We examined this hypothesis by testing the prediction that the permeability-related parameter Ktrans, a volume transfer constant12 derived from CTP, would 1) predict HT and 2) distinguish between hemorrhagic infarction (HI) and parenchymal hemorrhage (PH) in patients with AIS who receive intra-arterial thrombolysis with tissue plasminogen activator (tPA). The gene discussed is PLAT; the disease is hematocrit.