Background and study aims: A randomized in vivo animal study previously demonstrated that topical injection of mesna solution (sodium-2-mercaptoethanesulfonate) chemically softened submucosal connective tissues and facilitated mechanical dissection of the submucosal tissue plane. The present study evaluated the technical feasibility and safety of chemically assisted endoscopic submucosal dissection (CA-ESD) using mesna in 20 consecutive patients who underwent endoscopic excision of gastric neoplasm. Materials and methods: Following the margination of the lesion with a mucosal circumcision, 4 – 12 mL of 10 % mesna solution was injected into the submucosal layer. Mechanical submucosal dissection was then performed by bluntly cleaving the chemically treated submucosal layer with the tip of a cap-fitted gastroscope. The use of cautery was restricted to prophylactic hemostasis, dissection of the coagulated vessels and persistent submucosal tissues, and the final snare resection. Post-therapeutic ulceration repair and adverse events were followed up during a 1-week hospitalization and by repeat endoscopies at 1 day, 1 week, and 1 month after the procedure. Results: Sixteen gastric cancers and four adenomas were treated in this study. The sampled tissue measured 38.25 ± 14.53 mm, with an en bloc resection rate of 100 %. Mean operation time was 21.17 ± 11.6 minutes. The time spent using cautery was limited to 26.1 % of the total submucosal dissection time. Ulcerations healed normally without complications. Conclusions: This preliminary study demonstrates that submucosal injection of mesna facilitates and expedites mechanical submucosal dissection. The major limitations in this study include the single-arm study design and a small patient population.

Ultrasonographic elastography is a modality used to visualize the elastic properties of tissues. Technological advances in ultrasound equipment have supported the evaluation of elastography (EG) in endosonography (EUS). Currently, the usefulness of not only EUS-strain elastography (EUS-SE) but also EUS-shear wave elastography (EUS-SWE) has been reported. We reviewed the literature on the usefulness of EUS-EG for various diseases such as chronic pancreatitis, pancreatic solid lesion, autoimmune pancreatitis, lymph node, and gastrointestinal and subepithelial lesions. The importance of this new diagnostic parameter, “tissue elasticity” in clinical practice might be applied not only to the diagnosis of liver fibrosis but also to the elucidation of the pathogeneses of various gastrointestinal diseases, including pancreatic diseases, and to the evaluation of therapeutic effects. The most important feature of EUS-EG is that it is a non-invasive modality. This is an advantage not found in EUS-guided fine needle aspiration (EUS-FNA), which has made remarkable progress in the field of diagnostics in recent years. Further development of artificial intelligence (AI) is expected to improve the diagnostic performance of EUS-EG. Future research on EUS-EG is anticipated.

Background: Currently, no classification system using magnification endoscopy for the diagnosis of superficial Barrett’s esophagus (BE)-related neoplasia has been widely accepted. This nationwide multicenter study aimed to validate the diagnostic accuracy and reproducibility of the magnification endoscopy classification system, including the diagnostic flowchart developed by the Japan Esophageal Society—Barrett’s esophagus working group (JES-BE) for superficial Barrett’s esophagus-related neoplasms. Methods: The JES-BE acquired high-definition magnification narrow-band imaging (HM-NBI) images of non-dysplastic and dysplastic BE from 10 domestic institutions. A total of 186 high-quality HM-NBI images were selected. Thirty images were used for the training phase and 156 for the validation (test) phase. We invited five non-experts and five expert reviewers. In the training phase, the reviewers discussed how to correctly predict the histology based on the JES-BE criteria. In the validation phase, they evaluated whether the criteria accurately predicted the histology results according to the diagnostic flowchart. The validation phase was performed immediately after the training phase and at 6 weeks thereafter. Results: The sensitivity and specificity for all reviewers were 87% and 97%, respectively. Overall accuracy, positive predictive value, and negative predictive value were 91%, 98%, and 83%, respectively. The overall strength of inter-observer and intra-observer agreements for dysplastic histology prediction was κ = 0.77 and κ = 0.83, respectively. No significant difference in diagnostic accuracy and reproducibility between experts and non-experts was found. Conclusion: The JES-BE classification system, including the diagnostic flowchart for predicting dysplastic BE, is acceptable and reliable, regardless of the clinician’s experience level.

Endoscopic ultrasonography (EUS) has been applied to the diagnosis of various digestive disorders. Although it has been widely accepted and its diagnostic value is high, the dependence of EUS diagnosis on image interpretation done by the endosonographer has persisted as an important difficulty. Consequently, high interobserver reliability (IOR) in EUS diagnosis is important to demonstrate the reliability of EUS diagnosis. We reviewed the literature on the IOR of EUS diagnosis for various diseases such as chronic pancreatitis, pancreatic solid/cystic mass, lymphadenopathy, and gastrointestinal and subepithelial lesions. The IOR of EUS diagnosis differs depending on the disease; moreover, EUS findings with high IOR and those with IOR that was not necessarily high were used as diagnostic criteria. Therefore, to further increase the value of EUS diagnosis, EUS diagnostic criteria with high diagnostic characteristics based on EUS findings with high IOR must be established.

Esophageal varices are caused by the development of collateral circulation in the esophagus as a result of portal hypertension. It is important to administer appropriate preventive treatment because bleeding varices can be fatal. Esophageal varices have complex and diverse hemodynamics, and there are various variations for each case. Endoscopic ultrasound (EUS) can estimate the hemodynamics of each case. Therefore, observation by EUS in esophageal varices provides useful information, such as safe and effective treatment selection, prediction of recurrence, and appropriate follow-up after treatment. Although treatment for the esophagogastric varices can be performed without EUS imaging, understanding the local hemodynamics of the varices using EUS prior to treatment will lead to more safe and effective treatment. EUS observation is an indispensable tool for thorough variceal care.

In 2009, diagnostic criteria for early chronic pancreatitis (DCECP2009) were proposed by the Japan Pancreas Society. This study aimed to evaluate the interobserver reliability (IOR) of endoscopic ultrasound (EUS) criteria for diagnosis of early chronic pancreatitis (ECP) between DCECP2009 and 2019 diagnostic criteria for ECP (DCECP2019) to assess the validity of the revision from the perspective of EUS findings. Among patients who underwent a detailed observation of the pancreas by EUS at our institution between January 2018 and March 2019, EUS images of 97 patients were extracted. Images were reviewed by 12 gastrointestinal endoscopy experts (eight pancreatologists, group A and four nonpancreatologists, group B). The overall kappa (K)-values for the IOR of the DCECP2009 EUS criteria were 0.424 and 0.563:0.231 for groups A:B, whereas the overall K-values for the DCECP2019 criteria were 0.618, and 0.733:0.442 for groups A:B. Regarding changes in the final diagnosis of ECP based on clinical features and EUS findings, 20 cases were definite ECP, 53 were probable ECP, and 24 were normal according to DCECP2009. In contrast, seven were definite ECP, 19 were probable ECP, and 71 were normal according to DECEP2019. IOR of DCECP2019 was higher than that of DCECP2009, which indicates an improvement in precision.