[1] Washington Univ, Sch Med, Intervent Neuroradiol Sect, Mallinckrodt Inst Radiol, St Louis, MO USA
[2] Univ Florida, Dept Neurosurg, Gainesville, FL USA
[3] Washington Univ, Dept Neurol Surg, Sch Med, St Louis, MO USA
[4] Washington Univ, Sch Med, Dept Neurol, St Louis, MO 63110 USA