Background

The surgical management of Hepato-Pancreato-Biliary (HPB) cancer poses significant challenges, primarily due to the complexity of patients. However, the role of stereopsis (depth perception) in visualizing three-dimensional (3D) anatomical models remains relatively underexplored. Integrating stereoscopic technologies with 3D anatomical modelling holds promise for enhancing surgical planning and navigation, thereby addressing the inherent complexities of HPB surgeries.

Aim
This study aims to evaluate the effect of stereopsis on the preoperative surgical planning of colorectal liver metastases surgery.

Methods
A retrospective study was conducted with participants from the Department of Surgery, Leiden University Medical Centre (LUMC), to investigate the occurrence and severity of symptoms resulting from the use of a stereoscopic display. Subsequently, liver and transplant surgeons from the same department participated in another retrospective study comparing surgical plans for colorectal liver metastases performed stereoscopically with those performed monoscopically, within the same surgeon.

Results
14 out of 18 participants experienced (slight) symptoms from the use of a stereoscopic display, yet no one discontinued the study due to symptoms. In the subsequent study on the effect of stereopsis on preoperative surgical planning for colorectal liver metastases, 13 liver and transplant surgeons participated. Relative to a gold standard, there appears to be no significant difference between surgical plans executed monoscopically or stereoscopically. There is also no significant difference in the time taken to create these surgical plans (p=0.401). Despite the absence of significant difference between the plans, surgeons do express a (strong) preference for stereopsis in locating the tumor (61%), determining the surgical plan (61%), and assessing vascular involvement (69%).

Conclusion
It is evident that surgeons have a preference for stereopsis in visualizing 3D models, although our study found no discernible differences in outcomes between monoscopic and stereoscopic preoperative planning for colorectal liver metastases surgery. Future research is recommended to compare surgical plannings based on conventional two-dimensional imaging alone with conventional two-dimensional imaging supplemented by additional stereoscopic 3D models. This comparative analysis could offer further insights into the potential advantages of integrating stereoscopic technology into preoperative planning practices.

Introduction - Accurate intrahepatic anatomical localization remains challenging for laparoscopic liver resection (LLR) of patients with colorectal liver metastases (CRLMs). Image-guided surgery (IGS) systems utilizing augmented reality (AR) visualizations have been developed to assist in these procedures by projecting virtual models onto the laparoscopic view. However, AR visualization, often presented as a comprehensive model, requires improvements to achieve an effective and positive experience for surgeons. A user study was performed to develop and evaluate multiple AR and VR visualizations and identify the most promising and effective visualizations based on feedback from surgeons. Additionally, adapters with EM sensors are required to track the 30° laparoscopes and enable AR. The secondary objective was to develop and calibrate these adapters.

Methods - Multiple visualizations, categorized into three classes, were developed and assessed on a phantom and patients. The user study consisted of two phases. Phase 1 focused on the development and evaluation of these visualizations. Feedback from three surgeons was gathered using a custom-made survey that assessed experience, effectiveness, and usability. Phase 2 involved evaluating clinical usage of the visualizations and their applications by showing videos of these tests to seven surgeons from two hospitals.

Results - In Phase 1, five patients were included for AR-guided laparoscopic resection. Improvements were made compared to the gold standard whole liver model in AR experience, effectiveness, depth perception, and information balance. In Phase 2, the most promising visualizations from class 1 were the depth shader and target
structures visualization, both preferred by six surgeons. Additionally, all seven surgeons wanted the ability to augment a predefined virtual resection plan. For class 2, all seven surgeons found the US view promising and only one surgeon indicated they would use the virtual painter. Five surgeons indicated they would use the third-person and target view of class 3 during liver procedures. Furthermore, adapters with EM sensors were developed and calibrated to track the 30° laparoscopes and enable AR.

Conclusion - AR is promising in liver surgery when surgeons can easily interpret the visualization and have a positive experience. To be effective, AR systems should accurately localize and define vessels and tumor margins, provide clear depth perception, and offer well-balanced information. Several aspects of AR visualization for the entire liver model have been improved. Future research should further improve these visualization aspects, implement non-rigid registration techniques and on-demand patient-specific activation of structures. These advancements can enable AR integration into the surgical workflow, enhancing precision and effectiveness.