Received: 17 February 2018
Accepted: 18 February 2018
First Online: 1 March 2018
Ethics approval and consent to participate
: Written consent was obtained from each patient. The study protocol was endorsed by the local ethical committee (Goethe-University Medical School/UCT Frankfurt GS-04/09, SNO-08-2015).
: Not applicable.
: The authors declare that they have no conflict of interest.
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