ABSTRACT
Stroke mechanisms, size, location, and relative proportion of penumbra and infarct are quite variable between patients. According to positron emission tomography (PET) and magnetic resonance imaging (MRI)-based studies, survival (1) of the penumbra is highly individual and may last from less than three hours to beyond 48 hours (2,3). By six hours, about 75% of patients still have a meaningful, but highly variable penumbra. These data suggest that there is a need for a reliable and rapid imaging technique for the assessment of individual penumbra in acute stroke patients. This imaging technique should identify patients who may benefit from late recanalization. It should also identify patients with no penumbra, for whom thrombolysisinduced recanalization may not be associated with benefit, but who have a significant risk of intracranial hemorrhage, even in the early phase.
