Intrahepatic distant recurrence following complete radiofrequency ablation of small hepatocellular carcinoma: risk factors and early MRI evaluation

BACKGROUND: Radiofrequency ablation(RFA) is related to a high intrahepatic distant recurrence(IDR) rate,and the associations between IDR and relevant imaging features have not yet been fully investigated. This study aimed to determine both clinical and imaging risk factors of IDR after complete RFA for HBV-related small hepatocellular carcinoma(HCC)(≤3 cm).METHODS: Thirty-five patients(29 men and 6 women; mean age 60.7 years) with 40 HBV-related small HCCs who underwent complete RFA were included in our study. The incidence and potential clinical and MR imaging risk factors for IDR after RFA were assessed using the Kaplan-Meier method,the log-rank test and a stepwise Cox hazard model.RESULTS: The median follow-up period was 25(4-45) months,and IDR was observed in 20(57.1%) patients. The 12- and 24-month cumulative IDR-free survival rates were 76.7% and 61.3%,respectively. Univariate analysis revealed that pretreatment albumin <3.5 g/d L(P=0.026),multinodular tumor(P=0.032),ablative margin <3 mm(P=0.007),no or disrupted periablational enhancement within 24 hours(P=0.001) and at 1 month(P=0.043) after RFA,and hyperintensity of the central ablative zone on T1-weighted images(T1WI) at 1 month after RFA(P=0.004) were related to IDR. Multivariate analysis showed that pretreatment albumin <3.5 g/d L(P=0.032),mul-tinodular tumor(P=0.012),no or disrupted periablational enhancement within 24 hours after RFA(P=0.001),and hyperintensity of the central ablative zone on T1 WI at 1 month after RFA(P=0.003) were independent risk factors for IDR. During the 1-month follow-up,the apparent diffusion coefficient exhibited an up-and-down evolution without significant value in the prediction of IDR following RFA.CONCLUSIONS: Patients with HBV-related small HCC had a high IDR rate after RFA. The risk factors included low serum albumin,multiple nodules,lesions with no or disrupted periablational enhancement and persistent hyperintensity in the central ablative zone on T1 WI within 1 month after RFA.