1. Department of Neurosurgery, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan
2. Department of Human Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
3. Department of Human Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan