1. Department of Radiology, Okayama University Hospital, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
2. Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
3. Department of Radiological Technology, Okayama University Graduate School of Health Science, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan