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  • Print publication year: 2009
  • Online publication date: May 2010

3 - Neuroradiology

from Section I - Etiology, pathophysiology and imaging


Non-contrast CT (NCCT)

NCCT can be performed in less than a minute with a helical CT scanner, and is considered sufficient to select patients for intravenous thrombolysis with iv-RTP within 4.5 hours, or endovascular treatment within 6 hours. It is a highly accurate method for identifying acute intracerebral hemorrhage and subarachnoid hemorrhage, but quite insensitive for detecting acute ischemia. The approximate sensitivity of CT and perfusion CT (PCT) in different ischemic stroke subtypes is depicted inFigure 3.1. Focal hypoattenuation (hypodensity) is very specific and predictive for irreversible ischemia, whereas early edema without hypoattenuation indicates low perfusion pressure with increased MCV and therefore represents potentially salvageable tissue [1]. The “fogging effect” relates to the potential disappearance of hypoattenuation from approximately day 7 for up to 2 months after the acute stroke. It may result in false-negative NCCT in the subacute stage of ischemic stroke.

Prognosis in thrombolysed and non-thrombolysed patients is worse if there are clear early ischemic signs on NCCT [2, 3]. However, patients benefit from early intravenous and intra-arterial thrombolysis despite early ischemic signs [3, 4].

Non-contrast CT (NCCT) is highly accurate for identifying acute intracerebral hemorrhage and subarachnoid hemorrhage, but quite insensitive for detecting acute ischemia.

Perfusion CT (PCT)

PCT with iodinated contrast may be used in two ways:

as a slow-infusion/whole-brain technique

as dynamic perfusion CT with first-pass bolus-tracking methodology.

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