1 Department of Radiological Technology, Okayama University Graduate School of Health Sciences, 2-5-1 Shikata-cho kita-ku, Okayama, 700-8558, Japan. iguchi@ba2.so-net.ne.jp.
2 Department of Radiology, Hyogo Medical University, 1-1 Mukogawa-cho, Nishinomiya, 663-8501, Japan.