Infarct core

Last revised by Andrew Murphy on 22 May 2021

The infarct core denotes the part of an acute ischemic stroke that has already infarcted or is irrevocably destined to infarct regardless of reperfusion. It is also referred to as established infarct and is in distinction from the penumbra, which remains potentially salvageable. 

CT perfusion

On CT perfusion, the infarct core is defined as the area of the brain with 1,2

  1. increased mean transit time (MTT)
  2. markedly decreased relative cerebral blood flow (CBF): <30% normal
  3. decreased cerebral blood volume (CBV): <40% normal

By contrast, the ischemic penumbra will have only moderately decreased cerebral blood flow and normal or even increased cerebral blood volume due to autoregulation. 

It is of note that CT perfusion may overestimate infarct core on admission, especially in the early time window of a stroke, by predicting lesion in areas that will not show infarct on follow-up imaging, a phenomenon known as a ghost infarct core 3.


On MRI, the infarct core correlates closely with restricted diffusion on diffusion-weighted imaging 1

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Cases and figures

  • Case 1: increased MTT
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  • Case 1: markedly decreased CBF
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  • Case 1: decreased CBV
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