1. Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health (NIH), Bethesda, MD 20892, USA.
2. Department of nuclear medicine, Xiamen Cancer Center, First Affiliated Hospital of Xiamen University, Xiamen 361003, China.
3. Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
4. Laboratory of Computational Biology, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892, USA.