Long-term Effects of Interstitial Laser Coagulation in Porcine Liver with Portal Inflow Occlusion: Central versus Peripheral Lesions

Abstract

Interstitial laser coagulation (ILC) is an attractive modality for local destruction of unresectable hepatic metastases. Portal inflow occlusion considerably increases its destructive capacity, resulting in lesions 5 cm in diameter; however, effects on adjoining major intrahepatic structures are unknown. Therefore, the purpose of this study was to assess the effects of ILC with portal inflow occlusion on the central portion of the liver as compared to the peripheral portions. ILC was performed in pigs with portal inflow occlusion. Each animal received a single laser application with Nd:YAG light guided simultaneously through four interstitial fibers with 5 W per fiber during 6 minutes. Location of treatment was randomized to either central (n = 8) or peripheral (n = 8). Follow-up was for 1, 2, or 3 months with evaluation of liver functions and weight, as well as macroscopic and microscopic assessment of coagulated lesions and surrounding parenchyma. There was no treatment-related morbidity or mortality. No obstructive cholestasis or bile leakage was found. At every moment of evaluation, coagulated volumes in the central group were smaller than in the peripheral lesions (P = .03). Large vessels contiguous to the lesions in the central group were always intact and indications of portal hypertension or thrombosis of hepatic veins were not found. There were no significant differences between the two groups (liver functions [P > or = .15] and weight [P = .69]). ILC with portal inflow occlusion is a safe technique in the vicinity of vital structures in the liver of healthy pigs. These results justify studies to the feasibility and complication rate of portal inflow occlusion in patients with hepatic malignancies.