1. Department of Radiological and Medical Laboratory Sciences Nagoya University Graduate School of Medicine Nagoya‐shi Aichi‐ken Japan
2. Radiological Center University of Fukui Hospital Yoshida‐gun Fukui‐ken Japan
3. Department of Radiology University of Fukui Hospital Yoshida‐gun Fukui‐ken Japan
4. Department of Radiology University of Chicago Chicago IL USA
5. Gunma Prefectural College of Health Sciences Maebashi‐shi Gunma‐ken Japan