[1] Med Univ Vienna, Dept Neurosurg, Vienna, Austria
[2] Med Univ Vienna, Dept Radiol, Vienna, Austria
[3] IST Austria, Comp Graph & Digital Fabricat Grp, Klosterneuburg, Austria
[4] Otto von Guericke Univ, Inst Simulat & Graph, Magdeburg, Germany
[5] Kepler Univ Hosp, Univ Clin Neurosurg, Linz, Austria
[6] Univ Hosp Saarland, Dept Neurosurg, Homburg, Germany
[7] Univ Saarland, Med Fac, Homburg, Germany