[1] Univ Toronto, Univ Hlth Network, Toronto Western Hosp, Dept Neurol, Toronto, ON M5S 1A1, Canada
[2] Univ Toronto, Univ Hlth Network, Toronto Western Hosp, Dept Neuroradiol, Toronto, ON M5S 1A1, Canada
[3] Univ Toronto, Univ Hlth Network, Toronto Western Hosp, Dept Med Imaging, Toronto, ON M5S 1A1, Canada
[4] Univ Toronto, Univ Hlth Network, Toronto Western Hosp, Dept Pathol, Toronto, ON M5S 1A1, Canada
[5] Johns Hopkins Univ Hosp, Russell H Morgan Dept Radiol & Radiol Sci, Baltimore, MD 21287 USA