title: Prevalence of occult metastatic disease in patients undergoing 18F-FDG PET for primary diagnosis or staging of lung carcinoma and solitary pulmonary nodules.
abstract: BACKGROUND
  Accurate staging of lung cancer is essential in determining the most appropriate management plan, as detection of occult metastasis can significantly alter management.
  
  
  OBJECTIVE
  The aims of this study are to determine the prevalence of occult metastasis in patients undergoing 2-(18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET) for evaluation of suspected/proven lung carcinoma and correlate pre-PET TNM stage with prevalence of metastasis.
  
  
  METHODS
  FDG-PET, which identified patients with metastasis on institutional database, was re-evaluated by a nuclear medicine physician blinded to clinical information. The confidence level of metastasis was scored on a 5-point scale, with a score of >/=4 considered positive.
  
  
  RESULTS
  There were 67 of 645 (10%) patients identified with suspected occult metastasis on FDG-PET. Twelve patients scoring </=3 were excluded. Prevalence of occult metastasis was 10/156 (6%) in solitary pulmonary nodules (SPN); 22/319 (7%) and 23/170 (14%) in proven and suspected lung cancer, respectively. Positive predictive value of FDG-PET for metastasis was 8/10 (80%) in solitary pulmonary nodules, 14/20 (70%) and 17/21 (81%) in proven and suspected lung cancer, respectively. (18)F-FDG-avid lesions classified as false positives were patients with cholelithiasis, rib fractures and those with equivocal/negative bone scans or computed tomography on follow up. There was a higher incidence of true positive occult metastasis in patients in all stages of disease, particularly stage III disease.
  
  
  CONCLUSIONS
  (18)F-FDG PET is predictive for occult metastatic disease in patients with solitary pulmonary nodules and proven or suspected lung cancer and is more likely to be present in all stages, particularly in stage III. PET findings should be actively pursued with correlative investigation to identify benign pathology in patients who remain candidates for curative treatment.
authors.affiliation: Centre for Positron Emission Tomography, and Department of Medicine, University of Melbourne, and Ludwig Institute for Cancer Research, Austin Health, Melbourne, Victoria, Australia. szeting.lee@austin.org.au
authors.forename: S T
authors.initials: ST
authors.lastname: Lee
authors.forename: S U
authors.initials: SU
authors.lastname: Berlangieri
authors.forename: A M T
authors.initials: AM
authors.lastname: Poon
authors.forename: P
authors.initials: P
authors.lastname: Mitchell
authors.forename: K
authors.initials: K
authors.lastname: Pathmaraj
authors.forename: K
authors.initials: K
authors.lastname: Tabone
authors.forename: A J
authors.initials: AJ
authors.lastname: Byrne
authors.forename: G J
authors.initials: GJ
authors.lastname: O'Keefe
authors.forename: S R
authors.initials: SR
authors.lastname: Knight
authors.forename: C P
authors.initials: CP
authors.lastname: Clarke
authors.forename: A M
authors.initials: AM
authors.lastname: Scott
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging*; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D015995:Prevalence; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000473:pathology
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18