Chart for renal tumor microwave ablation from human study

Purpose

To define microwave ablation (MWA) charts according to time and power in human renal tumors and to compare them to the charts given by the HS AMICA manufacturer.

Materials and methods

A total of 54 patients with 54 renal cancers who underwent MWA were included. There were 36 men and 18 women with a mean age of 72.5 ± 10 [SD] years (range: 40–91 years). The system used for MWA was HS AMICA with the Amica-probe V4 applicator. The following variables (antero-posterior diameter, transverse diameter, cranio-caudal diameter and volume were measured on computed tomography examinations performed one month after MWA. The dimensions of the ablation zone were correlated with power (40 or 60 W) and exposure time (5, 10 and 15 min) used for MWA. Actual ablation dimensions were compared to the manufacturer's data.

Results

The variation of diameters, with a longer ablation time, was linear at 40 W with a volume increase of 30% for each additional 5 minutes. At 60 W, a more pronounced variation (volume increase of 112%) was observed. Compared to the manufacturer's chart, significantly larger ablation zones were obtained (P < 0.05), the differences being mainly marked for the antero-posterior diameter (≥ 1 cm).

Conclusion

MWA using AMICA generator produces reproducible ablation area for given time and power in renal tumor ablation. The charts presented here should be used instead of the manufacturer's chart, which is based on porcine liver and is significantly different.