, a reappraisal of the patient history and repetition of the physical examination may prevent unnecessary interventions.…”

Metabolic Imaging of Infection

“…18 F-FDG accumulates in all of these conditions, making 18 F-FDG PET/CT suitable for the evaluation of patients with FUO. In a recent study of 76 patients with FUO, 18 F-FDG PET/CT led to the final diagnosis of infection as the cause of FUO in 21% of patients, malignancy in 22% of patients, inflammatory noninfectious diseases in 12% of patients, and miscellaneous diagnoses in 5% of patients (17). A 56% diagnostic yield was found for 18 F-FDG PET/CT in the evaluation of FUO in a metaanalysis of 18 eligible studies including 905 patients (18).…”