[1] Childrens Hosp Philadelphia, Div Neurol, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Div Neuroradiol, Philadelphia, PA 19104 USA
[3] Univ Penn, Sch Med, Dept Neurol, Hosp Univ Penn, Philadelphia, PA 19104 USA
[4] Univ Penn, Clin & Translat Res Ctr, Philadelphia, PA 19104 USA