1. Department of Radiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
2. Department of Ultrasonography, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
3. Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China