Diagnostic performance of confocal laser endomicroscopy for optical diagnosis of gastric intestinal metaplasia: a meta-analysis

Gastric Intestinal Metaplasia: Challenges and the Opportunity for Precision Prevention

GIM is a persistent, premalignant lesion whereby gastric mucosa is replaced by metaplastic mucosa resembling intestinal tissue, arising in the setting of chronic inflammation, particularly in the context of Helicobacter pylori. While the overall rates of progression to gastric adenocarcinoma are low, estimated at from 0.25 to 2.5%, there are features that confer a much higher risk and warrant follow-up. In this review, we collate and summarise the current knowledge regarding the pathogenesis of GIM, and the clinical, endoscopic and histologic risk factors for cancer. We examine the current state-of-practice with regard to the diagnosis and management of GIM, which varies widely in the published guidelines and in practice. We consider the emerging evidence in population studies, artificial intelligence and molecular markers, which will guide future models of care. The ultimate goal is to increase the detection of early gastric dysplasia/neoplasia that can be cured while avoiding unnecessary surveillance in very low-risk individuals.

Confocal laser endomicroscopy in gastro-intestinal endoscopy: technical aspects and clinical applications

Confocal laser endomicroscopy (CLE) is an advanced endoscopic imaging technology that provides a magnified, cellular level view of gastrointestinal epithelia. In conjunction with topical or intravenous fluorescent dyes, CLE allows for an "optical biopsy" for real-time diagnosis. Two different CLE system have been used in clinical endoscopy, probe-based CLE (pCLE) and endoscope-based CLE (eCLE). Using pCLE, the device can be delivered: (I) into the luminal gastrointestinal tract through the working channel of standard endoscopes; (II) into extraluminal cystic and solid parenchymal lesions through an endoscopic ultrasound (EUS) needle; or (III) into the biliary system through an endoscopic retrograde cholangiopancreatography (ERCP) accessory channel. With eCLE, the probe is directly integrated into the tip of a conventional endoscope, however, these endoscopes are no longer commercially available. CLE has moderate to high diagnostic accuracy for neoplastic and inflammatory conditions through the gastrointestinal tract including: oesophageal, gastric and colonic neoplasia, pancreatic cysts and solid lesions, malignant pancreatobiliary strictures and inflammatory bowel disease. Some studies have demonstrated the diagnostic benefit of CLE imaging when combined with either conventional white light endoscopy or advanced imaging technologies. Therefore, optical biopsies using CLE can resolve diagnostic dilemmas in some cases where conventional imaging fails to achieve conclusive results. CLE could also reduce the requirement for extensive tissue sampling during surveillance procedures. In the future, CLE in combination with molecular probes, could allow for the molecular characterization of diseases and assess response to targeted therapy. However, the narrow field of view, high capital costs and specialized operator training requirements remain the main limitations. Future multi-center, randomized trials with a focus on conventional diagnostic applications, cost-effectiveness and standardized training will be required for definitive evidence. The objective of this review is to evaluate the technical aspects and current applications of CLE in patients with gastrointestinal and pancreatobiliary diseases and discuss future directions for this technique.

Intensity-based nonrigid endomicroscopic image mosaicking incorporating texture relevance for compensation of tissue deformation

Image mosaicking has emerged as a universal technique to broaden the field-of-view of the probe-based confocal laser endomicroscopy (pCLE) imaging system. However, due to the influence of probe-tissue contact forces and optical components on imaging quality, existing mosaicking methods remain insufficient to deal with practical challenges. In this paper, we present the texture encoded sum of conditional variance (TESCV) as a novel similarity metric, and effectively incorporate it into a sequential mosaicking scheme to simultaneously correct rigid probe shift and nonrigid tissue deformation. TESCV combines both intensity dependency and texture relevance to quantify the differences between pCLE image frames, where a discriminative binary descriptor named fully cross-detected local derivative pattern (FCLDP) is designed to extract more detailed structural textures. Furthermore, we also analytically derive the closed-form gradient of TESCV with respect to the transformation variables. Experiments on the circular dataset highlighted the advantage of the TESCV metric in improving mosaicking performance compared with the other four recently published metrics. The comparison with the other four state-of-the-art mosaicking methods on the spiral and manual datasets indicated that the proposed TESCV-based method not only worked stably at different contact forces, but was also suitable for both low- and high-resolution imaging systems. With more accurate and delicate mosaics, the proposed method holds promises to meet clinical demands for intraoperative optical biopsy.

Modular Robotic Scanning Device for Real-Time Gastric Endomicroscopy

Optical biopsy methods, such as probe-based endomicroscopy, can be used for the identification of early mucosal dysplasia in various gastrointestinal conditions and have potential applications in the screening of early-stage gastric cancer in vivo. However, it is difficult to scan a large area of the gastric mucosa for mosaicing during standard endoscopy. This paper proposes a novel 'snap-on' robotic scanning device that can integrate distally with a commercial endoscope. A customized low-cost endomicroscopy system is used for obtaining micro imaging. The developed device could scan a large area of gastric tissue during standard endoscopy. The device achieves positioning accuracy that is less than 0.23 mm. Experimental results showed that the device could achieve large area mosaicing (15.8-18.6 mm²) and demonstrated the potential clinical value of the device for real-time gastric tissue identification and margin assessment. This approach presents an important alternative to current histology techniques for gastrointestinal tract diagnosis.

Confocal Laser Endomicroscopy for the Diagnosis of Urothelial Carcinoma in the Bladder and the Upper Urinary Tract: Protocols for Two Prospective Explorative Studies

Background

Visual confirmation of a suspicious lesion in the urinary tract is a major corner stone in diagnosing urothelial carcinoma. However, during cystoscopy (for bladder tumors) and ureterorenoscopy (for tumors of the upper urinary tract) no real-time histopathologic information can be obtained. Confocal laser endomicroscopy (CLE) is an optical imaging technique that allows for in vivo high-resolution imaging and may allow real-time tumor grading of urothelial lesions.

Objective

The primary objective of both studies is to develop descriptive criteria for in vivo CLE images of urothelial carcinoma (low-grade, high-grade, carcinoma in situ) and normal urothelium by comparing CLE images with corresponding histopathology.

Methods

In these two prospective clinical trials, CLE imaging will be performed of suspicious lesions and normal tissue in the urinary tract during surgery, prior to resection or biopsy. In the bladder study, CLE will be performed in 60 patients using the Cystoflex UHD-R probe. In the upper urinary tract study, CLE will be performed in 25 patients during ureterorenoscopy, who will undergo radical treatment (nephroureterectomy or segmental ureter resection) thereafter. All CLE images will be analyzed frame by frame by three independent, blinded observers. Histopathology and CLE-based diagnosis of the lesions will be evaluated. Both studies comply with the IDEAL stage 2b recommendations.

Results

Presently, recruitment of patients is ongoing in both studies. Results and outcomes are expected in 2018.

Conclusions

For development of CLE-based diagnosis of urothelial carcinoma in the bladder and the upper urinary tract, a structured conduct of research is required. This study will provide more insight in tissue-specific CLE criteria for real-time tumor grading of urothelial carcinoma.

Trial Registration

Confocal Laser Endomicroscopy: ClinicalTrials.gov NCT03013894; https://clinicaltrials.gov /ct2/show/NCT03013894?term=NCT03013894&rank=1 (Archived by WebCite at http://www.webcitation.org/6wiPZ378I); and Dutch Central Committee on Research Involving Human Subjects NL55537.018.15; https://www.toetsingonline.nl /to/ccmo_search.nsf/fABRpop?readform&unids=6B72AE6EB0FC3C2FC125821F001B45C6 (Archived by WebCite at http://www.webcitation.org/6wwJQvqWh). Confocal Laser Endomicroscopy in the upper urinary tract: ClinicalTrials.gov NCT03013920; https://clinicaltrials.gov/ct2/show/NCT03013920? term=NCT03013920&rank=1 (Archived by WebCite at http://www.webcitation.org/6wiPkjyt0); and Dutch Central Committee on Research Involving Human Subjects NL52989.018.16; https://www.toetsingonline.nl/to/ccmo_search.nsf/fABRpop?readform&unids=D27C9C3E5755CFECC12581690016779F (Archived by WebCite at http://www.webcitation.org/6wvy8R44C).

Diagnostic performance of confocal laser endomicroscopy for atrophy and gastric intestinal metaplasia: A meta-analysis

OBJECTIVE

To systematically evaluate the diagnostic efficacy of confocal laser endomicroscopy (CLE) for gastric atrophy (GA) and gastric intestinal metaplasia (GIM).

METHODS

Literature search was performed in PubMed and the Cochrane Library for CLE, GA and GIM. The sensitivity, specificity and diagnostic odds ratio (DOR) in diagnosing GA and GIM were pooled for analysis. A summary receiver operating curve (SROC) was documented and the area under the curve was calculated.

RESULTS

Of the 10 studies included in this current analysis, the pooled sensitivity, specificity and DOR of CLE to diagnose GA and GIM were found to be 88%, 98% and 330.85, and 93%, 98% and 439.97, respectively. The area under the SROC were 0.9491 and 0.9812 for the diagnosis of GA and GIM, respectively. Higher sensitivity and specificity of this technique in diagnosing GA and GIM were found in patients without representative disease spectrum and those received pCLE by subgroup analysis.

CONCLUSION

CLE is of great value and may be considered an alternative modality for the early diagnosis of GA and GIM.

High Salt Intake Is Associated with Atrophic Gastritis with Intestinal Metaplasia

Background: Although several studies have investigated excessive salt intake as a risk factor for gastric precancerous lesions, such as atrophic gastritis and intestinal metaplasia, the evidence is insufficient to make a conclusion. We evaluated the association between gastric precancerous lesions and salt intake.Methods: From 2008 to 2015, the medical records of 728 subjects who underwent upper gastrointestinal endoscopy and sodium excretion in 24-hour urine tests were retrospectively reviewed. Sixty-six subjects were excluded due to diuretics use (n = 55), diagnosis with a gastric neoplasm (n = 4), or the cases of intestinal metaplasia in the absence of atrophy (n = 7), so 662 subjects were included. Atrophic gastritis and intestinal metaplasia were diagnosed by endoscopic findings. The subjects were grouped into three levels by tertiles of 24-hour urine sodium excretion.Results: A total of 192 (29.0%) had atrophic gastritis without intestinal metaplasia and 112 (16.9%) had atrophic gastritis with intestinal metaplasia. A total of 276 subjects (61.5%) were infected with Helicobacter pylori (H. pylori). In multivariate analyses, H. pylori infection [OR = 14.17; 95% confidence interval (CI), 7.12-28.22) was associated with atrophic gastritis without intestinal metaplasia. Highest levels of sodium excretion (OR = 2.870; 95% CI, 1.34-6.14), heavy smoking (≥20 pack-years) (OR = 2.75; 95% CI, 1.02-7.39), and H. pylori infection (OR = 3.96; 95% CI, 2.02-7.76) were associated with atrophic gastritis with intestinal metaplasia.Conclusions: Our endoscopy-based study suggested that high salt intake could be associated with an increased risk of atrophic gastritis with intestinal metaplasia.Impact: Low salt diet might be helpful to prevent gastric carcinogenesis. Cancer Epidemiol Biomarkers Prev; 26(7); 1133-8. ©2017 AACR.