Multiphase CT angiography collateral score in acute stroke

Last revised by Francis Deng on 13 May 2021

Multiphase CT angiography (mCTA) collateral score is a simple scoring system that allows quick evaluation of collateral vessel filling delay in acute ischemic stroke. In some studies, it has been shown to be a better predictor of clinical outcomes and eligibility for endovascular therapy (ECT) than a decision based on single-phase CT angiography 1.

mCTA collateral score

A score on a scale of 0 to 5 is given, with 5 being the best and 0 the worst 2:

  • 5: no filling delay compared to the asymptomatic contralateral hemisphere, normal pial vessels in the affected hemisphere
  • 4: a filling delay of one phase in the affected hemisphere, but the extent and prominence of pial vessels is the same
  • 3: a filling delay of two phases in the affected hemisphere, or a delay of one phase with a significantly reduced number of vessels in the ischemic territory
  • 2: a filling delay of two phases in the affected hemisphere with a significantly reduced number of vessels in the ischemic territory, or one phase delay showing regions without visible vessels
  • 1: only a few vessels are visible in the affected hemisphere in any phase
  • 0: no vessels visible in the affected hemisphere in any phase

Generally, a score of 3 or less indicates a poor prognosis 1. Therefore, some investigators have dichotomized the scores such that 0-3 is "poor" and 4-5 is "good" collateral status 2.

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Cases and figures

  • Case 1: mCTAs score: 0
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