1. University of Groningen, University Medical Center Groningen; Department of Nuclear Medicine and Molecular Imaging; 1, 9713 GZ Groningen The Netherlands
2. Department of Nuclear Medicine; University Hospital, Ghent University; De Pintelaan 185, 9000 Ghent Belgium
3. Central Research Laboratory; Hamamatsu Photonics K.K.; Hamakita Hamamatsu, Shizuoka 434-8601 Japan
4. Research Institute of Cyclotron and Drug Discovery Research; Southern TOHOKU Research Institute for Neuroscience; 7-115 Yatsuyamada Koriyama 963-8052 Japan
5. Department of Biofunctional Imaging; Fukushima Medical University; 1 Hikarigaoka Fukushima 960-1295 Japan
6. Research Team for Neuroimaging; Tokyo Metropolitan Institute of Gerontology; 35-2 Sakae-cho, Itabashi-ku Tokyo 173-0015 Japan