1. Department of Radiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
2. State Key Laboratory of Integrated Services Networks, Xidian University, Xi'an, China
3. Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
4. Chongqing Key Laboratory of Image Cognition, Chongqing University of Posts and Telecommunications, Chongqing, China