1. From the Department of Neuroradiology, University Hospital RWTH Aachen, Neuroradiologie, Universitätsklinikum Aachen, Pauwelsstr 30, 52074 Aachen, Germany (O.N., T.S., M.W.); and New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Mass (A.K., R.A., M.J.G.).