title: Superiority of 18F-FDG PET compared to 111In-labelled leucocyte scintigraphy in the evaluation of fever of unknown origin.
abstract: OBJECTIVE
  To compare the accuracy of positron emission tomography (PET) using (18)F-FDG (Fluorodeoxyglucose) PET with (111)In-labelled leucocytes scintigraphy (LS) in patients with fever of unknown origin (FUO).
  
  
  METHODS
  Twenty-three consecutive patients with FUO were prospectively studied using whole-body LS and PET. Performance of the two modalities for identifying a cause of FUO was evaluated. Final diagnosis was based on biopsy, microbiological tests, clinical and imaging follow-up.
  
  
  RESULTS
  Abnormal tracer uptake was seen in 3/23(13%) and 14/23(61%) patients on LS and PET respectively, suggesting a higher sensitivity (p < 0.01) for the latter. All LS positive cases were identified on PET and confirmed as infection. The causes of FUO in the other PET positive patients were: infection (n = 3), vasculitis (n = 3), non-infectious inflammatory conditions (n = 2) and cancer (n = 1). No specific diagnosis was reached in 2 patients. Of 13 patients without a definite diagnosis following PET and LS, 10 made a spontaneous recovery during the follow-up period and no definite cause for FUO was found on investigation. Still's disease, Polymyalgia rheumatica and Chronic fatigue syndrome/Myalgic encephalomyelitis were diagnosed in the remaining three patients during follow-up. The results thus showed an overall sensitivity of 86% for PET and 20% for LS (p < 0.01). The overall specificity for FDG PET was 78% as against 100% for LS. PET had a PPV of 86% and a NPV of 78% whereas LS had a PPV of 100% and a NPV of 40%.
  
  
  CONCLUSIONS
  PET has a higher sensitivity than LS in identifying the aetiology of FUO. PET/PET-CT, where available, should be used as the non-invasive investigation of choice in the assessment of patients with FUO.
authors.affiliation: Department of Nuclear Medicine, Addenbrookes Hospital, Cambridge CB2 0QQ, United Kingdom. s_n_bhushan@yahoo.com
authors.forename: N
authors.initials: N
authors.lastname: Seshadri
authors.forename: L I
authors.initials: LI
authors.lastname: Sonoda
authors.forename: A M
authors.initials: AM
authors.lastname: Lever
authors.forename: K
authors.initials: K
authors.lastname: Balan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005335:Fever of Unknown Origin / Q000175:diagnosis*; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D006801:Humans; D007205:Indium Radioisotopes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D017992:Parvovirus; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D011877:Radionuclide Imaging / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods
chemical_list: D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18