[en] Acute cerebral infarct is a clinical emergency potentially reversible if treated with thrombolysis during the first 3 to 6 hours of evolution. Clinical recovery is dependent on the severity and duration of cerebral hypoperfusion, as well as the success of vessel recanalization with thrombolysis. We present two recent consecutive patients with acute cerebral infarction treated with thrombolysis within the first 3 hours of evolution. Patient No.1 suffered a cardioembolic 'T' occlusion of the left carotid artery and left the anterior and middle cerebral arteries. Patient No.2 presented with a cardioembolic occlusion of the right middle cerebral artery from its origin, and occlusion a posterior silvian branch of the left middle cerebral artery. Evolution of both cases was dramatically opposite. We report on the quantification of hypoperfusion in the affected ischemic brain tissue in both patients in order to define prognostic parameters and therefore anticipate clinical evolution (au)