1. From the New England Center for Stroke Research, Department of Radiology, University of Massachusetts Medical School, Worcester (M.J.G., G.J.U., M.M., A.S.P.)
2. Department of Neurosurgery, Advocate Health, Chicago, IL (D.K.L.)
3. Department of Neurosurgery, Stony Brook University, NY (D.F.)
4. Harrington Heart and Vascular Center, University Hospitals Cleveland Medical Center, OH (H.G.B.)
5. Department of Neurosurgery, Kaiser Permanente Fontana Medical Center, CA (C.W.L.).