1. Department of Radiology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan

2. Department of Radiology, Yamaguchi Grand Hospital, Hofu, Yamaguchi, Japan

3. Department of Computer-aided Diagnosis and Biomedical Imaging Research Biomedical Engineering, Applied Medical Engineering Science Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi, Japan