Advanced endoscopic imaging technologies for in vivo cytological examination of gastrointestinal tract lesions: State of the art and proposal for proper clinical application

Since its introduction, conventional endoscopy has changed the management framework of a variety of gastrointestinal tract (GIT) diseases and is now considered a fundamental component in the evaluation and treatment of gastrointestinal diseases. Histologic analysis of specimens remains the gold standard for the final diagnosis of gastrointestinal lesions. However, such workup is time-consuming and labor-intensive. This restricts the endoscopists to immediately determine the necessity for resection during ongoing endoscopies, necessitating the need to repeat the procedure. Furthermore, overtreatment (resection of benign lesions) or undertreatment (biopsy instead of resection for neoplastic tissue) can lead to frustrations, unnecessary risks (e.g., bleeding) for the patients, and delay in definite treatment for the urgent cases.Recently, developments in endoscopic and imaging technologies (narrow-band imaging, autofluorescence imaging, confocal laser endoscopy and imaging, optical coherence tomography, and endoscopic ultrasound) can provide a wide variety of valuable tools for in vivo cytological diagnosis of neoplastic lesions of GIT, even beyond inner layer of the bowel. Such investigations, may therefore lead to an optimized rapid diagnosis of GIT lesions, providing important implications also for immediate therapy, during ongoing endoscopies (e.g., endoscopic resection of neoplastic tissue). Moreover the possibility to properly investigate in vivo progression of the extraluminal disease (lymph node status) allows reducing, if not eliminating the need of extensive resection just for proper staging.The present review convincingly describes the operating systems of each diagnostic modality, their clinical implications, and future vision of the role of these modern tools in the clinical diagnosis of GIT diseases.