[1] Univ Freiburg, Dept Neuroradiol, D-79106 Freiburg, Germany
[2] Oregon Hlth & Sci Univ, Dept Neurol, Portland, OR 97201 USA
[3] Oregon Hlth & Sci Univ, Dotter Intervent Inst, Portland, OR 97201 USA
[4] Brigham & Womens Hosp, Dept Neurosurg, Boston, MA USA
[5] Univ Pittsburgh, Med Ctr, Dept Neurol, Pittsburgh, PA USA
[6] Univ Pittsburgh, Med Ctr, Dept Radiol, Pittsburgh, PA USA
[7] Univ Pittsburgh, Med Ctr, Dept Neurosurg, Pittsburgh, PA USA
[8] Vancouver Gen Hosp, Dept Neurol, Vancouver, BC, Canada
[9] Vancouver Gen Hosp, Dept Neurosurg, Vancouver, BC, Canada
[10] Heidelberg Univ, Dept Neuroradiol, D-6900 Heidelberg, Germany