1. Department of Radiology; Wajokai Eniwa Hospital; Eniwa Japan
2. Department of Orthopedic Surgery; Wajokai Eniwa Hospital; Eniwa Japan
3. Department of Spine and Spinal Cord Disorders; National Hospital Organization, Hokkaido Medical Center; Sapporo Japan
4. Division of Biomedical Engineering and Science, Faculty of Health Sciences; Hokkaido University; Sapporo Japan