[1] Stanford Univ, Dept Radiol, Neuroradiol Sect, Stanford, CA 94305 USA
[2] Univ Melbourne, Murdoch Childrens Res Inst, Royal Childrens Hosp, Melbourne, Vic, Australia
[3] Univ Melbourne, Dept Paediat, Melbourne, Vic, Australia
[4] Univ Colorado, Dept Radiol, Pediat Neuroradiol Sect, Sch Med, Aurora, CO USA
[5] Hosp Sick Children, Dept Neurol, Toronto, ON, Canada
[6] Ohio State Univ, Dept Pediat & Neurol, Columbus, OH USA
[7] Nationwide Childrens Hosp, Columbus, OH USA
[8] Univ Texas MD Anderson Ctr, Dept Neuroradiol, Houston, TX 77030 USA