A fluorescence endomicroscopy for in vivo microscopy of the upper-and the lower GI tract

University of Vic, Vic, Catalonia, Spain
Gastrointestinal Endoscopy (Impact Factor: 4.9). 12/2005; 62(5):686-95. DOI: 10.1016/j.gie.2005.05.021
Source: PubMed

ABSTRACT This report describes the development and the clinical evaluation of a novel confocal endomicroscope for obtaining fluorescence images of cellular morphology of the mucosae of the upper- and the lower-GI tract in vivo. The work assessed the feasibility of performing in vivo microscopy at endoscopic examination and evaluated fluorescence imaging protocols.
Images were collected in real time by using two prototype endoscope configurations, featuring slightly different miniaturized fiber-optic confocal microscopes, fitted integrally into the tips of conventional endoscopes. Confocal scanning was performed at 488 nm illumination for excitation of exogenously applied fluorophores (topical acriflavine and intravenous fluorescein). The images were compared with conventional histology of biopsy specimens and the findings of white-light endoscopy.
Confocal endomicroscopy enabled imaging of cellular and subcellular structures (i.e., nuclei) of the GI tract. The crypts of the colonic mucosa, the villi of the terminal ileum and duodenum, the gastric pits of the stomach, and the squamous epithelium of the distal esophagus could be clearly visualized. Acriflavine strongly contrasted the cell nuclei of the surface epithelium, including the absorptive epithelial cells and the mucous secreting goblet cells. Fluorescein stained the extracellular matrix of the surface epithelium and also the subepithelial layers of the lamina propria. Images at increasing depth beneath the epithelium showed the mucosal capillary network. The findings correlated with the histology of biopsy specimens.
The development of a fluorescence confocal endomicroscope makes it practical to examine the upper- and the lower-GI mucosa in cellular detail during otherwise routine endoscopic examination. The results represent a major technical advance in the development of this new optical imaging modality for the in vivo examination of GI tissue.

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    • "Besides, the focusing and scanning should better be implemented at the distal end of a probe, which is usually a few millimeters in diameter in order to fit the requirements for endoscopy. In confocal microscopy, the use of piezoelectric actuator to physically deflect the tip of an optical fiber has been demonstrated [21]. This method for mechanical scanning at the distal of a probe, however, imposes difficulties on miniaturization. "
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    • "A plasma concentration of fluorescein in the vicinity of 20 mg/L was able to provide adequate fluorescent contrast. In people, the duration of effect for CEM procedures has been subjectively assessed and appears variable, lasting from 30 to 60 min based on previous reports (Polglase et al., 2005; Becker et al., 2008). As the procedure progresses, however, the signal-to-noise ratio appears to increase such that a significant decrease in image resolution and therefore quality occurs (Becker et al., 2008). "
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