Simulating a target lesion for endoscopic submucosal dissection training in an ex vivo pig model

Novel beagle model of gastric local fibrotic target lesions for the evaluation and training of endoscopic techniques

BACKGROUND

Novel endoscopic techniques used in the treatment of gastric lesions with local submucosal fibrosis need preclinical evaluation and training due to safety limitations. Therefore, the purpose of our study was to establish an animal model of gastric local fibrotic target lesions and assess its feasibility in the evaluation and training of endoscopic techniques.

METHODS

In six experimental beagles, a 50% glucose solution was injected into three submucosal areas of the fundus, body, and antrum of the stomach to create gastric local fibrotic target lesions (experimental group). On post-injection day (PID) 7, the injection sites were assessed endoscopically to confirm the presence of submucosal fibrosis formation, and the dental floss clip traction assisted endoscopic submucosal dissection (DFC-ESD) procedure was performed on the gastric local fibrotic target lesions to confirm its feasibility after endoscopic observation. The normal gastric mucosa of six control beagles underwent the same procedure (control group). All the resected specimens were evaluated by histological examination.

RESULTS

All 12 beagles survived without postoperative adverse events. On PID 7, 16 ulcer changes were observed at the injection sites (16/18) under the endoscope, and endoscopic ultrasonography confirmed the local submucosal fibrosis formation in all ulcer lesions. The subsequent DFC-ESD was successfully performed on the 32 gastric target lesions, and the mean submucosal dissection time in the ulcer lesions was greater than that in the normal gastric mucosa (15.3 ± 5.6 vs. 6.8 ± 0.8 min; P < 0.001). There was no difference in rates of en bloc resection, severe hemorrhage, or perforation between the two groups. Histological analysis of the ulcer lesions showed the absence of epithelial or muscularis mucosae and extensive submucosal fibrous tissue proliferations compared with normal gastric mucosa. Overall, endoscopists had high satisfaction with the realism and feasibility of the animal model.

CONCLUSION

We developed a novel animal model of gastric local fibrotic target lesions to simulate difficult clinical situations, which strongly appeared to be suitable for the preclinical evaluation and learning of advanced endoscopic techniques.

Ex vivo nonbiomaterial gel-based model for endoscopic training

Video 1Use of artificial model for endoscopic training.

Forrest Classification for Bleeding Peptic Ulcer: A New Look at the Old Endoscopic Classification

The management of peptic ulcer bleeding is clinically challenging. For decades, the Forrest classification has been used for risk stratification for nonvariceal ulcer bleeding. The perception and interpretation of the Forrest classification vary among different endoscopists. The relationship between the bleeder and ulcer images and the different stages of the Forrest classification has not been studied yet. Endoscopic still images of 276 patients with peptic ulcer bleeding for the past 3 years were retrieved and reviewed. The intra-rater agreement and inter-rater agreement were compared. The obtained endoscopic images were manually drawn to delineate the extent of the ulcer and bleeding area. The areas of the region of interest were compared between the different stages of the Forrest classification. A total of 276 images were first classified by two experienced tutor endoscopists. The images were reviewed by six other endoscopists. A good intra-rater correlation was observed (0.92–0.98). A good inter-rater correlation was observed among the different levels of experience (0.639–0.859). The correlation was higher among tutor and junior endoscopists than among experienced endoscopists. Low-risk Forrest IIC and III lesions show distinct patterns compared to high-risk Forrest I, IIA, or IIB lesions. We found good agreement of the Forrest classification among different endoscopists in a single institution. This is the first study to quantitively analyze the obtained and explain the distinct patterns of bleeding ulcers from endoscopy images.

Evaluation of a robotic arm-assisted endoscope to facilitate endoscopic submucosal dissection (with video)

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) is considered technically difficult and challenging using a conventional flexible endoscope, mainly due to the lack of proper countertraction to expose the submucosal dissection plane. This study aimed to evaluate the feasibility of a traction method using a dexterous robotic arm in ex vivo gastric ESD.

METHODS

ESD was performed in a total of 45 procedures using a portable endoscopic tool handler (PETH) (n = 30) and using the conventional method (n = 15) at various locations in the stomach. For each procedure, the performance data were recorded, including the total procedure time (minutes), incision time (minutes), dissection speed (mm²/minute), and blind dissection rate (%), to enable a comparison of the 2 ESD methods.

RESULTS

The total procedure time was significantly shorter with PETH-ESD than in conventional ESD (23 vs 36 minutes, P = .011). This result is mainly attributed to the dissection speed, which was significantly faster, by more than 2.5 times, using the PETH (122.3 ± 76.5 vs 47.5 ± 26.9 mm²/minute, P < .001). The blind dissection rate was greatly decreased in PETH-ESD (0 vs 20%, P < .001). There was no significant difference in the incision time (6.1 ± 5.0 vs 5.5 ± 2.9 min, P = .612).

CONCLUSIONS

The countertraction method using the PETH significantly improved the dissection speed and reduced blind dissection by enhancing direct visualization of the submucosal plane. With the advantages of multidirectional traction, fine tension control, and regrasping, this new device is expected to improve the performance of ESD and further facilitate advanced endoscopic procedures.

Training in endoscopic mucosal resection and endoscopic submucosal dissection: Face, content and expert validity of the live porcine model

Introduction

Endoscopic mucosal resection and endoscopic submucosal dissection are demanding procedures. This study aims to establish face, content and expert validity of the live porcine model in performing endoscopic mucosal resection, endoscopic submucosal dissection, complication management and to assess it as a training tool.

Material and methods

Tutors and trainees participating in live porcine model endoscopic mucosal resection and endoscopic submucosal dissection workshops filled out a questionnaire regarding the realism of the model compared to human setting and its role as a learning tool. A 10-point Likert scale was used.

Results

Ninety-one endoscopists (13 tutors; 78 trainees) were involved in four workshops. Median global classifications for the realism of the life porcine model ranged between 7.0-8.0 (interquartile range 5.0-9.0). Procedures resembled human cases with a median of 9.0 (8.0-9.0) for oesophageal multiband endoscopic mucosal resection; 8.5 (8.0-9.0) for oesophageal endoscopic submucosal dissection; 9.0 (8.0-10.0) for gastric endoscopic submucosal dissection; and 9.0 (8.5-9.75 and 8.0-9.69) for complication detection and management. The animal model as a learning tool had median scores of 9.0 (7.0-10.0) considering how procedures are performed; 9.0-9.5 (8.0-10.0) for usefulness for beginners; and 9.0-10.0 (5.0-10.0) regarding it a prerequisite.

Conclusions

Training in a live porcine model was considered very realistic compared to the human setting and was highly appreciated as a learning tool. This is the first study to establish face, content and expert validity of the live porcine model in performing multiband endoscopic mucosal resection, oesophageal and gastric endoscopic submucosal dissection. The validation of this model provides the rationale to incorporate it into formal teaching programmes.

A novel artificial tissue simulator for endoscopic submucosal resection training - a pilot study

Background

We developed a novel artificial simulator for endoscopic submucosal dissection (ESD) as a bridge between instructional videos and animal tissue training and aimed to evaluate the feasibility of using an artificial tissue model in ESD training.

Methods

Eight gastroenterology fellows from one medical center were enrolled in this ESD training program. Before and after the simulator training, attendees indicated on a 5-point scale the degree of difficulty in performing the following procedures: lesion marking, mucosal pre-cutting, circumferential incision, submucosal dissection, and hemostasis. After the simulator training, the participants completed a questionnaire regarding their opinions on the degree of realism and the feasibility of using this model for training.

Results

After watching an instructional video, attendees felt that the most difficult techniques were submucosal dissection and hemostasis. After using the artificial tissue simulator model, the attendees felt more confident in performing performing lesion marking (p = 0.026) and submucosal dissection (p = 0.037). However, they still felt that hemostasis was the most difficult techniques to master. Overall, the attendees thought the simulator was realistic in simulated lesion marking and its use was feasible for simulated lesion marking and submucosal dissection.

Conclusion

Our pilot study shows the feasibility of using a novel artificial tissue in performing ESD and we believe that the artificial tissue simulator acts well as a bridge between instructional videos and animal model training. The model is reusable and inexpensive, and could disseminate the techniques of the ESD more easily and quickly.

Impact of formal training in endoscopic submucosal dissection for early gastrointestinal cancer: A systematic review and a meta-analysis

AIM: To summarize the clinical impact of a formal training for the effectiveness and safety of endoscopic submucosal dissection for gastrointestinal cancer.

METHODS: We searched databases including PubMed, EMBASE and the Cochrane Library and Science citation Index updated to August 2014 to include eligible articles. In the Meta-analysis, the main outcome measurements were en bloc resection rate, local recurrence rate (R0) and the incidence of procedure-related complications (perforation, bleeding).

RESULTS: En bloc resection was high for both, dissecting stomach tumors with an overall percentage of 93.2% (95%CI: 90.5-95.8) and dissecting colorectal tumors with an overall percentage of 89.4% (95%CI: 85.1-93.7). Although the number of studies reporting R0 resection (the dissected specimen was revealed free of tumor in both vertical and lateral margins) was small, the overall estimates for R0 resection were 81.4% (95%CI: 72-90.8) for stomach and 85.9% (95%CI: 77.5-95.5) for colorectal tumors, respectively. The analysis showed that the percentage of immediate perforation and bleeding were very low; 4.96 (95%CI: 3.6-6.3) and 1.4% (95%CI: 0.8-1.9) for colorectal tumors and 3.1% (95%CI: 2.0-4.1) and 4.8% (95%CI: 2.8-6.7) for stomach tumors, respectively.

CONCLUSION: In order to obtain the same rate of success of the analyzed studies it is a necessity to create training centers in the western countries during the “several years” of gastroenterology residence first only to teach EGC diagnose and second only to train endoscopic submucosal dissection.

The feasibility of using simulated targets in the stomachs of live pigs for full endoscopic submucosal dissection training

Background/Aims

In endoscopic submucosal dissection (ESD) training, only a flat target lesion can usually be simulated in the normal mucosa. This study aimed to evaluate the feasibility of simulated targets in the stomachs of live pigs for complete training.

Methods

Six trained endoscopists with hands-on experience with ex vivo, isolated pig stomachs were enrolled in this pilot study. An endoscopic banding device was used to create a polyp that was snared, leaving an ulcerated lesion. This simulated target model was used to perform ESD in pigs. The en bloc resection rate, procedure time, complications, quality of resection, and participants’ opinions on the simulated targets were compared with the conventional model.

Results

En bloc resections were achieved in all six simulated targets and six conventional models. The mean size of the resected specimens was 32.2 mm (range, 20 to 39 mm) in the simulated target group and 23.5 mm (range, 11 to 40 mm) in the conventional group. The target model had a high quality of resection and had a high satisfaction rate for margin identification and correct peripheral marking.

Conclusions

Good identification of the lesion and ease of periphery marking in the target model may improve resection quality.

Endoscopic submucosal dissection training with ex vivo human gastric remnants

BACKGROUND

Endoscopic submucosal dissection (ESD) offers en bloc resection of early cancer or precancerous lesions, potentially saving patients from major organ resection, such as gastrectomy, colectomy, and esophagectomy. Japan now leads the world in ESD due to its high rate of gastric cancer. Western countries, with their lower gastric cancer rates, do not get as much experience with the technique. Training in ESD utilizing both in vivo and ex vivo porcine stomach has been shown to decrease rates of perforation and operative time. Both models can be prohibitively expensive or not generally available to the majority of endoscopists on a regular basis. This study describes the framework for using human gastric remnants from sleeve gastrectomy patients for ESD training.

METHODS

Patients undergoing sleeve gastrectomy for morbid obesity were consented for use of their gastric specimen before surgery. The specimen was weighed and measured by the pathologist and then used for ESD training. The specimen was mounted to a 15-mm laparoscopic port and secured using a pursestring suture. ESD was then performed through this port.

RESULTS

We were able to successfully use this model to resect multiple marked out lesions in an en bloc fashion. Training using this model has improved our dissection times from approximately 2 h to 30 min for a 2-cm simulated lesion.

CONCLUSIONS

ESD requires the endoscopist to perform a surgical dissection. Until now, development of these skills required intensive training on porcine models that are not widely available. We were able to create a method using the excised portion from sleeve gastrectomy patients, providing a more accessible and cost-effective model for ESD training and potentially other endoscopic therapeutic modalities.

Chromoendoscopy in magnetically guided capsule endoscopy

Background

Diagnosis of intestinal metaplasia and dysplasia via conventional endoscopy is characterized by low interobserver agreement and poor correlation with histopathologic findings. Chromoendoscopy significantly enhances the visibility of mucosa irregularities, like metaplasia and dysplasia mucosa. Magnetically guided capsule endoscopy (MGCE) offers an alternative technology for upper GI examination. We expect the difficulties of diagnosis of neoplasm in conventional endoscopy to transfer to MGCE. Thus, we aim to chart a path for the application of chromoendoscopy on MGCE via an ex-vivo animal study.

Methods

We propose a modified preparation protocol which adds a staining step to the existing MGCE preparation protocol. An optimal staining concentration is quantitatively determined for different stain types and pathologies. To that end 190 pig stomach tissue samples with and without lesion imitations were stained with different dye concentrations. Quantitative visual criteria are introduced to measure the quality of the staining with respect to mucosa and lesion visibility. Thusly determined optimal concentrations are tested in an ex-vivo pig stomach experiment under magnetic guidance of an endoscopic capsule with the modified protocol.

Results

We found that the proposed protocol modification does not impact the visibility in the stomach or steerability of the endoscopy capsule. An average optimal staining concentration for the proposed protocol was found at 0.4% for Methylene blue and Indigo carmine. The lesion visibility is improved using the previously obtained optimal dye concentration.

Conclusions

We conclude that chromoendoscopy may be applied in MGCE and improves mucosa and lesion visibility. Systematic evaluation provides important information on appropriate staining concentration. However, further animal and human in-vivo studies are necessary.

[Endoscopic submucosal dissection: only for expert endoscopists?]

Endoscopic submucosal dissection (ESD) can be applied to early gastrointestinal cancers. This technique was developed to achieve radical curative resection and to reduce unnecessary surgical interventions. ESD was designed in eastern countries and is not widely used in the West. Although ESD represents a major therapeutic advance in endoscopy and is performed with curative intent, the complication rate (hemorrhage, perforation) is higher than reported in other techniques, requiring from endoscopists the acquirement of technical skill and experience through a structured and progressive training program to reduce the morbidity associated with this technique and increase its potential benefits. Although there is substantial published evidence on the applications and results of ESD, there are few publications on training in this technique and a standardized training program is lacking. The current article aims to describe the various proposals for training, as well as the basic principles of the technique, its indications, and the results obtained, since theoretical knowledge that would guide endoscopists during the clinical application of ESD is advisable before training begins. Training in an endoscopic technique has a little value without knowledge of the technique's aims, the situations in which it should be applied, and the results that can be expected.