Objective: The purpose of our study was to elucidate whether the degree of arterial enhancement on CT is a significant risk factor for local tumor progression after percutaneous radiofrequency ablation of hepatocellular carcinomas (HCCs) larger than 2 cm.
Materials and methods: Percutaneous radiofrequency ablation procedures to treat 203 previously untreated HCCs larger than 2 cm in 190 patients were analyzed retrospectively. We assessed the technique effectiveness rate 1 month after the procedure and the cumulative local tumor progression rate. The tumors were classified into one of the following groups for qualitative analysis: group with evident contrast enhancement or group showing subtle or no contrast enhancement. We performed quantitative analysis of increments in the attenuation (in Hounsfield units [HU]) from unenhanced to arterial phase CT of the 78 HCCs for which unenhanced CT was available. To determine any significant risk factor, various factors, including the degree of arterial enhancement, were tested by multivariate analysis.
Results: The technique effectiveness rate was 99.0% (201/203). Local tumor progression was detected in 23.9% (48/201), and the cumulative rates of local tumor progression at 1, 2, and 3 years were 12.9%, 23.1%, and 27.6%, respectively. The two qualitative groups were significantly different in their cumulative local tumor progression rates (p = 0.009). Multivariate analysis revealed that the degree of arterial enhancement was a sole independent significant risk factor for local tumor progression (p = 0.026).
Conclusion: A high degree of arterial enhancement on CT after percutaneous radiofrequency ablation of HCCs larger than 2 cm is a significant risk factor for local tumor progression.