Conflict of interest

Kenji Masada, Masashi Morita, Munehiro Kanegawa, Yoji Sumimoto, Takashi Shimonaga, Haruyuki Kinoshita, and Hiroshi Sugino declare that they have no conflict of interest.

Human rights statements

Human rights statements and informed consent: all procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later revisions. Informed consent was obtained from all patients for being included in the study.

Informed consent

Informed consent was obtained from the patient for inclusion in this study.