title: Evaluation of interoperator variance in shunt fraction calculation after transcolonic scintigraphy for diagnosis of portosystemic shunts in dogs and cats.
abstract: OBJECTIVE
  To determine interoperator variance in shunt fraction calculation.
  
  
  METHODS
  Case series.
  
  
  METHODS
  101 transrectal portoscintigraphic studies.
  
  
  METHODS
  Results of dynamic portoscintigraphic studies were reviewed by 4 radiologists without knowledge of signalment, history, or medical profile. Results were judged to be negative or positive on the basis of the dynamic scan. Composite images were formulated, and hand-drawn regions of interest were determined for the heart and liver. Time-activity curves were generated, time-zero points were selected, curves were integrated during a 10-second interval, and shunt fractions were calculated.
  
  
  RESULTS
  Radiologists were in agreement regarding positive versus negative results for 99 of 101 studies. Interoperator variance in shunt fraction calculation ranged from 0.4 to 59.6%. For 51 studies with positive results, variance ranged from 2.5 to 59.6% (mean +/- SD, 22.8 +/- 14.5%); differences among reviewers were significant. For 48 studies with negative results, variance in shunt fraction ranged from 0.4 to 25.9% (mean, 5.3 +/- 5.8%); significant differences among reviewers were not detected. Shunt fraction calculations were not exactly reproducible among radiologists in 94 and 100% of studies with negative or positive results, respectively.
  
  
  CONCLUSIONS
  Results suggest that shunt fraction values are not reproducible among operators. Range in variability was greater in studies with positive results. This factor may be of particular clinical importance in reassessment of patients after incomplete shunt ligation.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: V F
authors.initials: VF
authors.lastname: Samii
authors.forename: A E
authors.initials: AE
authors.lastname: Kyles
authors.forename: C D
authors.initials: CD
authors.lastname: Long
authors.forename: L M
authors.initials: LM
authors.lastname: Mellema
authors.forename: R E
authors.initials: RE
authors.lastname: Pollard
authors.forename: P H
authors.initials: PH
authors.lastname: Kass
authors.forename: W J
authors.initials: WJ
authors.lastname: Hornof
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D002415:Cats; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging / Q000601:surgery / Q000662:veterinary; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D004285:Dogs; D008026:Ligation / Q000662:veterinary; D015588:Observer Variation; D011168:Portal System / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies