title: Clinical value of FDG-PET/CT in suspected paraneoplastic syndromes: a retrospective analysis of 137 patients.
abstract: OBJECTIVE
  Paraneoplastic syndromes (PNS) are relatively infrequent manifestations appearing before or after a cancer declares itself. Autoimmune mechanisms may be involved, but their cause and pathogenesis are often unknown. Due to disparity of symptoms, PNS remain a major diagnostic challenge. We examined the value of FDG-PET/CT for ruling in or out malignancy in a heterogeneous group of patients with suspected PNS.
  
  
  METHODS
  We retrospectively extracted data from all patients referred 2009-2013 with suspected PNS. Data included age, sex, follow-up period, scan report, further diagnostic procedures, and final clinical diagnosis. Conclusions of the scan reports were compared to the final follow-up outcome as determined during an average follow-up of 31 months (range 6-51.5) in patients who were not diagnosed with cancer in immediate continuation of a positive PET/CT scan.
  
  
  RESULTS
  A total of 137 patients were included. Main causes for referral were neurological (n = 67), rheumatological (n = 25), dermatological (n = 18), nephrological (n = 6), haematological (n = 2), abnormal biochemistry (n = 11), and others (n = 8). The cancer prevalence was 8.8%. The FDG-PET/CT results were as follows: nine true positives, 22 false positives, 103 true negatives, and three false negatives. Corresponding diagnostic values were: sensitivity 75%, specificity 82%, accuracy 82%, and positive and negative predictive values of 29% and 97%, respectively.
  
  
  CONCLUSIONS
  FDG-PET/CT has in patients with suspected PNS an impressively high negative predictive value and may be of value in ruling out PNS, the more so, the more the number of false positives can be minimized or used in differential diagnosis. We believe that FDG-PET/CT may become an important adjunct to the work-up and triage of patients with suspected PNS.
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense C, Denmark. stinebkristensen@gmail.com.
authors.forename: Stine Bjørn
authors.initials: SB
authors.lastname: Kristensen
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Hess
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Petersen
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense C, Denmark.
authors.forename: Poul Flemming
authors.initials: PF
authors.lastname: Høilund-Carlsen
mesh_terms: D000293:Adolescent; D000328:Adult; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D010257:Paraneoplastic Syndromes / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Diagnostic performance; FDG-PET/CT; False positives; Malignancy; Paraneoplasia