Value of Perfusion Parameters for Differentiating Hepatocellular Carcinoma and Liver Metastasis With Hypervascularity and a Normal Hepatic Background on Contrast-Enhanced Ultrasound Imaging: Contrast-Enhanced US in the Diagnosis of Focal Liver Lesions

OBJECTIVES: To retrospectively evaluate the value of contrast-enhanced ultrasound (CEUS) perfusion parameters in the differential diagnosis of hepatocellular carcinomas (HCCs) and metastatic liver tumors (MLTs) with hypervascularity. METHODS: Sixty-seven HCCs and 55 MLTs with arterial homogeneous/heterogeneous hyperenhancement on CEUS imaging and a normal liver background were included in this retrospective study. Six CEUS perfusion parameters were compared between HCCs and MLTs with different sizes and HCC differentiations: rise time (RT), time to peak (TTP), mean transit time, wash-out time (WT), maximum intensity (IMAX), and area under the curve (AUC). The area under the receiver operating characteristic curve (AUROC) was determined to compare the diagnostic efficacy of the parameters. RESULTS: The RT, TTP, and WT were significant longer and the IMAX and AUC were significantly higher in HCCs than in MLTs. In distinguishing between HCCs and MLTs, the AUROC was highest for the WT (0.922; sensitivity, 85.1%; specificity, 89.6%); the AUC and IMAX had the second and third highest AUROCs (AUC: 0.855; sensitivity, 76.1%; specificity, 80.6%; IMAX: 0.827; sensitivity, 76.1%; specificity, 77.6%). The AUROC was lowest for the TTP and RT (TTP: 0.719; sensitivity, 70.1%; specificity, 61.2%; RT: 0.707; sensitivity, 67.2%; specificity, 65.7%). In HCCs, both the tumor size and degree of differentiation affected the IMAX, AUC, and WT. In MLTs, perfusion parameters were not influenced by the tumor size. CONCLUSIONS: In HCCs and MLTs with hypervascularity and a normal liver background on CEUS imaging, various CEUS perfusion parameters, including IMAX, AUC, WT, RT, and TTP, differed significantly between tumor types. The WT may be the most useful parameter for differentiating between these tumors.