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Improving Colorectal Adenoma Detection: Technology or Technique?

2007; Elsevier BV; Volume: 132; Issue: 4 Linguagem: Inglês

10.1053/j.gastro.2007.03.017

1528-0012

Michael B. Wallace,

Gastric Cancer Management and Outcomes

Prevention of colorectal cancer (CRC) has become the central activity of most practicing gastroenterologists in the United States. The tool of our trade is the colonoscope. Without doubt, this technology has changed the practice of gastroenterology more than any other in the past 50 years. It is no surprise then, that we look intensively for new technological breakthroughs to further improve out ability to prevent CRC.Have We Placed Too Much Faith in Technology and Forgotten the Fundamentals of Good Technique?A growing body of evidence suggests that operator factors are as important as technology for improving CRC prevention. To measure quality in colonoscopy, whether applied to technique or technology, adenoma detection rate or miss rate has become the most accepted marker. Multiple studies1Rex D.K. Cutler C.S. Lemmel G.T. Rahmani E.Y. Clark D.W. Helper D.J. Lehman G.A. Mark D.G. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.Gastroenterology. 1997; 112: 24-28Abstract Full Text PDF PubMed Scopus (1375) Google Scholar, 2Postic G. Lewin D. Bickerstaff C. Wallace M.B. Colonoscopic miss rates determined by direct comparison of colonoscopy with colon resection specimens.Am J Gastroenterol. 2002; 97: 3182-3185Crossref PubMed Google Scholar have demonstrated that experienced gastroenterologists miss up to 6% of advanced adenomas and 24% of all adenomas. Why do we miss adenomatous polyps? The answer to this question is fundamental to addressing both technological and technique solutions for improvement. In simple terms, there are three scenarios for a missed adenoma.1. Polyp not detectedA polyp is not present in the field of endoscopic view due to anatomic locations, such as behind a fold or near the anal verge. The solutions to this problem are both technological (wide-angle viewing endoscopes) and technique (actively using the colonoscope to look behind folds and displacing folds to improve visualization).Endoscopes with a 2nd rear-view imaging system are now being actively studied.3Triadafilopoulos G. Watts D. Higgins J. Van Dam J. A novel retrograde-viewing auxiliary imaging device ("Third Eye Retroscope(TM)") improves the detection of simulated polyps in anatomical models of the colon.Gastrointest Endosc. 2006; 63: AB103Abstract Full Text Full Text PDF Google Scholar These systems allow simultaneous viewing in both forward and reverse directions. Circumstantial evidence from dual view systems comes from the virtual colonoscopy literature.4Silva A.C. Wellnitz C.V. Hara A.K. Three-dimensional virtual dissection at CT colonography: unraveling the colon to search for lesions.Radiographics. 2006; 26: 1669-1686Crossref PubMed Scopus (35) Google Scholar Wireless capsule endoscopes have also added dual views. The PillCam Eso (Given Imaging, Yoqneam, Israel) designed to examine the esophagus for Barrett's or varices and the PillCam Colon both use forward and reverse viewing cameras. Early trials on the esophageal pillcam suggest that the dual view can accurately detect both Barrett's epithelium and esophageal varices.5Eisen G.M. Eliakim R. Zaman A. Schwartz J. Faigel D. Rondonotti E. Villa F. Weizman E. Yassin K. deFranchis R. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study.Endoscopy. 2006; 38: 31-35Crossref PubMed Scopus (152) Google Scholar, 6Koslowsky B. Jacob H. Eliakim R. Adler S.N. PillCam ESO in esophageal studies: improved diagnostic yield of 14 frames per second (fps) compared with 4 fps.Endoscopy. 2006; 38: 27-30Crossref PubMed Scopus (67) Google Scholar Preliminary data on the dual-view pillcam colon also suggests some benefit of the dual view. The recently developed self-advanced Aer-o-scope (G.I. View Ltd, Ramat Gan, Israel) system for colonoscopy also uses wide-angle technology. Studies evaluating wide-angle colonoscopes have mixed results. Studies by Rex et al7Rex D.K. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar suggest that these colonoscopes reduced the adenoma miss rate for a single, highly experienced endoscopist, but actually increased adenoma miss rates when used by another colonoscopist. This suggests that advances in technology can be offset by user technique.Rex et al8Rex D.K. Colonoscopic withdrawal technique is associated with adenoma miss rates.Gastrointest Endosc. 2000; 51: 33-36Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar clearly demonstrated, using review of videotaped colonoscopies from a range of endoscopists with low and high adenoma detection rates, that colonoscopic techniques are highly associated with missed polyps. The most important of these techniques appears to be active back-and-forth inspection of regions behind folds and use of the colonoscope to displace or flatten folds. The amount of time inspecting the colon during withdrawal of the endoscope is also highly associated with adenoma detection rate.9Barclay R.L. Vicari J.J. Doughty A.S. Johanson J.F. Greenlaw R.L. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1074) Google Scholar Endoscopists who spent more time inspecting the colon had a 10-fold increase in adenoma detection.Although cross-study comparisons are limited, these data suggest that getting the polyp onto the screen is primarily an issue of technique and less of technology. As such, improvement efforts are better directed to improving endoscopic technique through monitoring (of adenoma detection rate, withdrawal time), education, and practice improvement interventions. In this area, waiting for a technological fix may distract us from the task at hand.2. Polyp recognizable but not recognizedSome polyps are within the field of view of a passing endoscope, but are not recognized by the endoscopist at the time of the procedure. Most of these polyps are small and of unclear clinical significance, but some are flat adenomas or even carcinomas with aggressive behavior. Improving the detection of these adenomas has both technical and technological solutions.Visual recognition research has consistent demonstrated that we "see what we look for."10Yotsumoto Y. Sekuler R. Out of mind, but not out of sight: intentional control of visual memory.Mem Cognit. 2006; 34: 776-786Crossref PubMed Scopus (13) Google Scholar Western gastroenterologists have only recently recognized that flat adenomas and carcinomas are present in the colon. In a tell-tale experiment, using back-to-back endoscopies on American patients by skilled Western and Eastern endoscopists, flat adenomas were indeed present and detectable, but only when they were actively searched for by endoscopists trained in the detection of flat lesions.11Saitoh Y. Waxman I. West A.B. Popnikolov N.K. Gatalica Z. Watari J. Obara T. Kohgo Y. Pasricha P.J. Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population.Gastroenterology. 2001; 120: 1657-1665Abstract Full Text Full Text PDF PubMed Scopus (353) Google Scholar Clues to their presence include subtle villiform texture, loss of vascular markings, and minimally raised morphology. Improving detection of recognizable but missed adenomas will also come predominantly from improved technique, particularly visual recognition of subtle patterns, and slow, careful inspection during colonoscopy. Technological advances may also improve detection of these adenomas by increasing the contrast between abnormal and normal tissue with methods such as chromoendoscopy, fluorescence, and narrow-band and multiband imaging, as well as exogenous contrast agents such as molecular imaging beacons.3. Polyp in field of view but not recognizableSome polyps are within the field of view, but have no distinguishing features compared with surrounding normal tissue and are thus unrecognizable without supplement methods. It is these polyps where technology has the most to offer. The most compelling evidence comes from randomized controlled trials of chromoendoscopy in high-risk patients. In chronic ulcerative colitis patients, Kiesslich et al12Kiesslich R. Fritsch J. Holtmann M. Koehler H.H. Stolte M. Kanzler S. Nafe B. Jung M. Galle P.R. Neurath M.F. Methylene blue-aided chromoendoscopy for the detection of intraepithelial neoplasia and colon cancer in ulcerative colitis.Gastroenterology. 2003; 124: 880-888Abstract Full Text Full Text PDF PubMed Scopus (778) Google Scholar showed that spraying the entire colon with a chromoendoscopy dye substantially increased the detection of dysplastic lesions compared to standard white light colonoscopy with random biopsy. In hereditary nonpolyposis colon cancer patients, Hurlstone et al13Hurlstone D.P. Karajeh M. Cross S.S. McAlindon M.E. Brown S. Hunter M.D. Sanders D.S. The role of high-magnification-chromoscopic colonoscopy in hereditary nonpolyposis colorectal cancer screening: a prospective "back-to-back" endoscopic study.Am J Gastroenterol. 2005; 100: 2167-2173Crossref PubMed Scopus (104) Google Scholar showed that panchromoendoscopy substantially increase the number and grade of adenomas detected compared with standard white light endoscopy (Figure 1).Newer digital chromoendoscopy methods, such as narrow-band and multiband imaging, produce contrast between polyps and normal in a way very similar to traditional chromoendoscopy, but without the variability in staining density, application, and washing techniques, and the inconvenience, mess, and cost of spraying dye agents throughout the colon. Both of these methods have now been coupled with high-resolution endoscopes, which may further improve lesion detection. Multiple studies are now underway, but data are not yet available in the colon. However, studies in Barrett's esophagus strongly suggest in an improvement in dysplasia detection.14Kara M.A. Bergman J.J. Autofluorescence imaging and narrow-band imaging for the detection of early neoplasia in patients with Barrett's esophagus.Endoscopy. 2006; 38: 627-631Crossref PubMed Scopus (75) Google ScholarSo will technology or technique come to the rescue? Numerous questions remain, such as what extent each of the 3 factors contributes to missed adenomas and which techniques, training, and technology will most improve adenoma detection. What is nearly certain, though, is that improvements in both technique and technology are needed; a retraining of our hands and eyes to put the polyp on the screen, and improved endoscopic imaging technologies to see the lesions we cannot otherwise see. Prevention of colorectal cancer (CRC) has become the central activity of most practicing gastroenterologists in the United States. The tool of our trade is the colonoscope. Without doubt, this technology has changed the practice of gastroenterology more than any other in the past 50 years. It is no surprise then, that we look intensively for new technological breakthroughs to further improve out ability to prevent CRC. Have We Placed Too Much Faith in Technology and Forgotten the Fundamentals of Good Technique?A growing body of evidence suggests that operator factors are as important as technology for improving CRC prevention. To measure quality in colonoscopy, whether applied to technique or technology, adenoma detection rate or miss rate has become the most accepted marker. Multiple studies1Rex D.K. Cutler C.S. Lemmel G.T. Rahmani E.Y. Clark D.W. Helper D.J. Lehman G.A. Mark D.G. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.Gastroenterology. 1997; 112: 24-28Abstract Full Text PDF PubMed Scopus (1375) Google Scholar, 2Postic G. Lewin D. Bickerstaff C. Wallace M.B. Colonoscopic miss rates determined by direct comparison of colonoscopy with colon resection specimens.Am J Gastroenterol. 2002; 97: 3182-3185Crossref PubMed Google Scholar have demonstrated that experienced gastroenterologists miss up to 6% of advanced adenomas and 24% of all adenomas. Why do we miss adenomatous polyps? The answer to this question is fundamental to addressing both technological and technique solutions for improvement. In simple terms, there are three scenarios for a missed adenoma.1. Polyp not detectedA polyp is not present in the field of endoscopic view due to anatomic locations, such as behind a fold or near the anal verge. The solutions to this problem are both technological (wide-angle viewing endoscopes) and technique (actively using the colonoscope to look behind folds and displacing folds to improve visualization).Endoscopes with a 2nd rear-view imaging system are now being actively studied.3Triadafilopoulos G. Watts D. Higgins J. Van Dam J. A novel retrograde-viewing auxiliary imaging device ("Third Eye Retroscope(TM)") improves the detection of simulated polyps in anatomical models of the colon.Gastrointest Endosc. 2006; 63: AB103Abstract Full Text Full Text PDF Google Scholar These systems allow simultaneous viewing in both forward and reverse directions. Circumstantial evidence from dual view systems comes from the virtual colonoscopy literature.4Silva A.C. Wellnitz C.V. Hara A.K. Three-dimensional virtual dissection at CT colonography: unraveling the colon to search for lesions.Radiographics. 2006; 26: 1669-1686Crossref PubMed Scopus (35) Google Scholar Wireless capsule endoscopes have also added dual views. The PillCam Eso (Given Imaging, Yoqneam, Israel) designed to examine the esophagus for Barrett's or varices and the PillCam Colon both use forward and reverse viewing cameras. Early trials on the esophageal pillcam suggest that the dual view can accurately detect both Barrett's epithelium and esophageal varices.5Eisen G.M. Eliakim R. Zaman A. Schwartz J. Faigel D. Rondonotti E. Villa F. Weizman E. Yassin K. deFranchis R. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study.Endoscopy. 2006; 38: 31-35Crossref PubMed Scopus (152) Google Scholar, 6Koslowsky B. Jacob H. Eliakim R. Adler S.N. PillCam ESO in esophageal studies: improved diagnostic yield of 14 frames per second (fps) compared with 4 fps.Endoscopy. 2006; 38: 27-30Crossref PubMed Scopus (67) Google Scholar Preliminary data on the dual-view pillcam colon also suggests some benefit of the dual view. The recently developed self-advanced Aer-o-scope (G.I. View Ltd, Ramat Gan, Israel) system for colonoscopy also uses wide-angle technology. Studies evaluating wide-angle colonoscopes have mixed results. Studies by Rex et al7Rex D.K. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar suggest that these colonoscopes reduced the adenoma miss rate for a single, highly experienced endoscopist, but actually increased adenoma miss rates when used by another colonoscopist. This suggests that advances in technology can be offset by user technique.Rex et al8Rex D.K. Colonoscopic withdrawal technique is associated with adenoma miss rates.Gastrointest Endosc. 2000; 51: 33-36Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar clearly demonstrated, using review of videotaped colonoscopies from a range of endoscopists with low and high adenoma detection rates, that colonoscopic techniques are highly associated with missed polyps. The most important of these techniques appears to be active back-and-forth inspection of regions behind folds and use of the colonoscope to displace or flatten folds. The amount of time inspecting the colon during withdrawal of the endoscope is also highly associated with adenoma detection rate.9Barclay R.L. Vicari J.J. Doughty A.S. Johanson J.F. Greenlaw R.L. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1074) Google Scholar Endoscopists who spent more time inspecting the colon had a 10-fold increase in adenoma detection.Although cross-study comparisons are limited, these data suggest that getting the polyp onto the screen is primarily an issue of technique and less of technology. As such, improvement efforts are better directed to improving endoscopic technique through monitoring (of adenoma detection rate, withdrawal time), education, and practice improvement interventions. In this area, waiting for a technological fix may distract us from the task at hand.2. Polyp recognizable but not recognizedSome polyps are within the field of view of a passing endoscope, but are not recognized by the endoscopist at the time of the procedure. Most of these polyps are small and of unclear clinical significance, but some are flat adenomas or even carcinomas with aggressive behavior. Improving the detection of these adenomas has both technical and technological solutions.Visual recognition research has consistent demonstrated that we "see what we look for."10Yotsumoto Y. Sekuler R. Out of mind, but not out of sight: intentional control of visual memory.Mem Cognit. 2006; 34: 776-786Crossref PubMed Scopus (13) Google Scholar Western gastroenterologists have only recently recognized that flat adenomas and carcinomas are present in the colon. In a tell-tale experiment, using back-to-back endoscopies on American patients by skilled Western and Eastern endoscopists, flat adenomas were indeed present and detectable, but only when they were actively searched for by endoscopists trained in the detection of flat lesions.11Saitoh Y. Waxman I. West A.B. Popnikolov N.K. Gatalica Z. Watari J. Obara T. Kohgo Y. Pasricha P.J. Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population.Gastroenterology. 2001; 120: 1657-1665Abstract Full Text Full Text PDF PubMed Scopus (353) Google Scholar Clues to their presence include subtle villiform texture, loss of vascular markings, and minimally raised morphology. Improving detection of recognizable but missed adenomas will also come predominantly from improved technique, particularly visual recognition of subtle patterns, and slow, careful inspection during colonoscopy. Technological advances may also improve detection of these adenomas by increasing the contrast between abnormal and normal tissue with methods such as chromoendoscopy, fluorescence, and narrow-band and multiband imaging, as well as exogenous contrast agents such as molecular imaging beacons.3. Polyp in field of view but not recognizableSome polyps are within the field of view, but have no distinguishing features compared with surrounding normal tissue and are thus unrecognizable without supplement methods. It is these polyps where technology has the most to offer. The most compelling evidence comes from randomized controlled trials of chromoendoscopy in high-risk patients. In chronic ulcerative colitis patients, Kiesslich et al12Kiesslich R. Fritsch J. Holtmann M. Koehler H.H. Stolte M. Kanzler S. Nafe B. Jung M. Galle P.R. Neurath M.F. Methylene blue-aided chromoendoscopy for the detection of intraepithelial neoplasia and colon cancer in ulcerative colitis.Gastroenterology. 2003; 124: 880-888Abstract Full Text Full Text PDF PubMed Scopus (778) Google Scholar showed that spraying the entire colon with a chromoendoscopy dye substantially increased the detection of dysplastic lesions compared to standard white light colonoscopy with random biopsy. In hereditary nonpolyposis colon cancer patients, Hurlstone et al13Hurlstone D.P. Karajeh M. Cross S.S. McAlindon M.E. Brown S. Hunter M.D. Sanders D.S. The role of high-magnification-chromoscopic colonoscopy in hereditary nonpolyposis colorectal cancer screening: a prospective "back-to-back" endoscopic study.Am J Gastroenterol. 2005; 100: 2167-2173Crossref PubMed Scopus (104) Google Scholar showed that panchromoendoscopy substantially increase the number and grade of adenomas detected compared with standard white light endoscopy (Figure 1).Newer digital chromoendoscopy methods, such as narrow-band and multiband imaging, produce contrast between polyps and normal in a way very similar to traditional chromoendoscopy, but without the variability in staining density, application, and washing techniques, and the inconvenience, mess, and cost of spraying dye agents throughout the colon. Both of these methods have now been coupled with high-resolution endoscopes, which may further improve lesion detection. Multiple studies are now underway, but data are not yet available in the colon. However, studies in Barrett's esophagus strongly suggest in an improvement in dysplasia detection.14Kara M.A. Bergman J.J. Autofluorescence imaging and narrow-band imaging for the detection of early neoplasia in patients with Barrett's esophagus.Endoscopy. 2006; 38: 627-631Crossref PubMed Scopus (75) Google ScholarSo will technology or technique come to the rescue? Numerous questions remain, such as what extent each of the 3 factors contributes to missed adenomas and which techniques, training, and technology will most improve adenoma detection. What is nearly certain, though, is that improvements in both technique and technology are needed; a retraining of our hands and eyes to put the polyp on the screen, and improved endoscopic imaging technologies to see the lesions we cannot otherwise see. A growing body of evidence suggests that operator factors are as important as technology for improving CRC prevention. To measure quality in colonoscopy, whether applied to technique or technology, adenoma detection rate or miss rate has become the most accepted marker. Multiple studies1Rex D.K. Cutler C.S. Lemmel G.T. Rahmani E.Y. Clark D.W. Helper D.J. Lehman G.A. Mark D.G. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.Gastroenterology. 1997; 112: 24-28Abstract Full Text PDF PubMed Scopus (1375) Google Scholar, 2Postic G. Lewin D. Bickerstaff C. Wallace M.B. Colonoscopic miss rates determined by direct comparison of colonoscopy with colon resection specimens.Am J Gastroenterol. 2002; 97: 3182-3185Crossref PubMed Google Scholar have demonstrated that experienced gastroenterologists miss up to 6% of advanced adenomas and 24% of all adenomas. Why do we miss adenomatous polyps? The answer to this question is fundamental to addressing both technological and technique solutions for improvement. In simple terms, there are three scenarios for a missed adenoma. 1. Polyp not detectedA polyp is not present in the field of endoscopic view due to anatomic locations, such as behind a fold or near the anal verge. The solutions to this problem are both technological (wide-angle viewing endoscopes) and technique (actively using the colonoscope to look behind folds and displacing folds to improve visualization).Endoscopes with a 2nd rear-view imaging system are now being actively studied.3Triadafilopoulos G. Watts D. Higgins J. Van Dam J. A novel retrograde-viewing auxiliary imaging device ("Third Eye Retroscope(TM)") improves the detection of simulated polyps in anatomical models of the colon.Gastrointest Endosc. 2006; 63: AB103Abstract Full Text Full Text PDF Google Scholar These systems allow simultaneous viewing in both forward and reverse directions. Circumstantial evidence from dual view systems comes from the virtual colonoscopy literature.4Silva A.C. Wellnitz C.V. Hara A.K. Three-dimensional virtual dissection at CT colonography: unraveling the colon to search for lesions.Radiographics. 2006; 26: 1669-1686Crossref PubMed Scopus (35) Google Scholar Wireless capsule endoscopes have also added dual views. The PillCam Eso (Given Imaging, Yoqneam, Israel) designed to examine the esophagus for Barrett's or varices and the PillCam Colon both use forward and reverse viewing cameras. Early trials on the esophageal pillcam suggest that the dual view can accurately detect both Barrett's epithelium and esophageal varices.5Eisen G.M. Eliakim R. Zaman A. Schwartz J. Faigel D. Rondonotti E. Villa F. Weizman E. Yassin K. deFranchis R. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study.Endoscopy. 2006; 38: 31-35Crossref PubMed Scopus (152) Google Scholar, 6Koslowsky B. Jacob H. Eliakim R. Adler S.N. PillCam ESO in esophageal studies: improved diagnostic yield of 14 frames per second (fps) compared with 4 fps.Endoscopy. 2006; 38: 27-30Crossref PubMed Scopus (67) Google Scholar Preliminary data on the dual-view pillcam colon also suggests some benefit of the dual view. The recently developed self-advanced Aer-o-scope (G.I. View Ltd, Ramat Gan, Israel) system for colonoscopy also uses wide-angle technology. Studies evaluating wide-angle colonoscopes have mixed results. Studies by Rex et al7Rex D.K. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar suggest that these colonoscopes reduced the adenoma miss rate for a single, highly experienced endoscopist, but actually increased adenoma miss rates when used by another colonoscopist. This suggests that advances in technology can be offset by user technique.Rex et al8Rex D.K. Colonoscopic withdrawal technique is associated with adenoma miss rates.Gastrointest Endosc. 2000; 51: 33-36Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar clearly demonstrated, using review of videotaped colonoscopies from a range of endoscopists with low and high adenoma detection rates, that colonoscopic techniques are highly associated with missed polyps. The most important of these techniques appears to be active back-and-forth inspection of regions behind folds and use of the colonoscope to displace or flatten folds. The amount of time inspecting the colon during withdrawal of the endoscope is also highly associated with adenoma detection rate.9Barclay R.L. Vicari J.J. Doughty A.S. Johanson J.F. Greenlaw R.L. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1074) Google Scholar Endoscopists who spent more time inspecting the colon had a 10-fold increase in adenoma detection.Although cross-study comparisons are limited, these data suggest that getting the polyp onto the screen is primarily an issue of technique and less of technology. As such, improvement efforts are better directed to improving endoscopic technique through monitoring (of adenoma detection rate, withdrawal time), education, and practice improvement interventions. In this area, waiting for a technological fix may distract us from the task at hand. A polyp is not present in the field of endoscopic view due to anatomic locations, such as behind a fold or near the anal verge. The solutions to this problem are both technological (wide-angle viewing endoscopes) and technique (actively using the colonoscope to look behind folds and displacing folds to improve visualization). Endoscopes with a 2nd rear-view imaging system are now being actively studied.3Triadafilopoulos G. Watts D. Higgins J. Van Dam J. A novel retrograde-viewing auxiliary imaging device ("Third Eye Retroscope(TM)") improves the detection of simulated polyps in anatomical models of the colon.Gastrointest Endosc. 2006; 63: AB103Abstract Full Text Full Text PDF Google Scholar These systems allow simultaneous viewing in both forward and reverse directions. Circumstantial evidence from dual view systems comes from the virtual colonoscopy literature.4Silva A.C. Wellnitz C.V. Hara A.K. Three-dimensional virtual dissection at CT colonography: unraveling the colon to search for lesions.Radiographics. 2006; 26: 1669-1686Crossref PubMed Scopus (35) Google Scholar Wireless capsule endoscopes have also added dual views. The PillCam Eso (Given Imaging, Yoqneam, Israel) designed to examine the esophagus for Barrett's or varices and the PillCam Colon both use forward and reverse viewing cameras. Early trials on the esophageal pillcam suggest that the dual view can accurately detect both Barrett's epithelium and esophageal varices.5Eisen G.M. Eliakim R. Zaman A. Schwartz J. Faigel D. Rondonotti E. Villa F. Weizman E. Yassin K. deFranchis R. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study.Endoscopy. 2006; 38: 31-35Crossref PubMed Scopus (152) Google Scholar, 6Koslowsky B. Jacob H. Eliakim R. Adler S.N. PillCam ESO in esophageal studies: improved diagnostic yield of 14 frames per second (fps) compared with 4 fps.Endoscopy. 2006; 38: 27-30Crossref PubMed Scopus (67) Google Scholar Preliminary data on the dual-view pillcam colon also suggests some benefit of the dual view. The recently developed self-advanced Aer-o-scope (G.I. View Ltd, Ramat Gan, Israel) system for colonoscopy also uses wide-angle technology. Studies evaluating wide-angle colonoscopes have mixed results. Studies by Rex et al7Rex D.K. Chadalawada V. Helper D.J. Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies.Am J Gastroenterol. 2003; 98: 2000-2005Crossref PubMed Scopus (114) Google Scholar suggest that these colonoscopes reduced the adenoma miss rate for a single, highly experienced endoscopist, but actually increased adenoma miss rates when used by another colonoscopist. This suggests that advances in technology can be offset by user technique. Rex et al8Rex D.K. Colonoscopic withdrawal technique is associated with adenoma miss rates.Gastrointest Endosc. 2000; 51: 33-36Abstract Full Text Full Text PDF PubMed Scopus (333) Google Scholar clearly demonstrated, using review of videotaped colonoscopies from a range of endoscopists with low and high adenoma detection rates, that colonoscopic techniques are highly associated with missed polyps. The most important of these techniques appears to be active back-and-forth inspection of regions behind folds and use of the colonoscope to displace or flatten folds. The amount of time inspecting the colon during withdrawal of the endoscope is also highly associated with adenoma detection rate.9Barclay R.L. Vicari J.J. Doughty A.S. Johanson J.F. Greenlaw R.L. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1074) Google Scholar Endoscopists who spent more time inspecting the colon had a 10-fold increase in adenoma detection. Although cross-study comparisons are limited, these data suggest that getting the polyp onto the screen is primarily an issue of technique and less of technology. As such, improvement efforts are better directed to improving endoscopic technique through monitoring (of adenoma detection rate, withdrawal time), education, and practice improvement interventions. In this area, waiting for a technological fix may distract us from the task at hand. 2. Polyp recognizable but not recognizedSome polyps are within the field of view of a passing endoscope, but are not recognized by the endoscopist at the time of the procedure. Most of these polyps are small and of unclear clinical significance, but some are flat adenomas or even carcinomas with aggressive behavior. Improving the detection of these adenomas has both technical and technological solutions.Visual recognition research has consistent demonstrated that we "see what we look for."10Yotsumoto Y. Sekuler R. Out of mind, but not out of sight: intentional control of visual memory.Mem Cognit. 2006; 34: 776-786Crossref PubMed Scopus (13) Google Scholar Western gastroenterologists have only recently recognized that flat adenomas and carcinomas are present in the colon. In a tell-tale experiment, using back-to-back endoscopies on American patients by skilled Western and Eastern endoscopists, flat adenomas were indeed present and detectable, but only when they were actively searched for by endoscopists trained in the detection of flat lesions.11Saitoh Y. Waxman I. West A.B. Popnikolov N.K. Gatalica Z. Watari J. Obara T. Kohgo Y. Pasricha P.J. Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population.Gastroenterology. 2001; 120: 1657-1665Abstract Full Text Full Text PDF PubMed Scopus (353) Google Scholar Clues to their presence include subtle villiform texture, loss of vascular markings, and minimally raised morphology. Improving detection of recognizable but missed adenomas will also come predominantly from improved technique, particularly visual recognition of subtle patterns, and slow, careful inspection during colonoscopy. Technological advances may also improve detection of these adenomas by increasing the contrast between abnormal and normal tissue with methods such as chromoendoscopy, fluorescence, and narrow-band and multiband imaging, as well as exogenous contrast agents such as molecular imaging beacons. Some polyps are within the field of view of a passing endoscope, but are not recognized by the endoscopist at the time of the procedure. Most of these polyps are small and of unclear clinical significance, but some are flat adenomas or even carcinomas with aggressive behavior. Improving the detection of these adenomas has both technical and technological solutions. Visual recognition research has consistent demonstrated that we "see what we look for."10Yotsumoto Y. Sekuler R. Out of mind, but not out of sight: intentional control of visual memory.Mem Cognit. 2006; 34: 776-786Crossref PubMed Scopus (13) Google Scholar Western gastroenterologists have only recently recognized that flat adenomas and carcinomas are present in the colon. In a tell-tale experiment, using back-to-back endoscopies on American patients by skilled Western and Eastern endoscopists, flat adenomas were indeed present and detectable, but only when they were actively searched for by endoscopists trained in the detection of flat lesions.11Saitoh Y. Waxman I. West A.B. Popnikolov N.K. Gatalica Z. Watari J. Obara T. Kohgo Y. Pasricha P.J. Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population.Gastroenterology. 2001; 120: 1657-1665Abstract Full Text Full Text PDF PubMed Scopus (353) Google Scholar Clues to their presence include subtle villiform texture, loss of vascular markings, and minimally raised morphology. Improving detection of recognizable but missed adenomas will also come predominantly from improved technique, particularly visual recognition of subtle patterns, and slow, careful inspection during colonoscopy. Technological advances may also improve detection of these adenomas by increasing the contrast between abnormal and normal tissue with methods such as chromoendoscopy, fluorescence, and narrow-band and multiband imaging, as well as exogenous contrast agents such as molecular imaging beacons. 3. Polyp in field of view but not recognizableSome polyps are within the field of view, but have no distinguishing features compared with surrounding normal tissue and are thus unrecognizable without supplement methods. It is these polyps where technology has the most to offer. The most compelling evidence comes from randomized controlled trials of chromoendoscopy in high-risk patients. In chronic ulcerative colitis patients, Kiesslich et al12Kiesslich R. Fritsch J. Holtmann M. Koehler H.H. Stolte M. Kanzler S. Nafe B. Jung M. Galle P.R. Neurath M.F. Methylene blue-aided chromoendoscopy for the detection of intraepithelial neoplasia and colon cancer in ulcerative colitis.Gastroenterology. 2003; 124: 880-888Abstract Full Text Full Text PDF PubMed Scopus (778) Google Scholar showed that spraying the entire colon with a chromoendoscopy dye substantially increased the detection of dysplastic lesions compared to standard white light colonoscopy with random biopsy. In hereditary nonpolyposis colon cancer patients, Hurlstone et al13Hurlstone D.P. Karajeh M. Cross S.S. McAlindon M.E. Brown S. Hunter M.D. Sanders D.S. The role of high-magnification-chromoscopic colonoscopy in hereditary nonpolyposis colorectal cancer screening: a prospective "back-to-back" endoscopic study.Am J Gastroenterol. 2005; 100: 2167-2173Crossref PubMed Scopus (104) Google Scholar showed that panchromoendoscopy substantially increase the number and grade of adenomas detected compared with standard white light endoscopy (Figure 1).Newer digital chromoendoscopy methods, such as narrow-band and multiband imaging, produce contrast between polyps and normal in a way very similar to traditional chromoendoscopy, but without the variability in staining density, application, and washing techniques, and the inconvenience, mess, and cost of spraying dye agents throughout the colon. Both of these methods have now been coupled with high-resolution endoscopes, which may further improve lesion detection. Multiple studies are now underway, but data are not yet available in the colon. However, studies in Barrett's esophagus strongly suggest in an improvement in dysplasia detection.14Kara M.A. Bergman J.J. Autofluorescence imaging and narrow-band imaging for the detection of early neoplasia in patients with Barrett's esophagus.Endoscopy. 2006; 38: 627-631Crossref PubMed Scopus (75) Google ScholarSo will technology or technique come to the rescue? Numerous questions remain, such as what extent each of the 3 factors contributes to missed adenomas and which techniques, training, and technology will most improve adenoma detection. What is nearly certain, though, is that improvements in both technique and technology are needed; a retraining of our hands and eyes to put the polyp on the screen, and improved endoscopic imaging technologies to see the lesions we cannot otherwise see. Some polyps are within the field of view, but have no distinguishing features compared with surrounding normal tissue and are thus unrecognizable without supplement methods. It is these polyps where technology has the most to offer. The most compelling evidence comes from randomized controlled trials of chromoendoscopy in high-risk patients. In chronic ulcerative colitis patients, Kiesslich et al12Kiesslich R. Fritsch J. Holtmann M. Koehler H.H. Stolte M. Kanzler S. Nafe B. Jung M. Galle P.R. Neurath M.F. Methylene blue-aided chromoendoscopy for the detection of intraepithelial neoplasia and colon cancer in ulcerative colitis.Gastroenterology. 2003; 124: 880-888Abstract Full Text Full Text PDF PubMed Scopus (778) Google Scholar showed that spraying the entire colon with a chromoendoscopy dye substantially increased the detection of dysplastic lesions compared to standard white light colonoscopy with random biopsy. In hereditary nonpolyposis colon cancer patients, Hurlstone et al13Hurlstone D.P. Karajeh M. Cross S.S. McAlindon M.E. Brown S. Hunter M.D. Sanders D.S. The role of high-magnification-chromoscopic colonoscopy in hereditary nonpolyposis colorectal cancer screening: a prospective "back-to-back" endoscopic study.Am J Gastroenterol. 2005; 100: 2167-2173Crossref PubMed Scopus (104) Google Scholar showed that panchromoendoscopy substantially increase the number and grade of adenomas detected compared with standard white light endoscopy (Figure 1). Newer digital chromoendoscopy methods, such as narrow-band and multiband imaging, produce contrast between polyps and normal in a way very similar to traditional chromoendoscopy, but without the variability in staining density, application, and washing techniques, and the inconvenience, mess, and cost of spraying dye agents throughout the colon. Both of these methods have now been coupled with high-resolution endoscopes, which may further improve lesion detection. Multiple studies are now underway, but data are not yet available in the colon. However, studies in Barrett's esophagus strongly suggest in an improvement in dysplasia detection.14Kara M.A. Bergman J.J. Autofluorescence imaging and narrow-band imaging for the detection of early neoplasia in patients with Barrett's esophagus.Endoscopy. 2006; 38: 627-631Crossref PubMed Scopus (75) Google Scholar So will technology or technique come to the rescue? Numerous questions remain, such as what extent each of the 3 factors contributes to missed adenomas and which techniques, training, and technology will most improve adenoma detection. What is nearly certain, though, is that improvements in both technique and technology are needed; a retraining of our hands and eyes to put the polyp on the screen, and improved endoscopic imaging technologies to see the lesions we cannot otherwise see.