Abstract: Objective To investigate the value of real-time contrast-enhanced ultrasound (CEUS) in the diagnosis and
differential diagnosis of renal solid renal lesions (RSLs). Methods We retrospectively analyzed 140 cases of 152 RSLs with a
mean diameter 3.1 ± 1.9 cm. CEUS was performed and the perfusion characteristics were analyzed using contrast pulse
sequences (CPS) technique. CEUS findings were compared with biopsy histopathologic findings. Results A total of 137
malignant lesions (including 127 renal clear cell carcinomas, 8 renal papillary carcinomas and 2 chromophobe cell carcinomas)
and 15 benign lesions (13 angiomyolipomas and 2 renal oncocytomas) were detected. Of the 137 malignant lesions, 98 (71.5%)
showed contrast agent fast perfusion and hyper-enhancement or iso-enahncement in cortical phase, 104 (75.9% ) showed
hypo-enhancement in later corticalmedullary and late phase, and 125 (91.2%) showed rim-like enhancement. Tumors with a
diameter ≤2 cm presented with homogeneous enhancement, and those ranging from 2 to 4 cm showed heterogeneous
enhancement with a honeycomb feature; tumors greater than 4 cm featured heterogeneous enhancement with large
no-enhancement necrotic areas. Of the benign lesions, 13 angiomyolipomas and 2 renal oncocytomas showed slow wash-in
and slow wash-out mode. The diagnostic specificity, accuracy and positive predictive value of CEUS for RSLs were 94.9%,
96.1%, and 73.7%, as compared to 72.3%, 71.1%, and 19.1% with conventional US, respectively (P<0.001). The sensitivity and
negative predictive value of CEUS were 93.3% and 99.2%, respectively, significantly higher than those of conventional US (60%
and 94.3%, P=0.084, and 0.062, respectively). Conclusion Real-time CEUS can provide valuable information for improving the
diagnosis and differential diagnosis of RSLs.