Multimodal Computed Tomography in Acute Ischemic Stroke
Multimodal Computed Tomography in Acute Ischemic Stroke
US Neurology, 2010;6(1):50–4
Abstract
Stroke is the third leading cause of death in the US, affecting 795,000 individuals annually. Currently, only a small percentage of acute stroke patients receive thrombolytic treatment. A significant limitation is the current use of strict time criteria in the decision to treat. As there are significant interindividual variations in response to an acute vascular occlusion, the goal of modern imaging such as multimodal computed tomography (CT) is to rapidly identify acute ischemic stroke patients and determine which patients are likely to benefit from treatment based on tissue perfusion status rather than time of presentation alone. Multimodal CT consists of a non-contrast head CT, CT angiogram (CTA) of the head and neck, and CT perfusion (CTP). The non-contrast head CT allows rapid triage of a patient with hemorrhagic versus ischemic stroke. The CTA allows identification of the site of vascular pathology with similar quality to digital subtraction angiography. The CTP scan allows for determination of the infarct core and surrounding ischemic penumbra, which remains at risk for infarction if perfusion is not restored. This allows the potential to prospectively treat only those patients likely to benefit from thrombolysis while protecting those patients unlikely to benefit from the risks associated with treatment.
Keywords Stroke, multimodal computed tomography (CT), non-contrast head CT, CT angiography, CT perfusion, ischemic penumbra
Disclosure: Sachin Rastogi, MD, has no conflicts of interest to declare. David S Liebeskind, MD, FAHA, is funded by National Institutes of Health (NIH)/National Institute of Neurological Disorders and Stroke (NINDS) grants K23NS054084 and P50NS044378.
Received: May 15, 2010 Accepted: June 28, 2010 Citation: US Neurology, 2010;6(1):50–54
Correspondence: David S Liebeskind, MD, FAHA, 710 Westwood Plaza, Los Angeles, CA 90095. E: davidliebeskind@yahoo.com
Stroke is the third leading cause of death in the US, affecting approximately 795,000 patients annually.1 A recent analysis shows that only 3–5% of acute stroke patients actually receive intravenous thrombolytic therapy.2 An important cause of non-treatment is the strict time criteria for acute medical and interventional therapies: many acute stroke patients are ineligible for treatment due to uncertainty in time of onset or delayed presentation.
The use of strict time criteria to make treatment decisions is not ideal since there are significant differences among individuals and their responses to an acute vascular event.3 The goal of advanced neuroimaging is to individualize acute stroke treatments based on assessment of tissue viability and vascular status rather than using strict time criteria alone. Acute intervention or treatment may be refined through improved selection of subjects likely to benefit balanced by the risk of potential harm, irrespective of the time of presentation.3 Multimodal computed tomography (CT), including noncontrast CT (NCT), CT angiography (CTA), and CT perfusion (CTP), is increasingly available and may serve as an ideal tool for rapid image evaluation and triage of the stroke patient.
The goal of a multimodal CT protocol in acute stroke is to answer four key questions:4
- Is there hemorrhage?
- Is there occlusion of a proximal artery or intravascular thrombus that can be targeted for thrombolysis?
- Is there a core of critically ischemic irreversibly infarcted tissue?
- Is there a penumbra of ischemic but potentially salvageable tissue?
The first question is readily addressed by NCT and the second question is addressed by CTA. The last two questions are the most challenging and may potentially be addressed by CTP.5
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Stroke, multimodal computed tomography (CT), non-contrast head CT, CT angiography, CT perfusion, ischemic penumbra
