Characterization of in vivo ablation zones following percutaneous microwave ablation of the liver with two commercially available devices: are manufacturer published reference values useful?

PURPOSE

To analyze in vivo ablation properties of microwave ablation antennae in tumor-bearing human livers by performing retrospective analysis of ablation zones following treatment with two microwave ablation systems.

MATERIALS AND METHODS

Percutaneous microwave ablations performed in the liver between February 2011 and February 2013 with use of the AMICA and Certus PR ablation antennae were included. Immediate postablation computed tomography images were evaluated retrospectively for ablation length, diameter, and volume. Ablation length, diameter, and volume indices were calculated and compared between in vivo results and references provided from each device manufacturer. The two microwave antenna models were then also compared versus each other.

RESULTS

Twenty-five ablations were performed in 20 patients with the AMICA antenna, and 11 ablations were performed in eight patients with the Certus PR antenna. The AMICA and Certus PR antennae showed significant differences in ablation length (P = .013 and P = .009), diameter (P = .001 and P = .009), and volume (P = .003 and P = .009). The AMICA ablation indices were significantly higher than the Certus PR ablation indices in length (P = .026) and volume (P = .002), but there was no significant difference in ablation diameter indices (P = .110).

CONCLUSIONS

In vivo ablation indices of human tumors are significantly smaller than reference ex vivo ablation indices, and there are significant differences in ablation indices and sphericity between devices.