1. Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan National Laboratory for Optoelectronics, Wuhan 430071, P. R. China.
2. Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P. R. China.
3. Department of Radiology, Chinese PLA General Hospital, Beijing 100853, P. R. China.
4. Jonsson Comprehensive Cancer Center, The Molecular Biology Institute, California NanoSystems Institute, Departments of Chemistry and Biochemistry and of Bioengineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.