Division of Nuclear Medicine, Department of Radiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, 701-0192, Japan. inubushi@med.kawasaki-m.ac.jp. Department of Radiology, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan. Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawaharacho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan. Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, 187-8551, Japan. Department of Radiology, Asahikawa Medical University, 2-1-1-1 Midorigaoka-higashi, Asahikawa, 078-8510, Japan. HIMEDIC Clinic WEST, 3-3-17 Minami Senba, Chuo-ku, Osaka, 542-0081, Japan.