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External validation of e-ASPECTS software for interpreting brain CT in stroke

Mair, Grant; White, Philip; Bath, Philip M.; Muir, Keith W.; Salman, Rustam Al-Shahi; Martin, Chloe; Dye, David; Chappell, Francesca M.; Vacek, Adam; Von Kummer, Rüdiger; Macleod, Malcolm; Sprigg, Nikola; Wardlaw, Joanna M.

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Grant Mair

Philip White

Stroke Association Professor of Stroke Medicine

Keith W. Muir

Rustam Al-Shahi Salman

Chloe Martin

David Dye

Francesca M. Chappell

Adam Vacek

Rüdiger Von Kummer

Malcolm Macleod

Professor of Stroke Medicine

Joanna M. Wardlaw


To test e-ASPECTS software in patients with stroke. Marketed as a decision-support tool, e-ASPECTS may detect features of ischemia or hemorrhage on computed tomography (CT) imaging and quantify ischemic extent using ASPECTS (Alberta Stroke Program Early CT Score).
Using CT from nine stroke studies, we compared software with masked experts. As per indications for software use, we assessed e-ASPECTS results for patients with/without middle cerebral artery (MCA) ischemia but no other cause of stroke. In an analysis outside the intended use of software, we enriched our dataset with non-MCA ischemia, hemorrhage, and mimics to simulate a representative ‘front door’ hospital population. With final diagnosis as the reference standard, we tested the diagnostic accuracy of e-ASPECTS for identifying stroke features (ischemia, hyperattenuated arteries, hemorrhage) in the representative population.
We included 4100 patients (51% female, median age 78 years, NIHSS 10, onset to scan 2·5 hours). Final diagnosis was ischemia (78%), hemorrhage (14%), or mimic (8%). From 3035 CTs with expert-rated ASPECTS, most (2084/3035, 69%) e-ASPECTS results were within one point of experts. In the representative population, the diagnostic accuracy of e-ASPECTS was 71% (95% confidence interval, 70-72%) for detecting ischemic features, 85% (83-86%) for hemorrhage. Software identified more false positive ischemia (12% vs 2%) and hemorrhage (14% vs <1%) than experts.
On independent testing, e-ASPECTS provided moderate agreement with experts and overcalled stroke features. Therefore, future prospective trials testing impacts of AI software on patient care and outcome are required before widespread implementation of stroke decision-support software.


Mair, G., White, P., Bath, P. M., Muir, K. W., Salman, R. A., Martin, C., …Wardlaw, J. M. (2022). External validation of e-ASPECTS software for interpreting brain CT in stroke. Annals of Neurology, 92(6), 943-957.

Journal Article Type Article
Acceptance Date Aug 30, 2022
Online Publication Date Sep 23, 2022
Publication Date 2022-12
Deposit Date Sep 14, 2022
Publicly Available Date Sep 24, 2023
Journal Annals of Neurology
Print ISSN 0364-5134
Electronic ISSN 1531-8249
Peer Reviewed Peer Reviewed
Volume 92
Issue 6
Pages 943-957
Public URL
Publisher URL


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