1. Department of Polymer Therapeutics Institute for Experimental Molecular Imaging Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering Faculty of Medicine RWTH Aachen University 52074 Aachen Germany
2. Department of Gastroenterology Shanghai 10th People's Hospital School of Medicine Tongji University Shanghai 200072 P. R. China
3. Department of Gynecology and Obstetrics Uniklinik RWTH Aachen 52074 Aachen Germany
4. Institute for Experimental Molecular Imaging Uniklinik RWTH Aachen and Helmholtz Institute for Biomedical Engineering Faculty of Medicine RWTH Aachen University 52074 Aachen Germany
5. Department of Gastroenterology, Huadong Hospital, Shanghai Medical College Fudan University Shanghai 200040 P. R. China