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ASPECTS (Alberta Stroke Program Early CT Score)

A 10-point topographic score of early ischemic change in the MCA territory on non-contrast CT. Start at 10 and subtract 1 point for each of 10 defined regions showing early ischemic change (hypoattenuation / loss of grey–white differentiation). Lower score = larger established core. ASPECTS ≥6 has historically been the threshold above which thrombectomy trials showed benefit; ≤5 indicates a large established infarct.
reviewed 2026-07-01

How to score

  • Start at 10; subtract 1 point for EACH region with early ischemic changeEarly ischemic change = parenchymal hypoattenuation and/or loss of grey–white differentiation. Focal swelling/sulcal effacement alone does NOT subtract a point in the original definition.
  • Assess only the two standardized axial levelsGanglionic level (at the thalamus/basal ganglia): C, L, IC, I, M1, M2, M3. Supraganglionic level (just above the basal ganglia): M4, M5, M6.
  • Score the affected hemisphere and compare with the contralateral side for symmetry
  • A region is counted once even if change spans both levels; the change must be within the defined ASPECTS region
  • Normal CT = 10; diffuse MCA-territory hypoattenuation = 0

Regions (10 total)

  • Subcortical: C (caudate), L (lentiform nucleus), IC (internal capsule), I (insular ribbon)Insular ribbon loss is an early, sensitive sign of MCA ischemia.
  • Cortical MCA: M1–M6M1–M3 at the ganglionic level (anterior, lateral, posterior MCA cortex); M4–M6 at the supraganglionic level (cortex superior to M1–M3).

Reporting must state

  • Numeric ASPECTS and the side
  • Which regions are affected (helps reproducibility and follow-up comparison)
  • Presence of a hyperdense MCA / dot sign and any large-vessel occlusion on CTA
  • Distinguish established infarct from chronic encephalomalacia / old infarct (do not subtract points for old change)Correlate with prior imaging and clinical onset time.

Tap each region showing early ischemic change (hypoattenuation / loss of grey–white differentiation).

ASPECTS
10/ 10

Small early ischemic core; favorable profile for reperfusion therapy.

ASPECTS regions (each = 1 point; Barber et al., Lancet 2000)

Ganglionic level: C, L, IC, I, M1, M2, M3. Supraganglionic level: M4, M5, M6.

C — Caudate head

Ganglionic level.

1

L — Lentiform nucleus

Ganglionic level.

1

IC — Internal capsule (posterior limb)

Ganglionic level.

1

I — Insular ribbon

Ganglionic level; sensitive early sign.

1

M1 — Anterior MCA cortex

Ganglionic level (frontal operculum).

1

M2 — MCA cortex lateral to insular ribbon

Ganglionic level (anterior temporal).

1

M3 — Posterior MCA cortex

Ganglionic level (posterior temporal).

1

M4 — Anterior MCA cortex, superior

Supraganglionic level (above M1).

1

M5 — Lateral MCA cortex, superior

Supraganglionic level (above M2).

1

M6 — Posterior MCA cortex, superior

Supraganglionic level (above M3).

1

Interpretation thresholds

10

Normal — no early ischemic change.

8–10

Small core; favorable for reperfusion therapy.

6–7

Moderate early ischemic change; most thrombectomy trials enrolled ASPECTS ≥6.

≤5

Large established infarct; historically excluded from early thrombectomy trials (large-core trials later showed benefit in selected patients).

0

Diffuse MCA-territory hypoattenuation.

  • ASPECTS applies to the anterior (MCA) circulation only. A separate pc-ASPECTS exists for the posterior circulation.
  • The original score does not subtract points for focal swelling/sulcal effacement alone — only for hypoattenuation / loss of grey–white differentiation.
  • Interobserver agreement improves with standardized windowing (narrow stroke windows) and side-by-side hemispheric comparison.

Sources

  • Barber PA, et al. Validity and Reliability of a Quantitative Computed Tomography Score in Predicting Outcome of Hyperacute Stroke Before Thrombolytic Therapy (ASPECTS). Lancet. 2000;355(9216):1670-1674.

Educational reference for clinicians — not medical advice. Verify against the primary source before acting on it; guidelines change. Final decisions rest with the interpreting physician and your institution's protocols.