Text and Data Mining valid from 2018-12-01
Received: 17 May 2018
Accepted: 19 November 2018
First Online: 4 December 2018
Ethics approval and consent to participate
: The protocol was approved by the clinical trial ethics committee/ institutional review board (IRB) at Qingdao Municipal Hospital, China. Informed consent was not required because the images and medical records of the patients had already been obtained and were anonymous.
: Not applicable.
: The authors declare that they have no competing interests.
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