1. From the College of Physicians and Surgeons, Columbia University (B.T.B.); Departments of Radiology (P.M.M., S.M., J.P-S.) and Neurological Surgery (P.M.M., J.P-S.), University Hospitals of Columbia and Cornell; and Doris and Stanley Tananbaum Stroke Center (H.S.C.), Neurological Institute, Columbia-Presbyterian Medical Center, New York, NY.