Ultrasound-guided percutaneous microwave ablation of splenic metastasis: report of four cases and literature review.

PURPOSE To investigate the feasibility, safety and efficacy of ultrasound guided percutaneous microwave (MW) ablation for small splenic metastasis. MATERIALS AND METHODS A total of four patients with five pathologically proven splenic metastases (from ovarian, pulmonary, gastric adenocarcinoma and hepatocellular carcinoma, respectively) 1.3 to 2.9 cm in diameter were treated with microwave ablation. A cooled-shaft needle antenna was percutaneously inserted into the tumour under ultrasound guidance. One thermocouple was placed about 0.5 cm away from the tumour to monitor temperature in real time during ablation. Microwaves were emitted at 60 W for 600 s routinely and prolonged as necessary to attain temperatures sufficient to ensure tumour killing. Treatment efficacy was assessed by contrast-enhanced imaging at 1, 3 and 6 months, and every 6 months thereafter. RESULTS All tumours were completely ablated at a single session and no complications occurred. No local tumour progression was observed at a mean follow up of 22 ± 17.1 months (range 4 to 43 months). The ablation zone was well defined on contrast-enhanced imaging and it gradually shrank with time. One new metastatic lesion was detected in the spleen at 11 months after the ablation and was successfully treated by another MW ablation. The post-ablation survival was mean 22 months. No other complications were observed except for fever and abdominal pain. CONCLUSIONS Ultrasound-guided percutaneous MW ablation appears to be a safe and effective minimally invasive technique for management of small splenic metastasis in selected patients.