Biophotonic endoscopy: a review of clinical research techniques for optical imaging and sensing of early gastrointestinal cancer

Abstract

Detection, characterization, and staging constitute the fundamental elements in the endoscopic diagnosis of gastrointestinal diseases, but histology still remains the diagnostic gold standard.New developments in endoscopic techniques may challenge histopathology in the near future. An ideal endoscopic technique should combine a wide-field, “red flag” screening technique with an optical contrast or microscopy method for characterization and staging, all simultaneously available during the procedure. In theory, biophotonic advances have the potential to unite these elements to allow in vivo “optical biopsy.”These techniques may ultimately offer the potential to increase the rates of detection of high risk lesions and the ability to target biopsies and resections, and so reduce the need for biopsy, costs, and uncertainty for patients. However, their utility and sensitivity in clinical practice must be evaluated against those of conventional histopathology.This review describes some of the most recent applications of biophotonics in endoscopic optical imaging and metrology, along with their fundamental principles and the clinical experience that has been acquired in their deployment as tools for the endoscopist. Particular emphasis has been placed on translational label-free optical techniques, such as fluorescence spectroscopy, fluorescence lifetime imaging microscopy (FLIM), two-photon and multi-photon microscopy, second harmonic generation (SHG) and third harmonic generation (THG) imaging, optical coherence tomography (OCT), diffuse reflectance, Raman spectroscopy, and molecular imaging.

Merging Biology and Solid‐State Lighting: Recent Advances in Light‐Emitting Diodes Based on Biological Materials

“…Biophotonics relates to a multidisciplinary research area interplaying biological matter and light . Roughly speaking, this field encompasses a wide scope of topics and applications, including biomedical optics and therapy, study of light generated by living organisms and tissues (i.e., bioluminescence and biophotons), design of biomimetics, biomaterials, and bioengineered compounds, as well as fabrication methods applied to sensors, lasers, etc. As a matter of fact, biophotonics has experienced a tremendous development since its first steps regarding, for example, the invention of the light microscope in the seventeenth century or the early works on bioluminescence and biophoton areas at the beginning of the nineteenth century .…”

ultraLM and miniLM: Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy

“…The miniLM had more stringent size requirements than the ultraLM due to the geometry and spatial restrictions of the SBF SEM chamber ( Figure 4A ). The design of the miniLM was inspired by fibre-coupled endoscopy imaging systems, which are also designed to fit into tight spaces ( Coda et al , 2015 ; Engelbrecht et al , 2010 ; Flusberg et al , 2005 ). Our solution consisted of a custom-built miniature objective attached to a coherent fibre bundle, which fed through the vacuum chamber door to a custom-built epi-fluorescence microscope ( Figure 4B ).…”

Non-invasive biomedical research and diagnostics enabled by innovative compact lasers

“…For example, some of these studies have focused on the examination of ex vivo tissues (biopsy studies) due to the lack of Raman probe availability. After showing the relevance of examining biopsied tissues, the feasibility of in vivo Raman spectroscopic point measurements of pathological tissues was displayed by using an early Raman probe, during routine clinical endoscopy [75,76]. Laser Doppler flowmetry (LDF), since its commercialisation in the early 1980s, has provided an everincreasing approach to non-invasive measurement of haemodynamics; allowing for measurements to avoid the use of radioactive markers employed in earlier techniques [38,77,78].…”