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History, clinical application, and future perspective of narrow band imaging and blue laser imaging

2022; Wiley; Volume: 34; Issue: S2 Linguagem: Inglês

10.1111/den.14228

1443-1661

Naohisa Yoshida, Yasushi Sano,

Gastric Cancer Management and Outcomes

Development of the NBI endoscopic system (Olympus Medical Systems, Tokyo, Japan) started at the National Cancer Center East Hospital by Dr Sano, Dr Muto and Mr Gono under the leadership of Professor Shigeaki Yoshida and Professor Hisao Tajiri in 1999.1, 2 NBI provides observation though irradiating light with two narrow-banded wavelengths (blue light 390–445 nm and green light 530–550 nm) which are easily absorbed by hemoglobin in the blood, highlighting capillaries and mucosal micropatterns in the mucosal surface layer. As cancerous tissues try to enlarge themselves by expanding blood vessels to take in nutrients, the surface of the mucosa changes into an intricate pattern with more capillaries as cancer expands, thus the use of NBI is helpful for early detection of cancer (Fig. 1). Antoine de Saint-Exupéry once wrote in The Little Prince that “what is essential is invisible to the eye”. He wrote, “anything essential is invisible to the eye. It is only in the heart that one can see rightly. One tends to make judgments based on what one can see and in one's own way, but what one can see will be gone sooner or later. The things that remain in one's heart forever lie in what one cannot see”. Narrow band imaging was truly a revolutionary idea. It was the idea of making the invisible visible with the help of science and technology, but it was an eccentric idea born out of obsessive observation, and trying to make the things which cannot be seen visible. I (Dr Sano) still vividly remember that December 14, 1999, when Mr Gono and I performed the world's first NBI vascular observation on a human body (subject Mr Gono) at the National Cancer Center East Hospital, was a day that gave me a sign that endoscopy in the 21st century would definitely change. We had not even decided on a name for NBI as of the beginning of 2000. I remember that the term NBI was suggested in an e-mail that Mr Gono sent me when I was to present my clinical data in the USA (Digestive Disease Week, DDW). It sounded so much like the National Basketball Association that I was initially anxious about how much recognition it would get. The feasibility study that verified the usefulness of NBI on the human body provided groundbreaking data, showing that vascular observation of tumor and inflammation would be possible under magnified endoscopy. I (Dr Sano) presented the world's first report on NBI at DDW in the USA in 2001,1 but unfortunately it gained little attention. NBI at that time was done in black and white, not color. This was because only short wavelengths of light were being detected. The fact is that when I presented a report on NBI at the symposium “The cutting edge of endoscopic diagnosis and treatment” of the 60th Congress of the Japan Gastroenterological Endoscopy Society (JGES; October 26, 2000, at Kobe Convention Center), Dr Masaharu Tatsuta (Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka), who was chairing the session, pointed out that the images were monochrome. He made the harsh comment, “for an endoscope to lose its color as we enter the 21st century would be like going backward in history”, for which I am grateful now. This was the moment when I recognized the need to give color to NBI. The final stage of color NBI was completed around 2003, and various pilot studies started in 2004.3-7 Since then, various improvements have been made, including adjustments for noise, light intensity and color, leading to the launch of the Olympus EVIS LUCERA SPECTRUM in June 2006. To establish a universal NBI magnifying endoscopic classification of colorectal tumors, the Japan NBI Expert Team (JNET) was formed within the “Research Group of the National Cancer Center Research and Development Fund” (Yutaka Saito Group) in 2011. The JNET Group meeting on June 6, 2014 reached a consensus on the universal NBI magnifying endoscopic classification of colorectal tumors (JNET classification)8 based on scientific grounds using a modified Delphi method (Fig. 2). According to previous reports, NBI not only significantly increases the polyp detection rate (odds ratio 1.62),9 but also reports a number of clinical uses of endoscopic diagnosis using the JNET classification. The sensitivity in differentiating neoplasia from non-neoplasia was 98.1–99.8%. The specificity in differentiating malignant neoplasia from benign neoplasia was 84.7–98.2% and the specificity in the differentiation D-SMC from other neoplasia was 99.8–100.0%.10 Generally, gastrointestinal endoscopic systems used a xenon lamp as light source at that time until 2012. Additionally, the technique of flexible spectral imaging color enhancement (FICE) which display color images with RGB components, assigning selected spectra in real time was used in Fujifilm endoscopic systems. The contrast of FICE seemed not enough and the improvement of it was expected. A light amplification by stimulated emission of radiation (LASER) endoscopic system (LASEREO; Fujifilm Co., Tokyo, Japan) was developed in 2012 with the help of many Japanese doctors.11-13 The system has two types of lasers with wavelengths of 410 and 450 nm for blue laser imaging (BLI) and linked color imaging (LCI) as narrow-band light (Fig. 3).12 The irradiation of phosphor by the 450-nm wavelength LASER enables a similar degree of illumination to a xenon lamp. BLI has two modes such as BLI mode and BLI-bright mode. BLI mode is useful for tumor characterization, acquiring clear and beautiful images about the mucosal patterns of surface blood vessels and structures (Fig. 4).11-13 BLI-bright mode and LCI are bright and they are expected to be useful for tumor detection. Endoscopic images of BLI magnification were almost similar to those of NBI magnification, but it is slightly different from them. However, a classification of BLI was not expected when BLI launched because there are lots of NBI classifications for tumor characterization. Thus, we examined whether a NBI classification could be used for BLI magnification in our previous study and 104 colorectal neoplasms were examined with both BLI and NBI magnification. The Hiroshima classification was one of NBI classifications and it was used in the study. The diagnostic accuracy of BLI magnification in the NBI classification was 74.0% (77/104), which was similar to that of NBI magnification (77.8%).12 The rate of consistency between BLI and NBI magnification in the NBI classification was 74.0%. Another study from our group showed the accuracy of differentiation between non-neoplastic and neoplastic lesions was 99.3% (312/314). In addition, the diagnostic accuracy of BLI without magnification for differentiating between neoplastic and non-neoplastic polyps of <10 mm was better than white light imaging (WLI) (95.2% vs. 83.2%, P < 0.05). The diagnostic accuracy of BLI magnification and pit pattern observation was compared in a previously published study.14 The diagnostic accuracy for the differentiation of neoplastic from non-neoplastic lesions was 98.4% with BLI and 98.7% with pit pattern observation. In addition, the diagnostic accuracy of BLI magnification for T1b cancers was 89.5%, while that of pit pattern observation was 92.1%. It indicates lots of T1b cancers can be diagnosed with BLI magnification. Now, the JNET classification, which was originally made with NBI as a unified classification of NBI, can also be performed with BLI according to the previous study described above.10, 12 For colorectal lesions, BLI-bright enables us to make a neoplastic lesion brownish, improving their detection. Our previous study about polyp visibility using short movies of polyps with BLI-bright and WLI with an original polyp visibility scoring system (score 4: excellent visibility–score 1: poor visibility) showed BLI-bright achieved higher scores than WLI.15 There have been several randomized controlled trials (RCTs) for detection using BLI. Our previous multicenter RCT organized by Dr Yutaka Saito showed that BLI-bright (n = 489) improved the mean number of adenomas detected per patient compared to WLI (n = 474; 1.27 ± 1.73 vs. 1.01 ± 1.36, P = 0.008).16 Another RCT of tandem colonoscopy showed that the polyp miss rate in the BLI-WLI group was 1.6%, which was significantly lower than that in the WLI-BLI group (10.0%, P = 0.001).17 In the West, the LED endoscope has been marketed instead of the LASER endoscope since 2016 because the LASER endoscope was not approved in some areas, including the USA and Europe. The LED endoscope uses four colors of LED lights and enables blue laser imaging (BLI-LED) and LCI, using multilight technology. LED endoscope is bright and BLI-LED is useful for tumor characterization. The endoscope has been used in Japan since 2020. Another LED endoscope from Olympus, which use five colors of LED lights and improves images of NBI also launched in 2020 among the world. We think these endoscopes will spread in the world due to its clear and bright images. NBI and BLI have gained the attention of endoscopists not only in Japan but also in the world. The first collaboration between the European Society of Gastrointestinal Endoscopy and JGES, the so-called International Evaluation of Endoscopy classification JNET (IEE-JNET) is now ongoing. It is surprising to see the extent to which science has no border. Since its launch, a variety of new findings have been published all over the world, and various studies using such tools as artificial intelligence (AI) are now in progress. We believe and hope that many discoveries and innovations such as AI diagnosis will keep growing in the field of endoscopy in the years to come. Author N.Y. is an Associate Editor of Digestive Endoscopy and has received a research grant from Fujifilm. The other author declares no conflict of interest for this article. None.