1. Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
2. Department
of Molecular and Medical Pharmacology and Crump Institute for Molecular
Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los
Angeles, California 90095, United States
3. Athinoula
A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
4. Division
of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
5. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany