To explore the utility of personalized 3D printed liver models in planning and navigating laparoscopic resections.

Project goal is to evaluate utility of personalized 3D printed models in preoperative planning and performing laparoscopic liver resections. Models will be developed with unique, low-cost approach. Project will consist of three overlapping modules/stages evaluating:

1. Accuracy of 3D printed liver models compared to computed tomography and standard surface or volume rendering
2. Whether 3D printed utilized in planning surgery affects the decision making regarding the surgical plan
3. Whether 3D printed models utilized in planning and navigating laparoscopic resections affect perioperative outcomes

Methodology of developing 3D models is described elsewhere. Printed models will be delivered to surgical team at least 5 days prior to the resection. Surgery will be performed in both arms according to the department's procedures and surgical oncology guidelines.

Inclusion Criteria:

• Age over 18
• Patient qualified to undergo liver tumor resection (either primary of metastatic; both benign and malignant lesions)
• Quality of imaging (CT or MRI or PET (positron emission tomography)/CT) satisfactory to develop 3D models
• Laparoscopic approach
• Informed consent

Exclusion Criteria:

• Open approach
• Technical limitations to model development
• No informed consent