ASPECTS stands for Alberta Stroke Program Early CT Score. It’s a standardized way to quantify early ischemic change on non-contrast CT (NCCT) in acute anterior-circulation (MCA territory) ischemic stroke. The goal is to estimate infarct “core” size quickly and consistently, because larger early infarcts are associated with worse outcomes and higher hemorrhage risk after reperfusion therapy. Radiopaedia+2PMC+2

How ASPECTS is scored

ASPECTS is a 10-point topographic scale applied to the affected MCA hemisphere:

• Start at 10 (normal).
• Subtract 1 point for each of 10 MCA regions showing early ischemic change (hypoattenuation, loss of gray-white differentiation, or focal swelling). Radiopaedia+2PMC+2

The 10 regions:
Deep structures (4):

1. C – Caudate
2. L – Lentiform nucleus
3. IC – Internal capsule
4. I – Insula

Cortical MCA regions (6):
5. M1 – Anterior MCA cortex (frontal operculum)
6. M2 – MCA cortex lateral to insula (anterior temporal/frontal)
7. M3 – Posterior MCA cortex (posterior temporal)
8. M4 – Anterior MCA territory above M1
9. M5 – Lateral MCA territory above M2
10. M6 – Posterior MCA territory above M3 Radiopaedia+2PMC+2

So, ASPECTS = 10 – (# abnormal regions).

Interpretation and clinical meaning

• 10–8: Small early ischemic core; generally better prognosis and lower hemorrhage risk.
• 7–6: Moderate core; outcomes vary, but still often treated with reperfusion if other criteria fit.
• ≤5: Large core/established infarct; higher risk of poor outcome and symptomatic hemorrhage, and historically excluded from early thrombectomy trials—though recent trials are expanding treatment to some low-ASPECTS patients. Radiopaedia+2AHA Journals+2

Many centers have used ASPECTS ≥6 as a practical thrombectomy threshold, while some guidelines allow treatment down to ASPECTS ≥3 in selected late-window patients. These cutoffs support decision-making but are not absolute rules. AHA Journals+2National Clinical Guideline for Stroke+2

Limitations

• Inter-rater variability: subtle NCCT changes are easy to miss; structured training improves consistency. PMC+1
• Scope: standard ASPECTS applies to anterior circulation; posterior circulation uses pc-ASPECTS separately. National Clinical Guideline for Stroke+1
• Not a stand-alone decision tool: should be integrated with clinical severity, timing, CTA/CTP/MRI, comorbidities, and local protocol.