Design of Virtual Endoluminal Surgery Simulator (VESS): Colorectal Endoscopic Submucosal Dissection Training Module

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Introduction: ESD is an endoscopic technique for the en bloc resection of gastrointestinal lesions. ESD is a widely-used technique in Asia, but not as prevalent in Europe or the US. The procedure is technically challenging and has higher adverse events (bleeding, perforation) compared to endoscopic mucosal resection. Inadequate training platforms and lack of established training curricula has restricted its wide acceptance in the US. Thus, we aim to develop the VESS for ESD procedures. The VESS platform will aim to provide a training and assessment platform by highly realistic visualization and high fidelity of simulating the colorectal ESD procedure. The goal of the ESD simulation is to deliver realistic haptic (touch) feedback to provide a more immersive virtual experience. This abstract describes the design and task analysis study performed to date.

Methods: Based on the ESD videos, we performed a detailed colorectal ESD task analysis to determine the critical procedural steps for the design of the VESS. Through the task analysis, the critical ESD steps including lesion identification, lesion marking, injection, circumferential cutting, dissection, intraprocedural complication management and post-procedure examination were detailed. Furthermore, endoscopic devices were allocated to each step of the task analysis.

Results: Using our task analysis, we constructed a hierarchical task tree that elaborates the order of tasks in these steps (Figure 1). Furthermore, we developed quantitative ESD performance metrics for each phase in the task tree. For the VESS design, we generated three dimensional (3D) virtual models for various colorectal mucosal lesions (Figure 2), using the Paris and Japanese tumor classifications. 3D models of ESD devices were created. We developed realistic ESD instrument-lesion interactions with our custom-designed haptic device. We designed the electromechanical interface with 2-degrees of freedom to manipulate a dummy endoscope to provide the users with haptic feedback (Figure 3).

Figure: Hierarchical task tree.

Figure: (a) Paris type 0 + Is tumor and (b) Japanese type 0 + ls tumor.

Figure. 3D: Design of the simulator.

Conclusion: We describe the initial phases of the design of the VESS for colorectal ESD. Through a task analysis, simulation software and Hardware-software interface developments will allow for the manipulation of virtual colorectal lesions using 3D endoscopic accessories with haptic feedback. Our quantitative ESD metrics will be used in future validation studies of the VESS simulator for performance score computation of trainees.