Magnetic resonance imaging of hemorrhagic stroke.

Stroke is the third leading killer of Americans and the major cause of disability in our population. It is pathologically obvious yet mechanistically very complex and perplexing. Many individual facets of stroke have been studied independently under very aberrant conditions with attention focused on occlusive stroke. The actual onset of hemorrhagic stroke has never been witnessed though. To achieve this ambitious goal we had to generate most of the procedures we used. With our central theory being that the event of stroke in Stroke Prone Spontaneously Hypertensive Rats (SPSHR) is closely tied to blood pressure, we studied the special physiology of these animals, and used a hypertensive dose of i.v. norepinephrine to induce stroke. We then utilized Magnetic Resonance Imaging (MRI) techniques for imaging conscious animals to image SPSHRs as they underwent hemorrhagic stroke. With a 4.7T MR scanner (Biospec, Bruker Medical) we used diffusion, perfusion, T1 and T2* weighted pulse sequences. In the most robust case, the hemorrhagic insult began at the head of the caudate putamen and was followed by a rapid filling of the ventricular system with blood. The drastic change in cerebral hemodynamics was confirmed with MR angiography. Behavioral tests were run prior to and following stroke, but only proved the ambiguity of such methods in comparison to the certainty of MRI. After imaging, animals were sacrificed and immunocytochemically stained for fibronectin and albumin. All animals were acquired and cared for in accordance with the guidelines published in the Guide for the care and use of laboratory animals (National Institute of Health Publications No. 85-23, Revised 1985)