Prediction of the ablated area by the spread of microbubbles during radiofrequency ablation of hepatocellular carcinoma

Background/Aim: Radiofrequency ablation (RFA) is effective for the treatment of hepatocellular carcinoma (HCC). To prevent the ablation of adjacent organs and vessels, the spread of microbubbles generated by heating during RFA was observed by ultrasonography (US) and used to predict the ablated area; however, several reports documented that discrepancies existed between the spread of microbubbles and the ablated area. Patients and Methods: The spread of microbubbles during RFA was observed by US in 24 patients with HCC and the areas were compared with the defect of enhancement in contrast enhanced (CE)-US, using Levovist in the same plane. Results: During the ablation, the posterior margin was obscure but the border could be visualized 5 min after the ablation. The size of the area of hyperechogenicity 5 min after ablation and that of the defect observed by CE-US was found to correlate (r(2) = 0.91, P < 0.0001). The shape of the hyperechogenicity corresponded well to the defect area, even in cases showing irregular spread of the microbubbles. Conclusion: The observation of microbubbles during RFA can predict the ablated area and might be useful to prevent the unfavorable ablation of adjacent organs and vessels.