Water-cooled microwave antenna for expanding ablation zone: in vitro porcine liver experiment

Objective: To expand coagulation zone in liver tissue by improving microwave ablation technique, so as to provide experimental evidence for clinical improvement of local efficacy. Methods: A novel microwave antenna with water-cooled shaft was used in fresh liver of pig in vitro. Microwave energy was applied in one session at 60～90W for 5～25min, and the diameter and appearances of coagulation were observed. Results: Coagulation diameters were (4.5～8.3)cm×(3.0～6.1)cm. Elevation of energy power alone resulted in significant increase of longitudinal diameter, while both longitudinal and transverse diameters were significantly increased when accompanied with prolongation of ablation time. 70～80W, 25min produced the best coagulation appearances and was considered as appropriate ablation parameters for clinical use. Conclusions: By using water-cooled microwave antenna, coagulation zones in the liver tissue were significantly expanded with increase of energy power and prolongation of ablation time, which may help to improve local efficacy of image-guided liver cancer ablation.