1. Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, United States
2. Physics & Biology in Medicine Interdepartmental Graduate Program, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, United States
3. Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, University of California Los Angeles, Los Angeles, California 90095, United States
4. Department of Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, California 90095, United States
5. Department of Molecular & Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, United States