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

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

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.

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.

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.