We report on a 28-year-old male, who suffered a stroke. His CT and MRI were performed with respect to the important time factor. Early visualisation of the ischaemic lesion with CT is not possible. Usually up to 24 hours after the event must elapse. Several early signs of ischaemia were derived on the basis of previous experience: ACM sign, density and change of contrast of the lentiform nucleus, reduced size of subarachnoid spaces on the side of the lesion 6 to 8 hours after the onset of clinical symptoms. MRI is a much more sensitive tool for imaging of ischaemic stroke. It is possible to demonstrate changes as early as 3 hours after the onset in the highly sensitive imaging FLAIR (Flow Attenuated Inversion Recovery) mode. As treatment is effective only within 3 hours from the onset of acute ischemic stroke this technique is insufficient, too. Perfusion weighted imaging (PWI) seems to be more promising as it demonstrates ischaemia as early as 1–2 hours after the onset of an acute stroke.

        Key words: ischaemic stroke, computerized tomography, magnetic resonance imaging, perfusion weighted imaging, CT, MRI, PWI, DWI