[1] Univ Western Ontario, Dept Med, Schulich Sch Med & Dent, London Hlth Sci Ctr, London, ON, Canada
[2] Univ Toronto, St Michaels Hosp, Dept Med, Div Neurol, Toronto, ON M5B 1W8, Canada
[3] Univ Toronto, Inst Clin Evaluat Sci, Toronto, ON, Canada
[4] Univ Western Ontario, Dept Med Imaging, Schulich Sch Med & Dent, London Hlth Sci Ctr, London, ON, Canada
[5] Univ Toronto, St Michaels Hosp, Dept Med, Toronto, ON M5B 1W8, Canada
[6] Univ Toronto, St Michaels Hosp, Dept Obstet & Gynecol, Toronto, ON M5B 1W8, Canada
[7] Univ Toronto, St Michaels Hosp, Dept Hlth Policy Management & Evaluat, Toronto, ON M5B 1W8, Canada