1 Department of Radiology, Tianjin Union Medical Center, 190 Jieyuan Road, Hongqiao District, Tianjin 300121, PR China.
2 Department of Radiology, Tianjin Union Medical Center, 190 Jieyuan Road, Hongqiao District, Tianjin 300121, PR China. Electronic address: cjr.liujun@vip.163.com.