Purpose
To assess technique effectiveness of magnetic resonance (MR)-guided radiofrequency (RF) ablation of primary and secondary hepatic malignancies.
Material and methods
In 63 patients primary (n = 19) or secondary (n = 80) liver tumors (mean diameter: 24.5mm; range: 4 – 60mm) were treated with 85 sessions of RF ablation under MR-guidance at an open 0.2 Tesla MR-Imager (Concerto, Siemens Medical Solutions, Germany). MR-compatible internally-cooled single or cluster electrodes (Cool-tip ®, Valleylab, Burlington, MA) were used. Preinterventional MR-imaging was performed using non-enhanced T1w (TR/TE: 300/20ms) and T2w (3500/110ms) sequences. Placement of the RF-electrodes was performed under MR-fluoroscopy (45/13ms). The facultative multiplanar images of MR-fluoroscopy required an acquisition time of 2.3 seconds. T2w sequences were used to monitor the extent of induced coagulation during the procedure. Technique effectiveness was assessed four months after the last RF ablation by dynamic high-field (1.5 Tesla) MR-imaging (Sonata, Siemens).
Results
MR-guided RF ablations were technical successful in 83/85 (97.6 %) assessed at the end of each session. Technique effectiveness was achieved in 92 of 99 liver tumors (92.9 %). Intrainterventional T2w sequences were accurate to near-online monitor die extend of induced coagulation. Therefore T2w sequences were helpful to guide the exact repositioning of the RF-electrode if overlapping coagulations were necessary. To achieve complete coagulation, 82/92 (89.1 %) tumors were treated in a single session by using MR monitoring, 9/92 (9.8 %) tumors were treated twice and 1/92 (1.1 %) tumor was treated three times. Follow-up indicated 2/85 (2.4 %) major and 7/85 (8.2 %) minor complications.
Conclusion
MR-guided percutaneous RF ablation is a safe and effective therapy in the local treatment of primary and secondary liver tumors. T2w sequences are accurate to monitor acute effects of induced coagulation subsequently being helpful to guide overlapping RF ablation.