[1] Xi An Jiao Tong Univ, Affiliated Hosp 1, Dept Neurosurg, Xian 710061, Peoples R China
[2] Univ Freiburg, Univ Med Ctr Freiburg, Fac Med, Dept Diagnost & Intervent Radiol,Div Med Phys, D-79108 Freiburg, Germany
[3] Shaanxi Univ Chinese Med, Affiliated Hosp, Xianyang 712000, Peoples R China