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Update on Colonoscopic Imaging and Projections for the Future

2009; Elsevier BV; Volume: 8; Issue: 4 Linguagem: Inglês

10.1016/j.cgh.2009.12.008

1542-7714

Douglas K. Rex,

Esophageal Cancer Research and Treatment

Recently, a large number of articles on new colonoscopic imaging technologies has appeared, and this issue of Clinical Gastroenterology and Hepatology has 3 more such articles.1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 2Buchner A. Shahid M.W. Heckman M.G. et al.High definition colonoscopy detects colorectal polyps at a higher rate than standard white light colonoscopy.Clin Gastroenterol Hepatol. 2010; 8: 364-370Abstract Full Text Full Text PDF PubMed Scopus (97) Google Scholar, 3Sanduleanu S. Driessen A. Gomez-Garcia E. et al.In vivo diagnosis and classification of colorectal neoplasia by chromoendoscopy-guided confocal laser endomicroscopy.Clin Gastroenterol Hepatol. 2010; 8: 371-378Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar This editorial reviews the current state of the art on colonoscopic imaging technologies and their clinical potential.The primary clinical goals of colonoscopic imaging developments are as follows: (1) improved detection of neoplasia, and (2) in vivo histologic diagnosis of detected lesions. Imperfect detection of cancer and precancerous lesions during colonoscopy can result from failure to use the colonoscope to its full capability (poor bowel preparation or suboptimal performance),4Rex D.K. Maximizing detection of adenomas and cancers during colonoscopy.Am J Gastroenterol. 2006; 101: 2866-2877Crossref PubMed Scopus (237) Google Scholar or from features of certain neoplasms that pose technical challenges for detection by the standard colonoscope platform even when used optimally. Thus, certain neoplasms are hidden from view by normal colorectal structures, and others are subtle in shape, color, and surface features so that they may be overlooked even though they are exposed to the colonoscope camera. Technologies have been developed to address both types of detection problems, as well as the problem of in vivo endoscopic determination of histology (Table 1). These technologies are discussed later according to the clinical problem they address.Table 1Goals for Colonoscopy Imaging Developments and the Technologies That Address the GoalsGoalTechnologyIncreased detection Exposing hidden mucosaWide angle of viewHooded colonoscopyThird-Eye Retroscope Highlighting flat lesionsPan-colonic chromoendoscopyNBI (Olympus)Fuji Intelligent Chromo EndoscopyI-Scan (Pentax)Autofluorescence (Olympus)Achieve in vivo histologic diagnosisConfocal laser microscopyEndocytoscopy (Olympus)NBI (Olympus)Fuji Intelligent Chromo EndoscopyI-Scan (Pentax)Autofluorescence (Olympus) Open table in a new tab Increasing Detection: Exposing Hidden MucosaA wide angle (≥170°) of view has been compared with a standard (140°) angle in 3 randomized trials.5Rex D. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar, 6Deenadayalu V.P. Chadalawada V. Rex D.K. 170 degrees wide-angle colonoscope: effect on efficiency and miss rates.Am J Gastroenterol. 2004; 99: 2138-2142Crossref PubMed Scopus (104) Google Scholar, 7Fatima H. Rex D.K. Rothstein R. et al.Cecal insertion and withdrawal times with wide-angle versus standard colonoscopes: a randomized controlled trial.Clin Gastroenterol Hepatol. 2008; 6: 109-114Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The only benefit observed was that some operators can withdraw faster without decreasing adenoma detection. The theoretical gain in mucosal exposure with 170° is about 5% compared with 140° when the scope is withdrawn along a centering line,8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar but manipulation of the scope tip likely compensates for this gain.Hooded colonoscopy has been evaluated in 10 randomized trials.1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar, 10Matsushita M. Hajiro K. Okazaki K. et al.Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap.Endoscopy. 1998; 30: 444-447Crossref PubMed Scopus (151) Google Scholar, 11Dafnis G.M. Technical considerations and patient comfort in total colonoscopy with and without a transparent cap: initial experiences from a pilot study.Endoscopy. 2000; 32: 381-384Crossref PubMed Scopus (41) Google Scholar, 12Lee Y.T. Hui A.J. Wong V.W. et al.Improved colonoscopy success rate with a distally attached mucosectomy cap.Endoscopy. 2006; 38: 739-742Crossref PubMed Scopus (64) Google Scholar, 13Kondo S. Yamaji Y. Watabe H. et al.A randomized controlled trial evaluating the usefulness of a transparent hood attached to the tip of the colonoscope.Am J Gastroenterol. 2007; 102: 75-81Crossref PubMed Scopus (133) Google Scholar, 14Harada Y. Hirasawa D. Fujita N. et al.Impact of a transparent hood on the performance of total colonoscopy: a randomized controlled trial.Gastrointest Endosc. 2009; 69: 637-644Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 15Lee Y.T. Lai L.H. Hui A.J. et al.Efficacy of cap-assisted colonoscopy in comparison with regular colonoscopy: a randomized controlled trial.Am J Gastroenterol. 2009; 104: 41-46Crossref PubMed Scopus (106) Google Scholar, 16Shida T. Katsuura Y. Teramoto O. et al.Transparent hood attached to the colonoscope: does it really work for all types of colonoscopes?.Surg Endosc. 2008; 22: 2654-2658Crossref PubMed Scopus (30) Google Scholar, 17Tada M. Inoue H. Yabata E. et al.Feasibility of the transparent cap-fitted colonoscope for screening and mucosal resection.Dis Colon Rectum. 1997; 40: 618-621Crossref PubMed Scopus (78) Google Scholar The only 2 studies to report gains in adenoma detection (gains in polyp detection have been reported in 4 of 8 other trials) are both by Horiuchi and colleagues,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar including the current study in Clinical Gastroenterology and Hepatology. Both of these studies used a modified tandem design, and both are flawed because the gains in adenoma detection in the control arms from the second colonoscopy are only 4%9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar and 5%,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar respectively. All other tandem studies have shown much higher gains from the second colonoscopy, with a mean gain of 22% in adenoma detection.18Waye J, Heigh RI, Fleischer DE, et al. The Third Eye Retroscope auxiliary system improves detection of adenomas in the colon—a prospective efficacy evaluation. Gastrointest Endosc (In press).Google Scholar Thus, current evidence does not indicate any consistent improvement in adenoma detection by hooded colonoscopy. No trial of hooded colonoscopy has been performed in North America.The Third-Eye Retroscope (Avantis Medical Systems, Sunnyvale, CA) is a catheter-based imaging system that is passed down the colonoscope working channel where it provides a retroflexed view of the colon. In an uncontrolled study, the device produced an 11% gain in adenoma detection as judged by adenomas that were detected only by the Third-Eye and not by the colonoscope.19van Rijn J.C. Reitsma J.B. Stoker J. et al.Polyp miss rate determined by tandem colonoscopy: a systematic review.Am J Gastroenterol. 2006; 101: 343-350Crossref PubMed Scopus (1021) Google Scholar This gain is similar to the calculated increase in mucosal exposure provided by the device.8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar A multicenter randomized tandem study is in progress at the time of this writing.ConclusionsThe verdict on the Third-Eye is undecided, and the results of the ongoing tandem study are critical. Studies of hooded colonoscopy in Western populations are needed.Increasing Detection: Highlighting Flat LesionsPan-colonic chromoendoscopy increases the detection of small flat adenomas4Rex D.K. Maximizing detection of adenomas and cancers during colonoscopy.Am J Gastroenterol. 2006; 101: 2866-2877Crossref PubMed Scopus (237) Google Scholar but is considered too time consuming to be used for routine colonoscopy.Electronic highlighting of flat lesions has been attempted with narrow band imaging (NBI) and postimaging processing methods including Fuji Intelligent Chromo Endoscopy (FICE) (Fujinon, Wayne, NJ) and I-Scan from Pentax (Montvale, NJ). There are too few data with I-Scan to make an assessment.20Hoffman A. Kagel C. Goetz M. et al.High definition colonoscopy (HD+) with I-Scan function allows to recognize and characterize flat neoplastic changes as precisely as chromoendoscopy.Gastrointest Endosc. 2008; 67: AB125Abstract Full Text Full Text PDF Google Scholar A single randomized trial with FICE was negative.21Pohl J. Lotterer E. Balzer C. et al.Computed virtual chromoendoscopy versus standard colonoscopy with targeted indigo carmine chromoscopy: a randomised multicentre trial.Gut. 2009; 58: 73-78Crossref PubMed Scopus (130) Google Scholar There have been 6 randomized trials of NBI,22Adler A. Pohl H. Papanikolaou I.S. et al.A prospective randomised study on narrow-band imaging versus conventional colonoscopy for adenoma detection: does narrow-band imaging induce a learning effect?.Gut. 2008; 57: 59-64Crossref PubMed Scopus (239) Google Scholar, 23Adler A. Aschenbeck J. Yenerim T. et al.Narrow-band versus white-light high definition television endoscopic imaging for screening colonoscopy: a prospective randomized trial.Gastroenterology. 2009; 136 (quiz, 715): 410e1-416e1Abstract Full Text Full Text PDF Scopus (170) Google Scholar, 24Kaltenbach T. Friedland S. Soetikno R. A randomised tandem colonoscopy trial of narrow band imaging versus white light examination to compare neoplasia miss rates.Gut. 2008; 57: 1406-1412Crossref PubMed Scopus (143) Google Scholar, 25Inoue T. Murano M. Murano N. et al.Comparative study of conventional colonoscopy and pan-colonic narrow-band imaging system in the detection of neoplastic colonic polyps: a randomized, controlled trial.J Gastroenterol. 2008; 43: 45-50Crossref PubMed Scopus (131) Google Scholar, 26Paggi S. Radaelli F. Amato A. et al.The impact of narrow band imaging in screening colonoscopy: a randomized controlled trial.Clin Gastroenterol Hepatol. 2009; 7: 1049-1054Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar, 27Rex D.K. Helbig C.C. High yields of small and flat adenomas with high-definition colonoscopes using either white light or narrow band imaging.Gastroenterology. 2007; 133: 42-47Abstract Full Text Full Text PDF PubMed Scopus (367) Google Scholar of which 5 were negative. NBI may have a beneficial learning effect in poor adenoma detectors.22Adler A. Pohl H. Papanikolaou I.S. et al.A prospective randomised study on narrow-band imaging versus conventional colonoscopy for adenoma detection: does narrow-band imaging induce a learning effect?.Gut. 2008; 57: 59-64Crossref PubMed Scopus (239) Google ScholarHigh-definition (HD) imaging recently was used in studies achieving the highest adenoma detection rates ever reported,26Paggi S. Radaelli F. Amato A. et al.The impact of narrow band imaging in screening colonoscopy: a randomized controlled trial.Clin Gastroenterol Hepatol. 2009; 7: 1049-1054Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar, 27Rex D.K. Helbig C.C. High yields of small and flat adenomas with high-definition colonoscopes using either white light or narrow band imaging.Gastroenterology. 2007; 133: 42-47Abstract Full Text Full Text PDF PubMed Scopus (367) Google Scholar, 28Kahi C. Anderson J. Waxman I. et al.The American College of Gastroenterology high definition chromocolonoscopy study: findings and implications of colorectal cancer screening.Am J Gastroenterol. 2009; 104: S559Google Scholar, 29East J.E. Stavrindis M. Thomas-Gibson S. et al.A comparative study of standard vs. high definition colonoscopy for adenoma and hyperplastic polyp detection with optimized withdrawal technique.Aliment Pharmacol Ther. 2008; 28: 768-776Crossref PubMed Scopus (89) Google Scholar with multiple individual examiners finding adenomas in 50% or more of average-risk screening patients.27Rex D.K. Helbig C.C. High yields of small and flat adenomas with high-definition colonoscopes using either white light or narrow band imaging.Gastroenterology. 2007; 133: 42-47Abstract Full Text Full Text PDF PubMed Scopus (367) Google Scholar, 28Kahi C. Anderson J. Waxman I. et al.The American College of Gastroenterology high definition chromocolonoscopy study: findings and implications of colorectal cancer screening.Am J Gastroenterol. 2009; 104: S559Google Scholar The retrospective study of HD reported in this issue of Clinical Gastroenterology and Hepatology2Buchner A. Shahid M.W. Heckman M.G. et al.High definition colonoscopy detects colorectal polyps at a higher rate than standard white light colonoscopy.Clin Gastroenterol Hepatol. 2010; 8: 364-370Abstract Full Text Full Text PDF PubMed Scopus (97) Google Scholar appears well controlled in many regards and has the advantage of studying average colonoscopists performing in routine practice. However, the only randomized trial of HD was negative.30Pellise M. Fernandez-Esparrach G. Cardenas A. et al.Impact of wide-angle, high-definition endoscopy in the diagnosis of colorectal neoplasia: a randomized controlled trial.Gastroenterology. 2008; 135: 1062-1068Abstract Full Text Full Text PDF PubMed Scopus (96) Google ScholarAutofluorescence as a means of improving adenoma detection has produced mixed results.31Matsuda T. Saito Y. Fu K.I. et al.Does autofluorescence imaging videoendoscopy system improve the colonoscopic polyp detection rate?—a pilot study.Am J Gastroenterol. 2008; 103: 1926-1932Crossref PubMed Scopus (109) Google Scholar, 32van den Broek F.J. Fockens P. Van Eeden S. et al.Clinical evaluation of endoscopic trimodal imaging for the detection and differentiation of colonic polyps.Clin Gastroenterol Hepatol. 2009; 7: 288-295Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Autofluorescence systems are expensive and thus far have been adapted only to the Olympus Lucera system (Olympus, Center Valley, PA) sold in Japan and the United Kingdom. Thus, discussion of autofluorescence as a means of improving adenoma detection is moot, at least for now for American endoscopists.ConclusionsElectronic highlighting (NBI, FICE, I-Scan) may produce a learning effect in poor adenoma detectors but otherwise has been ineffective in improving adenoma detection. HD deserves further study and is the most promising imaging development for flat lesion detection that is practical to use. (Note: The transition from standard resolution to HD is probably inevitable in any case: endoscopists prefer HD, there is no learning curve for its use, and the cost is trivial.)In Vivo Histologic AssessmentAccurate in vivo assessment of histology (Table 1) could play several clinically meaningful roles. First, removal of small distal colon hyperplastic polyps could be avoided, eliminating costs and risks. Second, small precancerous polyps could be resected and discarded without pathologic assessment. The resect and discard approach reduces pathology costs, and postpolypectomy surveillance colonoscopy intervals would be based on endoscopic assessment of histology. Finally, identification of cancer by real-time histology can improve selection of treatment.Confocal laser microscopy (CLM) provides virtual histology,33Kiesslich R. Burg J. Vieth M. et al.Confocal laser endoscopy for diagnosing intraepithelial neoplasias and colorectal cancer in vivo.Gastroenterology. 2004; 127: 706-713Abstract Full Text Full Text PDF PubMed Scopus (766) Google Scholar, 34Hurlstone D.P. Baraza W. Brown S. et al.In vivo real-time confocal laser scanning endomicroscopic colonoscopy for the detection and characterization of colorectal neoplasia.Br J Surg. 2008; 95: 636-645Crossref PubMed Scopus (71) Google Scholar, 35Wang T.D. Friedland S. Sahbaie P. et al.Functional imaging of colonic mucosa with a fibered confocal microscope for real-time in vivo pathology.Clin Gastroenterol Hepatol. 2007; 5: 1300-1305Abstract Full Text Full Text PDF PubMed Scopus (109) Google Scholar as shown again by Sanduleanu et al3Sanduleanu S. Driessen A. Gomez-Garcia E. et al.In vivo diagnosis and classification of colorectal neoplasia by chromoendoscopy-guided confocal laser endomicroscopy.Clin Gastroenterol Hepatol. 2010; 8: 371-378Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar in this issue of Clinical Gastroenterology and Hepatology. Differentiation of adenomatous from hyperplastic polyps, the degree of dysplasia of adenomas, and the presence of cancer all can be determined accurately. However, substantial training, expensive equipment, and significant intraprocedural time are needed for CLM. Similar capabilities and limitations may apply to the Olympus endocytoscopy super-magnification system.36Sasajima K. Kudo S.E. Inoue H. et al.Real-time in vivo virtual histology of colorectal lesions when using the endocytoscopy system.Gastrointest Endosc. 2006; 63: 1010-1017Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar, 37Eberl T. Jechart G. Probst A. et al.Can an endocytoscope system (ECS) predict histology in neoplastic lesions?.Endoscopy. 2007; 39: 497-501Crossref PubMed Scopus (51) Google Scholar NBI with optical magnification (not available in the United States) has been used to identify cancer and degree of dysplasia in some studies38Wada Y. Kudo S.E. Kashida H. et al.Diagnosis of colorectal lesions with the magnifying narrow-band imaging system.Gastrointest Endosc. 2009; 70: 522-531Abstract Full Text Full Text PDF PubMed Scopus (153) Google Scholar, 39Katagiri A. Fu K.I. Sano Y. et al.Narrow band imaging with magnifying colonoscopy as diagnostic tool for predicting histology of early colorectal neoplasia.Aliment Pharmacol Ther. 2008; 27: 1269-1274Crossref PubMed Scopus (121) Google Scholar, 40Kanao H. Tanaka S. Oka S. et al.Narrow-band imaging magnification predicts the histology and invasion depth of colorectal tumors.Gastrointest Endosc. 2009; 69: 631-636Abstract Full Text Full Text PDF PubMed Scopus (189) Google Scholar and is more practical than either CLM or endocytoscopy.NBI with38Wada Y. Kudo S.E. Kashida H. et al.Diagnosis of colorectal lesions with the magnifying narrow-band imaging system.Gastrointest Endosc. 2009; 70: 522-531Abstract Full Text Full Text PDF PubMed Scopus (153) Google Scholar, 39Katagiri A. Fu K.I. Sano Y. et al.Narrow band imaging with magnifying colonoscopy as diagnostic tool for predicting histology of early colorectal neoplasia.Aliment Pharmacol Ther. 2008; 27: 1269-1274Crossref PubMed Scopus (121) Google Scholar, 40Kanao H. Tanaka S. Oka S. et al.Narrow-band imaging magnification predicts the histology and invasion depth of colorectal tumors.Gastrointest Endosc. 2009; 69: 631-636Abstract Full Text Full Text PDF PubMed Scopus (189) Google Scholar, 41East J.E. Suzuki N. Saunders B.P. Comparison of magnified pit pattern interpretation with narrow band imaging versus chromoendoscopy for diminutive colonic polyps: a pilot study.Gastrointest Endosc. 2007; 66: 310-316Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 42Sano Y. Ikematsu H. Fu K.I. et al.Meshed capillary vessels by use of narrow-band imaging for differential diagnosis of small colorectal polyps.Gastrointest Endosc. 2009; 69: 278-283Abstract Full Text Full Text PDF PubMed Scopus (216) Google Scholar, 43Su M.Y. Hsu C.M. Ho Y.P. et al.Comparative study of conventional colonoscopy, chromoendoscopy, and narrow-band imaging systems in differential diagnosis of neoplastic and nonneoplastic colonic polyps.Am J Gastroenterol. 2006; 101: 2711-2716Crossref PubMed Scopus (243) Google Scholar, 44East J.E. Suzuki N. 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Hamamoto Y. et al.Narrow-band imaging in the diagnosis of colorectal mucosal lesions: a pilot study.Endoscopy. 2004; 36: 1094-1098Crossref PubMed Scopus (456) Google Scholar and without49Rastogi A. Keighley J. Singh V. et al.High accuracy of narrow band imaging without magnification for the real-time characterization of polyp histology and its comparison with high-definition white light colonoscopy: a prospective study.Am J Gastroenterol. 2009; 104: 2422-2430Crossref PubMed Scopus (143) Google Scholar, 50Rogart J.N. Jain D. Siddiqui U.D. et al.Narrow-band imaging without high magnification to differentiate polyps during real-time colonoscopy: improvement with experience.Gastrointest Endosc. 2008; 68: 1136-1145Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar, 51Sikka S. Ringold D.A. Jonnalagadda S. et al.Comparison of white light and narrow band high definition images in predicting colon polyp histology, using standard colonoscopes without optical magnification.Endoscopy. 2008; 40: 818-822Crossref PubMed Scopus (96) Google Scholar, 52Rastogi A. Pondugula K. Bansal A. et al.Recognition of surface mucosal and vascular patterns of colon polyps by using narrow-band imaging: interobserver and intraobserver agreement and prediction of polyp histology.Gastrointest Endosc. 2009; 69: 716-722Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar, 53Rastogi A. Bansal A. Wani S. et al.Narrow-band imaging colonoscopy—a pilot feasibility study for the detection of polyps and correlation of surface patterns with polyp histologic diagnosis.Gastrointest Endosc. 2008; 67: 280-286Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar, 54Rex D.K. Narrow-band imaging without optical magnification for histologic analysis of colorectal polyps.Gastroenterology. 2009; 136: 1174-1181Abstract Full Text Full Text PDF PubMed Scopus (230) Google Scholar, 55Ignjatovic A. East J. Suzuki N. et al.Optical diagnosis of small colorectal polyps at routine colonoscopy (Detect InSpect ChAracterise Resect and Discard; DISCARD trial): a prospective cohort study.Lancet Oncol. 2009; 10: 1171-1178Abstract Full Text Full Text PDF PubMed Scopus (299) Google Scholar optical magnification can differentiate adenomas from hyperplasia. Although fewer studies are available, FICE56Pohl J. Nguyen-Tat M. Pech O. et al.Computed virtual chromoendoscopy for classification of small colorectal lesions: a prospective comparative study.Am J Gastroenterol. 2008; 103: 562-569Crossref PubMed Scopus (131) Google Scholar, 57Togashi K. Osawa H. Koinuma K. et al.A comparison of conventional endoscopy, chromoendoscopy, and the optimal-band imaging system for the differentiation of neoplastic and non-neoplastic colonic polyps.Gastrointest Endosc. 2009; 69: 734-741Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar, 58Liu Y.X. Huang L.Y. Bian X.P. et al.Fuji Intelligent Chromo Endoscopy and staining technique for the diagnosis of colon tumor.Chin Med J (Engl). 2008; 121: 977-982PubMed Google Scholar and I-Scan20Hoffman A. Kagel C. Goetz M. et al.High definition colonoscopy (HD+) with I-Scan function allows to recognize and characterize flat neoplastic changes as precisely as chromoendoscopy.Gastrointest Endosc. 2008; 67: AB125Abstract Full Text Full Text PDF Google Scholar may allow this determination. These 3 technologies have the advantage over CLM and endocytoscopy of being push-button operated systems and are standard equipment on current-generation colonoscopes. Two recent studies showed that NBI without optical magnification assessment of diminutive (≤5 mm) or small (≤9 mm) lesions followed by resect and discard, would allow selection of the same postpolypectomy interval indicated by pathology, in 98% of cases.54Rex D.K. Narrow-band imaging without optical magnification for histologic analysis of colorectal polyps.Gastroenterology. 2009; 136: 1174-1181Abstract Full Text Full Text PDF PubMed Scopus (230) Google Scholar, 55Ignjatovic A. East J. Suzuki N. et al.Optical diagnosis of small colorectal polyps at routine colonoscopy (Detect InSpect ChAracterise Resect and Discard; DISCARD trial): a prospective cohort study.Lancet Oncol. 2009; 10: 1171-1178Abstract Full Text Full Text PDF PubMed Scopus (299) Google Scholar Autofluorescence for real-time histology has produced mixed results.32van den Broek F.J. Fockens P. Van Eeden S. et al.Clinical evaluation of endoscopic trimodal imaging for the detection and differentiation of colonic polyps.Clin Gastroenterol Hepatol. 2009; 7: 288-295Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar, 59Aihara H. Sumiyama K. Saito S. et al.Numerical analysis of the autofluorescence intensity of neoplastic and non-neoplastic colorectal lesions by using a novel videoendoscopy system.Gastrointest Endosc. 2009; 69: 726-733Abstract Full Text Full Text PDF PubMed Scopus (48) Google Scholar, 60McCallum A.L. Jenkins J.T. Gillen D. et al.Evaluation of autofluorescence colonoscopy for the detection and diagnosis of colonic polyps.Gastrointest Endosc. 2008; 68: 283-290Abstract Full Text Full Text PDF PubMed Scopus (53) Google ScholarConclusionsIn vivo or real-time endoscopic assessment is accurate and likely to transform small polyp management during colonoscopy.61Rex D.K. Fennerty M.B. Sharma P. et al.Bringing new endoscopic imaging technology into everyday practice: what is the role of professional GI societies? Polyp imaging as a template for moving endoscopic innovation forward to answer key clinical questions.Gastrointest Endosc. 2010; 71: 142-146Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar Push-button technologies will have the advantage for routine use in that they are inexpensive, easy to learn, fast to perform, and still accurate. CLM and endocytoscopy will remain in the research domain unless they gain a decided reimbursement advantage.Projections for the FutureThe true prevalence of adenomas in the average-risk screening population is greater than 50%, as defined by high-level adenoma detectors.27Rex D.K. Helbig C.C. High yields of small and flat adenomas with high-definition colonoscopes using either white light or narrow band imaging.Gastroenterology. 2007; 133: 42-47Abstract Full Text Full Text PDF PubMed Scopus (367) Google Scholar, 28Kahi C. Anderson J. Waxman I. et al.The American College of Gastroenterology high definition chromocolonoscopy study: findings and implications of colorectal cancer screening.Am J Gastroenterol. 2009; 104: S559Google Scholar These levels of detection probably can be achieved by any colonoscopist using modern bowel preparation methods and meticulous technique with white-light and HD colonoscopes. The greatest future gains in detection are likely to come via quality improvement programs that reduce variable performance with white-light colonoscopy. Thus, the potential gains in detection from poor detectors improving performance62Barclay R.L. Vicari J.J. Doughty A.S. et al.Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1074) Google Scholar, 63Chen S.C. Rex D.K. Endoscopist can be more powerful than age and male gender in predicting adenoma detection at colonoscopy.Am J Gastroenterol. 2007; 102: 856-861Crossref PubMed Scopus (334) Google Scholar overwhelms any gains proposed for the detection technologies described earlier. However, widespread gains in adenoma detection will produce an important downside: an enormous fraction of the increase in lesions detected are tiny adenomas of minimal significance.27Rex D.K. Helbig C.C. High yields of small and flat adenomas with high-definition colonoscopes using either white light or narrow band imaging.Gastroenterology. 2007; 133: 42-47Abstract Full Text Full Text PDF PubMed Scopus (367) Google Scholar, 28Kahi C. Anderson J. Waxman I. et al.The American College of Gastroenterology high definition chromocolonoscopy study: findings and implications of colorectal cancer screening.Am J Gastroenterol. 2009; 104: S559Google Scholar Increases in detection of tiny adenomas will move the colonoscopy paradigm further away from all other colorectal cancer prevention strategies, and toward cost ineffectiveness. Thus, computed tomography colonography does not even report lesions of 5 mm or less,64Zalis M.E. Barish M.A. Choi J.R. et al.CT colonography reporting and data system: a consensus proposal.Radiology. 2005; 236: 3-9Crossref PubMed Scopus (498) Google Scholar whereas colonoscopists remove more of these lesions with heavy costs (and risks if electrocautery is used). In this situation in vivo diagnosis of histology comes to the rescue. In vivo diagnosis followed by resect and discard allows colonoscopy to retain the advantages of complete clearing while reducing the costs of resecting diminutive polyps.54Rex D.K. Narrow-band imaging without optical magnification for histologic analysis of colorectal polyps.Gastroenterology. 2009; 136: 1174-1181Abstract Full Text Full Text PDF PubMed Scopus (230) Google Scholar, 55Ignjatovic A. East J. Suzuki N. et al.Optical diagnosis of small colorectal polyps at routine colonoscopy (Detect InSpect ChAracterise Resect and Discard; DISCARD trial): a prospective cohort study.Lancet Oncol. 2009; 10: 1171-1178Abstract Full Text Full Text PDF PubMed Scopus (299) Google Scholar In the resect and discard scheme, the endoscopic photograph of a small polyp could serve as the record of its histology, replacing the glass slide stored in the pathology suite. Eventually the range of adenoma findings considered low risk and the confidence in complete clearing will both increase to the point that many patients with low-risk adenomas could be followed up at 10-year intervals. As health care costs increase to staggering levels in the United States without proportional improvements in outcome, each specialty must identify areas in which costs are high relative to value. For gastroenterology, small polyp resection is such an area. In vivo endoscopic diagnosis of histology is a tool that can help. Recently, a large number of articles on new colonoscopic imaging technologies has appeared, and this issue of Clinical Gastroenterology and Hepatology has 3 more such articles.1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 2Buchner A. Shahid M.W. Heckman M.G. et al.High definition colonoscopy detects colorectal polyps at a higher rate than standard white light colonoscopy.Clin Gastroenterol Hepatol. 2010; 8: 364-370Abstract Full Text Full Text PDF PubMed Scopus (97) Google Scholar, 3Sanduleanu S. Driessen A. Gomez-Garcia E. et al.In vivo diagnosis and classification of colorectal neoplasia by chromoendoscopy-guided confocal laser endomicroscopy.Clin Gastroenterol Hepatol. 2010; 8: 371-378Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar This editorial reviews the current state of the art on colonoscopic imaging technologies and their clinical potential. The primary clinical goals of colonoscopic imaging developments are as follows: (1) improved detection of neoplasia, and (2) in vivo histologic diagnosis of detected lesions. Imperfect detection of cancer and precancerous lesions during colonoscopy can result from failure to use the colonoscope to its full capability (poor bowel preparation or suboptimal performance),4Rex D.K. Maximizing detection of adenomas and cancers during colonoscopy.Am J Gastroenterol. 2006; 101: 2866-2877Crossref PubMed Scopus (237) Google Scholar or from features of certain neoplasms that pose technical challenges for detection by the standard colonoscope platform even when used optimally. Thus, certain neoplasms are hidden from view by normal colorectal structures, and others are subtle in shape, color, and surface features so that they may be overlooked even though they are exposed to the colonoscope camera. Technologies have been developed to address both types of detection problems, as well as the problem of in vivo endoscopic determination of histology (Table 1). These technologies are discussed later according to the clinical problem they address. Increasing Detection: Exposing Hidden MucosaA wide angle (≥170°) of view has been compared with a standard (140°) angle in 3 randomized trials.5Rex D. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar, 6Deenadayalu V.P. Chadalawada V. Rex D.K. 170 degrees wide-angle colonoscope: effect on efficiency and miss rates.Am J Gastroenterol. 2004; 99: 2138-2142Crossref PubMed Scopus (104) Google Scholar, 7Fatima H. Rex D.K. Rothstein R. et al.Cecal insertion and withdrawal times with wide-angle versus standard colonoscopes: a randomized controlled trial.Clin Gastroenterol Hepatol. 2008; 6: 109-114Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The only benefit observed was that some operators can withdraw faster without decreasing adenoma detection. The theoretical gain in mucosal exposure with 170° is about 5% compared with 140° when the scope is withdrawn along a centering line,8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar but manipulation of the scope tip likely compensates for this gain.Hooded colonoscopy has been evaluated in 10 randomized trials.1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar, 10Matsushita M. Hajiro K. Okazaki K. et al.Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap.Endoscopy. 1998; 30: 444-447Crossref PubMed Scopus (151) Google Scholar, 11Dafnis G.M. Technical considerations and patient comfort in total colonoscopy with and without a transparent cap: initial experiences from a pilot study.Endoscopy. 2000; 32: 381-384Crossref PubMed Scopus (41) Google Scholar, 12Lee Y.T. Hui A.J. Wong V.W. et al.Improved colonoscopy success rate with a distally attached mucosectomy cap.Endoscopy. 2006; 38: 739-742Crossref PubMed Scopus (64) Google Scholar, 13Kondo S. Yamaji Y. Watabe H. et al.A randomized controlled trial evaluating the usefulness of a transparent hood attached to the tip of the colonoscope.Am J Gastroenterol. 2007; 102: 75-81Crossref PubMed Scopus (133) Google Scholar, 14Harada Y. Hirasawa D. Fujita N. et al.Impact of a transparent hood on the performance of total colonoscopy: a randomized controlled trial.Gastrointest Endosc. 2009; 69: 637-644Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 15Lee Y.T. Lai L.H. Hui A.J. et al.Efficacy of cap-assisted colonoscopy in comparison with regular colonoscopy: a randomized controlled trial.Am J Gastroenterol. 2009; 104: 41-46Crossref PubMed Scopus (106) Google Scholar, 16Shida T. Katsuura Y. Teramoto O. et al.Transparent hood attached to the colonoscope: does it really work for all types of colonoscopes?.Surg Endosc. 2008; 22: 2654-2658Crossref PubMed Scopus (30) Google Scholar, 17Tada M. Inoue H. Yabata E. et al.Feasibility of the transparent cap-fitted colonoscope for screening and mucosal resection.Dis Colon Rectum. 1997; 40: 618-621Crossref PubMed Scopus (78) Google Scholar The only 2 studies to report gains in adenoma detection (gains in polyp detection have been reported in 4 of 8 other trials) are both by Horiuchi and colleagues,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar including the current study in Clinical Gastroenterology and Hepatology. Both of these studies used a modified tandem design, and both are flawed because the gains in adenoma detection in the control arms from the second colonoscopy are only 4%9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar and 5%,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar respectively. All other tandem studies have shown much higher gains from the second colonoscopy, with a mean gain of 22% in adenoma detection.18Waye J, Heigh RI, Fleischer DE, et al. The Third Eye Retroscope auxiliary system improves detection of adenomas in the colon—a prospective efficacy evaluation. Gastrointest Endosc (In press).Google Scholar Thus, current evidence does not indicate any consistent improvement in adenoma detection by hooded colonoscopy. No trial of hooded colonoscopy has been performed in North America.The Third-Eye Retroscope (Avantis Medical Systems, Sunnyvale, CA) is a catheter-based imaging system that is passed down the colonoscope working channel where it provides a retroflexed view of the colon. In an uncontrolled study, the device produced an 11% gain in adenoma detection as judged by adenomas that were detected only by the Third-Eye and not by the colonoscope.19van Rijn J.C. Reitsma J.B. Stoker J. et al.Polyp miss rate determined by tandem colonoscopy: a systematic review.Am J Gastroenterol. 2006; 101: 343-350Crossref PubMed Scopus (1021) Google Scholar This gain is similar to the calculated increase in mucosal exposure provided by the device.8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar A multicenter randomized tandem study is in progress at the time of this writing.ConclusionsThe verdict on the Third-Eye is undecided, and the results of the ongoing tandem study are critical. Studies of hooded colonoscopy in Western populations are needed. A wide angle (≥170°) of view has been compared with a standard (140°) angle in 3 randomized trials.5Rex D. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar, 6Deenadayalu V.P. Chadalawada V. Rex D.K. 170 degrees wide-angle colonoscope: effect on efficiency and miss rates.Am J Gastroenterol. 2004; 99: 2138-2142Crossref PubMed Scopus (104) Google Scholar, 7Fatima H. Rex D.K. Rothstein R. et al.Cecal insertion and withdrawal times with wide-angle versus standard colonoscopes: a randomized controlled trial.Clin Gastroenterol Hepatol. 2008; 6: 109-114Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The only benefit observed was that some operators can withdraw faster without decreasing adenoma detection. The theoretical gain in mucosal exposure with 170° is about 5% compared with 140° when the scope is withdrawn along a centering line,8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar but manipulation of the scope tip likely compensates for this gain. Hooded colonoscopy has been evaluated in 10 randomized trials.1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar, 10Matsushita M. Hajiro K. Okazaki K. et al.Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap.Endoscopy. 1998; 30: 444-447Crossref PubMed Scopus (151) Google Scholar, 11Dafnis G.M. Technical considerations and patient comfort in total colonoscopy with and without a transparent cap: initial experiences from a pilot study.Endoscopy. 2000; 32: 381-384Crossref PubMed Scopus (41) Google Scholar, 12Lee Y.T. Hui A.J. Wong V.W. et al.Improved colonoscopy success rate with a distally attached mucosectomy cap.Endoscopy. 2006; 38: 739-742Crossref PubMed Scopus (64) Google Scholar, 13Kondo S. Yamaji Y. Watabe H. et al.A randomized controlled trial evaluating the usefulness of a transparent hood attached to the tip of the colonoscope.Am J Gastroenterol. 2007; 102: 75-81Crossref PubMed Scopus (133) Google Scholar, 14Harada Y. Hirasawa D. Fujita N. et al.Impact of a transparent hood on the performance of total colonoscopy: a randomized controlled trial.Gastrointest Endosc. 2009; 69: 637-644Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar, 15Lee Y.T. Lai L.H. Hui A.J. et al.Efficacy of cap-assisted colonoscopy in comparison with regular colonoscopy: a randomized controlled trial.Am J Gastroenterol. 2009; 104: 41-46Crossref PubMed Scopus (106) Google Scholar, 16Shida T. Katsuura Y. Teramoto O. et al.Transparent hood attached to the colonoscope: does it really work for all types of colonoscopes?.Surg Endosc. 2008; 22: 2654-2658Crossref PubMed Scopus (30) Google Scholar, 17Tada M. Inoue H. Yabata E. et al.Feasibility of the transparent cap-fitted colonoscope for screening and mucosal resection.Dis Colon Rectum. 1997; 40: 618-621Crossref PubMed Scopus (78) Google Scholar The only 2 studies to report gains in adenoma detection (gains in polyp detection have been reported in 4 of 8 other trials) are both by Horiuchi and colleagues,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar including the current study in Clinical Gastroenterology and Hepatology. Both of these studies used a modified tandem design, and both are flawed because the gains in adenoma detection in the control arms from the second colonoscopy are only 4%9Horiuchi A. Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device.Am J Gastroenterol. 2008; 103: 341-345Crossref PubMed Scopus (56) Google Scholar and 5%,1Horiuchi A. Nakayama Y. Kato N. et al.Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging.Clin Gastroenterol Hepatol. 2010; 8: 379-383Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar respectively. All other tandem studies have shown much higher gains from the second colonoscopy, with a mean gain of 22% in adenoma detection.18Waye J, Heigh RI, Fleischer DE, et al. The Third Eye Retroscope auxiliary system improves detection of adenomas in the colon—a prospective efficacy evaluation. Gastrointest Endosc (In press).Google Scholar Thus, current evidence does not indicate any consistent improvement in adenoma detection by hooded colonoscopy. No trial of hooded colonoscopy has been performed in North America. The Third-Eye Retroscope (Avantis Medical Systems, Sunnyvale, CA) is a catheter-based imaging system that is passed down the colonoscope working channel where it provides a retroflexed view of the colon. In an uncontrolled study, the device produced an 11% gain in adenoma detection as judged by adenomas that were detected only by the Third-Eye and not by the colonoscope.19van Rijn J.C. Reitsma J.B. Stoker J. et al.Polyp miss rate determined by tandem colonoscopy: a systematic review.Am J Gastroenterol. 2006; 101: 343-350Crossref PubMed Scopus (1021) Google Scholar This gain is similar to the calculated increase in mucosal exposure provided by the device.8East J.E. Saunders B.P. Burling D. et al.Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view.Am J Gastroenterol. 2007; 102: 2529-2535Crossref PubMed Scopus (69) Google Scholar A multicenter randomized tandem study is in progress at the time of this writing. ConclusionsThe verdict on the Third-Eye is undecided, and the results of the ongoing tandem study are critical. Studies of hooded colonoscopy in Western populations are needed. The verdict on the Third-Eye is undecided, and the results of the ongoing tandem study are critical. Studies of hooded colonoscopy in Western populations are needed.