[1] Washington Univ, Sch Med, Mallinckrodt Inst Radiol, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, Dept Neurol, St Louis, MO 63110 USA
[3] Washington Univ, Sch Med, Dept Neurol Surg, St Louis, MO 63110 USA
[4] Barnes Jewish Hosp South, Dept Radiol, St Louis, MO USA
[5] St Louis Childrens Hosp, Dept Radiol, St Louis, MO 63178 USA