[1] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94118 USA
[2] Univ Calif San Francisco, Dept Pediat, San Francisco, CA 94118 USA
[3] Childrens Hosp Los Angeles, Dept Radiol, Los Angeles, CA USA
[4] Childrens Hosp Los Angeles, Dept Pediat, Los Angeles, CA USA
[5] Univ Calif San Francisco, Dept Epidemiol, San Francisco, CA USA
[6] St Louis Univ, Sch Med, Dept Pediat, St Louis, MO USA
[7] Univ Calif San Francisco, Dept Radiol, San Francisco, CA USA
[8] Univ Washington, Dept Biostat, Seattle, WA USA
[9] Univ Washington, Sch Med, Dept Pediat, Seattle, WA USA
[10] Washington Univ, Sch Med, Mallinckrodt Inst Radiol, St Louis, MO USA