1. From the Division of Biomedical Engineering, National Defense Medical Research Institute, National Defense Medical College, Saitama, Japan (Y.S.)
2. Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan (K.K., K.H.)
3. Division of Medical Statistics, Translational Research Center for Medical Innovation, Foundation for Biomedical Research and Innovation at Kobe, Hyogo, Japan (E.N.)
4. Division of Statistical Analysis, Research Support Center, Shizuoka General Hospital, Japan (E.N.)