1. Department of Radiology, School of Medicine, Oita University, 1-1 Idaigaoka, Hasama-machi, Yufu City, Oita, Japan;
2. Advanced Molecular Imaging Center, School of Medicine, Oita University, Oita, Japan; and
3. Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan