Received: 19 October 2020
Accepted: 9 December 2020
First Online: 7 January 2021
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board of the Osaka General Medical Center. The board waived the need for informed consent, as this was a retrospective study.
: Not applicable
: TKinoshita received lecture fees and travel expenses from Canon Medical Systems for lectures given at national and international conferences. TKinoshita was also supported by a Fulbright Japan Graduate Study Program during the conduct of this research. For the remaining authors, no conflicts were declared.