Start at 10 points and subtract 1 point for each middle cerebral artery territory region with definite early ischaemic change. The final score ranges from 10 (no visible early ischaemic change) to 0 (all regions involved).

Region	Abbreviation	Description
Caudate nucleus	C	Caudate head
Lentiform nucleus	L	Putamen and globus pallidus
Internal capsule	IC	Posterior limb
Insular ribbon	I	Insular cortex
Anterior inferior MCA cortex	M1	Anterior inferior frontal territory
Lateral MCA cortex	M2	Cortex lateral to the insula
Posterior inferior MCA cortex	M3	Posterior temporal territory
Anterior superior MCA cortex	M4	Anterior superior frontal territory above the basal ganglia
Lateral superior MCA cortex	M5	Lateral posterior frontal territory above the basal ganglia
Posterior superior MCA cortex	M6	Parietal territory

Alberta Stroke Program Early CT Score (ASPECTS)