1. Interdisciplinary Endoscopy, Medical Department I, University Hospital Schleswig-Holstein , Campus Kiel, Kiel , Germany
2. Institute of Biomedical Optics, University of Luebeck , Luebeck , Germany
3. Department of Internal Medicine, Israelitic Hospital Hamburg , Hamburg , Germany
4. Institute of Pathology, University Hospital Schleswig-Holstein , Campus Kiel, Kiel , Germany