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Image-enhanced endoscopy: How far do we need to go?
EDITORIAL
Image-enhanced endoscopy: How far do we need to go? Flat tumors and laterally spreading tumors (LSTs) have greater malignant potential than polypoid lesions and are harder to detect during colonoscopy.1,2 Yet, their detection and detection of sessile serrated polyps (SSPs) continue to be a challenge. Tandem colonoscopy studies showed that 1 in 4 adenomas (particularly flat ones) could be missed during colonoscopy.3 When missed, they can lead to cancers. Close to 60% of postcolonoscopy colorectal cancers were attributed to missed lesions during prior colonoscopy.4 Much hope had been given that image-enhanced endoscopy (IEE) can improve our detection capability. However, studies on the effectiveness of IEE, such as narrow-band imaging (NBI), to improve colon polyp detection rates have been less than ideal.5,6 It was believed that perhaps the brightness of the first-generation NBI was not adequate. Thus, the main focus for improvement of IEE in the past few years has been on increasing brightness and image resolution. Other technologies have also been devised. In fact, the blue laser imaging bright (Fujifilm Co, Tokyo, Japan) and the second-generation NBI (Olympus America) are now commercially available. Some studies using these technologies have shown a higher colonic polyp detection rate, including the detection of the flat lesions.7,8 Others have not found a similar positive finding.9,10 We are particularly pleased to see that the efforts to produce an improved technology have continued. Linked color imaging (LCI) is a newly developed IEE modality that is based on the BLI technique with additional digital image processing. It uses a laser light source (Lasereo system, Fujifilm), and the technology is built into the conventional endoscope system. The LCI produces a brighter and clearer endoscopic view compared with BLI by using short-wavelength narrow-band laser light combined with more intense white laser light. Moreover, through digital image processing, LCI enhances the differences in color contrast in the red region of the spectrum, so the red color appears more vivid (red areas appear more red and white areas appear whiter).11 Thus, given brighter blood vessels in the background mucosa, lesions that interrupt the blood vessels (even lesions with slight tone differences such as SSPs) can be detected more clearly.12
In this month’s issue of Gastrointestinal Endoscopy, Suzuki et al13 report a study using LCI to evaluate the visibility of flat colonic lesions. Endoscopic images of 53 consecutive nongranular-type laterally spreading tumors 10 mm were evaluated between May 2015 and May 2016. Colonoscopy was performed by use of a Lasereo system (Fujifilm) with EC-L590ZP or L600ZP endoscopes.13 One image obtained by use of white-light imaging (WLI), BLI-bright, and LCI of the same lesion was obtained from a middle or distant view. A set of 53 images for each modality was presented to 6 endoscopists for interpretation. The 3 sets of the different modalities
This technology could be an important step toward perfecting endoscopic imaging; however, these results have to be confirmed in large clinical trials showing an improved detection rate and a decreased miss rate of colonic neoplasia.
Copyright ª 2017 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2017.05.002
were presented to each endoscopist on different days. The images, of the same size as those obtained by routine endoscopic monitoring, were electronically presented without zooming. The level of visibility was scored according to a 4-point scale: score 4, excellent; score 3, good (detectable with careful observation); score 2, fair (hardly detectable without careful examination); and score 1, poor (not detectable without repeated careful examination). The mean visibility scores of the 6 endoscopists were 2.74 1.08 for WLI, 2.94 0.97 for BLI-bright, and 3.36 0.72 for LCI. The score for LCI was significantly higher than that for BLI-bright (P < .001), which was also significantly higher than that for WLI (P < .001). LCI also performed significantly better than BLI-bright and WLI for SSPs, althoughdas one would expectdthe scores were lower than the respective scores in the non-SSP lesions. The authors concluded that the LCI technology improved the visibility of colon flat tumors in comparison with WLI and BLI-bright. However, there are limitations to the study that need to be overcome before a definite conclusion can be made about the utility of this new
698 GASTROINTESTINAL ENDOSCOPY Volume 86, No. 4 : 2017
www.giejournal.org
Hammad et al
technology. As the authors recognized, the number of lesions evaluated was relatively small. The performance of LCI was also assessed by the use of still endoscopic images focused on the lesion site. Using video clips could be more reflective of real-time colonoscopy polyp detection. Although it would be impractical to blind the interpreters to the image modality (because the modality can be identified just by looking at the images), recruiting interpreters from the same institution (as in this study) could cause significant bias, given their prior awareness of these novel technologies. It is also noteworthy that the visibility of colonic polyps was assessed according to a 4-point visibility scale; however, validation of the clinical utility of this scoring system was not assessed. For example, in a colonoscopy video study in which the same visibility score was used, new-generation NBI (Exera-III, Olympus America, Center Valley, Pa) was shown to improve polyp visibility in comparison with WLI (mean visibility score 3.14 vs 2.75, P < .0001); however, recently presented data from a tandem colonoscopy study showed no improvement in polyp detection with use of the same technology.8,10 A recent multicenter, crossover, prospective, randomized controlled trial comparing LCI and WLI endoscopy in 141 patients showed an overall increased polyp detection rate with the use of LCI compared with WLI (sensitivity 91% vs 73%, P < .0001); however, there was no significant difference in the adenoma detection rate (92% vs 85%, P Z .09).14 This technology could be an important step toward perfecting endoscopic imaging; however, these results have to be confirmed in large clinical trials showing an improved detection rate and a decreased miss rate of colonic neoplasia. We certainly hope that continuing improvement of the technology of IEE will be successful in improving the detection of flat lesions. Such a technology and, perhaps, the use of artificial intelligence to design computerized endoscopic diagnostic tools that quantitatively evaluate the quality of the endoscopic images and differentiate lesions based on image and lesion characteristics can help us attain that goal.12,15 DISCLOSURE Dr Kaltenbach and Dr Soetikno are consultants for Olympus America. The other author disclosed no financial relationships relevant to this publication. Hazem Hammad, MD Division of Gastroenterology and Hepatology Section of Advanced Therapeutic Endoscopy University of Colorado Anschutz Medical Campus
www.giejournal.org
Editorial
Tonya Kaltenbach, MD, MS University of California San Francisco Division of Gastroenterology Department of Medicine San Francisco Veterans Affairs Medical Center Roy Soetikno, MD, MS Graduate School of Business Stanford, California, USA Abbreviations: BLI, blue laser imaging; IEE, image-enhanced endoscopy; LCI, linked color imaging; NBI, narrow-band imaging; SSPs, sessile serrated polyps; WLI, white-light imaging.
REFERENCES 1. Kaku E, Oda Y, Murakami Y, et al. Proportion of flat- and depressedtype and laterally spreading tumor among advanced colorectal neoplasia. Clin Gastroenterol Hepatol 2011;9:503-8. 2. Soetikno RM, Kaltenbach T, Rouse RV, et al. Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults. JAMA 2008;299:1027-35. 3. Heresbach D, Barrioz T, Lapalus MG, et al. Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies. Endoscopy 2008;40:284-90. 4. le Clercq CM, Bouwens MW, Rondagh EJ, et al. Postcolonoscopy colorectal cancers are preventable: 1 population-based study. Gut 2014;63:957-63. 5. Kaltenbach 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;57:1406-12. 6. Aldler A, Aschenbeck J, Yenerim T, et al. Narrow-band versus white-light high definition television endoscopic imaging for screening colonoscopy: a prospective randomised trial. Gastroenterology 2009;136:410-6. 7. Yoshida N, Hisabe T, Hirose R, et al. Improvement in the visibility of colorectal polyps by using blue laser imaging. Gastrointest Endosc 2015;82:542-9. 8. Ogiso K, Yoshida N, Siah KT, et al. New-generation narrow band imaging improves visibility of polyps: a colonoscopy video evaluation study. J Gastroenterol 2016;51:883-90. 9. Oka S, Tamai N, Ikematsu H, et al. Improved visibility of colorectal flat tumors using image-enhanced endoscopy. Digestive Endosc 2015;27: 35-9. 10. Kaltenbach T, Soetikno R, Bansal A, et al. New generation narrow band imaging (n-NBI) for the detection of nonpolypoid and sessile serrated colorectal lesions by trainees and experts: a multicenter randomized tandem colonoscopy study. DDW 2017. 11. Okada M, Sakamoto H, Takezawa T, et al. Laterally spreading tumor of the rectum delineated with linked color imaging technology. Clin Endosc 2016;49:207-8. 12. Sun X, Dong T, Bi Y, et al. Linked color imaging application for improving the endoscopic diagnosis accuracy: a pilot study. Sci Rep 2016;6:33473. 13. Suzuki T, Hara T, Kitagawa Y, et al. Linked-color imaging improves endoscopic visibility of colorectal nongranular flat lesions. Gastrointest Endosc 2017;86:692-7. 14. Min M, Deng P, Zhang W, et al. Comparison of linked color imaging and white-light colonoscopy for colorectal polyp detection: a multicenter, randomized, crossover trial. Gastrointest Endosc. Epub 2017 Mar 9. 15. Miyaki R, Yoshida S, Tanaka S, et al. A computer system to be used with laser-based endoscopy for quantitative diagnosis of early gastric cancer. J Clin Gastroenterol 2015;49:108-15.
Volume 86, No. 4 : 2017 GASTROINTESTINAL ENDOSCOPY 699
Image-enhanced endoscopy: How far do we need to go? Flat tumors and laterally spreading tumors (LSTs) have greater malignant potential than polypoid lesions and are harder to detect during colonoscopy.1,2 Yet, their detection and detection of sessile serrated polyps (SSPs) continue to be a challenge. Tandem colonoscopy studies showed that 1 in 4 adenomas (particularly flat ones) could be missed during colonoscopy.3 When missed, they can lead to cancers. Close to 60% of postcolonoscopy colorectal cancers were attributed to missed lesions during prior colonoscopy.4 Much hope had been given that image-enhanced endoscopy (IEE) can improve our detection capability. However, studies on the effectiveness of IEE, such as narrow-band imaging (NBI), to improve colon polyp detection rates have been less than ideal.5,6 It was believed that perhaps the brightness of the first-generation NBI was not adequate. Thus, the main focus for improvement of IEE in the past few years has been on increasing brightness and image resolution. Other technologies have also been devised. In fact, the blue laser imaging bright (Fujifilm Co, Tokyo, Japan) and the second-generation NBI (Olympus America) are now commercially available. Some studies using these technologies have shown a higher colonic polyp detection rate, including the detection of the flat lesions.7,8 Others have not found a similar positive finding.9,10 We are particularly pleased to see that the efforts to produce an improved technology have continued. Linked color imaging (LCI) is a newly developed IEE modality that is based on the BLI technique with additional digital image processing. It uses a laser light source (Lasereo system, Fujifilm), and the technology is built into the conventional endoscope system. The LCI produces a brighter and clearer endoscopic view compared with BLI by using short-wavelength narrow-band laser light combined with more intense white laser light. Moreover, through digital image processing, LCI enhances the differences in color contrast in the red region of the spectrum, so the red color appears more vivid (red areas appear more red and white areas appear whiter).11 Thus, given brighter blood vessels in the background mucosa, lesions that interrupt the blood vessels (even lesions with slight tone differences such as SSPs) can be detected more clearly.12
In this month’s issue of Gastrointestinal Endoscopy, Suzuki et al13 report a study using LCI to evaluate the visibility of flat colonic lesions. Endoscopic images of 53 consecutive nongranular-type laterally spreading tumors 10 mm were evaluated between May 2015 and May 2016. Colonoscopy was performed by use of a Lasereo system (Fujifilm) with EC-L590ZP or L600ZP endoscopes.13 One image obtained by use of white-light imaging (WLI), BLI-bright, and LCI of the same lesion was obtained from a middle or distant view. A set of 53 images for each modality was presented to 6 endoscopists for interpretation. The 3 sets of the different modalities
This technology could be an important step toward perfecting endoscopic imaging; however, these results have to be confirmed in large clinical trials showing an improved detection rate and a decreased miss rate of colonic neoplasia.
Copyright ª 2017 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2017.05.002
were presented to each endoscopist on different days. The images, of the same size as those obtained by routine endoscopic monitoring, were electronically presented without zooming. The level of visibility was scored according to a 4-point scale: score 4, excellent; score 3, good (detectable with careful observation); score 2, fair (hardly detectable without careful examination); and score 1, poor (not detectable without repeated careful examination). The mean visibility scores of the 6 endoscopists were 2.74 1.08 for WLI, 2.94 0.97 for BLI-bright, and 3.36 0.72 for LCI. The score for LCI was significantly higher than that for BLI-bright (P < .001), which was also significantly higher than that for WLI (P < .001). LCI also performed significantly better than BLI-bright and WLI for SSPs, althoughdas one would expectdthe scores were lower than the respective scores in the non-SSP lesions. The authors concluded that the LCI technology improved the visibility of colon flat tumors in comparison with WLI and BLI-bright. However, there are limitations to the study that need to be overcome before a definite conclusion can be made about the utility of this new
698 GASTROINTESTINAL ENDOSCOPY Volume 86, No. 4 : 2017
www.giejournal.org
Hammad et al
technology. As the authors recognized, the number of lesions evaluated was relatively small. The performance of LCI was also assessed by the use of still endoscopic images focused on the lesion site. Using video clips could be more reflective of real-time colonoscopy polyp detection. Although it would be impractical to blind the interpreters to the image modality (because the modality can be identified just by looking at the images), recruiting interpreters from the same institution (as in this study) could cause significant bias, given their prior awareness of these novel technologies. It is also noteworthy that the visibility of colonic polyps was assessed according to a 4-point visibility scale; however, validation of the clinical utility of this scoring system was not assessed. For example, in a colonoscopy video study in which the same visibility score was used, new-generation NBI (Exera-III, Olympus America, Center Valley, Pa) was shown to improve polyp visibility in comparison with WLI (mean visibility score 3.14 vs 2.75, P < .0001); however, recently presented data from a tandem colonoscopy study showed no improvement in polyp detection with use of the same technology.8,10 A recent multicenter, crossover, prospective, randomized controlled trial comparing LCI and WLI endoscopy in 141 patients showed an overall increased polyp detection rate with the use of LCI compared with WLI (sensitivity 91% vs 73%, P < .0001); however, there was no significant difference in the adenoma detection rate (92% vs 85%, P Z .09).14 This technology could be an important step toward perfecting endoscopic imaging; however, these results have to be confirmed in large clinical trials showing an improved detection rate and a decreased miss rate of colonic neoplasia. We certainly hope that continuing improvement of the technology of IEE will be successful in improving the detection of flat lesions. Such a technology and, perhaps, the use of artificial intelligence to design computerized endoscopic diagnostic tools that quantitatively evaluate the quality of the endoscopic images and differentiate lesions based on image and lesion characteristics can help us attain that goal.12,15 DISCLOSURE Dr Kaltenbach and Dr Soetikno are consultants for Olympus America. The other author disclosed no financial relationships relevant to this publication. Hazem Hammad, MD Division of Gastroenterology and Hepatology Section of Advanced Therapeutic Endoscopy University of Colorado Anschutz Medical Campus
www.giejournal.org
Editorial
Tonya Kaltenbach, MD, MS University of California San Francisco Division of Gastroenterology Department of Medicine San Francisco Veterans Affairs Medical Center Roy Soetikno, MD, MS Graduate School of Business Stanford, California, USA Abbreviations: BLI, blue laser imaging; IEE, image-enhanced endoscopy; LCI, linked color imaging; NBI, narrow-band imaging; SSPs, sessile serrated polyps; WLI, white-light imaging.
REFERENCES 1. Kaku E, Oda Y, Murakami Y, et al. Proportion of flat- and depressedtype and laterally spreading tumor among advanced colorectal neoplasia. Clin Gastroenterol Hepatol 2011;9:503-8. 2. Soetikno RM, Kaltenbach T, Rouse RV, et al. Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults. JAMA 2008;299:1027-35. 3. Heresbach D, Barrioz T, Lapalus MG, et al. Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies. Endoscopy 2008;40:284-90. 4. le Clercq CM, Bouwens MW, Rondagh EJ, et al. Postcolonoscopy colorectal cancers are preventable: 1 population-based study. Gut 2014;63:957-63. 5. Kaltenbach 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;57:1406-12. 6. Aldler A, Aschenbeck J, Yenerim T, et al. Narrow-band versus white-light high definition television endoscopic imaging for screening colonoscopy: a prospective randomised trial. Gastroenterology 2009;136:410-6. 7. Yoshida N, Hisabe T, Hirose R, et al. Improvement in the visibility of colorectal polyps by using blue laser imaging. Gastrointest Endosc 2015;82:542-9. 8. Ogiso K, Yoshida N, Siah KT, et al. New-generation narrow band imaging improves visibility of polyps: a colonoscopy video evaluation study. J Gastroenterol 2016;51:883-90. 9. Oka S, Tamai N, Ikematsu H, et al. Improved visibility of colorectal flat tumors using image-enhanced endoscopy. Digestive Endosc 2015;27: 35-9. 10. Kaltenbach T, Soetikno R, Bansal A, et al. New generation narrow band imaging (n-NBI) for the detection of nonpolypoid and sessile serrated colorectal lesions by trainees and experts: a multicenter randomized tandem colonoscopy study. DDW 2017. 11. Okada M, Sakamoto H, Takezawa T, et al. Laterally spreading tumor of the rectum delineated with linked color imaging technology. Clin Endosc 2016;49:207-8. 12. Sun X, Dong T, Bi Y, et al. Linked color imaging application for improving the endoscopic diagnosis accuracy: a pilot study. Sci Rep 2016;6:33473. 13. Suzuki T, Hara T, Kitagawa Y, et al. Linked-color imaging improves endoscopic visibility of colorectal nongranular flat lesions. Gastrointest Endosc 2017;86:692-7. 14. Min M, Deng P, Zhang W, et al. Comparison of linked color imaging and white-light colonoscopy for colorectal polyp detection: a multicenter, randomized, crossover trial. Gastrointest Endosc. Epub 2017 Mar 9. 15. Miyaki R, Yoshida S, Tanaka S, et al. A computer system to be used with laser-based endoscopy for quantitative diagnosis of early gastric cancer. J Clin Gastroenterol 2015;49:108-15.
Volume 86, No. 4 : 2017 GASTROINTESTINAL ENDOSCOPY 699