Comparison of Two 2.45 GHz Microwave Ablation Devices with Respect to Ablation Zone Volume in Relation to Applied Energy in Patients with Malignant Liver Tumours.

Simple Summary: Ablation zone volumes (AZV) after microwave ablation (MWA) of malignant liver tumours remain highly unpredictable. The aims of the present study were to compare two 2.45 GHz MWA devices with respect to AZV in relation to the applied energy after MWA in patients with hepatocellular carcinoma or colorectal liver metastasis, and to identify potential confounders for this relationship. We confirmed the unpredictability of AZVs based on the applied output energy for both tumour types. We observed no differences in the ratio between AZV and the applied energy between tumour types. The ratio between AZV and applied energy was different between the two MWA devices; however, its reflected energy due to differences in cable and antenna design remains unclear and might contribute to these differences. Purpose: (i) to compare two 2.45 GHz MWA devices with respect to AZV in relation to the applied energy after MWA in patients with hepatocellular carcinoma (HCC) or colorectal liver metastasis (CRLM) and (ii) to identify potential confounders for this relationship. Methods: In total, 102 tumours, 65 CRLM and 37 HCC were included in this retrospective analysis. Tumours were treated with Emprint (n = 71) or Neuwave (n = 31) MWA devices. Ablation treatment setting were recorded and applied energy was calculated. AZV and tumour volumes were segmented on the contrast-enhanced CT scans obtained 1 week after treatment. The AZV to applied energy R(AZV:E) ratios were calculated for each tumour treatment and compared between both MWA devices and tumour types. Results: R(AZV:E)_EMPRINT was 0.41 and R(AZV:E)_NEUWAVE was 0.81, p < 0.001. Moderate correlation between AZV and applied energy was found for Emprint (r = 0.57, R² = 0.32, p < 0.001) and strong correlation was found for Neuwave (r = 0.78, R² = 0.61, p < 0.001). R(AZV:E)_CRLM was 0.45 and R(AZV:E)_HCC was 0.52, p = 0.270. Conclusion: This study confirms the unpredictability of AZVs based on the applied output energy for HCC and CRLM. No significant differences in R(AZV:E) were observed between CRLM and HCC. Significantly lower R(AZV:E) was found for Emprint devices compared to Neuwave; however, reflected energy due to cable and antenna design remains unclear and might contribute to these differences. [ABSTRACT FROM AUTHOR]