1. Department of Radiology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine Tsinghua University Beijing China
2. State Key Laboratory of Tribology, Department of Mechanical Engineering Tsinghua University Beijing China
3. Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing China
4. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering Tsinghua University Beijing China