Narrow-band imaging in the diagnosis of colorectal mucosal lesions: a pilot study

Chromoendoscopy and other novel imaging techniques

The newly developed high-resolution and magnification endoscopes offer features that allow more and new mucosal details to be seen. They are commonly used in conjunction with chromoendoscopy. The analysis of mucosal surface details is beginning to resemble histologic examination. More accurate recognition of small flat and depressed neoplastic lesions is possible. Endoscopic prediction of neoplastic and nonneoplastic tissue is possible by analysis of surface architecture of the mucosa, which influences the endoscopic management. For the diagnosis of flat adenomas, chromoendoscopy should be a part of the endoscopist's armamentarium. In inflammatory bowel disease, chromoendoscopy can be used for patients with long-standing UC to unmask flat intraepithelial neoplasia and is likely to become the new standard method for surveillance colonoscopy in the near future. The new detailed images seen with magnifying chromoendoscopy are the beginning of a new era in which advances in optical development, such as confocal endomicroscopy, allow a unique look at detailed cellular structures.

The utility of a novel narrow band imaging endoscopy system in patients with Barrett's esophagus

BACKGROUND

A narrow band imaging (NBI) endoscopy system has been developed that allows superficial surface imaging of esophageal tissue in vivo.

OBJECTIVE

The objective was to assess the potential of NBI for prediction of histology during screening and surveillance endoscopy in patients with Barrett's esophagus (BE).

DESIGN

A prospective cohort study.

SETTING

Veterans Affairs Medical Center.

PATIENTS

Fifty-one patients with known or suspected BE.

METHODS

NBI images were graded according to mucosal pattern (ridge/villous, circular and irregular/distorted) and vascular pattern (normal and abnormal), and correlated with histology in a prospective, blinded manner.

MAIN OUTCOME MEASUREMENTS

Biopsy-confirmed intestinal metaplasia (IM) and dysplasia were used as the outcome measures.

RESULTS

Of 51 patients (mean BE length 3.5 cm), 28 had IM without dysplasia, 8 had low-grade dysplasia (LGD), 7 had high-grade dysplasia (HGD), and 8 had cardiac-type mucosa. The sensitivity, specificity, and positive predictive value of ridge/villous pattern for diagnosis of IM without HGD were 93.5%, 86.7%, and 94.7%, respectively. The sensitivity, specificity, and positive predictive value of irregular/distorted pattern for HGD were 100%, 98.7%, and 95.3%, respectively. If biopsies were limited to areas with irregular/distorted pattern, no patient with HGD would have been missed. However, NBI was unable to distinguish areas of IM from those with LGD.

LIMITATIONS

The open study design without a control group was the main limitation.

CONCLUSIONS

NBI is a novel diagnostic tool with a high degree of accuracy for the detection of metaplastic and dysplastic tissue within the BE segment.

Detection and classification of the mucosal and vascular patterns (mucosal morphology) in Barrett's esophagus by using narrow band imaging

BACKGROUND

The detection of the mucosal morphology (ie, mucosal and vascular patterns) in Barrett's esophagus (BE) by magnifying (chromo)endoscopy may improve the distinction of high-grade intraepithelial neoplasia (HGIN) from nondysplastic specialized intestinal metaplasia (SIM). Narrow band imaging (NBI) is a new technique that uses optical filters to enhance the mucosal contrast without the need for chromoendoscopy.

OBJECTIVE

To use NBI for the characterization and the classification of the mucosal morphology in nondysplastic BE and in BE with HGIN.

DESIGN

Descriptive study.

SETTING

Single-center study in a tertiary referral center for the diagnosis and treatment of patients with BE.

PATIENTS

We used NBI with magnifying endoscopy to image and biopsy randomly selected areas in 63 patients with BE. A systematic image and a biopsy specimen evaluation process was followed, including unblinded assessment of an exploratory set of images and biopsy specimens, and blinded evaluation of learning and validation sets.

MAIN OUTCOME MEASUREMENTS

The relationship between the mucosal morphology and the presence of SIM and HGIN.

RESULTS

SIM was characterized by either villous/gyrus-forming patterns (80%), which were mostly regular and had regular vascular patterns, or a flat mucosa with regular normal-appearing long branching vessels (20%). HGIN was characterized by 3 abnormalities: irregular/disrupted mucosal patterns, irregular vascular patterns, and abnormal blood vessels. All areas with HGIN had at least 1 abnormality, and 85% had 2 or more abnormalities. The frequency of abnormalities showed a significant rise with increasing grades of dysplasia. The magnified NBI images had a sensitivity of 94%, a specificity of 76%, a positive predictive value of 64%, and a negative predictive value of 98% for HGIN.

LIMITATIONS

No data on observer agreement.

CONCLUSIONS

NBI with magnification reveals the mucosal morphology characteristics of nondysplastic BE and HGIN, without the need for staining and has a relatively high diagnostic value for HGIN when used for targeted detailed examination of areas of interest.

New approach to diagnosing ampullary tumors by magnifying endoscopy combined with a narrow-band imaging system

BACKGROUND

A newly developed narrow-band imaging (NBI) system, which uses modified optical filters, can yield clear images of microvessels and surface structure in gastric and colonic diseases. In the present study, we investigated the ability of magnifying endoscopy with NBI (MENBI) to diagnose and differentiate between benign and malignant ampullary tumors.

METHODS

Fourteen patients, whose ampullas were noted to be significantly enlarged or protruding with conventional endoscopy, were enrolled in the study. Specimens, which were obtained by forceps biopsy, endoscopic papillectomy, and/or surgery, were retrieved for histopathological examination. The correlation between MENBI images and histopathological findings was investigated. MENBI findings were classified as I, oval-shaped villi; II, pinecone/leaf-shaped villi; or III, irregular/nonstructured. In addition, tortuous, dilated, and network-like vessels noted on the ampullary lesions with MENBI were defined as abnormal vessels.

RESULTS

In 6 of 14 patients, the ampullary changes were proven to be inflammatory in forceps biopsy specimens, without any evidence of malignancy after more than 1 year of follow-up. In five patients, ampullary lesions were treated by endoscopic papillectomy, and in three, by pancreatoduodenectomy. All adenomas and adenocarcinomas had type II and/or type III surface structures, and patients whose ampulla had a type I surface structure had only inflammatory or hyperplastic changes. In addition, abnormal vessels were seen only in adenocarcinomas and never in adenomas.

CONCLUSIONS

MENBI has the ability and potential to predict histological characteristics of ampullary lesions.

Endomikroskopie

Endomicroscopy becomes possible due to the integration of a miniaturized confocal microscope in the distal tip of a conventional endoscope. Endomicroscopy enables subsurface analysis of the gut mucosa and in vivo histology during ongoing endoscopy in full resolution by point scanning laser fluorescence analysis. Cellular, vascular and connective structures can be seen in detail. Graduation of cellular changes with endomicroscopy allows an immediate in-vivo diagnosis of different gastrointestinal diseases. The diagnostic spectrum of confocal endomicroscopy is currently expanding from screening and surveillance for colorectal cancer towards Barrett's esophagus, Helicobacter pylori associated gastritis and early gastric cancer. The new detailed images seen with confocal laser endomicroscopy are unequivocally the beginning of a new era where this optical development will allow a unique look on cellular structures and functions at and below the surface of the gut.

Endoscopic detection of early lower gastrointestinal cancer

The prognosis for patients with malignancies of the lower gastrointestinal tract is strictly dependent on early detection of premalignant and malignant lesions. What should an ideal screening and surveillance colonoscopy be able to accomplish? The technique should allow detection of large but also discrete mucosal alterations. Ideally, endoscopic discrimination between neoplastic and non-neoplastic lesions would be possible during the ongoing procedure. At present, endoscopy can be performed with powerful new endoscopes. Comparable to the rapid development in chip technology, the optical features of the newly designed endoscopes offer resolutions, which allow new surface details to be seen. In conjunction with chromoendoscopy, the newly discovered tool video colonoscopy is much easier and more impressive today than with the previously used fibre-optic endoscopes. Recently, new endoscopic technologies such as narrow band imaging, endocytoscopy, or confocal laser endoscopy have allowed the discovery of a whole new world of image details which will surely improve the diagnostic yield in the field of early malignancies. This review summarises newly available technologies and clinical data about the diagnosis of early lower gastrointestinal cancers.

[Emerging endoscopic techniques. The arrival of virtual histology]

Endoscopic technology has evolved in such a way that gastroenterologists can now visualize and store high-resolution images of the gastrointestinal tract. This has improved the approach to precancerous and cancerous lesions of the gastrointestinal tract and biliary tree. However, certain difficulties remain, especially in relation to diagnosis. In the last few years, multiple techniques have been developed that, using the properties of light, enable an instantaneous histologic diagnosis to be made while endoscopy is being performed. What has been called the "optical biopsy" allows highly exact information to be obtained, both from the morphological and functional point of view. Some of these techniques, such as chromoendoscopy and magnification, are already being performed in clinical practice while others are still under investigation. The aim of the present article is to review the underlying principles and applications of these emerging techniques.

New imaging techniques at colonoscopy: tissue spectroscopy and narrow band imaging

Although colonoscopy has undergone impressive development in recent decades, there remains a need for better endoscopic visualization in specific circumstances (eg, dysplasia screening in ulcerative colitis and detection of flat colorectal lesions). Many techniques are under investigation; this article discusses different forms of spectroscopy and narrow band imaging. Ideal colonoscopy should have high diagnostic accuracy and the ability to screen large mucosal areas. The most successful clinical method probably will be a combination of techniques, providing wide-area surveillance (such as fluorescence endoscopy or immunoscopy) and point detection methods, such as narrow band imaging or confocal microendoscopy, that can be used to identify the lesion further.

Advances in colonic imaging: new endoscopic imaging methods

There is a need for better endoscopic visualization in specific circumstances like detection of flat colorectal lesions and dysplasia-screening in ulcerative colitis. Chromoendoscopy is a technique with proven success, but many more, novel endoscopic techniques are currently under investigation. In this article different point measurement and still imaging methods are discussed: Raman spectroscopy, elastic (light) scattering spectroscopy, fluorescence spectroscopy, optical coherence tomography and confocal laser microscopy. Furthermore, real-time endoscopic imaging methods are discussed. These include narrow band imaging, fluorescence imaging and endocytoscopy. The results of fluoroscence imaging might be improved by application of photosensitizers or coupling of fluorescent dyes to tumour-related antigens (immunoscopy). Most of these techniques still have to be developed further and are not yet available for routine use. In our opinion, a combination of a red-flag technique and a microscopic technique carries an enormous potential.

Narrow band imaging: a new diagnostic approach to visualize angiogenesis in superficial neoplasia

Although numerous gastrointestinal endoscopes pass through the oropharynx and the hypopharynx, it is extremely difficult to detect an early cancer in these sites during routine endoscopic examination. Most patients with cancer in these sites are usually diagnosed in advanced stages. If effective screening methods can detect an earlier stage, such as carcinoma in situ, it would obviously be of great benefit. Narrow band imaging is an innovative optical technology that can clearly visualize the microvascular structure of the organ surface. Herein, we demonstrate that narrow band imaging combined with magnifying endoscopy can identify a carcinoma in situ in oropharyngeal and hypopharyngeal mucosal lesions. Scattered irregular foci of microvascular proliferation projecting to the dysplastic squamous epithelium are the typical features. These results indicate that an approach to visualize angiogenesis or morphologic changes of microvessels in the superficial neoplasm can be a new diagnostic method not only for the head and neck region but also for other sites in the gastrointestinal tract.

Efficacy of magnifying chromoendoscopy for the differential diagnosis of colorectal lesions

Magnifying chromoendoscopy is an exciting new tool and offers detailed analysis of the morphological architecture of mucosal crypt orifices. In this review, we principally show the efficacy of magnifying chromoendoscopy for the differential diagnosis of colorectal lesions such as prediction between non‐neoplastic lesions and neoplastic ones, and distinction between endoscopically treatable early invasive cancers and untreatable cancers based on a review of the literature and our experience at two National Cancer Centers in Japan. Overall diagnostic accuracy by conventional view, chromoendoscopy and chromoendoscopy with magnification ranged from 68% to 83%, 82% to 92%, and 80% to 96%, respectively, and diagnostic accuracy of accessing the stage of early colorectal cancer using magnifying colonoscopy was over 85%. Although the reliability depends on the skill in magnifying observation, widespread applications of the magnification technique could influence the indications for biopsy sampling during colonoscopy and the indication for mucosectomy. Moreover, the new detailed images seen with magnifying chromoendoscopy are the beginning of a new period in which new optical developments, such as narrow band imaging system, endocytoscopy system, and laser‐scanning confocal microscopy, will allow a unique look at glandular and cellular structures.

Magnifying endoscopy combined with narrow band imaging system for early gastric cancer: correlation of vascular pattern with histopathology (including video)

BACKGROUND AND STUDY AIMS

The narrow band imaging (NBI) system consists of a sequential electronic endoscope system and a source of light equipped with new narrow band filters, yielding very clear images of microvessels on mucosal surfaces. The aim of this prospective study was to measure the correlation between the magnified images obtained with the NBI system and the histological findings, especially with regard to the vascular pattern. In addition, three-dimensional images of microvessels were reconstructed using a laser scanning microscope.

PATIENTS AND METHODS

Between July 2001 and August 2003, 165 patients with depressed-type early gastric cancer lesions were enrolled in the study. The lesions were carefully observed with magnification using the NBI system. The images, the pathological characteristics of the lesions, and three-dimensionally reconstructed images of the microvascular networks in biopsied specimens were carefully analyzed. The microvascular patterns were classified into three groups: A, fine network; B, corkscrew; and C, unclassified pattern. The endoscopic images were compared with the histological findings.

RESULTS

Of the three types of filter available for use with the NBI system, microvascular formation was best enhanced in B mode images produced using short wavelengths, which focus on the superficial mucosal layer. Among 109 cases of differentiated adenocarcinoma, the group A microvascular pattern was observed in 72 cases (66.1 %). Among 56 cases of undifferentiated adenocarcinoma, the group B pattern was observed in 48 cases (85.7 %; P = 0.0011) The microvascular structure observed using the NBI system corresponded with the superficial mucosal layer in the three-dimensional images obtained using laser scanning microscopy and the resected specimens.

CONCLUSIONS

Magnifying endoscopy performed in combination with the NBI system is not sufficient to replace conventional histology, but is capable of predicting the histological characteristics of gastric cancer lesions.