Ultrasound navigated RFA of liver tumors

Primary liver tumors and liver metastases are of high clinical relevance. They are the fifth most common kind of malignant tumors and the third most common cause of death in the group of malignant tumors. Ultrasound controlled Radio Frequency Ablation (RFA) is accepted as a gentle and inexpensive treatment but suffers from higher recurrence of tumors compared to surgical resection. The main reasons are that only ultrasound images are available during the intervention and radiological data can not be mapped onto the patient. Therefore, exact positioning of the applicator and control of ablation are very difficult to perform. Thus, RFA as therapy usually is chosen only in cases where surgical resection is not possible. As a part of the BMBF project "FUSION" we are developing a 3D ultrasound based navigation system and aim to improve the interventional process to achieve better outcome for patients who are treated with transcutane, ultrasound controlled RFA. The navigation system provides assistance by mapping radiological information (image sets as well as annotations) onto the patient. During an iterative process 3D ultrasound data can be acquired and target positions as well as trajectories of applicator positions can be planned. Ultrasound probe and applicator needle are navigated continuously and independently. Intuitive navigation scenes enable the physician to gain more orientation and confidence during the different steps of applicator positioning. The incorporation of 3D ultrasound fulfills different purposes: On the one hand, intrainterventional 3D data can be used to improve the registration process, on the other hand they can support the pre- and postinterventional comparison of treated tumors.