How well do blood flow imaging and collaterals on angiography predict brain at risk?

As endovascular therapy emerges as a principal approach to restore blood flow in the setting of acute stroke, better methods of patient selection need to be developed. Noninvasive studies of blood flow and angiographic results acquired prior to endovascular therapy may help determine areas of brain at risk of infarction and hemorrhagic transformation, both largely determined by the severity of cerebral ischemia. Pathophysiologic measures of collateral flow and perfusion that characterize ischemic severity prior to revascularization may optimize acute stroke decision-making, currently driven by arbitrary time parameters derived from population studies devoid of imaging.