Initial evaluation of a mixed-reality system for image-guided navigation during percutaneous liver tumor ablation

Minimally invasive ablation is a challenge for contemporary interventional radiology. This study aimed to investigate the feasibility of utilizing a mixed-reality system for this type of treatment. A HoloLens mixed reality and optical tracking system, which supports diagnosis, planning, and procedure implementation, was used for percutaneous liver tumor ablation. The system differentiated pathological liver changes at the diagnostic stage, allowing for the selection of the entry point and target during planning. Meanwhile, it provided a real-time fusion of intraoperative ultrasound images with a pre-operative hologram during the procedure. Additionally, the collision detection module enabled the detection of collisions between the ablative needle and anatomical structures, utilizing the actual needle trajectory. The system was evaluated in 11 patients with cancerous liver lesions. The mean accuracy of target point registration, selected at the planning stage, was 2.8 mm during the procedure's supporting stage. Additionally, operator depth perception improved, the effective needle trajectory was shortened, and the radiation dose was reduced for both the patient and the operator due to improved visibility of the needle within the patient's body. A generally improved understanding of the mutual spatial relationship between anatomical structures was observed compared to the classical two-dimensional view, along with improved depth perception of the operating field. An additional advantage indicated by the operators was the real-time highlighting of anatomical structures susceptible to damage by the needle trajectory, such as blood vessels, bile ducts, and the lungs, which lowers the risk of complications.