Advanced imaging in acute stroke management-Part II: Magnetic resonance imaging.

Worldwide, non-contrast computed tomography (NCCT) has been the imaging modality of choice in acute stroke, primarily due to its accessibility and short acquisition time. However, magnetic resonance imaging (MRI), specifically diffusion-weighted imaging (DWI), is much more sensitive to hyperacute ischemic changes. Multimodal MRI studies provide significantly more pathophysiological and prognostic information than NCCT. Finally, perfusion-weighted MRI permits visualization of the extent of the ischemic penumbra in individual patients. MRI-based penumbral imaging appears to be the most promising approach to expanding the thrombolysis population base to include patients with prolonged symptoms. This article describes advances in MRI techniques and their application to acute stroke management.