Virtual Reality-Based Preoperative Planning for Optimized Trocar Placement in Thoracic Surgery: A Preliminary Study

TL;DR

The study addresses variability in trocar placement during VATS by introducing a VR-based preoperative planning tool that encodes established principles (BDP/TTP) and is informed by an expert thoracic surgeon. It combines patient-specific 3D thoracic models, VR interaction (pivoting and hand-grabbing), and a voxelized operable-volume metric to plan trocar and camera placements. A preliminary study in right upper lobectomy with three trocars demonstrates high usability (SUS around 82) and efficient planning, with quantitative metrics showing feasible trajectory distances and a 1 L operable volume. The work offers a blueprint for VR systems in thoracic surgery planning and indicates potential benefits for reducing operative time, crowding, and fatigue, while guiding future clinical validation.

Abstract

Video-assisted thoracic surgery (VATS) is a minimally invasive approach for treating early-stage non-small-cell lung cancer. Optimal trocar placement during VATS ensures comprehensive access to the thoracic cavity, provides a panoramic endoscopic view, and prevents instrument crowding. While established principles such as the Baseball Diamond Principle (BDP) and Triangle Target Principle (TTP) exist, surgeons mainly rely on experience and patient-specific anatomy for trocar placement, potentially leading to sub-optimal surgical plans that increase operative time and fatigue. To address this, we present the first virtual reality (VR)-based pre-operative planning tool with tailored data visualization and interaction designs for efficient and optimal VATS trocar placement, following the established surgical principles and consultation with an experienced surgeon. In our preliminary study, we demonstrate the system's application in right upper lung lobectomy, a common thoracic procedure typically using three trocars. A preliminary user study of our system indicates it is efficient, robust, and user-friendly for planning optimal trocar placement, with a great promise for clinical application while offering potentially valuable insights for the development of other surgical VR systems.

Figures (4)

• Figure 1: Overview of the pivot mechanism in surgical trocar placement: A. Initial anterior view with trajectory endpoint spheres positioned in front of each controller; B. Spheres manipulated to define endpoints (green when near target); C. Endpoint verification displays working area and trajectory paths; D. Spheres moved to the skin to define entry points (green on contact); E. Green spheres and paths indicate valid entry, verifying trocar placement; F. Manipulation angle displayed for adjustment/confirmation.
• Figure 2: Overview of the hand grabbing method in camera placement: A. Initial posterior view and endoscopic camera; B. Pointing toward endoscopic camera and hold it by pressing grip button; C. Green camera optical axis line demonstrates valid placement; D. Volume of operable area displayed for adjustment/confirmation.
• Figure 3: Distribution of SUS Question Scores Across Participants.
• Figure 4: Distribution of UX Question Scores across Participants, with mean $\pm$ standard deviation displayed beside the respective bar plot.