2:26 PM Abstract No. 88 - Irreversible electroporation (IRE) in cirrhotic liver: preliminary experience in a large animal model

Abstract

Purpose To compare the efficacy of tissue ablation using IRE in cirrhotic versus normal liver parenchyma in a porcine model. Materials and Methods Eight pigs received a mixture containing iodized oil and ethanol into the hepatic artery to induce liver injury. Cirrhosis was allowed to develop over 4 weeks. Four control animals received a sham hepatic arterial injection of normal saline. CT-guided IRE lesions were created using paired electrodes (18g, 2 cm tip) and a Nanoknife generator (Angiodynamics, Fremont, CA) in cirrhotic (n=14 lesions) and normal liver (n=8 lesions) with the aid of cardiac gating. All animals were euthanized within three hours of the ablation procedure. IRE parameters and pathological data were recorded and analyzed. Immunohistochemical analysis of cleaved caspase-3 was used to assess for apoptosis. These data were compared and subject to statistical analysis using the Satterthwaite t-test. Results Cirrhosis was successfully induced in all experimental animals with histological analysis revealing a median METAVIR score of 3.38. The median calculated electrical resistance of the liver parenchyma during pulse application was greater in the cirrhotic parenchyma 113.9 ohm [95% CI: (92.2,134.7)] than normal liver 90.2 ohm [95% CI: (53.4,126.9)], but it failed to reach statistical significance (p=0.05). The mean ablation volume in the cirrhotic and normal livers at gross pathology was 17.2 cm3 [95% CI: (14.3,20)] and 11.8 cm3 [95% CI: (9.7,13.8)], respectively. Difference in ablation volumes was also not statistically significant (p=0.48). Histological analysis of ablation lesions was similar in both groups and characterized by hepatocellular dissociation often associated with hemorrhage and sinusoidal dilatation with minimal surrounding inflammation. Hepatocytes did not show any substantial evidence of apoptosis at the time of necropsy. Conclusion IRE tissue destruction appears equally effective in cirrhotic and normal liver parenchyma in a porcine model. Although, a trend toward greater electrical resistance was observed in the cirrhotic liver, it did not impact the overall volume of ablation.