Molecular Magnetic Resonance Imaging of Vascular Inflammation After Recanalization in a Rat Ischemic Stroke Model.

Abstract

Brain imaging has become central in the management of acute ischemic stroke. Detection of parenchymal injury and perfusion enables characterization of the extent of ischemic damage, which guides treatment decision-making. Additional assessment of secondary events, such as inflammation, which may particularly arise after recanalization, may improve diagnosis and (supplementary) treatment selection. Therefore, we developed and tested a molecular magnetic resonance imaging (MRI) approach for in vivo detection of vascular inflammation after transient middle cerebral artery occlusion in rats. Molecular MRI of VCAM-1 (vascular cell adhesion molecule-1) expression was performed with a targeted contrast agent, in addition to MR angiography, and diffusion-, T₂- and perfusion-weighted MRI, from 1 hour until 96 hours after transient middle cerebral artery occlusion in rats. VCAM-1 expression, detected with susceptibility-weighted MRI, was significantly enhanced at 6 hours after recanalization as compared with 1-hour postrecanalization, coinciding with a transient decline in perfusion after initial hyperperfusion. VCAM-1 levels declined after 24 hours, but remained elevated, particularly in lesion borderzones. The implementation of molecular MRI of vascular inflammation into imaging protocols after acute ischemic stroke could provide complementary information that may guide treatment decision-making before and after recanalization therapy.