Received: 13 November 2018
Revised: 1 April 2019
Accepted: 8 April 2019
First Online: 16 May 2019
Compliance with ethical standards
: Author D.P. is a member of the international MacTel Consortium and has received travel support for the meeting of this Study Group from the LMRI; Author F.G. declares that he has no conflict of interest. Author M.B. declares that he has no conflict of interest. Author K.R. declares that he has no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. In addition, a positive vote from the ethical committee of the University of Münster and the Westphalian Doctors Association was achieved and informed consent was obtained from all individual participants included in the study.