Parametric imaging with contrast-enhanced ultrasound for differentiating hepatocellular carcinoma from metastatic liver cancer

Aim: To evaluate the diagnostic performance of parametric imaging with contrast-enhanced ultrasound(CEUS) for differentiating hepatocellular carcinoma(HCC) from metastatic liver cancer(MLC).

Methods: 30 HCCs (mean diameter, 3.6±1.3 cm; range, 2.1-5.0 cm) and 30 MLCs (mean diameter, 2.8±1.5 cm; range, 1.2-5.0 cm) pathologically diagnosed or confirmed by clinical criteria that underwent CEUS were randomly included. CEUS was carried out using a multifrequency transducer (2-4 MHz) and a bolus injection of 2.4 mL SonoVue. The CEUS clips of the targeted lesion were recorded continuously for 6 minutes. By analyzing CEUS clips, parametric image could be obtained using the SonoLiver® software automatically. Quantitative parameters were compared between HCC and MLC groups. Receiver operating characteristic (ROC) curve analysis was further performed on parameters with significant difference between two groups.

Results: On parametric imaging, the maximum intensity, rise time, time to peak, mean transit time and washout time for HCC and MLC were 185.6±148.0 vs. 95.2±58.6 (P = 0.003), 25.7±6.3 s vs. 23.8±8.8 s (P = 0.341), 30.7±7.9 s vs. 27.8±10.5 s (P = 0.246), 90.2±45.7 s vs. 89.3±40.3 s (P = 0.805), 63.4±29.5 s vs. 37.2±33.8 s (P = 0.005), respectively. ROC analysis was further performed for washout time and it showed a cut-off point of 43.765 s for the differentiation between HCC and MLC, with the AUC value of 0.780 (95% CI: 0.646-0.914). The corresponding diagnostic specificity, sensitivity and accuracy were 72.0%, 84.6% and 78.4% respectively.

Conclusions: Parametric imaging of CEUS can display perfusion effects of HCC and MLC objectively and visually and washout time may serve as a useful parameter on the differential diagnosis between HCC and MLC.