Diagnostic efficacy of contrast-enhanced ultrasonography in solid renal parenchymal lesions with maximum diameters of 5 cm.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic efficacy of contrast-enhanced ultrasonography (CEUS) using a sulfur hexafluoride contrast agent and the cadence contrast pulse sequencing mode in differentiating solid renal parenchymal lesions (SRPLs) with a maximum diameter of 5 cm. METHODS: Seventy-one patients with 72 SRPLs with a maximum diameter of 5 cm underwent conventional ultrasonographic and CEUS examinations in our department. The final diagnoses were 44 renal cell carcinomas (RCCs; confirmed by pathologic examination), 24 renal angiomyolipomas (4 by pathologic examination and 20 by computed tomography, magnetic resonance imaging, and follow-up studies), 1 oncocytoma (by pathologic examination), 2 hypertrophied columns of Bertin, and 1 renal abscess (both by computed tomography, magnetic resonance imaging, and follow-up studies). Three observers who were blinded to other results and the final diagnoses reviewed the conventional ultrasonographic and CEUS images. RESULTS: Hyperenhancement in the late phase (30-90 seconds after agent injection) was the most important finding for predicting SRPLs with a maximum diameter of 5 cm to be RCCs. With this criterion, the specificity and sensitivity for diagnosing solid RCCs (