title: How do oncologists deal with incidental abnormalities on whole-body fluorine-18 fluorodeoxyglucose PET/CT?
abstract: BACKGROUND
  Combined positron emission tomography (PET)/computed tomography (CT) using fluorine-18 fluorodeoxyglucose (FDG) is an exciting technique for cancer evaluation, but false-positive results are a recognized limitation. The aim of the study was to evaluate how oncologists deal with focal extrathyroidal FDG abnormalities considered by imaging specialists to be unrelated to the referral indication.
  
  
  METHODS
  PET scan reports from a 12-month period from August 2002 to July 2003 in 1727 consecutive patients (mean age, 63 years) were reviewed. Incidental, nonphysiologic FDG abnormalities were classified based on the report conclusion. The frequency with which such abnormalities were investigated by oncologists and the final diagnosis were compared with the imaging diagnosis with a minimum potential follow-up of 2 years (mean, 27.5 months).
  
  
  RESULTS
  Incidental FDG abnormalities were reported in 199 (12%) of 1727 patients, including 181 with adequate follow-up. Of 59 cases with a suspected second malignancy, 34 (58%) were actively investigated, with 14 confirmed, 7 unexpected metastatic sites, and 10 other active pathologies. Only 1 further cancer was subsequently detected in the 25 (42%) patients not actively investigated. Conversely, of 122 sites presumed to be benign, only 10 (8%) were actively investigated. Only 2 were proven to relate to malignancy.
  
  
  CONCLUSIONS
  Although incidental abnormalities were common, most were benign and appropriately categorized by experienced readers. For actively investigated extrathyroidal abnormalities, a neoplastic basis was confirmed in over 60% of cases. Conversely, for cases deemed most likely benign by the PET/CT report or after review of readily available clinical information by the referring oncologist, the rate of malignancy was less than 2%.
authors.affiliation: Department of Nuclear Medicine, Cancer Center, Sun Yat-sen University, Guangdong, PR China.
authors.forename: Guohui
authors.initials: G
authors.lastname: Wang
authors.forename: Eddie W F
authors.initials: EW
authors.lastname: Lau
authors.forename: Ramdave
authors.initials: R
authors.lastname: Shakher
authors.forename: Danny
authors.initials: D
authors.lastname: Rischin
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ware
authors.forename: Emily
authors.initials: E
authors.lastname: Hong
authors.forename: David S
authors.initials: DS
authors.lastname: Binns
authors.forename: Annette
authors.initials: A
authors.lastname: Hogg
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Drummond
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Hicks
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis; D009378:Neoplasms, Multiple Primary / Q000175:diagnosis; D049268:Positron-Emission Tomography / Q000379:methods*; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18