Two-Photon Endoscopy: State of the Art and Perspectives

In recent years, the demand for non-destructive deep-tissue imaging modalities has led to interest in multiphoton endoscopy. In contrast to bench top systems, multiphoton endoscopy enables subcellular resolution imaging in areas not reachable before. Several groups have recently presented their development towards the goal of producing user friendly plug and play system, which could be used in biological research and, potentially, clinical applications. We first present the technological challenges, prerequisites, and solutions in two-photon endoscopic systems. Secondly, we focus on the applications already found in literature. These applications mostly serve as a quality check of the built system, but do not answer a specific biomedical research question. Therefore, in the last part, we will describe our vision on the enormous potential applicability of adult two-photon endoscopic systems in biological and clinical research. We will thus bring forward the concept that two-photon endoscopy is a sine qua non in bringing this technique to the forefront in clinical applications.

DIAGNOSTIC APPLICATION OF MULTIPHOTON MICROSCOPY IN EPITHELIAL TISSUES

Epithelial cancer comprises more than 85% of human cancers. The detection and treatment at the early stage has been demonstrated to apparently improve patient survival. In this review, we summarize our recent research works on the diagnostic application of epithelial tissue based on multiphoton microscopy (MPM), including identification of the layered structures of esophagus, oral cavity, skin and bronchus tissues, establishment of the diagnostic features for distinguishing gastric normal tissue from cancerous tissue, linking collagen alteration and ectocervical epithelial tumor progression for evaluating epithelial tumor progression, and differentiating normal, inflammatory, and dysplastic ectocervical epithelial tissues. These results provide the groundwork for developing MPM into clinical multiphoton endoscopy.