The Influence of Pre-ablation Embolization Particle Size on the Size of the Microwave Ablation Zone in a Porcine Orthotopic Renal Tumor Model.

Abstract

MATERIALS AND METHODS

In a transgenic porcine kidney, 32 sites were inoculation with 28 orthotopic RT produced. Experimental groups (23 tumors) underwent angiography with intra-arterial embolization utilizing various embolic materials (calibrated particles from 40 to 1200 μm and ethiodized oil) to complete vascular stasis of the RT. MWA using a standard protocol (3 minutes at 65 watts) was subsequently performed for all tumors. Next, a gross and histologic ex vivo analysis of the AZ was performed.

CONCLUSION

Pre-MWA arterial embolization in a porcine RT model produced a statistically significant increase in the AZ when compared to MWA alone. Using smaller particle size embolic material with distal embolization at the tumor arterioles (50-150 μm) produced the largest, almost 3-fold increase in AZ volume.

RESULTS

Control group AZ volume without prior embolization was 5.24 cm³ ± 0.55 cm³. AZ after embolization with 40 μm, 100 μm, 300-500 μm, 900-1200 μm particles were significantly larger than MWA alone (mean ± standard deviation: 15.39 cm³ ± 4.54, p =0.002; 11.07 cm³ ± 1.39 cm³, p= 0.001; 8.68 cm³ ± 0.77 cm³, p=0.001; 900-1200 μm: 9.90 cm³ ± 1.62 cm³, p=0.002 respectively). Liquid embolic, ethiodized oil emulsion did not create a significant increase in the AZ (5.92 cm³ ± 1.43 cm³ p=0.492).

PURPOSE

To combine arterial embolization with different embolic agents, followed by microwave ablation (MWA) in a porcine renal tumor (RT) to evaluate the ideal setting to produce the largest change in the size of the ablation zones (AZ).