[1] Washington Univ, Sch Med, Div Pediat Hematol Oncol, St Louis, MO 63110 USA
[2] Washington Univ, Dept Radiol, St Louis, MO 63110 USA
[3] Washington Univ, Dept Neurol, St Louis, MO 63110 USA
[4] Washington Univ, Sch Med, Dept Neurol, St Louis, MO USA
[5] Washington Univ, Div Diagnost Radiol, St Louis, MO USA