Received: 8 July 2019
Accepted: 5 September 2019
First Online: 7 October 2019
Ethics approval and consent to participate
: This study was performed in accordance with the ethical standards of the local ethics committee and with the 1964 Helsinki declaration and its later amendments. Images were acquired with clinical indication; patient consent for this retrospective study is waived.
: The authors declare that they have no competing interests.