Diagnosis of extent of early gastric cancer using flexible spectral imaging color enhancement

Artificial intelligence applications in pathological diagnosis of gastric cancer

Globally, gastric cancer is the third leading cause of death from tumors. Prevention and individualized treatment are considered to be the best options for reducing the mortality rate of gastric cancer. Artificial intelligence (AI) technology has been widely used in the field of gastric cancer, including diagnosis, prognosis, and image analysis. Eligible papers were identified from PubMed and IEEE up to April 13, 2022. Through the comparison of these articles, the application status of AI technology in the diagnosis of gastric cancer was summarized, including application types, application scenarios, advantages and limitations. This review presents the current state and role of AI in the diagnosis of gastric cancer based on four aspects: 1) accurate sampling from early diagnosis (endoscopy), 2) digital pathological diagnosis, 3) molecules and genes, and 4) clinical big data analysis and prognosis prediction. AI plays a very important role in facilitating the diagnosis of gastric cancer; however, it also has shortcomings such as interpretability. The purpose of this review is to provide assistance to researchers working in this domain.

Usefulness of artificial intelligence in early gastric cancer

Gastric cancer (GC) is a major cancer worldwide, with high mortality and morbidity. Endoscopy, important for the early detection of GC, requires trained skills, high-quality technologies, surveillance and screening programs. Early diagnosis allows a better prognosis, through surgical or curative endoscopic therapy. Magnified endoscopy with virtual chromoendoscopy remarkably improve the detection of early gastric cancer (EGC) when endoscopy is performed by expert endoscopists. Artificial intelligence (AI) has also been introduced to GC diagnostics to increase diagnostic efficiency. AI improves the early detection of gastric lesions because it supports the non-expert and experienced endoscopist in defining the margins of the tumor and the depth of infiltration. AI increases the detection rate of EGC, reduces the rate of missing tumors, and characterizes EGCs, allowing clinicians to make the best therapeutic decision, that is, one that ensures curability. AI has had a remarkable evolution in medicine in recent years, moving from the research phase to clinical practice. In addition, the diagnosis of GC has markedly progressed. We predict that AI will allow great evolution in the diagnosis and treatment of EGC by overcoming the variability in performance that is currently a limitation of chromoendoscopy.

Advances in the Aetiology & Endoscopic Detection and Management of Early Gastric Cancer

Simple Summary

Gastric adenocarcinoma has remained a highly lethal disease. Awareness and recognition of preneoplastic conditions (including gastric atrophy and intestinal metaplasia) using high-resolution white-light endoscopy as well as chromoendoscopy is therefore essential. Helicobacter pylori, a class I carcinogen, remains the main contributor to the development of sporadic distal gastric neoplasia. Management of early gastric neoplasia with endoscopic resections should be in line with standard indications. A multidisciplinary approach to any case of an early gastric neoplasia is imperative. Hereditary forms of gastric cancer require a tailored approach and individua-lized surveillance.

Abstract

The mortality rates of gastric carcinoma remain high, despite the progress in research and development in disease mechanisms and treatment. Therefore, recognition of gastric precancerous lesions and early neoplasia is crucial. Two subtypes of sporadic gastric cancer have been recognized: cardia subtype and non-cardia (distal) subtype, the latter being more frequent and largely associated with infection of Helicobacter pylori, a class I carcinogen. Helicobacter pylori initiates the widely accepted Correa cascade, describing a stepwise progression through precursor lesions from chronic inflammation to gastric atrophy, gastric intestinal metaplasia and neoplasia. Our knowledge on He-licobacter pylori is still limited, and multiple questions in the context of its contribution to the pathogenesis of gastric neoplasia are yet to be answered. Awareness and recognition of gastric atrophy and intestinal metaplasia on high-definition white-light endoscopy, image-enhanced endoscopy and magnification endoscopy, in combination with histology from the biopsies taken accurately according to the protocol, are crucial to guiding the management. Standard indications for endoscopic resections (endoscopic mucosal resection and endoscopic submucosal dissection) of gastric dysplasia and intestinal type of gastric carcinoma have been recommended by multiple societies. Endoscopic evaluation and surveillance should be offered to individuals with an inherited predisposition to gastric carcinoma.

Artificial intelligence and upper gastrointestinal endoscopy: Current status and future perspective

With recent breakthroughs in artificial intelligence, computer-aided diagnosis (CAD) for upper gastrointestinal endoscopy is gaining increasing attention. Main research focuses in this field include automated identification of dysplasia in Barrett's esophagus and detection of early gastric cancers. By helping endoscopists avoid missing and mischaracterizing neoplastic change in both the esophagus and the stomach, these technologies potentially contribute to solving current limitations of gastroscopy. Currently, optical diagnosis of early-stage dysplasia related to Barrett's esophagus can be precisely achieved only by endoscopists proficient in advanced endoscopic imaging, and the false-negative rate for detecting gastric cancer is approximately 10%. Ideally, these novel technologies should work during real-time gastroscopy to provide on-site decision support for endoscopists regardless of their skill; however, previous studies of these topics remain ex vivo and experimental in design. Therefore, the feasibility, effectiveness, and safety of CAD for upper gastrointestinal endoscopy in clinical practice remain unknown, although a considerable number of pilot studies have been conducted by both engineers and medical doctors with excellent results. This review summarizes current publications relating to CAD for upper gastrointestinal endoscopy from the perspective of endoscopists and aims to indicate what is required for future research and implementation in clinical practice.

Advanced endoscopic methods in gastrointestinal diseases: a systematic review

Endoscopic imaging is the main method for detecting gastrointestinal diseases, which adversely affect human health. White light endoscopy (WLE) was the first method used for endoscopic examination and is still the preliminary step in the detection of gastrointestinal diseases during clinical examination. However, it cannot accurately diagnose gastrointestinal diseases owing to its poor correlation with histopathological diagnosis. In recent years, many advanced endoscopic methods have emerged to improve the detection accuracy by endoscopy. Chromoendoscopy (CE) enhances the contrast between normal and diseased tissues using biocompatible dye agents. Narrow band imaging (NBI) can improve the contrast between capillaries and submucosal vessels by changing the light source acting on the tissue using special filters to realize the visualization of the vascular structure. Flexible spectral imaging color enhancement (FICE) technique uses the reflectance spectrum estimation technique to obtain individual spectral images and reconstructs an enhanced image of the mucosal surface using three selected spectral images. The i-Scan technology takes advantage of the different reflective properties of normal and diseased tissues to obtain images, and enhances image contrast through post-processing algorithms. These abovementioned methods can be used to detect gastrointestinal diseases by observing the macroscopic structure of the digestive tract mucosa, but the ability of early cancer detection is limited with low resolution. However, based on the principle of confocal imaging, probe-based confocal laser endomicroscopy (pCLE) can enable cellular visualization with high-performance probes, which can present cellular morphology that is highly consistent with that shown by biopsy to provide the possibility of early detection of cancer. Other endoscopic imaging techniques including endoscopic optical coherence tomography (EOCT) and photoacoustic endoscopy (PAE), are also promising for diagnosing gastrointestinal diseases. This review focuses on these technologies and aims to provide an overview of different technologies and their clinical applicability.

The utility of ultrathin endoscopy with flexible spectral imaging color enhancement for early gastric cancer

Many researchers suggested that ultrathin endoscopy improves patient acceptance of endoscopic examinations. However, ultrathin endoscopy provides less image resolution and luminous intensity. Therefore, we focused on the visibility of early gastric cancer on ultrathin endoscopy with Flexible spectral imaging color enhancement (FICE) in this study. Thirty-six patients with early gastric cancer were prospectively enrolled. One endoscopist performed the endoscopic examinations by white light conventional endoscopy (W-CE), white light ultrathin endoscopy (W-UE), FICE ultrathin endoscopy (F-UE) and white light plus FICE ultrathin endoscopy (WF-UE) in the patients. Four other endoscopists were asked to evaluate the visibility of gastric cancer on the W-CE, W-UE, F-UE and WF-UE images with a 5-point Likert scale. The lesions were classified as uncolored, normocolored or reddish. We examined the color difference between early gastric cancer and the surrounding mucosa. To examine the relationship between the color difference and the vessel density, we also measured the difference in vessel density using pathologic specimens stained with hematoxylin and eosin. The Likert score of WF-UE was significantly higher than those of the other three methods (p<0.001). The color difference of F-UE was higher than that of W-CE in the reddish group (p=0.049). The difference in vessel density was higher in the reddish group than in the normocolored group (p=0.048). In conclusion, the visibility of early gastric cancer from the surrounding mucosa using ultrathin endoscopy with FICE was better than that using white light conventional endoscopy, especially for reddish lesions.

[Characteristics analysis of early gastric cancer under white light endoscopy]

OBJECTIVE

To investigate endoscopic features of early gastric cancer and clinical features of the patients, which may be helpful to provide reasonable suggestions for physicians to diagnose early gastric cancer during preliminary screening of white light gastroscopy.

METHODS

A total of 271 patients who received endoscopic submucosal dissection or surgical operation to confirm early gastric cancer in Peking University Third Hospital from Apr. 2009 to Jun. 2017 were included for the retrospective review. Clinical information was collected, including gender, age, symptoms, family history and physical examination. The endoscopic characteristics of lesions under white light endoscopy were analyzed, including endoscopic long diameter, location, texture, spontaneous bleeding, mucosal color and morphology. The pathologic long diameter, infiltration depth and differentiation degree of early gastric cancer were also summarized.

RESULTS

The study included 271 patients and 279 lesions. Among the 271 cases, 190 were male, 81 were female, average age was (63.7±12.4) years. There were 88 cases (32.5%) and 61 cases (22.5%) with the symptom of abdominal pain and discomfort respectively. The patients with family history of gastric cancer were 20 (7.4%). Abdominal physical examinations of the patients were mostly normal, accounting for 86.0% (233/271). Total detection rate of helicobacter pylori (HP) was 34.2% (79/231), with the highest rate 45.5% (10/22) in 2011 and the lowest rate 28.1% (9/32) in 2014. Among the 279 lesions, the mean endoscopic long diameter was (2.01±1.20) cm. The lesions were mainly single, accounting for 97.0% (263/271). There were 114 cases (40.9%), 62 cases (22.2%), 54 cases (19.4%) in the antrum, angular sulcus and cardia of stomach respectively. The lesions were mostly fragile, accounting for 45.5% (56/123). Most lesions had spontaneous bleeding, accounting for 52.3% (146/279). The mucosal color was mostly normal, accounting for 72.8% (203/279). The most common macroscopic morphology was IIa+IIc type (100 cases, 35.8%) and the lesions usually had mucous membrane damage like erosion and shallow ulcer (127 cases,45.5%). Among the 279 lesions, the mean pathologic long diameter was (2.05±1.48) cm. Intramucosal carcinoma accounted for 61.6% (172/279) and moderate differentiated gastric cancers accounted for 52.8% (131/248).

CONCLUSION

In order to improve diagnosis of early gastric cancer,superficial elevation and depression of flat lesions as well as mucous membrane damage under white light endoscopy should be taken notice.

Focal Intramucosal Adenocarcinoma Occurring in Gastric Hyperplastic Polyps Treated with Endoscopic Mucosal Resection

Hyperplastic polyps are the most frequent benign epithelial gastric polyps. Although they are considered nonneoplastic, some cases have been reported with focal adenocarcinoma. We present the case of a 59-year-old woman with a sessile lesion of 15 mm on the distal gastric body associated with an extensive atrophic gastritis. Magnifying endoscopy with Fuji Intelligent Color Enhancement (FICE) revealed an irregular microsurface pattern at the apex, suggesting malignancy. A mucosectomy was performed. The histopathology revealed that the base corresponded to a hyperplastic polyp, where a tubular adenoma with high-grade dysplasia was established, with focal well-differentiated intramucosal tubular adenocarcinoma.

Magnifying Blue Laser Imaging versus Magnifying Narrow-Band Imaging for the Diagnosis of Early Gastric Cancer: A Prospective, Multicenter, Comparative Study

BACKGROUND/AIMS

The diagnostic efficacy of magnifying blue laser imaging (M-BLI) and M-BLI in bright mode (M-BLI-bright) in the identification of early gastric cancer (EGC) was evaluated for comparison to that of magnifying narrow-band imaging (M-NBI).

METHODS

This prospective, multicenter study evaluated 114 gastric lesions examined using M-BLI, M-BLI-bright, and M-NBI between May 2012 and November 2012; 104 EGCs were evaluated by each modality. The vessel plus surface classification system was used to evaluate the demarcation line (DL), microvascular pattern (MVP), and microsurface pattern (MSP).

RESULTS

M-BLI, M-BLI-bright, and M-NBI revealed a DL for 96.1, 98.1, and 98.1% and irregular MVP for 95.1, 95.1, and 96.2% of lesions, respectively, with no significant difference. Irregular MSP was observed by M-BLI, M-BLI-bright, and M-NBI in 97.1, 90.4, and 78.8% of lesions, respectively, with significant differences (p < 0.001). The proportion of moderately differentiated adenocarcinoma with irregular MSP on M-BLI and absent MSP on M-NBI was significantly higher than that with irregular MSP on M-BLI and M-NBI (35.0 and 9.9%, respectively; p = 0.002).

CONCLUSION

M-BLI and M-BLI-bright provided excellent visualization of microstructures and microvessels similar to M-NBI. Irregular MSP in a moderately differentiated adenocarcinoma might be frequently visualized using M-BLI and M-BLI-bright compared with using M-NBI.

Evaluation of the visibility of early gastric cancer using linked color imaging and blue laser imaging

Background

Blue laser imaging (BLI) and linked color imaging (LCI) are the color enhancement features of the LASEREO endoscopic system, which provide a narrow band light observation function and expansion and reduction of the color information, respectively.

Methods

We examined 82 patients with early gastric cancer (EGC) diagnosed between April 2014 and August 2015. Five expert and 5 non-expert endoscopists retrospectively compared images obtained on non-magnifying BLI bright mode (BLI-BRT) and LCI with those obtained via conventional white light imaging (WLI). Interobserver agreement was also assessed.

Results

In experts’ evaluation of the images, an improvement in visibility was observed in 73% (60/82) and 20% (16/82) of cases under LCI and BLI-BRT, respectively. In non-experts’ evaluation of the images, an improvement in visibility was observed in 76.8% (63/82) and 24.3% (20/82) of cases under LCI and BLI-BRT, respectively. There were no significant differences between experts and non-experts in the evaluation of the images. The improvement in visibility was significantly higher with LCI than with BLI-BRT in experts and non-experts (p < 0.01). With regard to tumor color on WLI, the improvement in the visibility of reddish and whitish tumors was significantly higher than that of isochromatic tumors when LCI was used. The improvement in visibility with LCI was observed in 71% (12/17) and 74% (48/65) of patients with and without Helicobacter pylori (Hp) eradication, respectively; no significant difference in improvement was observed between these groups. The interobserver agreement was good to satisfactory at ≥ 0.62.

Conclusions

In conclusion, our study showed that LCI improved the visibility of EGC, regardless of the level of endoscopists’ experience or Hp eradication in patients, particularly for EGCs with a reddish or whitish color. The improvement in visibility was significantly higher with LCI than that with BLI.

Clinical Usefulness of the VS Classification System Using Magnifying Endoscopy with Blue Laser Imaging for Early Gastric Cancer

BACKGROUND

Blue laser imaging (BLI) enables the acquisition of more information from tumors' surfaces compared with white light imaging. Few reports confirm the validity of magnifying endoscopy (ME) with BLI (ME-BLI) for early gastric cancer (EGC). We aimed to assess the detailed endoscopic findings from EGCs using ME-BLI.

METHODS

We enrolled 386 consecutive patients with 417 EGCs that were diagnosed using ME-BLI and resected by endoscopic submucosal dissection. Using the VS classification system, three highly experienced endoscopists (HEEs) and three less experienced endoscopists (LEEs) evaluated the demarcation line (DL), microsurface pattern (MSP), and microvascular pattern (MVP) within the endoscopic images of EGCs obtained using ME-BLI, assigning high-confidence (HC) or low-confidence (LC) levels. We investigated the clinicopathological features associated with each confidence level.

RESULTS

The HEEs' evaluations determined the presence of DL in 99%, irregular MSP in 96%, and irregular MVP in 96%, and the LEEs' evaluations determined the presence of DL in 98%, irregular MSP in 95%, and irregular MVP in 95% of the EGCs. When DL was present, HC levels in the Helicobacter pylori- (H. pylori-) eradicated group and noneradicated group were evident in 65% and 89%, a difference that was significant (p < 0.001).

CONCLUSIONS

In the diagnosis of EGC with ME-BLI, the VS classification system with ME-NBI can be applied, but identifying the DL after H. pylori was difficult.

Diagnostic ability of magnifying endoscopy with blue laser imaging for early gastric cancer: a prospective study

BACKGROUND

Blue laser imaging (BLI) is a new image-enhanced endoscopy technique that utilizes a laser light source developed for narrow-band light observation. The aim of this study was to evaluate the usefulness of BLI for the diagnosis of early gastric cancer.

METHODS

This single center prospective study analyzed 530 patients. The patients were examined with both conventional endoscopy with white-light imaging (C-WLI) and magnifying endoscopy with BLI (M-BLI) at Kyoto Prefectural University of Medicine between November 2012 and March 2015. The diagnostic criteria for gastric cancer using M-BLI included an irregular microvascular pattern and/or irregular microsurface pattern, with a demarcation line according to the vessel plus surface classification system. Biopsies of the lesions were taken after C-WLI and M-BLI observation. The primary end point of this study was to compare the diagnostic performance between C-WLI and M-BLI.

RESULTS

We analyzed 127 detected lesions (32 cancers and 95 non-cancers). The accuracy, sensitivity, and specificity of M-BLI diagnoses were 92.1, 93.8, and 91.6 %, respectively. On the other hand, the accuracy, sensitivity, and specificity of C-WLI diagnoses were 71.7, 46.9, and 80.0 %, respectively.

CONCLUSIONS

M-BLI had improved diagnostic performance for early gastric cancer compared with C-WLI. These results suggested that the diagnostic effectiveness of M-BLI is similar to that of magnifying endoscopy with narrow-band imaging (M-NBI).

Advanced endoscopic imaging in gastric neoplasia and preneoplasia

Conventional white light endoscopy remains the current standard in routine clinical practice for early detection of gastric cancer. However, it may not accurately diagnose preneoplastic gastric lesions. The technological advancements in the field of endoscopic imaging for gastric lesions are fast growing. This article reviews currently available advanced endoscopic imaging modalities, in particular chromoendoscopy, narrow band imaging and confocal laser endomicroscopy, and their corresponding evidence shown to improve diagnosis of preneoplastic gastric lesions. Raman spectrometry and polarimetry are also introduced as promising emerging technologies.

Evaluation of the Diagnostic Ability of Optical Enhancement System in Early Gastric Cancer Demarcation

This study aimed to evaluate the utility of optical enhancement (OE) in early gastric cancer demarcation. Twenty lesions of early gastric cancer were examined by PENTAX endoscopy system with OE-1 and OE-2 functions. The areas of tumor demarcation identified by 12 evaluators (6 novice and 6 experienced) were compared to the corresponding correct areas determined by postoperative histopathology findings. The misdiagnosed scores that were the sums of false-positive and false-negative areas were compared. Color of one hundred pixels from the inside of the cancerous area and the outside of the cancerous area was expressed as three-dimensional RGB component vectors. The mean vectors and covariance matrixes were calculated and the Mahalanobis distance, indicative of color differences between two areas, was tested. Comparisons of the misdiagnosed score revealed that OE-1 was preferred over WL-1 for gastric cancer demarcation for all 12 evaluators (p = 0.008) and in novice evaluators (p = 0.026). OE-2 was not significantly different from WL-2 in all cases. OE-1 images gave significantly larger Mahalanobis distances, indicative of color differences, than WL-1 images (p = 0.002). It was demonstrated that the OE Mode 1 has a significant advantage over the white light mode in demarcation of early gastric cancer.

Value of flexible spectral imaging color enhancement combined with magnifying endoscopy in diagnosis of early gastric cancer

AIM

To evaluate the value of flexible spectral imaging color enhancement (FICE) combined with magnifying endoscopy in the diagnosis of early gastric cancer.

METHODS

Patients with suspected early gastric cancer who underwent FICE combined with magnifying endoscopy from March 2015 to December 2015 were retrospectively analyzed. The endoscopic diagnosis criteria for early gastric cancer were made according to the microstructure, microvascular and demarcation line. Finally, the accuracy of FICE combined with magnifying endoscopy for the diagnosis of early gastric cancer was assessed by comparing with pathological results.

RESULTS

Of 177 lesions that underwent FICE and magnifying endoscopy, 26 were pathologically diagnosed as low grade intraepithelial neoplasia, 12 as high grade intraepithelial neoplasia, and 139 as non-cancer lesions. The sensitivity, specificity and Youden index of FICE combined with magnifying endoscopy were 68.4%, 87.8% and 56.2% for intraepithelial neoplasia, and 75.0%, 100% and 75.0% for early gastric cancer, respectively.

CONCLUSION

FICE combined with magnifying endoscopy can improve the diagnostic accuracy for early gastric cancer.

The use of optical imaging techniques in the gastrointestinal tract

With significant advances in the management of gastrointestinal disease there has been a move from diagnosing advanced pathology, to detecting early lesions that are potentially amenable to curative endoscopic treatment. This has required an improvement in diagnostics, with a focus on identifying and characterising subtle mucosal changes. There is great interest in the use of optical technologies to predict histology and enable the formulation of a real-time in vivo diagnosis, a so-called 'optical biopsy'. The aim of this review is to explore the evidence for the use of the current commercially available imaging techniques in the gastrointestinal tract.

Advanced Imaging Technology Other than Narrow Band Imaging

To improve the detection rate of gastrointestinal tumors, image-enhanced endoscopy has been widely used during screening and surveillance endoscopy in Korea. In addition to narrow band imaging (NBI) with/without magnification, various types of electronic chromoendoscopies have been used, including autofluorescence imaging, I-scan, and flexible spectral imaging color enhancement. These technologies enable the accurate characterization of tumors because they enable visualization of microvascular and microsurface patterns. The present review focuses on understanding the principle and clinical applications of advanced imaging technologies other than NBI.

Progress in digestive endoscopy: Flexible Spectral Imaging Colour Enhancement (FICE)-technical review

Background. A substantial advance in digestive endoscopy that has been made during the last decade is represented by digital chromoendoscopy, which was developed as a quicker and sometimes better alternative to the gold standard of dye spraying. Fujifilm developed a virtual coloration technique called Flexible spectral Imaging Color Enhancement (FICE). FICE provides a better detection of lesions of "minimal" esophagitis, of dysplasia in Barrett's esophagus and of squamous cell esophageal cancer. The use of FICE resulted in an improvement in the visualization of the early gastric cancer, being less invasive, and time consuming than the classic dye methods. Current evidence does not support FICE for screening purposes in colon cancer but it definitely improves characterization of colonic lesions. Its use in inflammatory bowel disease is still controversial and in video capsule endoscopy is considered a substantial progress. Conclusions. The use of FICE endoscopy in routine clinical practice can increase the diagnostic yield and can provide a better characterization of lesions. Future studies to validate its use, the good choice of channels, and the "perfect indications" and to provide common definitions and classifications are necessary.

Endoscopic prediction of tumor margin and invasive depth in early gastric cancer

Gastric cancer (GC) is the fifth most common cancer and the third leading cause of cancer-related deaths in the world. The prognosis of GC is clearly associated with the tumor stage, with a 5-year overall survival rate for early gastric cancer (EGC) exceeding 90%, which is significantly higher than that of advanced gastric cancer. Endoscopic resection, including endoscopic mucosal resection and endoscopic submucosal dissection, has been adopted in recent decades as the first treatment option of EGC in many countries for its minimal invasion and high curative rate. However, the horizontal and vertical margins are related to the curative resection of EGC and the prognosis of patients. Thus the accurate prediction of the tumor boundary and its invasive depth before treatment counts for much in planning the most appropriate treatment strategy and promising curative resection. To date, various endoscopic techniques have been identified to play a role in pretreatment evaluation, such as white light endoscopy, chromoendoscopy, narrow band imaging and endoscopic ultrasonography. This article aimed to summarize the diagnostic methods, applications and limitations of these different endoscopic techniques for identifying tumor horizontal and vertical margins in EGC, helping to increase preoperative evaluation of capabilities and to improve the curative resection rate of EGC.

Evaluation of a novel high-resolution magnifying videoendoscope that is capable of photodynamic diagnosis and therapy for gastric cancer

OBJECTIVE

To evaluate the usefulness of a novel high-resolution magnifying videoendoscope called the XG-0001 (Fujifilm, Tokyo, Japan) that is capable of PDD and PDT in experimental and clinical situations.

MATERIALS AND METHODS

The fluorescences of three photosensitizers (i.e., porfimer sodium (Photofrin), protoporphyrin IX and talaporfin sodium (Laserphyrin)) were studied experimentally via excitation with a purple diode laser (VDL, wavelength 405nm). Five consecutive patients with superficial early gastric cancer not indicated for surgery or other curative endoscopic treatment due to complicated serious diseases were enrolled in this study. After close endoscopic examinations, 2mg/kg of Photofrin were intravenously injected into the patients for PDT, and 5-aminolevulinic acid (ALA; 15-20mg/kg) was orally taken for PDD. PDD using VDL and PDT using an excimer-dye laser (630nm, 4mJ, 60Hz) were performed with the XG-0001.

RESULTS

Photofrin and Laserphyrin had experimentally the lowest and highest fluorescence intensities, respectively. The five patients comprised four men and one woman with a mean age 75.2 year and an age range of 56-83 years. Two additional cancerous lesions were newly detected by magnifying pharmacoendoscopy. In each patient, PDD was successfully performed. PDT could also safely performed and CR was obtained in 71.4% (5/7) of the cancerous lesions in five patients, and no serious complications were encountered.

CONCLUSION

The XG-0001, which is based on a simultaneous videoendoscopy method that uses an RGB color chip CCD, proved extremely useful in routine use and also in PDD and PDT for gastric cancer.

Present and future status of flexible spectral imaging color enhancement and blue laser imaging technology

The usefulness of flexible spectral imaging color enhancement (FICE) has been reported for evaluating the esophagus, stomach, and small and large intestine. Higher contrast is shown between cancer and the surrounding mucosa in the esophagus and stomach and may facilitate the detection of gastric cancers missed by white light imaging alone. The surface patterns of gastric mucosa are clearly visualized in non-malignant areas but are irregular and blurred in malignant areas, leading to clear demarcation. Capsule endoscopy with FICE detects angiodysplasia and erosions of the small intestine. The surface and vascular pattern with FICE is useful for the differential diagnosis of colorectal polyps. However, FICE remains somewhat poor at visualizing mucosal microvasculature on a tumor surface. Narrow-band imaging (NBI) is dark in observing whole gastric mucosa and poor at visualizing mucosal microstructure. Blue laser imaging (BLI) has the potential to resolve these limitations. Narrow-band laser light combined with white light shows irregular microvessels on both differentiated and undifferentiated gastric cancer similar to those using NBI. In addition, irregular surface patterns including minute white zones are clearly seen on the uneven surface of differentiated lesions, resulting in exclusion of undifferentiated lesions. Using both distant and close-up views, a high contrast between green intestinal metaplasia and brown gastric cancer may lead to early detection of gastric cancers and determination of a demarcation line. BLI produces high-contrast images in esophageal cancer with clear vision of intrapapillary capillary loops and also predicts the histopathological diagnosis and depth of invasion in colorectal neoplasms.

Red-flag technologies in gastric neoplasia

Given its morbidity and mortality, the early detection and diagnosis of gastric cancer is an area of intense research focus. This article reviews the emerging use of enhanced endoscopic imaging technologies in the detection and management of gastric cancer. The combined use of white-light endoscopy with enhanced imaging technologies, such as magnification narrow-band imaging, chromoendoscopy, and autofluorescence endoscopy, demonstrates promise in the improved ability to detect and delineate gastric neoplasia. However, widespread clinical use is still limited, mainly because of the restricted availability of the technologies.

Premalignant conditions of gastric cancer

Premalignant lesions of gastric cancer encompass a variety of conditions such as chronic gastritis, intestinal metaplasia and dysplasia, in which elevated risk of developing gastric cancer have been documented. Among them, intestinal metaplasia is frequently encountered in our daily endoscopic examination, yet its clinical significance is often underestimated despite of a number of reports demonstrating genetic and epigenetic alterations in the intestinal metaplastic mucosa. In this review, I will describe the molecular mechanisms of phenotypic changes from gastric mucosa to intestinal metaplasia based on our analysis of mouse model of intestinal metaplasia generated by ectopic expression of CDX2 in conjunction with the studies with human intestinal metaplasia.

Screening for precancerous lesions of upper gastrointestinal tract: from the endoscopists' viewpoint

Upper gastrointestinal tract cancers are one of the most important leading causes of cancer death worldwide. Diagnosis at late stages always brings about poor outcome of these malignancies. The early detection of precancerous or early cancerous lesions of gastrointestinal tract is therefore of utmost importance to improve the overall outcome and maintain a good quality of life of patients. The desire of endoscopists to visualize the invisibles under conventional white-light endoscopy has accelerated the advancements in endoscopy technologies. Nowadays, image-enhanced endoscopy which utilizes optical- or dye-based contrasting techniques has been widely applied in endoscopic screening program of gastrointestinal tract malignancies. These contrasting endoscopic technologies not only improve the visualization of early foci missed by conventional endoscopy, but also gain the insight of histopathology and tumor invasiveness, that is so-called optical biopsy. Here, we will review the application of advanced endoscopy technique in screening program of upper gastrointestinal tract cancers.