1. Department of Radiology, Tohoku Medical and Pharmaceutical University Hospital, 1-12-1 Fukumuro, Miyagino-ku, Sendai 983-8512, Japan
2. Department of Radiological Technology, Tohoku University School of Health Sciences, 2-1 Seiryo Aoba-ku, Sendai 980-8575, Japan
3. Gastroenterology Center, Tohoku Medical and Pharmaceutical University Hospital, 1-12-1 Fukumuro, Miyagino-ku, Sendai 983-8512, Japan