FLUORESCENCE ENDOSCOPY OF GASTROINTESTINAL-DISEASES - BASIC PRINCIPLES, TECHNIQUES, AND CLINICAL-EXPERIENCE

Visual detection of tumors, especially during the early stages, is exp ected to be improved considerably by examining the fluorescence either of tumor-selective exogenous dyes such as protoporphyrin IX, induced by 5-aminolevulinic acid, or by analyzing the autofluorescent properti es of healthy and neoplastic tissue. The present paper describes techn ical devices using light sources for fluorescence excitation, and sens itive detection systems such as intensified cameras and optical multic hannel analyzers used for fiber-assisted point measurements. In the di scussion of these systems, special consideration is given to their com mercial availability and potential for endoscopic applications in the gastrointestinal tract. In this clinical discipline, the major interes t lies in the ability to locate malignancies in the esophagus and colo n. In recent years, there has been increasing clinical experience in t his area, particularly in detecting adenocarcinoma in Barrett's esopha gus and malignant alterations in the colon, such as in ulcerative coli tis and polyps. Although several research groups have reported sensiti vities and specificities for fluorescence gastroscopy of more than 80% , the potential benefits of the technique to patients need to be evalu ated in further clinical studies.