Stroke Imaging Protocols

Abstract

A stroke occurs when blood flow to a portion of the brain is suddenly interrupted. Strokes can arise when a cerebral artery is blocked by a blood clot (ischemic stroke) or when there is spontaneous rupture of a blood vessel within or on the surface of the brain (haemorrhagic stroke). When the blood supply to part of the brain is cut off during a stroke, the brain tissue normally supplied by the affected artery can survive for some time because it can receive blood from collateral blood vessels. The rate of death of brain cells is determined by the volume and speed of delivery of blood supplied by the collateral circulation, which is extremely variable. Brain tissue that receives sufficient perfusion from the collateral vessels is more responsive to treatment and more likely to return to normal function if the obstructed artery is recanalized (opened). However, brain cells with poor collateral blood are more susceptible to further injury during treatment (e.g. haemorrhage) and are more likely to die (infarct), resulting in permanent brain damage.