title: The Diagnostic Role of FDG PET/CT in Patients with Fever of Unknown Origin.
abstract: OBJECTIVE
  Fever of unknown origin (FUO) is a challenge for the physician and needs use of clinical, laboratory, and imaging studies and also invasive and/or non-invasive interventions to detect the etiology. The aim of present study was to assess the role of FDG PET/CT in determining the etiology in patients with FUO.
  
  
  METHODS
  Twenty-four patients (median age 52, range 5-77 years, 6 female, 18 male) who were diagnosed with FUO were retrospectively analyzed in this study. Before the FDG PET/CT studies, none of them had a definitive reason for their diseases investigated by conventional radiological or scintigraphic methods, clinical and laboratory observations.
  
  
  RESULTS
  The positive result was achieved in 19 (79.2%) of 24 patients as findings of the FDG PET/CT. However, FDG PET/CT was useful for definitive diagnosis in 12 (63.2%) of 19 positive patients. Malignant diseases were determined to be the underlying cause of FUO in 5 (41.6%) of 12 patients. Noninfectious inflammatory causes were detected in 2 (16.7%) patients, infections were exhibited in 3 (25%) patients, and miscellaneous diseases demonstrated in 2 (16.7%) patients. In 7 patients the detected pathological uptakes on FDG PET/CT were not helpful for the definitive diagnosis. In remaining 5 patients who showed no pathological uptake in the FDG PET/CT, diagnosis could not be established by other methods, as well. The sensitivity, specificity, and positive and negative predictive values for the determination of FUO etiology were 92.3%, 45.4%, 63.1%, and 100% for FDG PET/CT.
  
  
  CONCLUSIONS
  Our results demonstrate that FDG PET/CT seems to have considerable contribution to reveal the reason of undiagnosed patients with FUO investigated by conventional diagnostic methods, clinical and laboratory observations.
  
  
  BACKGROUND
  None declared.
authors.affiliation: Istanbul University Cerrahpasa Faculty of Medicine, Department of Nuclear Medicine, İstanbul, Turkey.
authors.forename: Nurhan
authors.initials: N
authors.lastname: Ergül
authors.forename: Metin
authors.initials: M
authors.lastname: Halac
authors.forename: Tevfik F
authors.initials: TF
authors.lastname: Cermik
authors.forename: Resat
authors.initials: R
authors.lastname: Ozaras
authors.forename: Sait
authors.initials: S
authors.lastname: Sager
authors.forename: Cetin
authors.initials: C
authors.lastname: Onsel
authors.forename: Ilhami
authors.initials: I
authors.lastname: Uslu
keywords: Fluorodeoxyglucose F18; positron-emission tomography; fever of unknown origin; diagnosis