1. Yale Positron Emission Tomography Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT 06520, USA.
2. Department of Laboratory Medicine, Yale University, New Haven, CT 06520, USA.
3. Department of Neurology, Yale University, New Haven, CT 06520, USA.
4. Department of Neurosurgery, Yale University, New Haven, CT 06520, USA.
5. UCB Pharma, B-1420 Braine-l’Alleud, Belgium.
6. Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA.