W Liu1, M Q Shi1, Y S Ge1, P Y Wang2, X Wang3. 1. Department of Radiology, Yantai Affiliated Hospital of Binzhou Medical University, No 774 Jinbu Road, Yantai, 264100, PR China. 2. Department of Radiology, Yantai Affiliated Hospital of Binzhou Medical University, No 774 Jinbu Road, Yantai, 264100, PR China; Binzhou Medical University, No 346 Guanhai Road, 264003, Yantai, Shandong, PR China. Electronic address: wangpeiyuan1640@163.com. 3. Binzhou Medical University, No 346 Guanhai Road, 264003, Yantai, Shandong, PR China. Electronic address: wangxia7512@163.com.