1. Department of Surgery, Toho University Ohashi Medical Center 1 , 2-22-36 Ohashi, Meguro, Tokyo 153-8515, Japan
2. Honorary of Physics, Iwate Medical University 2 , 2-14-6 Kawaramachi, Wakabayashi, Sendai, Miyagi 984-0816, Japan
3. Department of Radiology, School of Medicine, Iwate Medical University 3 , 2-1-1 Idaidori, Yahaba, Iwate 028-3694, Japan