Light-Induced Fluorescence Techniques for Gastrointestinal Tumour Detection

Gastrointestinal tumors have major place in the statistics of newly developed cancers every year, as the colon cancer is on third place, stomach cancer is on fifth place, and esophageal cancer is also in the top ten of tumors according statistics of cancer incidence. Usually the tumors are detected on advanced III and IV stage, where the perspectives for the patients are not very optimistic (Danon, 2003; Jemal, 2011). Up to now white light endoscopy is the main method in detection of gastrointestinal tumors. White-light endoscopy is wellestablished and wide used modality. However, despite the many technological advances that have been occurred, conventional white light endoscopy is suboptimal and usually detects lesions, which already have symptoms of obstruction, bleeding and pain, related to tumor growth. Misdiagnoses, related to difficulties in differentiation of inflammatory from initial stage adenocarcinoma also have negative effect on the diagnostic accuracy (Da Costa, 2003). Only experienced gastroenterologists with long practice in endoscopy observations could find slight initial changes to dysplastic and neoplastic stages of esophageal, stomach or colon mucosa. The limitations of standard endoscopy for detection and evaluation of cancerous changes in gastrointestinal tract are significant challenge and initiate development of new diagnostic modalities. Such detection and visualization techniques, additional to standard endoscopy equipment, including optical detection of tissues alterations are investigated and their feasibilities for clinical usage are evaluated. Advances in fiber optics, light sources, detectors have led to the development of several novel methods for tissue evaluation in situ. Optical methods applied for such tissue evaluation often are referred under term “optical biopsy”, which indicate their possibilities to make an instant diagnosis at endoscopy, previously possible only by using of histological and/or cytological analysis (Wang, 2004). The new optical approaches are based on light-tissue interactions and differences occurred between normal and abnormal tissue sites. In gastroenterology several optical methods are applied recently, such as optical coherent tomography (Tumlinson, 2004), chromo-endoscopy, confocal fluorescent microscopy (DaCosta, 2003a; 2003b), Raman