Objective To determine the value of contrast-enhanced ultrasonography (CEUS) in the diagnosis of renal occupying lesions. Methods Seventy-eight patients with a preliminary diagnosis of renal masses in West China Hospital, Sichuan University were examined by CEUS. The characteristics of enhancement, phase of enhancement/decline, pseudocapsule sign, and time-intensity curve (TIC) were compared between the malignant and benign lesions. Results Of the 78 renal occupying lesions, 50 were malignant and 28 were benign. Malignant lesions showed enhanced signs to various degrees. The renal clear cell carcinoma mainly presented as “fast wash-in and fast wash-out”, while the other malignant lesions presented as “slow wash-in and fast wash-out”. Pseudocapsule signs were found mostly in renal clear cell carcinoma. No enhancement was found in renal cyst. Renal angiomyolipoma presented as diffuse hypo-enhancement characterized with “slow wash-in and slow wash-out”. The time-to-peak (TTP) in malignant lesions appeared earlier than benign lesions. Higher levels of peak intensity (PI) and area under the curve (AUC) were found in malignant lesions compared with the benign lesions (P
