[1] Mallinckrodt Med, St Louis, MO 63134 USA
[2] Univ Penn, Med Ctr, Dept Neuroradiol, Philadelphia, PA 19104 USA
[3] St Johns Hosp, Div Neuroradiol, Springfield, IL USA
[4] Univ Washington, Dept Neuroradiol, Seattle, WA 98195 USA
[5] Univ Western Ontario, Dept Diagnost Radiol, London, ON N6A 3K7, Canada
[6] Univ Western Ontario, Dept Clin Neurol Sci, London, ON N6A 3K7, Canada
[7] Univ Bonn, Radiol Klin, D-5300 Bonn, Germany
[8] McGill Univ, Montreal Neurol Inst, Dept Diagnost Radiol, Montreal, PQ, Canada
[9] Univ Munich, Klinikum Grosshadern, Inst Radiol Diagnost, D-8000 Munchen, Germany
[10] Univ Iowa Hosp & Clin, Dept Radiol, Iowa City, IA 52242 USA