Recent advances in chromoscopic colonoscopy and endomicroscopy

Confocal Laser Endomicroscopy in Gastrointestinal and Pancreatobiliary Diseases: A Systematic Review and Meta-Analysis

Confocal laser endomicroscopy (CLE) is an endoscopic-assisted technique developed to obtain histopathological diagnoses of gastrointestinal and pancreatobiliary diseases in real time. The objective of this systematic review is to analyze the current literature on CLE and to evaluate the applicability and diagnostic yield of CLE in patients with gastrointestinal and pancreatobiliary diseases. A literature search was performed on MEDLINE, EMBASE, Scopus, and Cochrane Oral Health Group Specialized Register, using pertinent keywords without time limitations. Both prospective and retrospective clinical studies that evaluated the sensitivity, specificity, or accuracy of CLE were eligible for inclusion. Of 662 articles identified, 102 studies were included in the systematic review. The studies were conducted between 2004 and 2015 in 16 different countries. CLE demonstrated high sensitivity and specificity in the detection of dysplasia in Barrett's esophagus, gastric neoplasms and polyps, colorectal cancers in inflammatory bowel disease, malignant pancreatobiliary strictures, and pancreatic cysts. Although CLE has several promising applications, its use has been limited by its low availability, high cost, and need of specific operator training. Further clinical trials with a particular focus on cost-effectiveness and medicoeconomic analyses, as well as standardized institutional training, are advocated to implement CLE in routine clinical practice.

Enhanced imaging colonoscopy facilitates dense motion-based 3D reconstruction

We propose a novel approach for estimating a dense 3D model of neoplasia in colonoscopy using enhanced imaging endoscopy modalities. Estimating a dense 3D model of neoplasia is important to make 3D measurements and to classify the superficial lesions in standard frameworks such as the Paris classification. However, it is challenging to obtain decent dense 3D models using computer vision techniques such as Structure-from-Motion due to the lack of texture in conventional (white light) colonoscopy. Therefore, we propose to use enhanced imaging endoscopy modalities such as Narrow Band Imaging and chromoendoscopy to facilitate the 3D reconstruction process. Thanks to the use of these enhanced endoscopy techniques, visualization is improved, resulting in more reliable feature tracks and 3D reconstruction results. We first build a sparse 3D model of neoplasia using Structure-from-Motion from enhanced endoscopy imagery. Then, the sparse reconstruction is densified using a Multi-View Stereo approach, and finally the dense 3D point cloud is transformed into a mesh by means of Poisson surface reconstruction. The obtained dense 3D models facilitate classification of neoplasia in the Paris classification, in which the 3D size and the shape of the neoplasia play a major role in the diagnosis.

Detection of intestinal cancer by local, topical application of a quenched fluorescence probe for cysteine cathepsins

Early detection of colonic polyps can prevent up to 90% of colorectal cancer deaths. Conventional colonoscopy readily detects the majority of premalignant lesions, which exhibit raised morphology. However, lesions that are flat and depressed are often undetected using this method. Therefore, there is a need for molecular-based contrast agents to improve detection rates over conventional colonoscopy. We evaluated a quenched fluorescent activity-based probe (qABP; BMV109) that targets multiple cysteine cathepsins that are overexpressed in intestinal dysplasia in a genetic model of spontaneous intestinal polyp formation and in a chemically induced model of colorectal carcinoma. We found that the qABP selectively targets cysteine cathepsins, resulting in high sensitivity and specificity for intestinal tumors in mice and humans. Additionally, the qABP can be administered by either intravenous injection or by local delivery to the colon, making it a highly valuable tool for improved detection of colorectal lesions using fluorescence-guided colonoscopy.

Analysis of interobserver variability for endomicroscopy of the gastrointestinal tract

BACKGROUND

Endomicroscopy allows in vivo microscopic investigation of enteral mucosa during endoscopic examinations. The aim of this study was to determine interobserver variability in the evaluation of endomicroscopic pictures of several organs by groups of investigators composed of confocal experts, pathologists and students.

METHODS

Twenty-five selected representative endomicroscopic pictures of the colon, stomach and oesophagus (total number, 75) were evaluated based on tissue, inflammatory and neoplastic changes (secondary endpoints). The endomicroscopic presence of neoplastic features was the primary endpoint and correlated with the final histological diagnosis.

RESULTS

The kappa values for experts examining colon, stomach, and oesophagus pictures were 0.80, 0.91, and 0.488, respectively; for students 0.74, 0.684, and 0.527 and for pathologists 0.749, 0.633, and 0.346, respectively. Neoplasia was accurately diagnosed in 67-97% of patients with no significant differences between the 3 groups. Tissue differentiation was determined best by pathologists, whereas the degree of inflammation was better diagnosed by experts and students. In all 3 groups the diagnosis of oesophageal diseases was the most difficult.

CONCLUSIONS

Endomicroscopic images can be interpreted with high concordance. In our study, the diagnostic reliability was not different between students, endomicroscopic experts, and pathologists. Thus, endomicroscopy could be an additional and reliable imaging modality for diagnosing mucosal neoplasia of the gut.

The race for mainstream gastrointestinal endoscopy: frontrunners

In recent years, gastrointestinal endoscopy has evolved and branched out from a primary naked-eye diagnostic technique to a multitude of sophisticated investigative and therapeutic procedures. While many of the new endoscopic techniques are currently too complex or expensive to make it to mainstream clinical practice, others are already bringing major progress to the management of digestive diseases. In this review we will discuss a selected group of the emerging techniques and technologies used to increase the diagnostic yield in the colon and small intestine, including Third Eye® Retroscopes®, colon capsule endoscopy, spiral enteroscopy and confocal laser endomicroscopy. We will also discuss over-the-scope clip devices, a relatively simple and inexpensive tool potentially capable of noninvasive closing intestinal perforations and allowing the removal of infiltrating tumors.

Relationship between pit patterns of colorectal polypoid lesions classified by magnifying chromoendoscopy and expression of hMLH1 and hMSH2 proteins in colorectal mucosa

AIM: To explore the relationship between pit patterns of colorectal polypoid lesions classified by magnifying chromoendoscopy and expression of human MutL homolog 1/2 (hMLH1/2) proteins in colorectal mucosa.

METHODS: Colorectal lesions in 146 patients were classified as type I to V pit patterns by magnifying chromoendoscopy using the Kudo criteria. All lesions were pathologically confirmed as nonneoplastic, adenomatous or cancerous lesions. Colorectal mucosal biopsy specimens were used to detect the expression of hMLH1 and hMSH2 proteins by immunohistochemistry.

RESULTS: A total of 256 polypoid lesions were found in 146 patients by magnifying chromoendoscopy. The rates of loss of hMLH1 and hMSH2 protein expression increased gradually from type I to type V pit patterns in 256 polypoid lesions [hMLH1: 0.0% (0/11), 1.61% (1/62), 19.68% (25/127), 33.33% (1/3), 32.26% (10/31), 36.36%(8/22); hMSH2: 0.00% (0/11), 3.22% (2/62), 16.53% (21/127), 33.33% (1/3), 35.48% (11/31), 40.90% (9/22); all P < 0.01]. The rates of loss of hMLH1 and hMSH2 expression were 2.70% and 4.05% in nonneoplastic lesions, 23.07% and 16.92% in adenoma lesions, and 25% and 30.76% in cancerous lesions. The rates of loss of hMLH1 and hMSH2 protein expression were significantly higher in cancerous lesions than in adenomatous and nonneoplastic lesions (both P < 0.01). There was no significant difference between the rate of loss of hMLH1 and that of hMSH2 protein expression in all lesions (all P > 0.05).

CONCLUSION: The rates of loss of hMLH1 and hMSH2 protein expression gradually increased from type I to type V pit patterns, suggesting that mutation or functional deficiency of DNA mismatch repair genes is an early event in colorectal carcinogenesis. Lesion classification by magnifying chromoendoscopy or detection of the loss of hMLH1 and hMSH2 protein expression can help identify precancerous and colorectal lesions from colorectal lesions.

Chemoprevention of colorectal cancer: feasibility in everyday practice?

Chemoprevention means the use of agents to prevent, delay, or reverse carcinogenesis. This review was designed to critically discuss the most promising agents in colorectal cancer (CRC) chemoprevention. Aspirin is the best studied chemopreventive agent for CRC. Optimal chemoprevention requires long-term use and high dose of aspirin that may increase the risk of gastrointestinal bleeding. Nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors may also be candidates for chemoprevention. The regular use of nonsteroidal anti-inflammatory drugs, however, causes adverse effects including gastrointestinal bleeding, and cyclooxygenase-2 inhibitors may increase the risk of cardiovascular events. In patients with ulcerative colitis 5-aminosalicylates reduce the risk of CRC and dysplasia. Ursodeoxycholic acid can reduce the risk of dysplasia or CRC in patients with primary sclerosing cholangitis and ulcerative colitis. Current data are insufficient to support the use of hormone replacement therapy to reduce the risk of CRC. Statins may have chemopreventive effects, but further investigation of their overall benefits in preventing CRC is warranted. Antioxidant supplements cannot prevent CRC. The usefulness of selenium, folate, calcium, and vitamin D awaits further evaluation. Chemoprevention cannot yet be accepted as standard medical practice. Use of chemopreventive agents cannot be a substitute for colorectal surveillance.

Role of Fuji intelligent chromo endoscopy in observation of pit pattern and blood capillary form of colonic lesions

AIM: To compare Fuji intelligent chromo endoscopy (FICE) and staining techniques in differential diagnosis for colonic tumor and non-tumor lesions.

METHODS: From March 2007 to May 2008, 245 patients with colon neoplasm or polypoid lesions were included. The patients underwent a magnifying ordinary colonoscopy, a magnifying FICE technique and magnifying staining technique. The pit pattern and blood capillary form of the lesions were examined, an endoscopic diagnosis was made and compared with the pathologic diagnosis.

RESULTS: A total of 480 neoplasms were detected in 245 patients. There was significant difference in detecting lesions between conventional magnifying endoscopy and FICE larger models (90.0% vs 98.8%, P < 0.01). FICE magnifying endoscopy better revealed mucosal structure of capillaries than staining magnifying endoscopy (P < 0.01), but there was not significant difference in revealing duct openings. FICE showed higher coincidence rate of diagnosis, higher sensitivity and specificity of the colorectal cancer than staining techniques (92.2% vs 81.0%, 95.3% vs 85.6%, 88.4% vs 75.6%, all P < 0.01).

CONCLUSION: FICE operates easily with higher coincidence rate of diagnosis and has a satisfactory clinical practical value in diagnosing colonic cancers.

Endoscopic mucosal resection of colonic lesions: current applications and future prospects

The introduction of submucosal fluid injection has remarkably extended the range of endoscopically resectable polyps. The limiting factor for endoscopic resection is not polyp size, but polyp depth. Endoscopic ultrasound is a useful adjunctive diagnostic tool to assess the depth of invasion. The success of are section ultimately depends on pathologic confirmation of a benign nature of this lesion or of a cancer limited to the mucosa. Selected well-differentiated cancers without lymphovascular invasion of the superficial submucosa can be successfully resected endoscopically.