Effects of Microvascular Permeability Changes on Contrast-Enhanced T1 and Pharmacokinetic MR Imagings After Ischemia

Background and Purpose-Brain enhancement on contrast-enhanced T1-weighted imaging (CET1-WI) after ischemic stroke is generally accepted as an indicator of the blood-brain barrier disruption. However, this phenomenon usually starts to become visible at the subacute phase. The purpose of this study was to evaluate the time-course profiles of K-trans, cerebral blood volume (v(p)), and CET1-WI with early detection of blood-brain barrier changes on K-trans maps and their role for prediction of subsequent hemorrhagic transformation in acute middle cerebral arterial infarct. Methods-Twenty-six patients with acute middle cerebral arterial stroke and early spontaneous reperfusion, whose MR images were obtained at predetermined stroke stages, were included. T2*-based MR perfusion-weighted images were acquired using the first-pass pharmacokinetic model to derive K-trans and v(p). Parenchymal enhancement observed on maps of K-trans, v(p), and CET1-WI at each stage was compared. Association among these measurements and hemorrhagic transformation was analyzed. Results-K-trans map showed significantly higher parenchymal enhancement in ischemic parenchyma as compared with that of v(p) map and CET1-WI at early stroke stages (P<0.05). The increased K-trans at acute stage was not associated with parenchymal enhancement in CET1-WI at the same stage. Parenchymal enhancement in CET1-WI started to occur at the late subacute stage and tended to be luxury reperfusion-dependent. Patients with hemorrhagic transformation showed higher mean K-trans values as compared with patients without hemorrhagic transformation (P=0.02). Conclusions-Postischemic brain enhancement on routine CET1-WI seems to be closely related to the luxury reperfusion at the late subacute stage and is not dependent on microvascular permeability changes at the acute stage.