The major determinant of clinical recovery in acute ischaemic stroke is early reperfusion of the ischaemic penumbra. To this end, the advent of thrombolytic therapy is driving major reorganisations in acute stroke services with many more patients presenting to hospital earlier. This, coupled with major advances in brain imaging techniques, means that opportunities to improve understanding of the pathophysiology of acute stroke in the clinical setting now exist. Both CT and MR based structural and perfusion imaging are increasingly used in treatment decisions and have been used to demonstrate the contribution of indices such as age, hyperglycaemia, haematocrit and oxygen to …