Probe-based confocal endomicroscopy is accurate for differentiating gastric lesions in patients in a Western center

Objective： Probe-based confoeal laser endomicroscopy （pCLE） technique may improve the diagnosis of gastric mucosal lesions allowing acquisition of high-resolution in vivo images at the cellular and mierovaseular levels. This study aims to evaluate the accuracy of pCLE for the differential diagnosis of non-neoplastic and neoplastic gastric lesions.Methods： Twenty gastric mucosal lesions from 10 patients were evaluated during endoscopic procedure and were examined by pCLE. Diagnostic pCLE was followed by biopsies or endoscopic resection of suspected lesions. A senior pathologist evaluated the specimens and was blinded to the pCLE results.Results： Patients＇ mean age was 68.3 （range, 42-83） years and six were men. Thirteen suspicious flat or elevated lesions （classified as 0-Is, 0-IIa or 0-IIa ＋ IIc） and seven pre-malignant lesions （atrophy and intestinal metaplasia） were evaluated. One patient was studied during his long-term follow-up after partial gastrectomy and presented severe atrophy, intestinal metaplasia, and xanthomas at the stump mucosa. The location of gastric lesions was in the body （n=10 lesions）, the antrum （n=9） and the incisura angularis （n=1）. All neoplastic lesions and all but one benign lesion were properly diagnosed by pCLE. pCLE incorrectly diagnosed one small antrum lesion as adenoma, however the final diagnosis was intestinal metaplasia. The final histological diagnosis was neoplastic in 9 and benign lesions in 11. In this small case series, pCLE accuracy was 95% （19/20 lesions）.Conclusions： pCLE is accurate for real time histology of gastric lesions, pCLE may change the management of patients with gastric mucosal lesions, guiding biopsies and endoscopic resection, and avoiding further diagnostic workup or unnecessary therapy.

Software for automated classification of probe-based confocal laser endomicroscopy videos of colorectal polyps

AIM:To support probe-based confocal laser endomi-croscopy (pCLE) diagnosis by designing software for the automated classification of colonic polyps. METHODS:Intravenous fluorescein pCLE imaging of colorectal lesions was performed on patients under-going screening and surveillance colonoscopies, followed by polypectomies. All resected specimens were reviewed by a reference gastrointestinal pathologist blinded to pCLE information. Histopathology was used as the criterion standard for the differentiation between neoplastic and non-neoplastic lesions. The pCLE video sequences, recorded for each polyp, were analyzed off-line by 2 expert endoscopists who were blinded to the endoscopic characteristics and histopathology. These pCLE videos, along with their histopathology diagnosis, were used to train the automated classification software which is a content-based image retrieval technique followed by k-nearest neighbor classification. The performance of the off-line diagnosis of pCLE videos established by the 2 expert endoscopists was compared with that of automated pCLE software classification. All evaluations were performed using leave-one-patient- out cross-validation to avoid bias. RESULTS:Colorectal lesions (135) were imaged in 71 patients. Based on histopathology, 93 of these 135 lesions were neoplastic and 42 were non-neoplastic. The study found no statistical significance for the difference between the performance of automated pCLE software classification (accuracy 89.6%, sensitivity 92.5%, specificity 83.3%, using leave-one-patient-out cross-validation) and the performance of the off-line diagnosis of pCLE videos established by the 2 expert endoscopists (accuracy 89.6%, sensitivity 91.4%, specificity 85.7%). There was very low power (< 6%) to detect the observed differences. The 95% confidence intervals for equivalence testing were:-0.073 to 0.073 for accuracy, -0.068 to 0.089 for sensitivity and -0.18 to 0.13 for specificity. The classification software proposed in this study is not a "black box" but an informative tool based on the query by example model that produces, as intermediate results, visually similar annotated videos that are directly interpretable by the endoscopist. CONCLUSION:The proposed software for automated classification of pCLE videos of colonic polyps achieves high performance, comparable to that of off-line diagnosis of pCLE videos established by expert endoscopists.

Real-time in vivo distal margin selection using confocal laser endomicroscopy in transanal total mesorectal excision for rectal cancer

BACKGROUND Transanal total mesorectal excision(TaTME)allows patients with ultralow rectal cancer to be treated with sphincter-saving surgery.However,accurate delineation of the distal resection margin(DRM),which is essential to achieve R0 resection for low rectal cancer in TaTME,is technically demanding.AIM To assess the feasibility of optical biopsy using probe-based confocal laser endomicroscopy(pCLE)to select the DRM during TaTME for low rectal cancer.METHODS A total of 43 consecutive patients who were diagnosed with low rectal cancer and scheduled for TaTME were prospectively enrolled from January 2019 to January 2021.pCLE was used to determine the distal edge of the tumor as well as the DRM during surgery.The final pathological report was used as the gold standard.The diagnostic accuracy of pCLE examination was calculated.RESULTS A total of 86 pCLE videos of 43 patients were included in the analyses.The sensitivity,specificity and accuracy of real-time pCLE examination were 90.00%[95%confidence interval(CI):76.34%-97.21%],86.96%(95%CI:73.74%-95.06%)and 88.37%(95%CI:79.65%-94.28%),respectively.The accuracy of blinded pCLE reinterpretation was 86.05%(95%CI:76.89%-92.58%).Furthermore,our results show satisfactory interobserver agreement(κ=0.767,standard error=0.069)for the detection of cancer tissue by pCLE.There were no positive DRMs(≤1 mm)in this study.The median DRM was 7 mm[interquartile range(IQR)=5-10 mm].The median Wexner score was 5(IQR=3-6)at 6 mo after stoma closure.CONCLUSION Real-time in vivo pCLE examination is feasible and safe for selecting the DRM during TaTME for low rectal cancer(clinical trial registration number:NCT04016948).

Cancer risk in IBD: How to diagnose and how to manage DALM and ALM

The risk of developing neoplasia leading to colorectal cancer is significantly increased in ulcerative colitis (UC) and most likely in Crohn's disease. Several endoscopic surveillance strategies have been implemented to identify these lesions. The main issue is that colitisassociated neoplasms often occurs in flat mucosa, often being detected on taking random biopsies rather than by identification of these lesions via endoscopic imaging. The standard diagnostic procedure in long lasting UC is to take four biopsies every 10 cm. Image enhancement methods, such as chromoendoscopy and virtual histology using endomicroscopy, have greatly im- proved neoplasia detection rates and may contribute toreduced random biopsies by taking targeted "smart" biopsies. Chromoendoscopy may effectively be performed by experienced endoscopists for routine screening of UC patients. By contrast, endomicroscopy is often only available in selected specialized endoscopic centers. Importantly, advanced endoscopic imaging has the poten- tial to increase the detection rate of neoplasia whereas the interplay between endoscopic experience and interpretation of histological biopsy evaluation allows the physician to make a proper diagnosis and to find the appropriate therapeutic approach. Colitis-associated intraepithelial neoplasms may occur in flat mucosa of endoscopically normal appearance or may arise as dysplasia-associated lesion or mass (DALM), which may be indistinguishable from sporadic adenomas in healthy or non-colitis mucosa [adenoma-like mass (ALM)]. The aim of this review was to summarize endoscopic and histological characteristics of DALM and ALM in the context of therapeutic procedures.