1. Department of Radiology, Beijing Friendship Hospital Capital Medical University 95 Yong‐an Road Beijing 10050 China
2. Department of Radiology Weill Cornell Medical College 407 East 61st Street New York 10044 USA
3. Department of Radiology Shandong Provincial Hospital Affiliated to Shandong First Medical University 324 Jing‐wu Road Jinan 250021 China