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

Collateral Scoring on mCTA

Collaterals are measured on muli-phase CTA by comparing backfilling arteries beyond the blocked artery to similar arteries in the opposite unaffected hemisphere. Vascular enhancement distal to occlusion is scored in anterior and posterior MCA territories as:

Category

Score

Description

Good

 

 

 

 

 

5

 

 

Compared to asymptomatic contralateral hemisphere, there is no delay and normal or increased prominence of peripheral vessels/ normal extent within the occluded arteries territory within the symptomatic hemisphere.

4

 

Compared to asymptomatic contralateral hemisphere there is a delay of one phase in filling in of peripheral vessels but prominence and extent is the same.

Intermediate

 

 

 

 

 

3

 

 

Compared to asymptomatic contralateral hemisphere there is a delay of two phases in filling in of peripheral vessels but prominence and extent is the same or there is a one phase delay and decreased prominence (thinner vessels) / reduced number of vessels in some part of the territory occluded.

2

 

 

Compared to asymptomatic contralateral hemisphere there is a delay of two phases in filling in of peripheral vessels and decreased prominence and extent or a one-phase delay and some regions with no vessels in some part of the territory occluded.

Poor

 

 

 

 

1

 

Compared to asymptomatic contralateral hemisphere there are just a few vessels visible in any phase within the occluded vascular territory.

0

Compared to asymptomatic contralateral hemisphere there are no vessels visible in any phase within the occluded vascular territory.

*On a  single phase, multiphase or dynamic CTA:  no or minimal collaterals in a region greater than 50% of the MCA territory when compared to pial filling on the contralateral side can also be considered as poor collaterals. 

 

 




Figure. Upper panel shows a patient with a left M1 MCA occlusion (arrow) and good collaterals (backfilling arteries) on multi-phase CTA. Middle Panel shows a patient with a left M1 MCA occlusion (arrow) and intermediate collaterals. Lower panel shows a patient with a right M1 MCA occlsion (arrow) and poor collaterals (minimal backfilling arteries) on multi-phase CTA.