The Development of a Virtual Simulator for Colorectal Endoscopic Submucosal Dissection (ESD)

Introduction: Colorectal cancer is one of the most common cancers in the United States. Endoscopic Submucosal Dissection (ESD) is an emerging minimally invasive technique that allows complete en-bloc resection and a much lower recurrence rate at long-term follow-ups. However, performing colorectal ESD is technically demanding since the colorectal wall is thin and constantly moving, and potentially higher rates of complications (e.g., bleeding and perforations). Hence, an adequate training for colorectal ESD is needed to acquire basic proficiency with minimum complications.

Objectives: A virtual reality (VR)-based simulator with visual and haptic feedback for training in colorectal ESD is being developed, which the aim to allow trainees to attain competence in a controlled environment with no risk to patients. In this work, a newly developed application of the virtual simulator that promotes the endoscopists to perform and assess technical skills in ESD is developed. Training tasks are built based on physics-based computational models of human anatomy with tumors.

Methods: The main modules of the VR-based simulator for colorectal ESD involve: (1) rendering; (2) haptic interface; (3) physics-based simulation; and (4) performance recording and assessment metrics. The rendering engine allows surgical tasks to be performed in the three-dimensional virtual environment. Haptic feedback mechanisms allow users to physically feel the interaction forces. Physics-based simulation technologies are employed to enable the complicated simulation for performing virtual surgical tool-tissue interactions. The simulator can also collect learners’ performance data to offer feedback based on the built-in metrics.

Results: Four training tasks involving marking, injection solution, circumferential cutting, and submucosal dissection are designed to practice skills with different surgical tools. The marking task aims to identify the lesion. The injection solution task minimizes the risk of bleeding and perforation to protect the muscularis. In the circumferential cutting task, the objective is initial incision of the lesion with the surgical tools. The objective of the dissection task is to remove the tumor from the connective tissue of the submucosa under the lesion.

Conclusions: The VR-based simulator enables realistic ESD tasks to provide a possibility for developing, validating and objectively evaluating the performance metrics in colorectal ESD training, and offers an opportunity to rise up the learning curve before application to patients.