Irreversible electroporation in porcine liver: short- and long-term effect on the hepatic veins and adjacent tissue by CT with pathological correlation.

OBJECTIVE: The objective of the study was to determine the short- and long-term effects of irreversible electroporation (IRE) on the hepatic veins and the perivascular tissue through serial computed tomography (CT) with pathological correlation.
MATERIALS AND METHODS: Multiple IRE lesions were created percutaneously by ultrasound guidance in livers of 11 Yorkshire pigs using a prototype IRE generator. Paired electrodes were used. Three pigs were killed at the same day; 2 pigs, at 2 days; 2 pigs, at 2 weeks; 2 pigs, at 4 weeks; and 2 pigs, at 8 weeks. Contrast-enhanced CT was performed in all pigs initially and thereafter at selected intervals. Pathological sections were performed for correlation. Initial CT scans were analyzed for lesions for degree of circumferential contact (< 25%, 26%-50%, 51%-75%, and 76%-100%) to the hepatic veins for analysis of any contour deformity. The hepatic veins were also analyzed for any thrombus and for any narrowing. Those lesions with follow-up scans were also analyzed for changes over time.
RESULTS: Twenty-three lesions showed contiguity to the hepatic veins between 3 to 9 mm in size at the initial CT. No contour deformity due to perivascular tissue sparing is detected for any lesion. There was no thrombus detected in any vessel at any time point. Vessel narrowing was seen in 9 of 23 veins on the initial CT, all less than 50% in diameter and all with lesion contact of greater than 25% in circumference, but 2 of 3 veins with follow-up scans showed return-to-normal caliber. No late narrowing of any hepatic vein was seen on the long-term follow-up.
CONCLUSION: Irreversible electroporation creates uniform tissue ablation around the hepatic veins without perivascular tissue sparing. Vessel narrowing may occur acutely but without long-term sequela.