Impact of an immediate short waiting period on ultrasound-based ablative margin assessment following radiofrequency ablation for hepatocellular carcinoma

Purpose: This study aimed to evaluate whether an immediate short waiting period after radiofrequency ablation (RFA) can improve the accuracy of ultrasound (US)-based assessment of the ablation zone in patients with hepatocellular carcinoma (HCC). Methods: A prospective cohort study was conducted involving 41 patients who underwent US-guided RFA for HCC. Tumor margin conspicuity, electrode tip visibility, and operator confidence in assessing the ablative margin were recorded immediately following electrode deactivation and at 1-minute intervals for 5 minutes. Post-ablation computed tomography was performed to confirm the sufficiency of the ablative margins. The Friedman test and post-hoc Conover analysis were used to assess changes over time. Results: Over time, significant improvements were observed in tumor margin visibility, electrode tip visualization, and operator confidence in ablative margin assessment (all P<0.001). Repositioning and additional ablation were required in 29.3% (12/41) of patients, with all achieving sufficient ablative margins. Larger tumor size was associated with decreased operator confidence (P=0.008). No major complications occurred. Conclusion: A short waiting period following RFA enhances the visibility of tumor margins and electrode tips on US, thereby increasing operator confidence in assessing ablative margin sufficiency. Implementing an immediate short waiting period may improve the accuracy of treatment.