1. Department of Radiology, West China Hospital; Sichuan University; Chengdu China
2. Department of Radiology; First Affiliated Hospital of Kunming Medical University; Kunming China
3. Department of Radiology; First Affiliated Hospital of Chongqing Medical University; Chongqing China
4. Mallinckrodt Institute of Radiology; Washington University School of Medicine; St. Louis Missouri USA