This study aims to develop a system based on mixed reality imaging for assistance in percutaneous ultrasound-guided liver interventions. A liver phantom, an ultrasound scanner with an abdominal probe, an electromagnetic tracking system for localization of the ultrasound probe, and the percutaneous needle were used to develop the system. A gelatin liver phantom was fabricated, including a set of lesions (with agarose, glycerol, and sephadex) and artificial blood vessels 3D printed with thermoplastic polyurethane (TPU) elastic fibres. Intraoperative ultrasound images from a BK5000 ultrasound scanner were acquired using a video capture system and transmitted to 3D Slicer. The NDI Aurora electromagnetic tracking system, coupled to the ultrasound probe and intracorporeal needle, was used for real-time trajectory tracking, providing us with spatial localization information. These images are then sent to the augmented reality HoloLens device as the primary visualization system. This work lays the groundwork for the development of a more comprehensive system to assist ultrasound-guided percutaneous liver interventions in order to improve the accuracy and safety of these procedures. The use of mixed reality imaging technology allows a better integration of image-guided surgery systems, such as the one presented in this work, in real clinical environments, and closer to the patient.