Imaging of acute stroke: state of the art.

The high incidence of stroke, plus its fatal or debilitating outcome, has prompted tremendous advances over the last two decades on both diagnostic and therapeutic fronts. Multiple randomized trials have proven the utility of thrombolytic agents with rejuvenation of the role of diagnostic imaging. State of the art imaging (mainly computed tomography and magnetic resonance imaging) is crucial for patient selection (eg, excluding intracranial hemorrhage), diagnosis of stroke and prediction of prognosis. Here, we discuss the anatomic and physiologic changes due to an ischemic insult as manifested by modern imaging techniques, including diffusion and perfusion imaging, as well as demonstration of vascular disease by cross sectional angiography supplemented by three dimensional postprocessing. The main target of management is "Penumbra", or salvageable tissue, which is primarily dependent upon the expediency of the whole process, better expressed by the phrase "Time is Brain".