Abstract:Objective To evaluate the contrast-enhanced ultrasound (CEUS) features of different sizes of clear cell renal cell carcinomas (ccRCCs).Methods The CEUS images of 106 ccRCCs were retrospectively evaluated. All tumors were divided into 3 groups according to tumor size: ≤4 cm, 4~7 cm and >7 cm. The ultrasound contrast agent arrival time, peak enhancement degree, perfusion heterogeneity and the peritumoral hyperenhanced rim (PHR) were compared among groups by qualitative observation. Quantitative parameters including the maximum intensity(IMAX),rise time(RT), time to peak(TTP), wash in perfusion rate(WIR), mean transit time(mTT) and the area under the curve (AUC) were compared between the tumor and the peripheral renal cortex (PRC) within group and that of the tumor among groups. Results There were significant differences in the contrast agent arrival time, perfusion heterogeneity and the PHR detection among groups (P<0.05, respectively); In quantitative analysis, IMAX and AUC values of the RCC were significantly different among groups (P<0.05, respectively). All quantitative features showed no significant differences between the tumor and the PRC in the ≤4 cm group (P>0.05,respectively). In the 4~7 cm and >7 cm group, IMAX and AUC were higher in the tumor than the PRC (P<0.05,respectively).Conclusion The CEUS features of different sizes of ccRCCs were different, and qualitative and quantitative evaluation can provide more information for ccRCC ultrasonic diagnosis.