OBJECTIVETo investigate the value of real-time contrast-enhanced ultrasound (CEUS) in the diagnosis and differential diagnosis of renal solid renal lesions (RSLs).

METHODSWe 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.

RESULTSA 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-enhancement 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).

CONCLUSIONReal-time CEUS can provide valuable information for improving the diagnosis and differential diagnosis of RSLs.