Funding for this research was provided by:
National Research Foundation of Korea (NRF-2017R1A2B4006020)
Received: 3 March 2020
Revised: 30 May 2020
Accepted: 7 August 2020
First Online: 10 September 2020
Compliance with ethical standards
: The scientific guarantor of this publication is Chan Kyo Kim.
: The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
: Insuk Sohn, PhD, kindly provided statistical advice for this manuscript.
: This retrospective study was approved by our institutional review board, with a waiver of the requirement for informed consent.
: Institutional Review Board approval was obtained. Approval from the institutional animal care committee was not required because this study was on human subjects.
: • Retrospective• Diagnostic or prognostic study• Performed at one institution