Hepatic Microwave Ablation With Multiple Antennae Results in Synergistically Larger Zones of Coagulation Necrosis

Background: Microwave ablation is a promising treatment for unresectable liver tumors. Unlike radiofrequency ablation, microwave ablation may be performed with multiple simultaneously active antenna.

Methods: Microwave ablation was performed in an in vivo porcine liver model by using a single antenna (n _ 11) or three antennae in a triangular array, activated either sequentially (n _ 11) or simultaneously (n _ 13). Lesions were measured and assigned a qualitative shape score.

 

Hepatic Microwave Ablation With Multiple Antennae Results in Synergistically Larger Zones of Coagulation Necrosis

Results: Single-antenna microwave lesions had a mean volume of 7.4 _3.9 cm3, compared with 14.6 _ 5.2 cm3 and 43.1 _ 4.3 cm3 for sequential and simultaneous multiple-probe ablations, respectively (P _ .001; analysis of variance). Simultaneous lesions were rounder than sequential ablations and were more effective near blood vessels. Simultaneous lesions created with probe separation of _1.7 cm were round and confluent, whereas clefts were present with distances _1.7 cm (P _ .001).

Conclusions: Microwave ablation has several theoretical advantages over currently available radiofrequency devices. Simultaneous three-probe microwave ablation lesions were three times larger than sequential lesions and nearly six times greater in volume than single-probe lesions. Additionally, simultaneous multiple-probe ablation results in qualitatively better lesions, with more uniform coagulation and better performance near blood vessels. Simultaneous multiple-probe ablation may decrease inadequate treatment of large tumors and decrease recurrence rates after tumor ablation.