Multimodal Computed Tomography in Acute Ischaemic Stroke
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 inter-individual variations in response to an acute vascular occlusion, the goal of modern imaging such as multimodal computed tomography (CT) is to rapidly identify acute ischaemic 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 haemorrhagic versus ischaemic 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 ischaemic 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.