Acute Ischemic Stroke: A Review of Imaging, Patient Selection, and Management in the Endovascular Era. Part I: Initial Management and Imaging

Abstract

Till recently, the mainstay of management of acute ischemic stroke (AIS) has been intravenous thrombolysis. However, response to treatment and outcomes in the presence of a large vessel occlusion (LVO) were largely suboptimal. Endovascular thrombectomy techniques with stentrievers and aspiration catheters have revolutionized stroke treatment significantly, improving outcomes in this once untreatable disease. The interventional radiologist must play an active role in the stroke team in streamlining imaging as well as endovascular management. The focus of this review article is on initial management and imaging. Initial measures consist of patient resuscitation, basic investigations and assessment of stroke severity using the National Institutes of Health Stroke Scale (NIHSS), all of which have therapeutic and prognostic implications to be considered by the neurointerventionist. Imaging must aim to be swift and efficient. Choice of a modality must be based on available infrastructure as well as clinical-radiologic factors such as the time since ictus or posterior circulation involvement. Computed tomography (CT) is the preferred modality for its speed, whereas magnetic resonance imaging (MRI) remains the gold standard problem solving technique for detection of stroke. Exclusion of hemorrhagic stroke and other stroke mimics is the first objective. Thereafter, imaging is targeted toward assessing the parenchyma and vasculature. Defining the core and penumbra is the most important goal of parenchymal imaging. The core may be defined by the presence of early ischemic changes on CT, CT angiographic source images, or diffusion restriction on MRI. The penumbra is approximated by collateral status or perfusion methods. The prime directive of vascular imaging, either CT or magnetic resonance angiography (MRA) is to establish the presence of an LVO. Once confirmed, the decision for thrombolysis and/or thrombectomy is based on clinical and imaging criteria, the most ideal being that of a moderately severe stroke with a small core and LVO on imaging.

Keywords

stroke - mechanical thrombectomy - neurointervention

• References

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