Understanding Alberta Stroke Program Early CT Score (ASPECTS) Faculty of Medicine - University of Calgary


  • Alberta Stroke Program Early CT score (ASPECTS) is a 10-point quantitative topographic CT scan score
  • ASPECTS was developed to offer the reliability and utility of a standard CT examination with a reproducible grading system to assess early ischemic changes on pretreatment CT studies in patients with acute ischemic stroke of the anterior circulation

How to compute ASPECTS

  • ASPECTS is determined from evaluation of two standardized regions of the MCA territory: the basal ganglia level, where the thalamus, basal ganglia, and caudate are visible, and the supraganglionic level, which includes the corona radiata and centrum semiovale
  • All cuts with basal ganglionic or supraganglionic structures visible are required to determine if an area is involved. The abnormality should be visible on at least two consecutive cuts to ensure that it is truly abnormal rather than a volume averaging effect
  • To compute the ASPECTS, 1 point is subtracted from 10 for any evidence of early ischemic change for each of the defined regions.  
  • A normal CT scan receives ASPECTS of 10 points. 
  • A score of 0 indicates diffuse involvement throughout the MCA territory 

Axial NCCT images showing the MCA territory regions as defined by ASPECTS. C- Caudate, I- Insularribbon, IC- Internal Capsule, L- Lentiform nucleus, M1- Anterior MCAcortex, M2- MCA cortex lateral to the insular ribbon, M3- PosteriorMCA cortex, M4, M5, M6 are the anterior, lateral and posterior MCAterritories immediately superior to M1, M2 and M3, rostral to basalganglia. Subcortical structures are allotted 3 points (C, L, and IC).MCA cortex is allotted 7 points (insular cortex, M1, M2, M3, M4, M5and M6)