Confocal laser endoscopy for diagnosing intraepithelial neoplasias and colorectal cancer in vivo

Background & Aims: A confocal laser endoscopy system has recently been developed that may allow subsurface imaging of living cells in colonic tissue in vivo. The aim of the present study was to assess its potential for prediction of histology during screening colonoscopy for colorectal cancer. Methods: Twenty-seven patients underwent colonoscopy with the confocal endoscope using acriflavine hydrochloride or fluorescein sodium with blue laser illumination. Furthermore, 42 patients underwent colonoscopy with this system using fluorescein sodium. Standardized locations and circumscript lesions were examined by confocal imaging before taking biopsy specimens. Confocal images were graded according to cellular and vascular changes and correlated with conventional histology in a prospective and blinded fashion. Results: Acriflavine hydrochloride and fluorescein sodium both yielded high-quality images. Whereas acriflavine hydrochloride strongly labeled the superficial epithelial cells, fluorescein sodium offered deeper imaging into the lamina propria. Fluorescein sodium was thus used for the prospective component of the study in which 13,020 confocal images from 390 different locations were compared with histologic data from 1038 biopsy specimens. Subsurface analysis during confocal laser endoscopy allowed detailed analysis of cellular structures. The presence of neoplastic changes could be predicted with high accuracy (sensitivity, 97.4%; specificity, 99.4%; accuracy, 99.2%). Conclusions: Confocal laser endoscopy is a novel diagnostic tool to analyze living cells during colonoscopy, thereby enabling virtual histology of neoplastic changes with high accuracy. These newly discovered diagnostic possibilities may be of crucial importance in clinical practice and lead to an optimized rapid diagnosis of neoplastic changes during ongoing colonoscopy.