Abstract: Objective To investigate the feasibility, safety and efficacy of ultrasound-guided percutaneous microwave ablation
(MWA) of splenic tumors. Methods Seven patients with 8 pathologically confirmed splenic tumors (including 2 metastases
from the ovary and 4 from the lung, gastric adenocarcinoma, hepatocellular carcinoma, or rectal carcinoma; 1 hemangioma
and 1 inflammatory pseudotumor) with sizes ranging from 1.3 to 6.2 cm (mean 3.1±1.9 cm) were treated with MWA. A cooled
shaft needle antenna was percutaneously inserted into the tumor under ultrasound guidance. A thermocouple was placed
about 0.5 cm away from the tumor to monitor the temperature in real time during the ablation. The microwave emitting power
was set at 50-60 W. The treatment efficacy was assessed by contrast-enhanced imaging at 1, 3 and 6 months following the
procedure, and every 6 months thereafter. Results All the tumors were completely ablated in a single session and no
complications occurred. No local tumor progression was observed during a median follow up time of 13 months (4 to 92
months). The ablation zone, well defined on contrast-enhanced imaging, was gradually reduced with time. A new metastatic
lesion was detected in the spleen at 11 months after the ablation in a ovarian carcinoma patient and was successfully treated by
a second MWA. The post-ablation survival of the patients with splenic metastasis was 13 months (range 4 to 92 months). No
complications other than fever and abdominal pain were observed in these patients. Conclusion Ultrasound-guided
percutaneous MWAis a safe and effective minimally-invasive technique for treatment of splenic tumors in selected patients.