1. Research Team for Neuroimaging Tokyo, Metropolitan Institute of Gerontology 35‐2, Sakae‐cho, Itabashi‐ku Tokyo 173‐0015Japan
2. Institute of Cyclotron and Drug Discovery Research Southern TOHOKU Research Institute for Neuroscience 7‐115, Yatsuyamada Koriyama 963‐8052Japan
3. Department of Biofunctional Imaging Fukushima Medical University 1, Hikarigaoka Fukushima 960‐1295Japan
4. Department of Engineering Tokyo Nuclear Services Co. LTD 1‐3‐5, Taito, Taito‐ku Tokyo 110‐0016Japan
5. Industrial Equipment Division Sumitomo Heavy Industries, Ltd. ThinkPark Tower 1‐1, Osaki 2‐chome, Shinagawa‐ku Tokyo 141‐6025Japan
6. Radioisotope Center Tokyo Metropolitan Institute of Gerontology 35‐2, Sakae‐cho, Itabashi‐ku Tokyo 173‐0015Japan
7. Faculty of Health Science Hokkaido University of Science 7‐Jo 15‐4‐1, Maeda, Teine‐ku Sapporo 006‐8585Japan
8. School of Health Science International University of Health and Welfare 2600‐1, Kitakanemaru Ohtawara 324‐8501 Japan