Usefulness of contrast-enhanced ultrasonography to evaluate the post-treatment responses of radiofrequency ablation for hepatocellular carcinoma: comparison with dynamic CT.

Objective: Contrast-enhanced ultrasonography (CEUS) with Sonazoid® and dynamic computed tomography (CT) were used to evaluate radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). Local recurrence rate was used as the gold standard of evaluation.

Methods: From January 2007 to December 2011, 86 HCCs from 70 patients were treated with RFA. CEUS with Sonazoid and dynamic CT were then used to evaluate the effect of RFA. For CEUS and dynamic CT, effects were classified as follows: (1) complete ablated response with safety margin >5 mm (CRSM+); (2) complete ablated response but with safety margin <5 mm (CRSM-); (3) incomplete, residual tumor detected after treatment.

Results: CEUS judged 33 cases as CRSM+, while dynamic CT identified 49 cases. None of these 33 cases from the CEUS group had local recurrences, while dynamic CT had 1 case. CEUS judged 49 cases as CRSM-, compared to 34 cases with dynamic CT. Of these, 9 cases of CEUS and 8 cases of dynamic CT showed local recurrences. Two cases diagnosed as 'incomplete' by CEUS and dynamic CT had recurrences within 1 year.

Conclusion: CEUS can be used to assess the efficacy of RFA for HCC, with the potential to reduce the number of CT scans required for confirmation.