|Year : 2007 | Volume
| Issue : 1 | Page : 1-10
|Narrow band imaging: A wide field of possibilities
JF Rey1, K Kuznetsov1, R Lambert2
1 Institute Arnault Tzanck, St Laurent du Var, France
2 I.A.R.C. Lyon, France
Click here for correspondence address and email
|Date of Submission||06-Aug-2006|
|Date of Acceptance||22-Nov-2006|
| Abstract|| |
The application of opto-electronic in video-endoscopes aims to improve accuracy in diagnosis, through image processing and digital technology. Narrow band imaging (NBI), one of the most recent techniques, consists of using interference filters for the illumination of the target in narrowed red, green, and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels in the mucosa and increases the contrast of the epithelial surface and of the subjacent vascular network. NBI is combined to magnifying endoscopy with an optical zoom. After being studied in prototypes the opto-electronic technique, now available in the most recent models of video-endoscopes that use the sequential R/G/B system of illumination, should be adapted in the near future for the instruments utilizing the non-sequential system of illumination. This new technique aims to characterize the surface of the distinct types of digestive epithelia, including intestinal metaplasia in the Barrett's esophagus. The technique also allows characterizing the disorganization of the vascular pattern in inflammatory disorders of the digestive mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel.
Keywords: Narrow band imaging
|How to cite this article:|
Rey J F, Kuznetsov K, Lambert R. Narrow band imaging: A wide field of possibilities. Saudi J Gastroenterol 2007;13:1-10
The surface of the digestive mucosa, accessible to the endoscopic vision with recent standard models of video-endoscope can be altered by inflammation or by a neoplastic growth. The inflammatory disorders usually spread on a diffuse sector of the mucosa altered by erosions, hypertrophy, or atrophy and a red color of the surface suggests hyperhemia. Early pre-malignant or malignant, neoplastic lesions often present as circumscribed and non-protruding artifacts; they are characterized by a slight discoloration and/or a slight variation of the relief (elevation or depression), changing our cognitive appreciation of the abnormal. The morphology of the non-protruding precursors of advanced cancer in the digestive mucosa has been codified in the Paris classification.
The endoscopic criteria for the diagnosis of the superficial neoplastic lesions are now challenged by a double technological advance:
- The optical zoom offers a new vision of the epithelial crests in surface, the so-called 'pit-pattern' and an improved interpretation of the color change through the morphologic analysis of the superficial vascular network, which is altered in tumoral angiogenesis.
- The digital reconstitution of the image, captured by the video-endoscope, opens the route for the image processing. The modulation in the amplitude of specific wavelengths in the reflected light results in structure enhancement. The color modulation of the reflected light results in objective evaluating the blood content and hemoglobin in the mucosa (Index of Hemoglobin).,,6]
Narrow band imaging (NBI), associates both groups of technological advance i.e., magnifying endoscopy and image processing.,, In the instrument, developed by the Olympus Corporation, the incident light is distributed in discontinuous narrow bands of photons in the Blue, Green, and Red (R/G/B), which have distinct depth of penetration into mucosa. This gives access to an improved analysis of the architecture in surface and of the capillary network just under the surface. The classification and understanding of chronic inflammatory processes in the digestive mucosa (gastritis, colitis) become more reliable. With respect to the treatment decision, NBI technique confers an increased reliability for the classification of the lesions in four groups:
- Benign without malignant potential;
- Benign with a malignant potential;
- Malignant with invasion limited to the mucosa and/or the submucosa;
- malignant with in-depth invasion of the digestive wall.
| Technical background in Opto-electronics|| |
Image reconstitution in the electronic video-endoscope
Video-endoscopes use the white light of the Xenon source for the illumination. The reflected light is captured by the CCD chip at the tip of the instrument for image reconstitution. The reflectance spectrum differs from the emission spectrum of the light source in three respects:
- Loss of photons that are absorbed in the tissue;
- Loss of photons that are scattered in the tissue and will not be captured by the CCD in spite of not being absorbed;
- Addition of fluorescence photons when an excitable molecule is present in the mucosa.
In the live observation, the spectral composition of the reflected light is influenced by the structure of the tissue and the blood flow:,,
- The depth of penetration of the incident photons in the digestive mucosa depends on their wavelength: superficial for the blue band, in depth for the red band and intermediate for the green band (the range in the distance of penetration is between 0.15 and 0.30 mm).
- Hemoglobin is the major responsible agent for the absorption of the visible light with a principal peak in the blue part (415 nm) of spectrum. This explains the red color of the vessels.
- The laminar structures of the digestive mucosa, including those, which are altered in inflammation or neoplasia, act as scattering element and interfere with the reflectance spectrum.
Two different systems are used in the image reconstitution from the reflected photons, captured by the CCD with the analogical/digital transformation. In a 'color' CCD, pixels are selectively attributed to specific wavelength ranges such as red, green, and blue (R/G/B) or cyan, magenta, yellow, and black (CYMK). The CCD captures and transfers in a single step the full range of the white light to the processor for reconstitution of the natural color in the video-monitor. This system is non-sequential. In a 'monochrome' CCD, pixels are not selectively attributed to specific colors and are transferred in a sequential mode in the R/G/B bands to the processor. A rotating interference R/G/B filter is interposed after the source of the white light and the mucosa is illuminated alternatively in each of the three R/G/B bands. The system is sequential. In the present study the reconstitution of the captured image will be analyzed in the sequential system.
| Broadband imaging in the sequential system|| |
In the R/G/B sequential imaging system, a rotating interference broadband R/G/B filter is interposed after the white light of the Xenon lamp. Its rotation maintains the full range of the white light spectrum in the incident light. Indeed, the three broadband filters (about 80-100 nm for each band) cover all the spectrum of the visible light between 390 and 655 nm. The characteristics of these filters are: 390-495 nm (range with the 50% of transmittance) for the Blue (B) channel; 500-575 nm (range with the 50% of transmittance) for the Green (G) channel; 585-655 nm (range with the 50% of transmittance) for the Red (R) channel. Noteworthy, there is no significant gap between the three broadband filters, neither a significant difference in the average depth of the penetration in the gastrointestinal mucosa. With each of the three bands, the reflected photons reproduce a very similar morphologic image,, The CCD, coupled to the processor, sequentially transforms the analogical in a digital signal and a single natural color image is reconstructed from the three R/G/B monochromatic images and displayed on the color monitor.
| NBI in the sequential system|| |
In the NBI sequential imaging system, the spectral characteristics of the incident light are changed. A rotating interference narrowband R/G/B filter is interposed after the Xenon light source. There are gaps between the three narrowband obtained; they do not cover the full range of the visible spectrum and therefore differ for the depth of penetration. As a consequence, the morphologic images reconstituted from the reflected photons will be slightly different for each of the three channels (R, G, and B): they correspond, respectively, to the surface (small capillaries), the middle, and the deep layers (large collecting vessels) of the mucosa. The single image, displayed on the monitor, combines the morphology of the three-narrowband images.
The respective centering wavelengths of the narrowband filters have been selected after studies of the characteristics of five different narrowband filters. The experimental studies were conducted on the vascular system of the mucosa of the ventral face of the human tongue.,, The vascular system of the mucosa at this level is comparable to that of the gastrointestinal mucosa including superficial capillaries loops just under the surface, large collecting veins in the depth and intermediate size vessels in between the surface and depth. The photons with a short wavelength in the blue part of the spectrum (415 nm) reproduce a morphologic image of the mucosal surface and the superficial network of capillaries: they scatter with a minimal depth of penetration and are selectively absorbed by hemoglobin, giving a good contrast for small vessels. The images obtained in the blue part of the spectrum with a broadband or with a narrowband will differ [Figure - 1]. The photons in the red part of the spectrum (600 nm), less scattered, penetrate more deeply: their longer wavelength is outside of the hemoglobin absorption band and a good contrast from the adjacent tissues is obtained only for large vessels. The red photons reproduce a morphologic image of large collecting vessels in the depth. The photons with an intermediate wavelength, in the green part of the spectrum produce a transition image.
According to the results of the experimental analysis, the engineers selected three filters to be used in this prototype: for the B channel - a narrowband centered on 415 nm (width = 30 nm) with an average penetration depth of 0.17 mm; for the G channel - a narrowband centered on 540 nm (width = 20 nm) with an average penetration depth of 0.24 mm; for the R channel - a narrowband centered on 600 nm (width = 20 nm) with an average penetration depth of 0.28 mm. The radiance in each of the R/G/B bands also plays a role. A priority to the demonstration of the epithelial crests of the surface and the distribution of the superficial capillaries is ensured by a higher radiance obtained in the blue band.
| Magnification with the optical zoom|| |
There are two types of magnification available in endoscopy: electronic and optical. The electronic enlarged image provides the endoscopist with an image of bigger size with no improvements of resolution, while the optical magnification, with a zoom objective placed at the tip of the endoscope, just distal to the CCD, gives additional details of the tissue features. In synthesis, the endoscope with optical zoom is comparable to the dissecting microscope. The magnifying power of the optical zoom can reach up to ´150, but ´80 is enough for the most applications. When the zoom is activated, the focal distance between the objective and the mucosal surface decreases in proportion to the power of magnification, therefore the tip of the instrument is placed at a few millimeters (~3 mm) from the target and a small area of the mucosa is explored. A transparent hood, fixed at the tip of the endoscope, helps to maintain the adequate distance, particularly in the cardiac region. The observation in magnification gives access to the microstructure of the surface of the digestive mucosa,,,,,,,, and to the morphology of the superficial vascular network.,,,,,,,
| The magnifying video-endoscope with NBI processing|| |
The Olympus Corporation encouraged clinical trials of magnifying video-endoscope with the prototype of NBI processing and further developments are still expected. The current available prototype functions in the sequential system and is equipped with the CLV U40 light source, the CV 240 processor, and a magnifying video-endoscope GIF Q-240Z. In this instrument with a single light source, the broadband R/G/B interference filter, providing the normal color image, can be switched, by pressing the button located on the front panel of the light source, to the narrowband interference filter (wavelengths centered on 415, 540, and 600 nm), providing the NBI image. The video-monitor can alternatively display the standard colored image or the image in NBI.
When the NBI interference filter is switched on, the three R/G/B reflected images are assigned to the corresponding R, G, B channels of the processor and transformed from analogical to digital signals. The reconstituted NBI image, displayed on the endoscopic monitor is well contrasted for the surface architecture but poorly contrasted for the network of the superficial and thin capillaries. Indeed, hemoglobin strongly absorbs the blue light and the capillaries are reproduced in yellow from the reflected light of the two other colors (red + green = yellow). The poor contrast can be corrected by post-processing the NBI image with a PC (personal computer), connected to a second (computer) monitor. The contrast of the capillaries in a dark color results from a digital treatment using, as a matrix element, a transformation coefficient K. When the NBI is switched on, two NBI images are displayed: an 'incomplete' non-processed image in the endoscopic video-monitor and a 'complete' processed image in the computer monitor affected by the PC [Figure - 2].
| Endoscopy with NBI imaging|| |
The endoscopic examination with NBI is performed in usual fashion, with no special requirements for the patient's preparation and sedation. The first step is a careful standard observation in order to identify endoscopic landmarks and any abnormalities of the surface or the color. Then magnifying endoscopy (´80) is carried-out, using a lever located next to the up-and-down knob of the endoscope. Specific points of interest such as epithelial squamo-columnar junction, columnar metaplasia in the esophagus and any mucosal abnormalities are screened. At each point of interest magnification is successively switched from the normal color to NBI imaging. Histological control with selective biopsies is required to confirm the endoscopic diagnosis of the epithelial type or the presence of neoplasia. Still-magnified pictures of zones with specific characters are automatically captured on the computer hard disc, in standard and NBI colors, when pressing the endoscope freeze button. The reliability for the analysis of the fine structure of the mucosa in inflammation and in neoplasia with the NBI prototype relies on the comparison of the recorded images with histology and the patient's history.
The structure enhancement function is placed at a maximum level during all steps of the endoscopic exploration; chromoscopy can help, but should not be used systematically. When using chromoscopy, a non-colored contrast agent is preferred and 10-15 mL of a freshly prepared 3% solution of acetic acid are sprayed in the mucosal surface., Then the exploration in NBI is conducted for comparison, before and after spraying the agent. This proves helpful in the analysis of the epithelial crests of the surface, particularly in the Barrett's esophagus. On the other hand, acetic acid provokes a vascular congestion impairing the precise analysis of the capillary network.
The NBI image
The magnified endoscopic image provided with the broadband sequential system is, to some extent, brighter than that provided by the narrowband system. The normal image is colored in pink, the NBI image is colored in brownish gray. On the other hand, the contrast of the surface is far superior in the NBI image. The analysis of the different epithelial types is more reliable as shown for the squamo-columnar epithelial junction in the distal esophagus [Figure - 3]. Similarly abnormal zones with grooved and irregular patterns or with depressions or an amorphous non-structural pattern are more visible. In synthesis, NBI will increase the diagnostic yield for intestinal metaplasia and for intraepithelial neoplasia. The analysis of the vascular network is enhanced in the NBI image and the small and superficial vessels of the mucosa are darkened. This proves helpful in the assessment of the hypervascularization in zones with inflammation and to describe the degree of tumoral angiogenesis with abnormal vessels. Spraying of acetic acid should be avoided when the vessels are analyzed.
| Applications in diagnostic endoscopy|| |
The NBI technique is not just an alternative to well-established methods of exploration. The recent models of video-endoscopes in association with chromoscopy already have enough efficacies in the diagnosis and morphologic classification of superficial neoplastic lesions in the digestive tract. In fact, NBI coupled to magnification introduces a new dimension in the analysis of the mucosal surface.,,,,,,, The legitimate indications [Table - 1] of this new technique are based on the capacity to describe the microstructure in surface and the subepithelial vessels. In metaplasia the assessment of the surface pattern has the priority; in inflammation the assessment of the vascular pattern has the priority. In superficial neoplasia both elements are important.
NBI in the esophagus and in the EG region
Stratified squamous epithelium
During a regular endoscopy, the spraying of iodine potassium-iodide solution (lugol) has enough efficacies for the detection of superficial neoplastic lesions on the squamous epithelium, including classification of the morphology and evaluation of the limits. Magnification endoscopy contributes to the analysis of the vascular network rather to the analysis of the neoplastic surface. In the esophagus the capillaries ascend in the papillas of the stratified epithelium and the intrapapillary capillary loops (IPCL) have a regular pin-hair shape. In the subjacent lamina propria the IPCL are connected by arborescent vessels to large drainage veins. The Japanese school has shown that the abnormal pattern of the vessels has a predictive value for the progression of intraepithelial neoplasia to sub-mucosal carcinoma., The elementary abnormalities (dilatation, irregular caliber, tortuosity, polymorphous appearance) can be classified in three groups:
- The pin-hair pattern of the IPCL is maintained but they are dilated and elongated; this occurs either in esophagitis or in low-grade intraepithelial neoplasia.
- The pin-hair pattern disappears and is replaced by a punctuated pattern where the capillaries agglomerate in dense package and show tortuosity, irregularities in the caliber; this characterizes high-grade intraepithelial neoplasia or carcinoma in situ .
- The punctuated pattern is replaced by large and irregular neo-vessels; this occurs in invasive carcinoma when there is invasion in depth of the lamina propria or of the submucosa.
In the esophagus the capillaries loops are analyzed with more reliability in magnification with NBI, with enhanced contrast and a dark color [Figure - 4] than in normal color magnification. This applies also to the superficial neoplastic lesions of the squamous epithelium in the bronchial tree. A recent study of the capillaries in neoplastic squamous lesions of the esophagus was conducted in 41 patients: a numerical analysis of the red, green, and blue bands of the image was conducted to estimate a contrast value between the small vessels and the background mucosa in the regular and for the NBI images. The color contrast-ratio between vessels and mucosa was significantly greater for the NBI image. Noteworthy this study confirms the predictive value of endoscopy for the depth of invasion of superficial cancer, which has been suggested in recent years., In the later study the endoscopic classification in three layers for the mucosa (m1, m2, m3) and in three layers for the submucosa (sm1, sm2, sm3), was compared to that of the pathologist in histological controls. The overall accuracy of the experienced endoscopists reached 85.2% for NBI images. The incremental increase in prediction is higher for novices than for experienced operators using magnifying endoscopy.
Distal to the squamous stratified epithelium; different types of columnar epithelium are present. Just below the squamo-columnar junction in a normal position, a short segment of cardiac epithelium with mucous glands ensures the transition to the oxyntic epithelium of the gastric fundus. Inflammation (carditis) is frequent at this level and small areas of intestinal metaplasia of the complete type are found in 25% of patients. If the epithelial squamo-columnar junction migrates proximally in the esophagus there is a segment of columnar metaplasia in the distal esophagus (Barrett's esophagus) with a mosaic of epithelial types, reversed to mucosa of the gastric fundus, transitional mucosa of the cardia, and an intestinal epithelium. In the esophagus, intestinal metaplasia of the incomplete type is called a specialized epithelium. Long segments (at least 3 cm) of columnar metaplasia are easily detected; however, confusion arises near the junction of esophagus to stomach between intestinal metaplasia in a short segment of the Barrett's esophagus or in the inflamed mucosa of the cardia (carditis). In synthesis, the EG region involves the distal esophagus and the cardia; at this level adenocarcinomas can develop either from the distal esophagus with metaplasia or from the stomach at the cardia.
Columnar epithelium in the esophagus or at the EG junction is the privileged target of magnification endoscopy, using contrast agents. The technique proved able to describe the surface microstructure and distinctive patterns of the fundic and cardiac types of epithelium and of intestinal metaplasia.,,,,, The procedure reaches a further degree in efficacy when coupled to NBI.,, At the epithelial junction the contrast between the stratified squamous epithelium and the columnar epithelium is striking [Figure - 3]. Distal to the epithelial junction the cardiac type of epithelium shows epithelial crests separated by narrow groves. In the columnar lined esophagus, the zones with the fundic or cardiac type of epithelium show the same pattern as in the stomach. In the areas of intestinal metaplasia no pits are present and the epithelial crests, long, and sinuous, are separated by wide groves, with a ridged pattern [Figure - 5].
The objective of endoscopy in secondary prevention of cancer is the identification of areas of intestinal metaplasia in this sector of the digestive mucosa and the identification of adjacent flat areas with intra-epithelial neoplasia. Standard endoscopy has a poor efficacy in achieving both objectives, even with the help of contrast agents (methylene blue, acetic acid). Magnification improved the efficacy of the analysis, which is further increased by the NBI technique. Intraepithelial neoplasia adjacent to intestinal metaplasia is suggested in areas with irregular epithelial crests, shifting from long and large to short and dense crests and in areas with a non-structural amorphous surface. The study of the surface microstructure is completed by that of the vascular pattern: large and irregular vessels suggest neoplasia.
The question arises whether, when the region is explored with magnification coupled to NBI, selective biopsies could substitute the Seattle protocol with its multiple and blind tissue sampling. Further comparative studies are required. In one series (personal data), upper GI endoscopy with magnification coupled to NBI and histological control was performed in patients with a symptomatic GERD or in a surveillance protocol for the previously diagnosed Barrett's esophagus. The aim of the study was double: identify the endoscopic pattern of intestinal metaplasia; identify adjacent areas with intraepithelial neoplasia. The presence of the specialized epithelium was diagnosed in 51 patients at endoscopy and was confirmed at histology in 40. The very high specificity of the endoscopic pattern in patients with long segments of metaplasia was less for patients with short segments [Table - 2]. The decreased specificity is explained by the ambiguity in positioning the squamo-columnar epithelial junction and by directing biopsies at an inappropriate site. Intraepithelial neoplasia was detected in 16 out of the 40 patients with confirmed intestinal metaplasia (40%); this is a fairly high proportion [Table - 3].
| NBI in the stomach|| |
In recent years, the surface microstructure of the gastric mucosa has been evaluated with the help of magnifying endoscopy; distinct patterns in the fundus (regular small pit openings) and in the antrum (epithelial crests separated by narrow sulci) have been described. The vascular network has also been assessed: in the fundic mucosa, the sub-epithelial capillaries, surrounding the gastric pits, are organized in a regular honeycomb pattern, while in the antrum they are coiled, elongated and placed at the center of the epithelial crests. The vascular network of sub-epithelial capillaries is completed by collecting veinules with a larger size and an oblique direction. They are disposed in a starfish design called the regular arrangement of collecting veinules (RAC).,
The surface of the gastric mucosa should be described in persons with no H. pylori infection. However inflammation of the gastric mucosa, related to H. pylori infection, occurs with a high frequency. The altered surface and the vascular network of the mucosa, have been described in magnification.
The analysis of the vascular network is expected to be more precise when magnification is coupled to NBI. The H. pylori infection has an impact on the appearance of the sub-epithelial capillaries, which turn to be congestive, but the major impact occurs in the morphology of the collecting veinules, which loose their regular starfish design in the fundus and may even be completely invisible. After eradication of H. pylori the collecting veinules reappear.
In chronic gastritis, alterations of the sub-epithelial capillary network and of the collecting veinules correlate with the degree of mucosal atrophy . In confirmed chronic gastritis with atrophy, the surface microstructure of the mucosa is also altered by the occurrence of the large zones in the antrum or in the fundus with a depressed surface or an amorphous pattern. Areas with intestinal metaplasia are suspected when there is a depression with large and long epithelial crests separated by deep sulci. Magnification coupled to NBI is expected to improve their analysis as shown in the exploration of the antral mucosa [Figure - 6].
The burden of gastric cancer is excessively high in Japan and early detection has been a priority in this country during the last decades. Most precursors of advanced cancer have a non-protruding morphology. There is ample demonstration that they are well detected and analyzed when the standard endoscopic observation is coupled to chromoscopy (indigocarmine). However, the majority of those non-protruding lesions is depressed and can be misdiagnosed with gastric erosions or ulcer scars. Magnification is expected to improve histological prediction rather than to increase the yield of detection. In recent years, the magnified image of the surface of the depressed neoplastic lesions has been compared to that of non-neoplastic depressions: neoplasia is suggested when zones of irregular elevation or zones with an amorphous pattern, are present. No doubt that the NBI technique will help in assessing the nature of the lesion, the frontiers of the neoplastic area in surface and the invasion in the submucosa. A major contribution is expected for the analysis of the vascular network: in neoplastic depressions there is a disappearance of the normal pattern of the vessels, which form circles or show an irregular diameter and multiple branching and sinuosity.
| NBI in the duodenum|| |
During upper GI endoscopy, the duodenum offers an easy access to the morphology of the intestinal villi. Their atrophy is an important feature for the diagnosis of gluten enteropathy and other less frequent intestinal disorders including lymphoma. Standard video-endoscopy coupled to chromoscopy (indigocarmine) detects the mosaic pattern of the mucosa in the subtotal atrophy; however, the evaluation of incomplete atrophy is not fully reliable. Magnification with NBI provides a clear vision of the intestinal villi and will contribute to classification of the villous morphology in degrees of atrophy and to the evaluation of the response to treatment .
| NBI in the large bowel|| |
Inflammatory bowel disease
Colonoscopy plays a major role in the diagnosis and classification of inflammatory bowel disease and in management and surveillance after diagnosis. The NBI technique is expected to contribute to the classification and re-evaluation of colitis through a fine description of the most early mucosal abnormalities at the surface and in the vascular network. There is an increased risk of cancer in long standing ulcerative colitis and Crohn's disease; but endoscopy has a poor efficacy in the early diagnosis of flat neoplastic areas in the inflamed mucosa. No doubt that magnification with NBI will help in analyzing the surface of suspected zones. In this respect the attention should focus on the abnormal vascular patterns, because the early alterations suggesting neoplasia are often limited to the depth of the mucosa in ulcerative colitis.
Superficial neoplasia in the large bowel
Superficial neoplastic lesions in the mucosa of the large bowel are reliably detected using a high-resolution video-endoscope coupled to chromoscopy (indigocarmine). The Japanese school provided ample demonstration of the contribution of magnification for the analysis of the pit pattern in discrete lesions classified as type 0 in respect to their morphological appearance in endoscopy. The pit pattern has been classified in five types corresponding to three groups with clinical relevance: Types I and II for normal or non-neoplastic - Type III for low grade intraepithelial neoplasia - Types IV and V for high grade intra-epithelial neoplasia or cancer. Magnification with NBI will confer more reliability to the so-called optical biopsy from the observation of the pit pattern. This has been confirmed for the surface microstructure by the use of the visual analog scales. In addition the new technique should provide more information on the depth of tumoral invasion in relation to the alteration of the vascular network.
| Conclusion|| |
Magnification with NBI confers a further strength to the clinical utility of magnification. The improved morphologic analysis of epithelial crests on the surface of the mucosa increases the reliability of the detection of intestinal metaplasia in the Barrett's esophagus. The more precise analysis of the abnormal surface architecture (pit pattern) of neoplastic lesions should have relevance for treatment decision. The most important contribution of the new technique is probably the clear vision of the vascular network of the mucosa. This will stimulate the study of neo-angiogenesis in superficial digestive cancer and increase our knowledge on the pathophysiology of inflammatory conditions. Noteworthy, chromoscopy is not helpful when the exploration aims to study the vessels. Finally, there is a great potential for further developments by modifying the characteristics of the interference filters. This concerns the depth of penetration of the light and to the morphology of the image as well as the color rendering.
| Acknowledgment|| |
We are glad to thank Mr. Kazuhiro Gono From Olympus Corporation, Ishikawa-cho, Hachioji-shi, Tokyo 192-8507, Japan, for his contribution to the revision of this manuscript.
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J F Rey
Institute Arnault Tzanck, Avenue du Dr Maurice Donat, 06700 St Laurent du Var
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6]
[Table - 1], [Table - 2], [Table - 3]
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