Advances in confocal laser endomicroscopy in GI diseases

Confocal laser endomicroscopy (CLE) has been introduced into clinical practice for nearly a decade. Its diagnostic accuracy was well approved in GI diseases. As a viable area, application and study of CLE were advanced in different aspects. Validation of preliminary criteriaBesides the original single-center trial, multi-center diagnostic studies of CLE regarding colorectal polyps, Barrett's esophagus, and gastric intestinal metaplasia have been carried out. Otherwise, meta-analysis based on current trials was also available. The diagnostic criteria of CLE was validated by better evidence, which supports its application in the daily practice. In addition, combination of red-flag surveillance and CLE guided biopsy for gastric atrophy, intestinal metaplasia, intraepithelial neoplasia and early gastric cancer is being carried out in a multi-center study, which involves four endoscopic units in Chinese hospitals. Translational medicineAs an instrument combined with confocal microscopy, approaches for ex vivo or in vitro studies were introduced into in vivo examination, including the in vivo molecular diagnosis of GI tumors using antibodies or peptides, and in vivo assessment of intestinal barrier function by observing intestinal epithelial shedding. Epithelial shedding observed by CLE was showed to be associated with IBD severity and prognosis. Expansion of diagnostic capabilityBesides the common GI diseases such as inflammation, metaplasia and neoplasia, diagnosis capability of CLE was expanded rapidly. For example, CLE diagnosis of celiac disease has been well established with well-defined criteria. Applications of CLE in biliary stricture, gastric lymphoma, GI graft-versus-host disease, antibiotics associated colitis were also explored. Renovation of technologySoftware for automated classification of CLE videos of colorectal polyps has been developed. Tethered capsule endomicroscopy enables less invasive examination of GI tract. Volumetric laser endomicroscopy was proved to be able to detect subsquamous Barrett's adenocarcinoma. Training and educationSome worried that learning of this technique may be difficult. However, the learning curve studies on diagnosis of gastric intestinal metaplasia and colorectal polyps have proved that after a short session of training on interpretation of CLE images, the beginners can achieve a high level of reading accuracy with at least substantial level of interobserver agreement. Once they achieve the high reading accuracy, almost all can maintain their high quality of reading skill.