Evaluation of the efficacy of laser-based endomicroscopy as a complement to white-light colonoscopy and chromoendoscopy for early detection of colon dysplasia in patients with PSC-IBD. White-light colonoscopy is a routinely used procedure in colorectal cancer surveillance programs. However, it does not permit detection of early dysplastic lesions. Chromoendoscopy by applying a dye (indigo-carmine) through the colonoscope helps to identify flat lesions but is not suitable for accurate endoscopic diagnosis of dysplasia and intraepithelial neoplasia Under this aim we will perform a clinical study evaluating a newly developed technique allowing for in vivo confocal microscopy assessment of the colon mucosa using laser-based endomicroscopy together with intravenous administration of fluorescein (FITC).

Chromoendoscopy by applying a dye (indigo-carmine) through the colonoscop is the new standard for cancer surveillance in patients with IBD . It gives the opportunity to identify suspected areas of dysplasia and to take targeted biopsies. The diagnostic accuracy improves and the chances for detecting dysplastic areas increase. In recent years new endoscopic techniques have been developed, including laser-based endomicroscopy. There is an increasing need for structured evaluation of the efficiency of these techniques. Laser-based endomicroscopy, taking in vivo confocal microscopy pictures during the colonoscopy examination, is the most promising new method. This method is established in highly rated centers for the early diagnosis of neoplasia in the bile ducts and the esophagus but its role for detection early malignancies in the colon is not known and studying this issue is of very high clinical value.

Specific questions: Does the use of laser-based endomicroscopy increase the chances for early detection of dysplasia? What is the intraobserver variability? What is the learning curve for interpretation of confocal microscopy pictures? Material and methods: A laser-based endomicroscope (Cellvizio®, Mauna Kea Technologies) have been acquired and the examination procedure has been established at the Unit for Gastroenterology and Hepatology, Karolinska University Hospital Huddinge. Eighty patients with PSC and IBD included in annual surveillance with colonoscopy with routine biopsy regime will be included in the study. After informed consent, patients are investigated with laser-based endomicroscopy during surveillance colonoscopy. Each colonic segment will be examined before and after staining with indigo-carmin. After intra-venous fluorescein (FITC) injection, all macroscopically abnormal lesions will be examined by endomicroscopy. Intravenous administration of FITC makes it possible to obtain in vivo microscopic pictures with up to a 1000x magnification of the colon mucosa. The Cellvizio® technique allows for evaluation of epithelial and endothelial cell structures in areas with suspicious changes as well as for acquisition of directed biopsies. Confocal pictures from all sites where biopsies have been taken are saved for future blind re-evaluation. The biopsies are taken according to the routine standard with minimum of 2 biopsies from each 10 cm in the colon. For the immunological and microbiological (specific aim 2) parts of the study, additional 16 biopsies are gathered from left, transverse, and right colon. All the laser-based endomicroscopy pictures and sequences are saved for further evaluation and further application in arranging pedagogical sessions for evaluation of the learning curve of the technique.

Inclusion Criteria:

• clinical diagnosis of PSC-IBD

Exclusion Criteria:

• the lack of informed consent, allergy to fluorescein, B-blockers treatment

Eighty patients with PSC and IBD included in annual surveillance with colonoscopy with routine biopsy regime will be included in the study.