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Confocal laser endomicroscopy and endocytoscopy

Alexander Meining, MD
Section Editor
John R Saltzman, MD, FACP, FACG, FASGE, AGAF
Deputy Editor
Kristen M Robson, MD, MBA, FACG


Confocal laser endomicroscopy and endocytoscopy are emerging endoscopic technologies that permit high-resolution assessment of gastrointestinal mucosal histology at a cellular and sub-cellular level. Endomicroscopy and endocytoscopy dramatically expand the imaging capabilities of flexible endoscopy by their ability to obtain "optical biopsies" of nearly any accessible endoluminal surface.

The examinations are carried out in vivo with real-time image display. The techniques have primarily been applied to the differentiation of colon polyps and for the detection of dysplasia and neoplasia in conditions such as Barrett's esophagus and ulcerative colitis. Since the first visible neoplastic changes in epithelial cancers occur at a cellular level, these imaging techniques may allow for earlier diagnosis and treatment. In addition, confocal laser endomicroscopy and endocytoscopy may allow for targeted biopsies of abnormal mucosa, thereby decreasing the number of biopsies required to diagnose dysplasia or neoplasia while increasing diagnostic yield.

This topic will review confocal laser endomicroscopy and endocytoscopy, including the technical aspects of the procedures, their indications, and efficacies. Chromoendoscopy, magnification endoscopy, optical coherence tomography, narrow band imaging, and autofluorescence endoscopy are discussed elsewhere. (See "Chromoendoscopy" and "Magnification endoscopy" and "Optical coherence tomography in the gastrointestinal tract" and "Barrett's esophagus: Evaluation with narrow band imaging" and "Barrett's esophagus: Evaluation with autofluorescence endoscopy".)


Confocal laser endomicroscopy — Confocal laser endomicroscopy (CLE) is based upon the principle of illuminating a tissue with a low-power laser and then detecting fluorescent light reflected from the tissue [1]. The laser is focused at a specific depth and only light reflected back from that plane is refocused and able to pass through the pinhole confocal aperture. As a result, scattered light from above and below the plane of interest is not detected, increasing spacial resolution. The area being examined is scanned in the horizontal and vertical planes and an image is reconstructed. In this manner, microscopic imaging of biological tissue in vivo is possible due to the high lateral resolution of confocal imaging.

Since CLE relies upon tissue fluorescence, intravenous and/or topically applied contrast agents are required. Intravenous fluorescein is used to highlight the vasculature, lamina propria, and intracellular spaces of this tissue being examined. However, it does not stain cell nuclei. Nuclear staining can be achieved using topical contrast agents such as acriflavine and cresyl violet, but there is concern over mutagenic potential with the topical agents. (See 'Adverse events' below.)

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Literature review current through: Nov 2017. | This topic last updated: Aug 21, 2017.
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