Colonoscopy is regarded as the "gold standard" for diagnosis of colorectal cancer. The sensitivity is uncertain but proposed to be (75-95%), however flat adenomas which are easily missed, are often not recognised. Fluorescence imaging may increase the sensitivity of standard white light colonoscopy by identifying more polyps and flat adenomas which will make the resection of adenomas more complete.
In this study hexaminolevulinate (HAL) will be administered locally as a photosensitiser, using different doses to find the optimal imaging conditions as well as making patient safety assessments.
Both standard white light and blue light (fluorescence) inspection will be performed.
