[1] Washington Univ St Louis, Louis Sch Med, St Louis, MO USA
[2] Washington Univ St Louis, Louis Sch Med, Div Diagnost Radiol, Sect Neuroradiol, St Louis, MO USA
[3] Washington Univ St Louis, Louis Sch Med, Dept Otolaryngol Head & Neck Surg, St Louis, MO USA
[4] Washington Universityin St Louis, Sch Med, 660 S Euclid Ave,Campus Box 8115, St Louis, MO 63110 USA