1. Department of Radiology, Division of Functional and Diagnostic Imaging Research, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo, 650-0017, Japan.
2. Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.
3. Toshiba Medical Systems Corporation, Otawara, Tochigi, Japan.
4. Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.
5. Department of Radiology, Osaka Police Hospital, Osaka, Japan.