Software-assisted monitoring of MR-guided RFA of malignant liver tumors: Initial clinical results

Abstract

Purpose: To evaluate feasibility and effectivity of software-assisted monitoring of MR guided Radiofrequencyablation (RFA) of malignant liver tumors. Materials and Methods: MR-guided RFA of n=10 primary and n=18 secondary malignant liver tumors was performed for n=20 patients in an interventional MR unit (Magnetom Espree 1.5T, Siemens Medical Solutions, Forchheim). The tumor size was between 10 and 60 mm. Monopolar and bipolar internally-cooled MR compatible RF electrodes were used (Valleylab,Cool-tip, Burlington, MA and Celon AG, ProSurge, Teltow). Therapy monitoring was assisted by a software comparing tumor and tumor ablation state until complete tumor destruction within a given safety margin of 1 cm (MeVisSafir, Fraunhofer Mevis, Bremen). Therefore MR data were immediately transferred via DICOM to a MeVis workstation. Results: MRguided RF ablation by using MeVisSafir was technically successful in 20/20 (100%) patients as assessed at the end of each session. Complete coagulation was intended in 27/28 tumors by using the software-assistent. To achieve complete coagulation 1/28 tumors required a second session. MeVisSafir was able to monitor the extent of coagulation necrosis and to determine the safety margin. Furthermore, it was supportive in guiding overlapping ablations for complete tumor coagulation for larger livertumors (>30mm). Conclusions: Software-assisted MR-guided RFA of liver malignancies is feasible and effective, especially for the therapy monitoring of larger malignant liver tumors.