Irreversible electroporation ablation with bipolar electrodes: Ultrasound findings of ablation zones

Abstract

Purpose: This study aimed to explore the ultrasound and contrast-enhanced ultrasound (CEUS) imaging characteristics and dimensions of ablation lesions after irreversible electroporation of the swine liver and evaluate the more suitable method for postoperative follow-up through correlation analysis with postoperative histopathology.

Methods: Irreversible electroporation procedures were conducted on three swine with single bipolar electrodes. The procedures were carried out after open surgery. Twenty-four ablation areas were created under ultrasound guidance. Ultrasound and CEUS evaluations were performed immediately and 48 h after irreversible electroporation. Liver samples were harvested 48 h after irreversible electroporation for histopathological analysis.

Results: The ablation area appeared as a hypoechoic and well-defined lesion on ultrasound and showed no enhancement on CEUS immediately after irreversible electroporation. After 48 h, the ablation zone appeared as an inhomogeneous hyperechoic area with a hyperechoic margin and blurred boundary under ultrasound. CEUS clearly showed the boundary of the ablation area, which revealed centripetal enhancement. The dimensions of the ablation area measured on CEUS 48 h after irreversible electroporation showed the highest correlation with the pathologic ablation zone size (length: r = 0.909, width: r=0.942, p < 0.001), but the lowest with ultrasound measurement (length: r = 0.676, width: r=0.842, p < 0.001).

Conclusion: Compared with ultrasound, CEUS can accurately measure the dimension of the ablation area, especially 48 h after irreversible electroporation.