1. From the Department of General, Visceral and Transplant Surgery, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (Huettl, Boedecker, Vradelis, Kneist, Lang, Huber)
2. the Institute of Simulation and Graphics, Faculty of Computer Science, Otto-von-Guericke-University Magdeburg, Madgeburg, Germany (Heinrich, Hansen)
3. the Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (Ludt)
4. the Department of General and Visceral Surgery, St. Georg Hospital, Eisenach, Germany (Kneist).