1 Department of Computer Science, Chair of Computer Science 5 (Pattern Recognition), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 3, 91058, Erlangen, Germany. andreas.maier@fau.de.
2 Peter L. Reichertz Institute for Medical Informatics, University of Braunschweig - Institute of Technology, Muehlenpfordtstr. 23, 38106, Brunswick, Germany.
3 Institute of Medical Informatics, University of Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany.
4 Division of Medical Image Computing, German Cancer Research Center, Heidelberg (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.