1. Department of Nuclear Medicine Xijing Hospital Fourth Military Medical University Xi'an Shaanxi 710032 P. R. China
2. State Key Laboratory of Vaccines for Infectious Diseases Center for Molecular Imaging and Translational Medicine Xiang'An Biomedicine Laboratory School of Public Health Xiamen University Xiamen 361102 P. R. China
3. Departments of Diagnostic Radiology Chemical and Biomolecular Engineering and Biomedical Engineering Yong Loo Lin School of Medicine and College of Design and Engineering National University of Singapore Singapore 119074 Singapore
4. Clinical Imaging Research Centre Centre for Translational Medicine Yong Loo Lin School of Medicine National University of Singapore Singapore 117599 Singapore
5. Nanomedicine Translational Research Program NUS Center for Nanomedicine Yong Loo Lin School of Medicine National University of Singapore Singapore 117597 Singapore
6. Institute of Molecular and Cell Biology Agency for Science Technology, and Research (A*STAR) 61 Biopolis Drive, Proteos Singapore 138673 Singapore