Seeing the invisible: Three-dimensional liver modeling from simulation to the scalpel.

Liver resection requires precise, millimetric decisions within highly variable, patient-specific vascular and biliary anatomy. As the complexity of procedures increases (such as in major or extended hepatectomies, central lesions, and borderline future liver remnant scenarios), reliance on "2D cognition" can heighten the risk of planning errors and postoperative complications. This study aims to synthesize the role of 3D liver technologies, including digital visualization and planning, 3D printing, and intraoperative navigation (such as augmented reality and mixed reality), as a decision-making pipeline. This is a narrative, question-driven review of clinically relevant studies focused on liver resection workflows that utilize 3D visualization/planning, 3D printing, or intraoperative navigation. Across diverse studies, the most significant benefits of 3D planning are observed in anatomically complex or borderline cases. These benefits primarily enhance decision transparency and process-level endpoints (e.g., mapping, plan modifications, intraoperative orientation). However, consistent effects on morbidity and liver-specific outcomes are limited due to confounding factors and inconsistencies in endpoints. Augmented reality and mixed reality navigation face challenges related to registration stability and liver deformation, making uncertainty management and local accuracy reporting crucial. 3D printing appears most beneficial as a selective tool for high-stakes anatomy, as well as for communication and education, with feasibility influenced by time and cost considerations. "3D" should be assessed as an end-to-end measurement pipeline with explicit error budgets. Future studies should prespecify decision endpoints, standardize outcome definitions, and report task-relevant accuracy, particularly concerning navigation and critical biliary/vascular structures.