**5. Computer-assisted pancreas navigation**

Existing computer-assisted navigation solutions address the needs of the pancreatic MDs to some extent, yet there remains room for improvement. The application of IRE as a treatment for pancreatic cancer bears additional challenges, which are partially covered by existing solutions:


Low usage numbers of stereotactic needle guidance in the pancreatic use case highlights that not all problems have yet been addressed to support the complete perioperative procedure. A study recently published by He et al. [47] demonstrated the feasibility of robot-assisted percutaneous IRE treatment of pancreatic head cancer in 9 cases. With respect to spatial accuracy, the stereotactic percutaneous navigation outperformed the stereotactic laparoscopic navigation in existing reporting. Therefore, stereotactic percutaneous needle guidance can be seen as the foundation to achieve reliable and reproducible navigation results. Yet, it only constructs one part of a dedicated computer-assisted pancreatic IRE workflow.

#### **5.1 IRE planning tool**

Preoperative image data are essential to generate a safe and feasible ablation plan with an optimal needle configuration to treat the tumor. We developed a dedicated preoperative planning tool, which makes use of CT/MRI image data in combination with 3D reconstructions to simulate IRE needle configurations. The tool allows the MD to define target and entry positions on multiplanar reconstructions (MPR) of the tomographic images with the possibility to select different needle configurations (layout and spacing). Under consideration of IRE-related constraints (spacing and parallelism), the trajectories can be optimized to cover the region of interest. The segmentations are conducted by a radiologist using dedicated software and can be tailored upon the type of intervention. Unlike for the open approach, preoperative segmentations for a percutaneous approach could include structures like the stomach, colon, or liver as well. This information is beneficial for the determination of the access window and to evaluate risk structures in the vicinity of the needles.

The planning tool was evaluated in the course of a clinical study of IRE in a laparotomy setting at the local hospital (Inselspital, Bern, Switzerland). **Figure 6** demonstrates the application of the planning tool to 1 out of 10 cases. During the surgery, the decision was to place the needles according to plan # 1 as the superior mesenteric vein was not mobilizable enough to obtain a window for the inferior right needle in #2. The 3D planning tool proved beneficial in both the preoperative

**Figure 6.**

*Preoperative plan on axial plane with segmentation overlay (left). Two IRE configurations with 3D reconstructions (middle). Image plane at needle tip in direction of the trajectory to visualize distances between the needles in millimeter (right).*

as well as intraoperative phase as it increased the MDs spatial understanding during the generation of the ablation plan.
