1Washington University in St. Louis, St. Louis, MO, United States, 2Neurology, Washington University in St. Louis, St. Louis, MO, United States, 3Radiology, Washington University in St. Louis, St. Louis, MO, United States, 4Biostatistics, University of North Carolina At Chapel Hill, Chapel Hill, NC, United States, 5Neurology, University of North Carolina At Chapel Hill, Chapel Hill, NC, United States, 6Radiology, University of North Carolina At Chapel Hill, Chapel Hill, NC, United States