1. Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
2. Laboratory for in Vivo Cellular and Molecular Imaging, ICMI-BEFY/MIMA, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
3. Small Animal Imaging Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, Maryland 21702, United States
4. Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States