[1] Univ Washington, Sch Med, Dept Neurol Surg, Seattle, WA 98195 USA
[2] Univ Washington, Sch Med, Dept Radiol, Seattle, WA 98195 USA
[3] Seattle Childrens Hosp, Dept Neurol Surg, Div Neurol Surg, Seattle, WA 98105 USA
[4] Univ Milano Bicocca, Dept Neurosci & Biomed Technol, Milan, Italy