[1] Chung Ang Univ Hosp, Dept Radiol, Seoul, South Korea
[2] Univ Toronto, Div Neuroradiol, Toronto Western Hosp, Toronto, ON, Canada
[3] Univ Hlth Network, Toronto, ON, Canada
[4] Univ Hong Kong, Div Neurosurg, Dept Surg, Hong Kong, Peoples R China
[5] Second Mil Med Univ, Dept Neurosurg, Changhai Hosp, Shanghai, Peoples R China
[6] Univ Toronto, Div Neurosurg, Toronto Western Hosp, Toronto, ON, Canada
[7] Mayo Clin, Dept Radiol, Rochester, MN USA
[8] Mayo Clin, Dept Neurosurg, Rochester, MN USA