The role of neuroimaging in acute stroke

Background: There is a need for early recognition, diagnosis, and therapy in patients with acute stroke. The most important therapies are thrombolysis or aspirin in hyperacute ischemic stroke and, for secondary prevention, antiplatelet agents, statins, ACE inhibitors (for lowering blood pressure), warfarin, and carotid endarterectomy or stenting. Imaging technology has a crucial role to play in the diagnosis and treatment of stroke. In recent years, significant advances have been made due to the availability of physiological imaging using a variety of techniques, ranging from computerized tomography (CT) to magnetic resonance imaging (MRI), which enable clinicians to define brain anatomy and physiology in greater detail than ever before. Objective: In this article we discuss the imaging techniques currently available for patients with acute stroke, with an emphasis on the utility of these techniques for diagnosis and refining patient selection for early interventions. This is placed in the context of the needs of developing countries. Discussion: infarcted tissue is another issue to be considered when instituting thrombolysis, and its clinical usefulness is being assessed in a number of ongoing trials. Penumbral tissue can be identified by perfusion MRI. CT perfusion (CTP) is an emerging alternative, providing similar information about the penumbra and infarct core. A combined approach of NCCT, CT angiography (CTA), and CTP is now being employed at many centers and is known as multimodal CT imaging (MMCT). MMCT provides information about the pathophysiology of acute stroke which is comparable to that provided by MRI, and the technique has the potential to refine patient selection for thrombolysis.