1 Department of Anesthesiology, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan.
2 Transrational Research Promotion and Education Center, Tsukuba Clinical Research and Development Organization, University of Tsukuba, Tsukuba, Japan.
3 Department of Anesthesiology, University of Tsukuba Hospital, Tsukuba, Japan.
4 Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
5 Department of Head and Neck Surgery, Saitama Prefectural Cancer Center, Kita-Adachi, Japan.
6 Department of Health Services Research, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
7 Department of Radiology, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan.
8 Department of Otorhinolaryngology, Head and Neck Surgery, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan.