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Progress in the practice of clinical gastroenterology has been made possible, in many respects, by advances in gastrointestinal endoscopy. At the start of the new millennium, unprecedented developments in endoscopic technology suggest that even greater achievements in diagnosing and treating gastrointestinal disorders are possible. However, clinically important endoscopic advances are not routinely met with rapid acceptance and utilization by the general endoscopic community. Reasons for this delay include the cost of acquiring new technology, the difficulty in obtaining additional training once one’s clinical practice has become established, and the (at times appropriate) skepticism regarding any new technology. This review focuses on new developments that are likely to change the day-to-day practice of gastroenterology. We begin with an overview of several relevant technologies that form the basis of the studies discussed in later sections, and present a problem-oriented review of several clinical issues for which significant progress has been made over the past few years. We include several topics that, although not directly addressing endoscopic technique, have the potential to impact general endoscopic practice significantly. Esophagogastroduodenoscopy at the Start of the New Millennium

BACKGROUND & AIMS: Endoscopic screening for sporadic colorectal cancer relies in part on the detection of adenomatous polyps. Nonpolypoid adenomas or flat dysplasia may go unrecognized by conventional endoscopy. This study attempted to develop and test a novel endoscopic method for detecting polypoid and nonpolypoid colonic adenomas. METHODS: Colectomy specimens from 3 patients with familial adenomatous polyposis containing polypoid and nonpolypoid adenomas were illuminated with excitation light at 351 and 364 nm. Endoscopic images of the net tissue fluorescence emitted were collected over the spectral bandwidth from 400 to 700 nm. Each raw image was corrected for differences in distance and instrument light collection efficiency by normalizing to a spatially averaged image. Intensity thresholding was then used to identity regions of diseased mucosa. RESULTS: The average fluorescence intensity from normal mucosa was found to be greater than that from adenomas by a factor of 2.2 +/- 0.6. The sensitivity and specificity for detecting a region of dysplasia varied with the threshold value selected. At a threshold of 75% of the average normal intensity, a sensitivity of 90% and a specificity of 92% were achieved. CONCLUSIONS: Fluorescence images of colonic mucosa can be collected endoscopically, and dysplasia can be detected and localized with high sensitivity and specificity. These results show the potential of this technique to direct endoscopic biopsy. (Gastroenterology 1996 Nov;111(5):1182-91)

Background & Aims: The aim of this study was to assess the potential of 3 spectroscopic techniques (fluorescence, reflectance, and light-scattering spectroscopy) individually and in combination, for evaluating low- and high-grade dysplasia in patients with Barrett's esophagus (BE). Methods: Fluorescence spectra at 11 excitation wavelengths and a reflectance spectrum were acquired in approximately 1 second from each site before biopsy using an optical fiber probe. The measured fluorescence spectra were combined with the reflectance spectra to extract the intrinsic tissue fluorescence. The reflectance spectra provided morphologic information about the bulk tissue, whereas light-scattering spectroscopy was used to determine cell nuclear crowding and enlargement in Barrett's epithelium. Results: Significant differences were observed between dysplastic and nondysplastic BE in terms of intrinsic fluorescence, bulk scattering properties, and levels of epithelial cell nuclear crowding and enlargement. The combination of all 3 techniques resulted in superior sensitivity and specificity for separating high-grade from non–high-grade and dysplastic from nondysplastic epithelium. Conclusions: Intrinsic fluorescence, reflectance, and light-scattering spectroscopies provide complementary information about biochemical and morphologic changes that occur during the development of dysplasia. The combination of these techniques (Tri-Modal Spectroscopy) can serve as an excellent tool for the evaluation of dysplasia in BE. GASTROENTEROLOGY 2001;120:1620-1629

Background & Aims: We conducted a study to assess the potential of light-scattering spectroscopy (LSS), which can measure epithelial nuclear enlargement and crowding, for in situ detection of dysplasia in patients with Barrett's esophagus. Methods: Consecutive patients with suspected Barrett's esophagus underwent endoscopy and systematic biopsy. Before biopsy, each site was sampled by LSS using a fiberoptic probe. Diffusely reflected white light was spectrally analyzed to obtain the size distribution of cell nuclei in the mucosal layer, from which the percentage of enlarged nuclei and the degree of crowding were determined. Dysplasia was assigned if more than 30% of the nuclei exceeded 10 μm and the histologic findings compared with those of 4 pathologists blinded to the light-scattering assessment. The data were then retrospectively analyzed to further explore the diagnostic potential of LSS. Results: Seventy-six sites from 13 patients were sampled. All abnormal sites and a random sample of nondysplastic sites were reviewed by the pathologists. The average diagnoses were 4 sites from 4 different patients as high-grade dysplasia (HGD), 8 sites from 5 different patients as low-grade dysplasia (LGD), 12 as indefinite for dysplasia, and 52 as nondysplastic Barrett's. The sensitivity and specificity of LSS for detecting dysplasia (either LGD or HGD) were 90% and 90%, respectively, with all HGD and 87% of LGD sites correctly classified. Decision algorithms using both nuclear enlargement and crowding further improved diagnostic accuracy, and accurately classified samples into the 4 histologic categories. Conclusions: LSS can reliably detect LGD and HGD in patients with Barrett's esophagus. GASTROENTEROLOGY 2000;119:677-682