AIM:To investigate the association between B-mode ultrasound classification of small hepatocellular carcinoma(HCC) and outcome after radiofrequency ablation(RFA).METHODS:Ninety-seven cases of HCC treated using RFA between April 2001 and March 2006 were reviewed.Ultrasound images were classified as follows:type 1,with halo(n=29);and type 2,without halo(n=68).Type 2 was further categorized into three subgroups:type 2a,homogenous hyperechoic(n=9);type 2b,hypoechoic with smooth margins(n=43);and type 2c(n=16),hypoechoic with irregular or unclear margins.Patients with type 2a HCC were excluded from analysis due to the small number of cases.RESULTS:Two year recurrence rates for type 2b,type 1 and type 2c were 26%,42% and 69%,respectively,with significant differences between type 2b and type 2c(P<0.01),and between type 1 and type 2c(P<0.05).Five year survival rates were 89%,43% and 65%,respectively.Survival was significantly longer for type 2b than for other types(type 1 vs type 2b,P<0.01;type 2b vs type 2c,P<0.05).On univariate analysis,factors contributing to recurrence were number of tumors,tumor stage,serum level of lens culinaris agglutinin-reactive alpha-fetoprotein and ultrasound classification(P<0.05).Factors contributing to survival were tumor stage and ultrasound classification(P<0.05).Multivariate analysis identified ultrasound classification as the only factor independently associated with both recurrence and survival(P<0.05).CONCLUSION:B-mode ultrasound classification of small HCC is a predictive factor for outcome after RFA. AIM: To investigate the association between B-mode ultrasound classification of small hepatocellular carcinoma (HCC) and outcome after radiofrequency ablation (RFA). METHODS: Ninety-seven cases of HCC treated using RFA between April 2001 and March 2006 were reviewed .Ultrasound images Type 2, without halo (n = 68). Type 2 was further categorized into three subgroups: type 2a, homogenous hyperechoic (n = 9); type 2b , hypoechoic with irregular or unclear margins. Patients with type 2a HCC were excluded from analysis due to the small number of cases .RESULTS: Two year recurrence rates (n = 42) for type 2b, type 1 and type 2c were 26%, 42% and 69% respectively, with significant differences between type 2b and type 2c (P <0.01), and between type 1 and type 2c year survival rates were 89%, 43% and 65%, respectively. Survival was significantly longer for type 2b than for other types (type 1 vs type 2b, P <0.01; typ e 2b vs type 2c, P <0.05) .On univariate analysis, factors contributing to recurrence were number of tumors, tumor stage, serum level of lens culinaris agglutinin-reactive alpha-fetoprotein and ultrasound classification (P <0.05) .Factors contributing to Multivariate analysis identified ultrasound classification as the only factor independently associated with both recurrence and survival (P <0.05). CONCLUSION: B-mode ultrasound classification of small HCC is a predictive factor for outcome after RFA.