title: Determinants of diagnostic performance of 18F-FDG PET/CT in patients with fever of unknown origin.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: aDivision of Internal Medicine bDepartment of Radiology and Nuclear Medicine cDivision of Pulmonology, University Hospital Zurich dCentre of Competence Multimorbidity eDynamics of Health Aging, University Research Priority Program, University of Zurich, Zurich, Switzerland.
authors.forename: Ashoka M V
authors.initials: AM
authors.lastname: Pereira
authors.forename: Lars
authors.initials: L
authors.lastname: Husmann
authors.forename: Bert-Ram
authors.initials: BR
authors.lastname: Sah
authors.forename: Edouard
authors.initials: E
authors.lastname: Battegay
authors.forename: Daniel
authors.initials: D
authors.lastname: Franzen
mesh_terms: D000328:Adult; D000368:Aged; D005335:Fever of Unknown Origin / Q000000981:diagnostic imaging*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18