High-resolution Microendoscopy Research Articles

High-resolution Fiber-optic Microendoscopy for <em>in situ</em> Cellular Imaging

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution. Traditionally, multiple experiments are run in parallel, with individual samples removed from the study at sequential time points for evaluation by light microscopy. Several intravital techniques have been developed, with confocal, multiphoton, and second harmonic microscopy all demonstrating their ability to be used for imaging in situ 1. With these systems, however, the required infrastructure is complex and expensive, involving scanning laser systems and complex light sources. Here we present a protocol for the design and assembly of a high-resolution microendoscope which can be built in a day using off-the-shelf components for under US$5,000. The platform offers flexibility in terms of image resolution, field-of-view, and operating wavelength, and we describe how these parameters can be easily modified to meet the specific needs of the end user.We and others have explored the use of the high-resolution microendoscope (HRME) in in vitro cell culture 2-5, in excised 6 and living animal tissues 2,5, and in human tissues in vivo 2,7. Users have reported the use of several different fluorescent contrast agents, including proflavine 2-4, benzoporphyrin-derivative monoacid ring A (BPD-MA) 5, and fluoroscein 6,7, all of which have received full, or investigational approval from the FDA for use in human subjects. High-resolution microendoscopy, in the form described here, may appeal to a wide range of researchers working in the basic and clinical sciences. The technique offers an effective and economical approach which complements traditional benchtop microscopy, by enabling the user to perform high-resolution, longitudinal imaging in situ.

Optical molecular imaging for detection of Barrett’s-associated neoplasia

Recent advancements in the endoscopic imaging of Barrett's esophagus can be used to probe a wide range of optical properties that are altered with neoplastic progression. This review summarizes relevant changes in optical properties as well as imaging approaches that measures those changes. Wide-field imaging approaches include narrow-band imaging that measures changes in light scattering and absorption, and autofluorescence imaging that measure changes in endogenous fluorophores. High-resolution imaging approaches include optical coherence tomography, endocytoscopy, confocal microendoscopy, and high-resolution microendoscopy. These technologies, some coupled with an appropriate contrast agent, can measure differences in glandular morphology, nuclear morphology, or vascular alterations associated with neoplasia. Advances in targeted contrast agents are further discussed. Studies that have explored these technologies are highlighted; as are the advantages and limitations of each.

Endoscopic imaging: How far are we from real-time histology?

Currently, in gastrointestinal endoscopy there is increasing interest in high resolution endoscopic technologies that can complement high-definition white light endoscopy by providing real-time subcellular imaging of the epithelial surface. These 'optical biopsy' technologies offer the potential to improve diagnostic accuracy and yield, while facilitating real-time decision-making. Although many endoscopic techniques have preliminarily shown high accuracy rates, these technologies are still evolving. This review will provide an overview of the most promising high-resolution imaging technologies, including high resolution microendoscopy, optical coherence tomography, endocytoscopy and confocal laser endoscopy. This review will also discuss the application and current limitations of these technologies for the early detection of neoplasia in Barrett's esophagus, ulcerative colitis and colorectal cancer.

Ex vivo high resolution imaging with a miniaturized microendoscope to discriminate between benign and malignant mucosa in the upper aerodigestive tract

•Continued refinement of this optical imaging technology may lead to improved ability to accurately determine optical margins, facilitate the sparing of uninvolved normal tissue, and find application to novel technological platforms, such as robotic surgery. Figure 1. High Resolution Microendoscope (HRME). The device consists of a fiber-optic bundle which can deliver high resolution narrow field images of tissue morphology. The image is magnified by a microscope objective. Surface staining with a nuclear dye is required to display the morphology of the epithelial nuclei.

Optical technologies for detection and diagnosis of oral neoplasia

The goal of our research is to develop an approach to early detection and diagnosis of oral neoplasia using opticalbased technologies such as fluorescence spectroscopy and imaging, high-resolution microendoscopy and molecularly-targeted optical contrast agents. Although patients with early disease have better chances for cure and functional outcome, most patients present with advanced tumours when treatment is less successful and often causes severe deficits in speech, swallowing, facial appearance and quality of life. To improve outcomes we must improve detection and diagnosis of early neoplastic changes. Changes in tissue architecture, morphology, and molecular composition that occur during carcinogenesis also produce changes in the optical properties of tissue. These changes can be detected non-invasively, in vivo, and in near real-time using optical spectroscopy and imaging. Our research group has developed multi-spectral imaging devices for wide field visualization of early changes in oral mucosa. We are investigating whether these devices can improve the clinician's ability 1) to improve visualization of early neoplastic changes in oral mucosa that can be difficult to see using normal white light examination in community settings, 2) to choose optimal sites within lesions to perform biopsies, and 3) to visualize the peripheral margins of disease. We have also shown that using computer algorithms and disease probability maps, optical imaging and spectroscopy can provide objective discrimination between normal and abnormal oral mucosa with good sensitivity and specificity – similar to that of oral cancer specialists. We are now developing simplified optical devices to use in screening and diagnosis in community settings.