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Article History

Received: 19 February 2018

Accepted: 15 November 2018

First Online: 26 November 2018

Ethics approval and consent to participate

: The study was approved by the Institutional Review Board and Ethics Committee of Gunma University Hospital (CIRU 12–40). All patients agreed to participate in this study and provided written informed consent.

: Informed consent for publication was obtained from all the participants.

: All authors declare that they have no conflict of interest, except YT who received research grant from Nihon Medi-Physics Co. Ltd.

: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.