Hui Liu1, Weidong Ren2, Dongyu Li1, Lu Sun1. 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.