Evaluation of Cerebral Perfusion in Patients Undergoing Intravenous Recombinant Tissue Plasminogen Activator Thrombolysis

Currently, the indication for thrombolytic therapy using intravenous recombinant tissue plasminogen activator (rt-PA) is restricted strictly to patients with acute ischemic stroke within 4.5 h of onset. The effect of rt-PA declines over time; therefore, we need to minimize the time delay while generating imaging information. The use of cerebral blood flow imaging is not recommended within this time window. Conversely, the balance of efficacy and the risk of bleeding complications differ among patients > 4.5 h after onset. Several ongoing studies are using mismatch concepts to extend the therapeutic time window for rt-PA. Long-awaited reliable software, such as RAPID and PMA, are now available to analyze computed tomography/magnetic resonance perfusion data. Patients with wake-up stroke (WUS) are another group that can be used to expand rt-PA candidates. Diffusion fluid-attenuated inversion recovery mismatch is a promising imaging surrogate to select good candidates with WUS. These trials will cause a therapeutic paradigm shift from time-based to tissue-based strategies in the near future.