Received: 9 February 2021
Accepted: 29 April 2021
First Online: 31 May 2021
: This study was approved by the institutional review board of Gunma University Hospital (2017 − 135). Written informed consent was obtained from all participants. All procedures were performed according to the Declaration of Helsinki.
: Not applicable.
: None of the authors has a conflict of interest that could inappropriately influence this work.