Received: 24 October 2020
Accepted: 14 December 2020
First Online: 6 January 2021
Ethics approval and consent to participate
: Ethics approval was provided by the Ethics Committee of the Faculty of Medicine, Khon Kaen University, as instituted by the Helsinki Declaration, and this study was a retrospective study; for this type of study, formal consent is not required. The reference number of ethical approval is HE621442.
: All images in this manuscript contain no individual personal data.
: The authors declare that they have no competing interests.