1. From the Department of Materials Science & Engineering (A.S.T.) and Institute for Medical Engineering and Science, (A.S.T., E.R.E.), Massachusetts Institute of Technology, Cambridge, MA; Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA (E.R.E.); Department of Interventional Neuroradiology, Hôpital Neurologique Pierre Wertheimer, Bron, France (F.T.); and Institut des Neurosciences Cognitives, CNRS, Bron, France (F.T.).