1. Graduate School of Tianjin Medical University, Heping District, Tianjin 300070, P. R. China
2. Department of Radiology, Tianjin Children’s Hospital, Beichen District, Tianjin 300134, P. R. China
3. Department of Neurosurgery, Tianjin Children’s Hospital, Beichen District, Tianjin 300134, P. R. China