1. Institute of Exercise and Occupational Medicine, Faculty of Medicine, Medical Center, University of Freiburg, 79106 Freiburg, Germany
2. Narkose Suedbaden, 79110 Freiburg, Germany
3. Department of Diagnostic and Interventional Radiology, Division of Medical Physics, Faculty of Medicine, Medical Center, University of Freiburg, 79106 Freiburg, Germany
4. Department of Medicine II, Gastroenterology, Hepatology, Endocrinology and Infectious Diseases, Faculty of Medicine, Medical Center, University of Freiburg, 79106 Freiburg, Germany