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Original research
Per-region interobserver agreement of Alberta Stroke Program Early CT Scores (ASPECTS)
  1. Patrick Nicholson1,
  2. Christopher Alan Hilditch2,
  3. Ain Neuhaus3,
  4. Seyed Mohammad Seyedsaadat4,
  5. John Charles Benson4,
  6. Ian Mark4,
  7. Chun On Anderson Tsang5,
  8. Joanna Schaafsma6,
  9. David F Kallmes4,
  10. Timo Krings7,
  11. Waleed Brinjikji4
  1. 1 Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
  2. 2 Department of Neuroradiology, Salford Royal NHS Foundation Trust, Manchester, UK
  3. 3 Radcliffe Department of Medicine, University of Oxford, Oxford, UK
  4. 4 Department of Neuroradiology, Mayo Clinic, Rochester, Minnesota, USA
  5. 5 Division of Neurosurgery, Department of Surgery, Queen Mary Hospital, The University of Hong Kong, Hong Kong, Pok Fu Lam, Hong Kong
  6. 6 Medicine - Division of Neurology, Toronto Western Hospital, Toronto, Ontario, Canada
  7. 7 Division of Neuroradiology, Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
  1. Correspondence to Dr Patrick Nicholson, Neuroradiology, Toronto Western Hospital, Toronto, ON M5T 2S8, Canada; paddynicholson{at}


Background and purpose The Alberta Stroke Program Early CT Score (ASPECTS) is a commonly used scoring system to select patients with stroke for endovascular treatment (EVT). However, the inter- and intra-reader variability is high.

Objective To determine whether the inter- and intra-reader variability is different for various regions of the ASPECTS scoring system by evaluating the interobserver variability of ASPECTS between different readers in a per-region analysis.

Materials and methods All patients with acute ischemic stroke who proceeded to EVT in our institutions over a 4-year period were retrospectively identified from a prospectively maintained database. Images were reviewed by two experienced neuroradiologists, who recalculated the ASPECTS independently. We examined each region of the ASPECTS system to evaluate agreement between the raters in each area.

Results 375 patients were included. The median total ASPECTS was 9 (IQR 8–9). The most common region showing ischemic change was the insula, with the M6 region being least commonly affected. Overall interobserver agreement for ASPECTS using Cohen’s κ was 0.56 (95% CI 0.51 to 0.61). The region with the highest agreement was the insula (κ=0.56; 0.48 to 0.64). The region with the lowest agreement was M3 (κ=0.34; 0.12 to 0.56). Agreement was relatively good when ASPECTS were dichotomized into 0–5 versus 6–10 (κ=0.66; 0.49 to 0.84).

Conclusions Substantial interobserver variability is found when calculating ASPECTS. This variability is region dependent, and practitioners should take this into account when using ASPECTS for treatment decisions in patients with acute stroke.

  • stroke
  • CT

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  • Contributors Each author has made substantial contributions to the conception or design of the work, or the acquisition, analysis, or interpretation of data; drafting the work or revising it critically for important intellectual content; final approval of the version published; and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding SMS is supported by a postdoctoral fellowship grant from the AHA (award number 19POST34381067).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement No data are available.