Jinling Hu1, Lu Sun1, Weidong Ren2, Min Xu1. 1. Department of Ultrasound, Shengjing Hospital of China Medical University, 36# of Sanhao St. Heping District, Shenyang 110004, China. 2. Department of Ultrasound, Shengjing Hospital of China Medical University, 36# of Sanhao St. Heping District, Shenyang 110004, China renwd01@163.com.