1. Department of Radiology, University of New Mexico Health Sciences Center, 1 University of New Mexico, MSC 10 5530, Albuquerque, NM 87131.
2. Department of Pathology and Laboratory Medicine, University of Kentucky, Lexington, KY.
3. Department of Neurology, University of New Mexico, Albuquerque, NM.
4. Department of Anesthesia and Perioperative Care, Center for Cerebrovascular Research, University of California San Francisco, San Francisco, CA.