Findings of multidetector row computed tomography of HCCs treated by HIFU ablation

PurposeWe evaluated the efficacy of high-intensity focused ultrasound (HIFU) ablation for hepatocellular carcinoma (HCC), and a long-term study by follow-up multidetector-row computed tomography (CT) was conducted to evaluate the changes occurring in the treatment area following the HIFU ablation.Materials and methodsHIFU ablation was carried out in 14 patients with small HCCs (≤3 lesions, ≤3 cm in diameter). The HIFU system (Chongqing Haifu Tech) was used under ultrasound guidance. The evaluations were performed by follow-up CT at 1 week, 1, 3, 6 and 12 months after the HIFU ablation.ResultsHIFU ablation was carried out successfully in 11 of the 14 patients. At 1 week after the HIFU, a peripheral rim enhancement was found in all cases (100%). This finding was persistent in 6 of the 11 cases (54.5%) at 1 month, and in 1 of the 11 (9%) cases at 3 months after HIFU ablation. In all cases, the rim enhancement disappeared by 6 or 12 months after the HIFU ablation. At the 12 months follow-up, a decrease in the diameter of the ablated lesions was found. The enhancement around the treated area was found to be persistent at the 12 months follow-up in the one case of recurrence of the treated site in which the safety margin was not sufficiently wide. During the follow-up period, there were 2 cases with residual of HCC tumors. We performed radiofrequency ablation (RFA) for these residual tumors after the HIFU ablation.ConclusionTo ascertain the cause of the peripheral enhancement on follow-up CT images after the HIFU ablation, in particular, to determine whether it might be caused by residual tumor or recurrence at the treated site, careful follow-up is important, especially in cases where the safety margin of the ablated area was not sufficiently wide.