Contrast enhanced second generation ultrasound for the staging of renal tumours in comparison to histology and computed tomography

Aim: Renal cell carcinoma is often incidentally detected with ultrasound. Here we compare contrast enhanced ultrasound in a large number of patients with computed tomography as reference method and histology as golden standard to determine its ability for the characterisation of renal lesions.

Methods: After a preliminary period of 150 patients with known kidney tumours 168 patients were prospectively investigated with contrast enhanced ultrasound. 112 patients were finally included since contrast enhanced CT and histology was available. Technical features: Acuson Sequoia (Siemens, Erlangen, Germany), mechanical index <0.2, bolus injection of 2.4ml of BR1 (Bracco, Italy), continuous scanning up to 3 minutes.

Results: 84 renal cell carcinoma (75%), 7 urothelial cell carcinoma (6%), 4 renal cell adenoma (4%), 3 angiomyolipoma (3%), 2 pseudotumours (2%), others (4, 4%). 6 adrenal tumours (5%) and 2 retroperitoneal lesions (2%) were initially thought to be of renal origin. 7% of the lesions were cystic. The tumour staging for renal cell carcinoma was correctly predicted by CEUS in 83% and by CT with 73%. Sensitivity and specificity for vein involvement was 80% and 97% for contrast enhanced ultrasound and for CT 40% and 99% respectively. The use of ultrasound contrast agents was helpful in 25%, in detail in cystic lesions and when vascularisation of the lesion could not be demonstrated by conventional ultrasound.

Conclusion: CEUS is comparable to CT in the characterisation of renal masses and in the staging of renal cell carcinoma.