1. Department of Radiology, Tangdu Hospital, The Fourth Military Medical University, Xi’an 710038, Shaanxi, P.R. China
2. Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi’an 710038, Shaanxi, P.R. China
3. Student Brigade, The Fourth Military Medical University, Xi’an 710032, Shaanxi, P.R. China