Diffusion and perfusion imaging in acute diagnostics of cerebral ischaemia

Most potential therapeutic strategies for ischaemic stroke attempt to save the brain tissue in the so-called penumbra which reflects potentially salva geable brain tissue. Therefore, new diagnostic procedures are trying to def ine infarct core versus penumbra in the acute stage of ischaemic stroke. Co mputer tomography which is typically employed in this setting cannot attain this goal. Its main role is the exclusion of intracerebral hemorrhage. New functional MRI methods, such as diffusion weighted imaging (DWI) and perfu sion weighted imaging (PWI) are promising to give a better definition of th e underlying pathophysiology. A number of studies have indicated that DWI m ay define with infarct core. Other studies have suggested that the region w ith a prolongation of mean transit time (minus the core) as determined by P WI may be an indicator for ischaemic penumbra. in this article we give some examples employing DWI and PWI in acute stroke. Although not only our data indicates that the above-mentioned first working hypothesis on underlying pathophysiology has to be significantly modified, the additional informatio n to be obtained by DWI and PWI appears to be relevant and potentially very useful in improving therapeutic decisions in acute stroke.