Image-Guided Microwave Ablation of Liver Tumours Using a 150-W Generator: Ex Vivo and Multicenter in Vivo...

To assess the predictability of Emprint HP-Generator (150 W, 2.45 GHz) in terms of ablation volume and sphericity both in the ex vivo and in vivo setting.

In an ex vivo setting, 48 ablations were performed on porcine livers at varying ablation times with a constant power of 150 W. MRI assessment of the ablation volumes was performed. In the in vivo setting consecutive procedures with 150W application with no rampage, single antenna positioning and availability of a contrast-enhanced computed tomography (CECT) immediately after the ablation were included. A semi-automated segmentation tool was used for volume estimation and spherical index (SI) was calculated.

In the ex vivo group, mean ablation time was 5.3 ± 2.5 min (range 1-10 min), mean ablation diameter was 37.7 ± 5.8 mm (range 21.3-49 mm) and mean ablation volume was 20.1 ± 10.8 cm³ (range 3-38.4 cm³) with a mean SI of 0.83 ± 0.08. In the in vivo group 78 percutaneous liver ablations (tumour mean diameter 23.2 ± 11 mm) in 65 patients (M46; F19; mean age 66.8 ± 11.3) were retrospectively enrolled from two institutions. The mean ablation time was 4,9 ± 2,5 min (range 1-10 min), mean ablation diameter was 41.3 ± 9.6 mm (range 16-73 mm) and mean ablation volume was 27.8 ± 15.6 cm³(range 6.4-105.6 cm³). Mean SI was 0.85 ± 0.11. Ablation volumes tend to be larger in case of hepatocellular carcinoma (HCC) compared to other histology (33.7 ± 21.2 cm³ vs 24.8 ± 10.5 cm³; p = 0.08). Both in ex vivo and in vivo settings, the SI remained stable regardless of ablation time and volume (Pearson's r 0.08, p 0.46), while ablation volumes increased linearly with time (Pearson's r 0.79, p < 0.001). Clavien-Dindo 1 complications were registered (4/65, 6.1%).

The Emprint HP-generator enables the creation of large predictable volumes in both settings. SI remains consistent regardless of ablation time and volume.