MRI evaluation of treatment of embolic stroke in rat with intra-arterial and intravenous rt-PA.

Using magnetic resonance imaging (MRI), we investigated treatment of a rat model of embolic stroke with rt-PA via intra-arterial (IA) and intravenous (IV) routes of administration. Rats were treated with rt-PA by either IA (n = 13) or IV (n = 13) routes at 3 h after stroke induction. Diffusion, perfusion, T2, and magnetization transfer MRI were performed prior to and at 1-3 and at 24 h after embolization. The IA treated group exhibited smaller lesion volumes than the IV treated group (p = 0.02). The relative areas with low ADCW and cerebral blood flow (CBF) after IA rt-PA intervention were significantly (p < or = 0.03) smaller than those in the IV treated group at 24 h after embolization. Significant differences (p < 0.02) between IA and IV treated groups in the relative area with high T2 and inverse of the apparent forward transfer rate of magnetization (kINV) in the ipsilateral hemisphere were also detected at 24 h after embolization. The IA treated group exhibited less intracerebral hemorrhage (27%) than the IV treated (64%) groups. Our data suggest that the beneficial effects of IA rt-PA treatment can be detected by changes in CBF, ADCW, T2, and kINV.