Agreement between core laboratory and study investigators for imaging scores in a thrombectomy trial

J Neurointerv Surg. 2018 Dec;10(12):e30. doi: 10.1136/neurintsurg-2018-013867. Epub 2018 May 14.


Purpose: We aimed to assess the agreement between study investigators and the core laboratory (core lab) of a thrombectomy trial for imaging scores.

Methods: The Alberta Stroke Program Early CT Score (ASPECTS), the European Collaborative Acute Stroke Study (ECASS) hemorrhagic transformation (HT) classification, and the Thrombolysis In Cerebral Infarction (TICI) scores as recorded by study investigators were compared with the core lab scores in order to assess interrater agreement, using Cohen's unweighted and weighted kappa statistics.

Results: There were frequent discrepancies between study sites and core lab for all the scores. Agreement for ASPECTS and ECASS HT classification was less than substantial, with disagreement occurring in more than one-third of cases. Agreement was higher on MRI-based scores than on CT, and was improved after dichotomization on both CT and MRI. Agreement for TICI scores was moderate (with disagreement occurring in more than 25% of patients), and went above the substantial level (less than 10% disagreement) after dichotomization (TICI 0/1/2a vs 2b/3).

Conclusion: Discrepancies between scores assessed by the imaging core lab and those reported by study sites occurred in a significant proportion of patients. Disagreement in the assessment of ASPECTS and day 1 HT scores was more frequent on CT than on MRI. The agreement for the dichotomized TICI score (the trial's primary outcome) was substantial, with less than 10% of disagreement between study sites and core lab.

Trial registration number: NCT02523261, Post-results.

Keywords: CT; MRI; angiography; stroke.

Publication types

  • Clinical Trial

MeSH terms

  • Aged
  • Brain Ischemia / diagnostic imaging*
  • Brain Ischemia / therapy
  • Cerebral Infarction / diagnostic imaging
  • Cerebral Infarction / therapy
  • Clinical Laboratory Techniques / standards*
  • Diagnostic Imaging / methods
  • Diagnostic Imaging / standards*
  • Female
  • Humans
  • Magnetic Resonance Imaging / methods
  • Magnetic Resonance Imaging / standards
  • Male
  • Middle Aged
  • Physicians / standards*
  • Research Personnel / standards*
  • Retrospective Studies
  • Severity of Illness Index*
  • Stroke / diagnostic imaging*
  • Stroke / therapy
  • Thrombectomy / methods
  • Tomography, X-Ray Computed / methods
  • Tomography, X-Ray Computed / standards
  • Treatment Outcome

Associated data