Image-Guided Method in the Rat for Inducing Cortical or Striatal Infarction and for Controlling Cerebral Blood Flow Under MRI

Background and Purpose-Experimental models are essential for research on ischemic stroke, the second most common cause of death worldwide. The failure of clinical trials on neuroprotective treatment may be due in part to poor animal models. To push the translation of new therapies, we describe a new rat model that captures key elements of human brain ischemia. The model includes imaging and neurointerventional tools that represent the near future of clinical diagnosis and treatment of stroke. Methods-Using Sprague-Dawley rats (n=26), we navigated a microwire with fluoroscopy and MRI guidance from the ventral tail artery to 2 different positions in the middle cerebral artery to establish local occlusion. Animals were scanned with 9.4-T MRI before occlusion, during ischemia, and after reperfusion. Results-We detected stroke lesions, corresponding to the level of occlusion, in all animals by diffusion-weighted and T2 images. We measured lesion volume (mm(3)+/- SD) on T2 scans at 24 hours to be 23.2 +/- 29.8 in the somatosensory cortex group and 107.9 +/- 80 in the striatum group. Conclusion-We present a new rat model for focal stroke with the possibility to cause lesions in different regions of the brain under fluoroscopic and MRI control. The model will be highly useful for extended studies on the ischemic penumbra, alterations in neural connectivity, and for investigating neurotransmitter-mediated events and biochemical changes in the hyperacute phase of brain ischemia. Also, the model uses clinical routine microcatheters facilitating superselective administration of therapeutics directly to the cerebral circulation. (Stroke. 2012;43:2437-2443.)