Objective: The objective of our study was to evaluate contrast-enhanced sonography in the diagnosis of malignancy in complex cystic renal masses.
Materials and methods: We analyzed a series of 40 cystic renal masses (diameter, 2-8 cm) with a complex pattern at contrast-enhanced CT in 40 consecutive subjects (18 men, 22 women; mean age +/- SD, 62 +/- 11 years). Each renal mass was scanned using sonography without contrast material and after IV injection of sulfur hexafluoride-filled microbubbles during the arterial (15-40 seconds) and venous (40-120 seconds from injection) phases. Two radiologists in consensus assessed onsite the enhancement patterns in the peripheral wall and intracystic septa and the evidence of solid endocystic components. Three blinded readers with 2, 6, and 10 years of experience in renal imaging performed a retrospective off-site interpretation of unenhanced sonography, contrast-enhanced sonography, and CT images and made a benign or malignant diagnosis according to refer ence diagnostic criteria for contrast-enhanced sonography and to the Bosniak classification for CT.
Results: Final diagnoses comprised two multilocular cystic nephromas, two inflammatory and seven hemorrhagic cysts, and eight uncomplicated benign cysts and 21 cystic renal cell carcinomas. The overall diagnostic accuracy of contrast-enhanced sonography was better than unenhanced sonography and CT (contrast-enhanced sonography vs unenhanced sonography vs CT: reader 1, 83% vs 30% vs 75%; reader 2, 83% vs 30% vs 63%; reader 3, 80% vs 30% vs 70%; p < 0.05, McNemar test).
Conclusion: Contrast-enhanced sonography was found to be better than unenhanced sonography and CT in the diagnosis of malignancy in complex cystic renal masses.