title: Observer variation in interpreting 18F-FDG PET/CT findings for lymphoma staging.
abstract: Many studies demonstrate a high accuracy for PET in staging lymphoma, but few assess observer variation. This study quantified agreement for staging lymphoma with PET/CT.
  
  
  METHODS
  The PET/CT images of 100 patients with lymphoma who had been referred for staging were reviewed by 3 experienced observers, with 2 observers reviewing each series a second time. Ann Arbor stage and individual nodal and extranodal regions were assessed. Weighted kappa (kappa(w)) and intraclass correlation coefficient were used to compare ratings.
  
  
  RESULTS
  Intra- and interobserver agreement was high for Ann Arbor stage (kappa(w) = 0.79-0.91), number of nodal regions involved (intraclass correlation coefficient, 0.83-0.93), and presence of extranodal disease (kappa = 0.74-0.86). High agreement was also observed for all nodal regions (kappa(w) > 0.60) except hilar (kappa(w) = 0.56-0.82) and infraclavicular (kappa(w) = 0.14-0.55). Lower agreement was observed for bowel involvement (kappa(w) = 0.37-0.71).
  
  
  CONCLUSIONS
  Experienced observers had a high level of agreement using PET/CT for lymphoma staging, supporting its use as a robust noninvasive staging tool. Further research is needed to evaluate observer variability for restaging during and after chemotherapy.
authors.affiliation: PET Imaging Centre, Kings College London, London, United Kingdom. nucmedpet@drhofman.com
authors.forename: Michael S
authors.initials: MS
authors.lastname: Hofman
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Smeeton
authors.forename: Sheila C
authors.initials: SC
authors.lastname: Rankin
authors.forename: Tom
authors.initials: T
authors.lastname: Nunan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Doherty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008223:Lymphoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18