The American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee provides reviews of new or emerging endoscopic technologies that have the potential to affect the practice of GI endoscopy. Evidence-based methodology is used, with a MEDLINE literature search to identity pertinent pre-clinical and clinical studies on the topic and a MAUDE (Food and Drug Administration Center for Devices and Radiological Health) database search to identify the reported complications of a given technology. Both are supplemented by accessing the "related articles" feature of PubMed and by scrutinizing pertinent references cited by the identified studies. Controlled clinical trials are emphasized, but; in many cases, data from randomized controlled trials are lacking. In such cases, large case series, preliminary clinical studies, and expert opinions are used. Technical data are gathered from traditional and Web-based publications, proprietary publications, and informal communications with pertinent vendors. For this review, the MEDLINE database wits searched through January 2010 by using the keywords "autofluorescence imaging" and "autofluorescence endoscopy". Reports on Emerging Technologies are drafted by one or two members of the ASGE Technology Committee, reviewed and edited by the committee as a whole, and approved by the governing board of the ASGE. These reports are scientific reviews provided solely for educational and informational purposes. Reports on Emerging Technologies are not rules and should not be construed as establishing a legal standard of care or as encouraging advocating, requiring, or discouraging any particular treatment or payment for such treatment.
"However signs of disease, particularly early stage cancer, may be missed in viewing the 7-9 hours of images generated . Autofluorescence imaging (AFI) exploits the fact that cancerous intestinal tissue exhibits a considerably lower autofluorescent response than healthy tissue when excited by blue or UV light, and offers improved prospects for cancer detection compared to white-light inspection  . A commercial AFI system  is endoscope-based (and hence unable to access the small intestine). "
[Show abstract][Hide abstract] ABSTRACT: Variations in tissue autofluorescence (AF) can be exploited to detect early signs of intestinal cancer, however current endoscopic AF systems are only able to inspect the oesophegus and large intestine. We present the design, fabrication and testing of a pill capable of inducing and detecting AF from mammalian intestinal tissue. The prototype comprises an application specific integrated circuit (ASIC), illumination LED, optical filters to minimize sensor response to crosstalk from the illumination wavelength, a pulse counter/control unit and a radio transmitter. The ASIC contains a single photon avalanche diode detector (SPAD), and integrate high voltage charge pump (up to 37.9 V) power supply. The SPAD operates above its breakdown voltage to operate in Geiger mode, and exhibits a detection efficiency peak at 465 nm, sufficiently close to human tissue autofluorescence's peak of 520±10 nm. The ASIC was fabricated using a commercial high-voltage CMOS process. The complete device uses only 21.4 mW.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study is to evaluate an endoscopic trimodal imaging (ETMI) system (high resolution, autofluorescence, and NBI) in the detection and differentiation of colorectal adenomas.
A prospective randomised trial of tandem colonoscopies was carried out using the Olympus XCF-FH260AZI system. Each colonic segment was examined twice for lesions, once with HRE and once with AFI, in random order per patient. All detected lesions were assessed with NBI for pit pattern and with AFI for colour. All lesions were removed and sent for histology. Any lesion identified on the second examination was considered as missed by the first examination. Outcome measures are adenoma miss rates of AFI and HRE, and diagnostic accuracy of NBI and AFI for differentiating neoplastic from non-neoplastic lesions.
Ninety-four patients underwent colonoscopy with ETMI (47 in each group). Among 47 patients examined with AFI first, 31 adenomas in 15 patients were detected initially [detection rate 0.66 (0.52-0.75)]. Subsequent HRE inspection identified six additional adenomas. Among 47 patients examined with HRE first, 29 adenomas in 14 patients were detected initially [detection rate 0.62 (0.53-0.79)]. Successive AFI yielded seven additional adenomas. Adenoma miss rates of AFI and HRE were 14% and 16.2%, respectively (p = 0.29). Accuracy of AFI alone for differentiation was lower than NBI (63% vs. 80%, p < 0.001). Combined use of AFI and NBI achieved improved accuracy for differentiation (84%), showing a trend for superiority compared with NBI alone (p = 0.064).
AFI did not significantly reduce the adenoma miss rate compared with HRE. AFI alone had a disappointing accuracy for adenoma differentiation, which could be improved by combination of AFI and NBI.
International Journal of Colorectal Disease 09/2011; 27(3):331-6. DOI:10.1007/s00384-011-1312-7 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on the design, fabrication, testing and packaging of a miniaturised system capable of detecting autofluorescence (AF) from mammalian intestinal tissue. The system comprises an application specific integrated circuit (ASIC), LED, optical filters, control unit and radio transmitter. The ASIC contains a high voltage charge pump and single photon avalanche diode detector (SPAD). The charge pump biases the SPAD above its breakdown voltage to operate in Geiger mode. The SPAD offers a photon detection efficiency of 37% at 520nm, which corresponds to the autofluorescence emission peak of the principle human intestinal fluorophore, flavin adenine dinucleotide (FAD). The ASIC was fabricated using a commercial triple-well high-voltage CMOS process. The complete device operates at 3V and draws an average of 7.1mA, enabling up to 23 hours of continuous operation from two 165mAh SR44 batteries.
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