Evaluation of local tumor residue after percutaneous radiofrequency ablation therapy for hepatocellular carcinoma.

BACKGROUND/AIMS This study's purpose was to compare the efficacy of CO2-enhanced ultrasonography (US) with that of Sonazoid-enhanced US and conventional US in detecting local tumor residue after percutaneous radiofrequency (RF) ablation therapy for hepatocellular carcinoma. MATERIALS AND METHODS Between February 2009 and March 2010, 141 lesions of 121 hepatocellular carcinoma patients were treated by percutaneous RF ablation, and 22 tumor residues were detected in 22 patients by contrast-enhanced computed tomography. These 22 patients were examined by conventional US, Sonazoid-enhanced US (0.5 mL/body of Sonazoid, intravenous administration), and CO2-enhanced US (10 mL of CO2, hepatic arterial administration). RESULTS Tumor residue was confirmed by CO2-enhanced US in all the 22 patients (sensitivity: 100%) in 19 of the 22 patients by Sonazoid-enhanced US (sensitivity: 86%; 3 lesions that were not detected by this modality were located deeper than the sonographic depth (p=0.0109)), and in 17 of the 22 patients by conventional US (sensitivity: 77%; 5 lesions that were not detected by this modality were smaller in terms of the sonographic tumor size (p=0.0278)). CONCLUSION Although CO2-enhanced US requires angiography, it was superior to both Sonazoid-enhanced US and conventional US for detecting tumor residues, particularly deep-seated ones, after percutaneous RF ablation.