Magnetic resonance imaging in cerebral ischemia: focus on neonates.

Magnetic resonance imaging (MRI) has dramatically changed our ability to diagnose and treat stroke as well as follow its evolution and response to treatment. Early stroke and ischemia can be visualized using diffusion-weighted imaging (DWI), which utilizes proton diffusion within tissues as a reporter for evolving neuropathology that reflects cytotoxic edema, particularly during the first several days after injury. Historically, T2-weighted imaging (T2WI) has been used for evaluation of vasogenic edema and also is a reliable indicator of injured tissue late after injury. While visual analysis of MR data can provide information about the evolution of injury, quantitative analyses allow definitive and objective evaluations of injury size and location and the effectiveness of novel therapeutic strategies. We review the clinical basis of imaging for stroke and ischemia diagnosis and the methods for post-processing of MR data that could provide novel insights into the evolution and pathophysiology of stroke in the newborn.