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Standard endoscopic examination (upper gastrointestinal endoscopy and colonoscopy) fails to detect the cause of gastrointestinal hemorrhage in approximately 5% of patients. Before the availability of wireless capsule endoscopy and double-balloon enteroscopy, imaging modalities for the small intestine distal to the ligament of Treitz included barium contrast examination and/or enteroclysis, push, passive, or intraoperative enteroscopy, technetium 99m labeled sulfur colloid scanning, angiography, and computed tomography, although the diagnostic yield of all of these imaging modalities was low. In 2001, wireless capsule endoscopy became available for the evaluation of patients with probable small intestinal hemorrhage. Advantages of wireless capsule endoscopy include that the procedure is noninvasive, requires no sedation, and does not expose the patient to ionizing radiation. In patients with obscure gastrointestinal hemorrhage, studies have demonstrated an additional 25 to 50% diagnostic yield using wireless capsule endoscopy when compared to other diagnostic modalities. The major limitations of capsule endoscopy were its inability to obtain a biopsy, precisely localize a lesion, or perform therapeutic endoscopy. In 2001, the double-balloon enteroscope was introduced. This new endoscopic technique provides the gastroenterologist with an opportunity for further evaluation and treatment of abnormalities detected on wireless capsule endoscopy or other small intestinal imaging studies.

Background & Aims: Computed tomographic colonography (CTC) was first described more than a decade ago. Recent advances in imaging hardware and software and results of clinical trials based on new methods for performing and interpreting images suggest that CTC may now be assessed as a method for colorectal cancer screening., Methods: The Research Policy Committee of the American Gastroenterological Association assembled a task force to review the results of recent clinical trials and quantitative mathematical models pertaining to CTC. The goal of the task force was to assess the current knowledge about CTC and to evaluate the issues that will define its impact., Results: Limitations in evaluating the current state of CTC technology include a wide variation in results of clinical trials. There are as yet insufficient data on the use of CTC in routine clinical practice. Limitations in the use of quantitative mathematical models make predictions based on such models of limited value. The cancer risk and therefore clinical importance of small colorectal polyps detected by CTC and/or nonpolypoid neoplasia not detected by CTC remains largely unknown., Conclusions: CTC is attractive as a colon imaging modality. It is therefore anticipated that CTC will have a significant impact on the practice of gastroenterology. However, the magnitude of the impact is currently unknown. Whether the ongoing implementation of CTC will increase or decrease the number of referrals for colonoscopy or shift the procedure from colorectal cancer screening to therapeutic interventions (e.g., polypectomy) is unknown at the present time. Multidisciplinary collaboration between gastroenterology and radiology to promote effective implementation and ongoing quality assurance will be important.

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.

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 microm 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.

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.