Objective  To investigate the enhancement pattern features of hepatocellular carcinoma(HCC) on contrast-enhanced ultrasound (CEUS) and explore the diagnostic value of CEUS for predicting tumor differentiation.

  Methods  CEUS features of 81 cases of pathologically confirmed HCC were retrospectively analyzed. The enhancement pattern was defined as "quick in-quick out" when the lesion was enhanced in arterial phase and showed as hypoechoic in portal phase; when the lesion was enhanced in arterial phase and showed as hypoechoic in late phase, the enhancement pattern was defined as "quick in-slow out". According to the final pathological results, HCCs were categorized into well-differentiated group and poorly-to-moderately differentiated group. The diagnostic value of CEUS for the HCC differentiation was summarized.

  Results  Of these 81 HCC patients, 38 were diagnosed as well-differentiated HCCs and 43 as poorly-to-moderately differentiated HCCs. The enhancement pattern was "quick in-slow out" in 17 patients (21.0%, 17/81) with well-differentiated HCCs, "quick in-quick out" in 21 patients (25.9%, 21/81)with well-differentiated HCCs, and "quick in-quick out" in 43 patients (53.1%, 43/81) with poorly-to-moderately differentiated HCCs. The "quick in-slow out" pattern was more common in the well-differentiated HCC group than in the poorly-to-moderately differentiated HCC(χ²=24.35, P < 0.01).Its diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rate were 44.7%, 100%, 100%, 67.2%, and 74.1%, respectively.

  Conclusion  The "quick in-slow out" enhancement pattern may be helpful for predicting and diagnosing the well-differentiated HCC.