Microwave Ablation of Small Hepatic Metastases Using MR Guidance and Monitoring: Clinical Safety and Efficacy

BACKGROUND: To evaluate the technical success and clinical safety of magnetic resonance (MR)-guided microwave ablation (MWA) of small hepatic metastases. MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. A retrospective analysis of the patient data revealed 50 patients with small hepatic metastases (34 men, 16 women) who underwent MWA under MR guidance and monitoring. After the procedure, the intervention-related complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE) and Society of Interventional Radiology (SIR) classification system. Furthermore, the overall survival (OS) and local tumor-free survival (LTP) of the patients were analyzed. RESULTS: The patients who underwent MR-guided MWA achieved technical success. The mean energy, ablation duration per tumor, and procedure duration were 55.3 ± 9.4 kJ, 11.7 ± 5.6 min and 89.5 ± 30.9 min, respectively. Most adverse events and complications were CTCAE grade 1 or 2 or SIR classification grade A or B. The 1-, 2-, and 3-year local tumor progression (LTP) rates were 65.9%, 31.5% and 18.5%, respectively, with a mean LTP of 19.216 months (95% CI: 16.208, 22.224); and the 1-, 2- and 3-year overall survival (OS) rates were 81.8%, 60.8% and 44.7%, respectively, with a mean OS of 26.378 months (95% CI: 23.485, 29.270). Multivariate Cox’s regression analysis further illustrated that tumor location (challenging locations vs ordinary locations) and the anesthesia (general anesthesia VS local anesthesia) were important factors affecting LTP and OS. CONCLUSION: MR-guided MWA can successfully treat small hepatic metastases with potentially favorable safety and technical efficacy.