Objectives: This study aims to explore the influence of liver stiffness on the gray-scale ultrasound (US), contrast-enhanced ultrasound (CEUS), and the Liver Imaging Reporting and Data System (LI-RADS) v2017 classification of hepatocellular carcinoma (HCC). Methods: This study consecutively enrolled 211 patients with HCC who underwent hepatectomy in six hospitals from January 2019 to April 2024. All patients underwent gray-scale US and CEUS examinations. Their clinical characteristics, gray-scale US features, the classification of color Doppler flow imaging (CDFI), and the perfusion characteristics of CEUS were evaluated, and they were classified according to the CEUS LI-RADS. The blood flow classification of CDFI was determined according to Adler's method. Liver stiffness was divided into ≤S2 (n=104) and >S2 (n=107) according to the Scheuer scoring grading system, and a stratified analysis was conducted according to the tumor size. In the double-image section of CEUS, the maximum diameters of the lesions in two-dimensional US and the arterial phase of CEUS were measured, and the invasive margin of the tumor was calculated from the difference between the two values. Results: We analyzed a total of 11 clinical characteristics, 16 two-dimensional US features, and 7 CEUS features. The results showed that liver stiffness had no significant effect on the CEUS LI-RADS classification (p>0.05), but it influenced the onset time of lesion washout (80 s vs. 90 s, p<0.01) and the washout rate (65.0% vs. 80.3%, p=0.039). The results of the stratified analysis showed that in the subgroup of HCC >3 cm, the washout rate in the group with liver stiffness >S2 was lower than that in the group with liver stiffness ≤ S2 (p < 0.05). Conclusions: Liver stiffness has no significant effect on the LI-RADS classification. However, the harder the liver is, the later the onset time of lesion washout and the lower the washout rate will be.

Hepatocellular Carcinoma, Contrast-Enhanced Ultrasound, LI-RADS Classification, Scheuer Score