Effects of microvascular permeability changes on contrast-enhanced t1 and pharmacokinetic mr imagings after ischemia

Abstract

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, cerebral blood volume (vp), and CET1-WI with early detection of blood-brain barrier changes on K 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 and vp. Parenchymal enhancement observed on maps of K, vp, and CET1-WI at each stage was compared. Association among these measurements and hemorrhagic transformation was analyzed. RESULTS - : K map showed significantly higher parenchymal enhancement in ischemic parenchyma as compared with that of vp map and CET1-WI at early stroke stages (P<0.05). The increased K 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 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. © 2013 American Heart Association, Inc.