Received: 9 March 2019
Accepted: 13 June 2019
First Online: 27 June 2019
Ethics approval and consent to participate
: The study protocol was reviewed and approved by the Institutional Review Board of Samsung Medical Center (IRB No. 2018-05-188-001). The IRB waived the informed consent requirement for this retrospective review.
: Not applicable.
: The authors declare that they have no competing interests.