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

AbstractBackground: Microwave ablation is a promising treatment for unresectable liver tumors. Unlike radiofrequency ablation, microwave ablation may be performed with multiple simultaneously active antennae. 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. Results: Single-antenna microwave lesions had a mean volume of 7.4 +mn; 3.9 cm3, compared with 14.6 +mn; 5.2 cm3 and 43.1 +mn; 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.