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Alberta Stroke Program Early CT Score (ASPECTS) Calculator

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What does ASPECTS stand for?

ASPECTs stands for Alberta Stroke Program Early CT Score.

What is the ASPECTS in stroke?

Alberta Stroke Program Early CT score (ASPECTS) is a 10-point quantitative score used to assess early ischemic changes on non-contrast CT head studies.

What is the clinical significance of the ASPECTS / How to interpret the ASPECT Score?

  • Reliable and reproducible grading system on non-contrast CT examinations of the head for detection of early ischemic changes in patients suspected of having acute large anterior circulation occlusion.
  • It is used as part of the assessment for eligibility in receiving interventional mechanical thrombectomy treatment.
  • It quantifies CT changes in early middle cerebral artery stroke. A lower score suggests poorer outcome.
  • Patients with scores ≥8 have a higher chance for an independent outcome.
  • Patients with ASPECTS 0–4 had significantly worse outcome than patients with ASPECTS 5–10 and did not benefit from faster treatment, thus suggesting a cutoff ASPECTS ≤4 to identify patients with poor response to intravascular treatment.

What is normal ASPECTS score?

An ideal ASPECTS score is 10 when none of the vital structures are involved by acute ischemic changes. But patients with scores ≥8 have a higher chance for an independent outcome.

What are the anatomical regions used to assess acute stroke in ASPECTS?

The template consists of 10 anatomically defined regions. 

  • Subcortical : 4 subcortical structures [caudate (C); lentiform (L); internal capsule (IC); insular ribbon (I)]
  • Cortical : 6 for cortical structures in the MCA territory, labeled M1–M6.
    • Ganglionic : On the level of the caudate head or below are hereby allotted to the ganglionic level,
    • Supraganglionic : Above the level of the caudate head.

How are ASPECT scores calculated?

For each ASPECTS region that presents with early ischemic changes with loss of gray-white differentiation on at least two consecutive cuts, the overall score of 10 is reduced by 1.

What are the recommended window settings for calculating ASPECTS?

Ideal window settings for calculating ASPECTS are window level of 30 H with a window width of 80 H.

What are the pitfalls while calculating ASPECTS?

  • Motion artifacts.
  • Atrophy, white matter ischemic changes (leucoaraiosis) and old infarcts need to be properly evaluated.


ASPECTS can be used to assess extent of infarction on DWI images and is termed as DWI-ASPECTS. DWI-ASPECTS within 3 h after symptom onset has been proven to predict functional outcome (Modified Rankin Scale, MRS) and mortality after 3 months in patients undergoing IV-thrombolysis.

  • DWI-ASPECTS >5 within 3 h after onset : Good functional outcome 7 days after IV-thrombolysis.
  • DWI-ASPECTS >7 from 3-24h after onset:  Good functional out come in 3 months (MRS ≥3).

What is pc-ASPECTS?

pc- ASPECTS stands for Posterior Circulation ASPECTS and is a similar scale for evaluation of posterior circulation. Points are subtracted from 10 as follows:

  • Thalami (1 point each)
  • Occipital lobes (1 point each)
  • Midbrain (2 points)
  • Pons (2 points)
  • Cerebellar hemispheres (1 point each)

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About the Author

Dr. Amar Udare, MD, DNB

Dr Amar Udare Dr. Amar Udare is a board-certified radiologist. He is a clinical assistant professor at the University of Calgary. He has a passion for teaching (#FOAMrad and #FOAMed) and has been a semi-finalist for the 2018 and 2020 Aunt-Minnie Most effective Radiology Educator Awards. He has authored multiple peer-reviewed publications which can be accessed on PubMed and Google Scholar.


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