Received: 27 March 2018
Accepted: 12 September 2018
First Online: 10 October 2018
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board of Samsung Medical Center in compliance with the Declaration of Helsinki (IRB number 201510110). No consent for patient participation was needed.
: Not applicable.
: The authors declare that they have no competing interests.
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