Clinical Application of Perfusion and Diffusion in Stroke

Stroke is an emergent neurological condition where time is of the essence. Multimodal computed tomography (CT) and magnetic resonance imaging (MRI) techniques such as diffusion-weighed imaging (DWI) and perfusion-weighted imaging (PWI) represent powerful tools that offer unique insight into stroke pathophysiology. Information obtained from these imaging techniques allows further tissue-based management decisions and individualization of acute stroke reperfusion therapy. The prospect of extending the time window for acute stroke treatment beyond the current time-based treatment windows has been re-emphasized by the results of recent trials. This has led to re-emergence and increased performance of multimodal CT and MRI in emergent stroke settings. Multimodal imaging not only allows differentiation of hemorrhage and infarction but also areas of dead neural tissue or core, and viable tissue, or penumbra, which can benefit from reperfusion therapeutic options. This chapter reviews the use of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) in the workup of acute stroke patients, their current clinical utility, as well as their advantages and disadvantages. The latest trials on stroke intervention are also reviewed.