Morphological Analysis of the Interstitial Ultrasonic Ablation in Porcine Liver in vivo

Abstract

Background: The shape of the induced thermal ablation area is as important as its dimension. The aim of this study was to analyze the size reproducibility and the aspect of the interstitial ultrasonic ablation obtained by a planar transducer in porcine liver in vivo. Methods: Five pigs were used. Two complete ultrasonic lesions were made in each animal under pedicle clamping. All the lesions underwent MR examination on day 7 and then a histological analysis. Results: The tested probe has the advantage of providing a step-by-step and highly directional treatment in the target zone. The ultrasonic lesions presented as well-defined and homogenous areas of tissue coagulation. The lesion volumes ranged from 8.1 to 92.3 cm³ with an averaged lesion length of 56 mm at gross examination. Three-dimensional reconstruction of the lesions from the MR images showed cylindrical and conical shapes. Large intrahepatic vessels distorted the lesion shape, and the vicinity of the application to the liver surface increased significantly the volume of the ultrasonic necrosis. Histological examination showed complete necrosis in the area of damage. Conclusion: The ultrasonic ablation has a regular shape, always with sharply defined borders. However, it showed some variability in the size of the induced lesions.