1. Department of Radiology, The Jikei University Hospital, 3-19-18 Nishi-Shimbashi, Minato-ku, Tokyo 105-8471, Japan
2. Department of Radiology, Jikei University Kashiwa, Hospital, 163-1 Kashiwashita, Kashiwa-shi, Chiba 277-8567, Japan
3. Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
4. Department of Radiological Sciences, Tokyo Metropolitan University, 7-2-10 Higashi-Ogu, Arakawa-ku, Tokyo 116-8551, Japan