1. Department of Respiratory Medicine, Tokyo Dental College Ichikawa General Hospital, Ichikawa, Chiba 272‑8513, Japan
2. Department of Neurosurgery, Tokyo Dental College Ichikawa General Hospital, Ichikawa, Chiba 272‑8513, Japan
3. Department of Pathology and Laboratory Medicine, Tokyo Dental College Ichikawa General Hospital, Ichikawa, Chiba 272‑8513, Japan
4. Tokyo Gamma Unit Center, Tsukiji Neurological Clinic, Tokyo 104‑0045, Japan