The aim of this study was to develop a new middle cerebral artery occlusion (MCAO) model in rabbits using a less invasive, endovascular interventional technique. The new animal model's technical feasibility and its success in producing lesions was evaluated using magnetic resonance imaging (MRI).

Ten rabbits were used to develop the MCAO models using a transfemoral catheter-based technique. After catheterization of the common carotid artery, a microcatheter was introduced coaxially through the catheter to cannulate the internal carotid artery and to embolize the MCA with polyvinyl alcohol particles. We evaluated how successful we were in selecting the vessels, catheterization, embolization, and also evaluated how many of the animals survived until the end of experiment. Diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI) were performed in one-hour intervals to monitor the ischemic lesion for a total of six hours following successful occlusion of the target artery. The relative volume of the lesion was calculated as a hemispheric lesion volume (HLV, %). The signals of the lesion and contralateral normal brain (control) were measured in each image at every time point. Lesion-to-control signal-intensity ratio (SIR) of DWI, and T2WI were obtained together with relative apparent diffusion coefficient (rADC).

Catheterization and embolization of the internal carotid artery were successful in all 10 rabbits, which showed relevant lesions on MRI. All rabbits survived until the end of the experiment. The HLV (mean±standard deviation) was 35.7±14.6%. The relative ADC was 0.80±0.13. The lesion signals on DWI and T2WI showed a gradual increase as time passed, while the ADC value of the lesion gradually decreased (p<0.0001).

The rabbit MCAO model using an endovascular interventional technique is technically feasible, and provides a reproducible lesion in the target arterial territory. MRI successfully revealed a typical finding of acute cerebral infarction. This model is also believed to be suitable for the MRI investigation of acute cerebral ischemia.