[1] Stanford Univ, Sch Med, Dept Neurol & Neurol Sci, Stanford, CA 94305 USA
[2] Stanford Univ, Sch Med, Dept Radiol, Stanford, CA 94305 USA
[3] Stanford Univ, Sch Med, Dept Neurosurg, Stanford, CA 94305 USA
[4] Stanford Univ, Sch Med, Stanford Stroke Ctr, Stanford, CA 94305 USA