title: Observer variability of an angiographic grading scale used for the assessment of intracranial aneurysms treated with flow-diverting stents.
abstract: OBJECTIVE
  Novel angiographic grading scales for the assessment of intracranial aneurysms treated with flow-diverting stents have been recently developed because previous angiographic grading scales cannot be applied to these aneurysms. The purpose of this study was to evaluate the inter- and intraobserver variability of the novel O'Kelly Marotta grading scale, which was developed specifically for the angiographic assessment of aneurysms treated with flow-diverting stents.
  
  
  METHODS
  Multiple raters (n = 31) from the disciplines of neuroradiology and neurosurgery were presented with pre- and posttreatment angiographic images of 14 aneurysms treated with intraluminal flow diverters. Raters were asked to classify pre- and posttreatment angiograms by using the OKM grading scale. Statistical analyses were subsequently performed with calculation of a generalized multirater κ statistic for assessment of inter- and intraobserver variability and by performing a Wilcoxon signed rank sum test for assessment of group differences.
  
  
  RESULTS
  Variability analysis of the OKM grading scale yielded substantial (κ = 0.74) and almost perfect (κ = 0.99) inter- and intraobserver agreement, respectively, with no statistically significant differences between raters with a background of neuroradiology versus neurosurgery or attending physician versus trainee.
  
  
  CONCLUSIONS
  The OKM grading scale for the assessment of intracranial aneurysms treated with flow-diverting stents is a reliable grading scale that can be used equally well by users of varying backgrounds and levels of training. Comparison with interobserver variability of pre-existing angiographic grading scales shows equal or better performance.
authors: Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
authors: M D
authors: MD
authors: Joshi
authors: C J
authors: CJ
authors: O'Kelly
authors: T
authors: T
authors: Krings
authors: D
authors: D
authors: Fiorella
authors: T R
authors: TR
authors: Marotta
mesh_terms: D001807:Blood Vessel Prosthesis; D002533:Cerebral Angiography / Q000379:methods*; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000601:surgery*; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D015607:Stents; D016896:Treatment Outcome