Imaging of cerebral perfusion in acute stroke.

Rapid imaging of cerebral perfusion in acute stroke is needed for timely triage of patients for thrombolytic therapy. Accurate quantitative perfusion imaging is required for proper assessment of penumbral brain parenchyma truly at risk for extension of infarction from the irreversible core infarction. CT and MRI techniques offer rapidity and availability for acute stroke imaging, including that of cerebral perfusion. CT perfusion techniques are readily available, but suffer from limited brain coverage of present multislice scanners. MRI offers whole brain coverage, but suffers from less availability and higher cost than CT. Presently, development is directed towards increasing the quantitative accuracy of cerebral perfusion imaging and validation of surrogate parameters, such as time to peak (TTP). In the future, the need for rapid and frequent assessment of cerebral perfusion and its metabolic correlates, with minimal or no radiation, will probably be met by MRI.