1Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Department of Neurology, Massachusetts General Hospital, Boston, MA, United States, 3Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, United States, 4Department of Radiology, Massachusetts General Hospital, Boston, MA, United States, 5Department of Cardiology, Massachusetts General Hospital, Boston, MA, United States, 6Department of Psychiatry, Spaulding Rehabilitation Hospital, Charlestown, MA, United States, 7Department of Neurology, Yale School of Medicine, New Haven, CT, United States