1. From the Departments of Radiology (H.P., T.M., A.H.M., Z.Z., W.S.) and Neurosurgery (G.A.H.) and the Cardiovascular Research Center (H.P., T.M., Z.Z., W.S.), University of Virginia, Charlottesville, and Interdepartmental Program in Vascular Biology and Transplantation, Boyer Center for Molecular Medicine and Department of Surgery (Y.W., G.T.), Yale University School of Medicine, New Haven, Conn.