1. Department of Environmental Medicine, Kochi Medical School, Nankoku, Kochi, Japan
2. School of Information, Kochi University of Technology, Nankoku, Kochi, Japan
3. Department of Radiology, Kochi Medical School Hospital, Nankoku, Kochi, Japan
4. Department of Radiology, School of Medicine, Juntendo University, Bunkyo City, Tokyo, Japan