[1] Univ Calgary, Fac Med, Dept Clin Neurosci, Calgary, AB T2N 2T9, Canada
[2] Univ Calgary, Fac Med, Dept Med, Calgary, AB T2N 2T9, Canada
[3] Univ Calgary, Fac Med, Dept Radiol, Calgary, AB T2N 2T9, Canada
[4] Univ Calgary, Fac Med, Dept Community Hlth Sci, Calgary, AB T2N 2T9, Canada
[5] Med Univ S Carolina, Dept Med, Div Biostat & Epidemiol, Charleston, SC 29425 USA
[6] Univ Miami, Miller Sch Med, Dept Neurol, Miami, FL 33136 USA
[7] Natl Inst Neurol Disorders & Stroke, Bethesda, MD USA
[8] Univ Michigan, Sch Med, Dept Emergency Med, Ann Arbor, MI USA