Ultrasound-Guided Percutaneous Radiofrequency Ablation of Liver Tumors: How We Do It Safely and Completely

Ultrasound-guided percutaneous radiofrequency (RF) ablation has become one of the most promising local cancer therapies for both resectable and nonresectable hepatic tumors. Although RF ablation is a safe and effective technique for the treatment of liver tumors, the outcome of treatment can be closely related to the location and shape of the tumors. There may be difficulties with RF ablation of tumors that are adjacent to large vessels or extrahepatic heat-vulnerable organs and tumors in the caudate lobe, possibly resulting in major complications or treatment failure. Thus, a number of strategies have been developed to overcome these challenges, which include artificial ascites, needle track ablation, fusion imaging guidance, parallel targeting, bypass targeting, etc. Operators need to use the right strategy in the right situation to avoid the possibility of complications and incomplete thermal tissue destruction; with the right strategy, RF ablation can be performed successfully, even for hepatic tumors in high-risk locations. This article offers technical strategies that can be used to effectively perform RF ablation as well as to minimize possible complications related to the procedure with representative cases and schematic illustrations.

Evaluation of hepatocellular carcinoma ablative margin using three-dimensional ultrasound-CT image fusion in a phantom study / 中华超声影像学杂志

Objective To design and construct a hepatocellular carcinoma(HCC) phantom,and assess the accuracy of three dimensional ultrasound (3DUS)-CT image fusion in evaluating ablative margin (AM).Methods The phantom was constructed by carrageenan gel and additives.A sphere-shaped HCC model surrounded by a 5 mm layer of AM model was embedded into a cylindrical-shaped ground substance model to form the phantom.After radiofrequency ablation (RFA),HCC model in the phantom was ablated into ablative lesion model.The ultrasound and CT image,macroscopic appearance and stability of the phantom were observed.Twenty-four phantoms were made and ablated into different ablative lesion models in which AM was achieved or not achieved.Outline the HCC and 5mm AM in the 3DCT image and fuse 3DCT image with the 3DUS image of the ablative lesion model to see whether the ablative area could cover the AM,as well as in which quadrant complete ablation of the AM had not been achieved and the maximal thickness of the unachieved AM.The result of the 3DUS-CT image fusion was compared with gross specimen.Results The ultrasound and CT image,macroscopic appearance and stability of the phantom met the demand of this study.The sensitivity,specificity and accuracy of 3DUS-CT image fusion were 93.8％,85.7％ and 91.3％respectively.The quadrant in which complete ablation of AM was not achieved matched with gross specimen.The maximal thickness of the unachieved AM measured by 3DUS-CT image fusion and gross specimen were (3.5 ± 2.0) mm and (3.2 ± 2.0) mm respectively,and no statistic difference was found between the two results.Conclusions The phantom made of carrageenan gel and additives was suitable for the evaluation of AM.3DUS-CT image fusion evaluation of AM was accurate.