1. The Key Laboratory of Biomedical Information Engineering, Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
2. Department of Radiology, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an 710061, China
3. Baoan Hospital, Southern Medical University, Shenzhen 518101, China
4. Department of Nuclear Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
5. Center for Integrative Medicine, School of Medicine, University of Maryland, 520 W. Lombard Street, Baltimore, MD 21201, USA