[1] Abbott NW Hosp, Neurosci Inst, Div Neurointervent Radiol, Minneapolis, MN 55407 USA
[2] Univ Iowa, Dept Radiol, Iowa City, IA 52242 USA
[3] Washington Univ, Mallinckrodt Inst Radiol, St Louis, MO USA
[4] Washington Univ, Mallinckrodt Inst Radiol, Dept Neurosurg, St Louis, MO USA
[5] Washington Univ, Mallinckrodt Inst Radiol, Dept Neurosurg, Dept Neurol, St Louis, MO USA
[6] Washington Univ, Dept Neurol, St Louis, MO USA