1. Department of Radiology, The Second Xiangya Hospital, Central South University, No. 139 Middle Remin Rd, Changsha, Hunan, 410011, P.R. China.
2. Department of Radiology, First Hospital of Changsha, Hunan, P.R. China.
3. Changsha Public Health Treatment Center, Hunan, P.R. China.
4. Department of Radiology, Quality Control Center, Changsha, Hunan, P.R. China.