Magnetic resonance imaging characterization of hemorrhagic transformation of embolic stroke in the rat.

Intracranial hemorrhage is a critical factor when considering efficacy and safety of thrombolytic intervention after thromboembolic stroke. This study tested whether magnetic resonance imaging could identify tissue for hemorrhagic transformation after the onset of embolic stroke. Rats subjected to embolic stroke with and without recombinant tissue-type plasmogen activator (rt-PA) treatment were followed-up with magnetic resonance imaging using the inverse of the apparent forward transfer rate for magnetization transfer (kinv), gadolinium-chelate contrast-enhanced magnetic resonance imaging, and diffusion-, perfusion-, and T2-weighted imaging. Rats with embolic stroke either were treated with rt-PA 1 (n = 16) or 4 hours (n = 13) after stroke onset or were not treated (n = 15). From these groups, at total of 17 rats had intracerebral hemorrhage. Tissue progressing to hemorrhage and adjacent to the site of hemorrhage was analyzed to identify magnetic resonance imaging markers that characterize hemorrhagic tr...