Computed Tomographic-Guided Radiofrequency Ablation of Recurrent or Residual Hepatocellular Carcinomas around Retained Iodized Oil after Transarterial Chemoembolization

Objective: To assess the clinical efficacy, safety, and risk factors influencing local tumor progression, following CT-guided radiofrequency ablation (RFA) of recurrent or residual hepatocellular carcinoma (HCC), around iodized oil retention. Materials and Methods: Sixty-four patients (M : F = 51 : 13, 65.0 ${\pm}$ 8.2 years old) with recurrent or residual HCC (75 index tumors, size = 14.0 ${\pm}$ 4.6 mm) had been treated by CT-guided RFA, using retained iodized oil as markers for targeting. The technical success, technique effectiveness rate and complications of RFA were then assessed. On pre-ablative and immediate follow-up CT after RFA, we evaluated the size of enhancing index tumors and iodized oil retention, presence of abutting vessels, completeness of ablation of iodized oil retention, and the presence of ablative margins greater than 5 mm. Also, the time interval between transarterial chemoembolization and RFA was assessed. The cumulative local tumor progression rate was calculated using the Kaplan-Meier method, and the Cox proportional hazards model was adopted, to clarify the independent factors affecting local tumor progression. Results: The technical success and technique effectiveness rate was 100% and 98.7%, respectively. Major complications were observed in 5.6%. The cumulative rates of local tumor progression at 1 and 2 years were 17.5% and 37.5%, respectively. In multivariate analyses, partial ablation of the targeted iodized oil retention was the sole independent predictor of a higher local tumor progression rate. Conclusion: CT-guided RFA of HCC around iodized oil retention was effective and safe. Local tumor progression can be minimized by complete ablation of not only index tumors, but targeted iodized oil deposits as well.