Diagnostic performance of contrast-enhanced ultrasound in the evaluation of renal masses in patients with renal impairment

Objective: To evaluate the performance of contrastenhanced ultrasound (CEUS) in the risk stratification of indeterminate renal lesions picked up incidentally on abdominal imaging, in patients with renal impairment. Methods: A retrospective study was performed of nonconsecutive patients who underwent CEUS at our tertiary care centre for indeterminate renal lesions between March 2010 and September 2014. A total of 63 patients with 74 nodules were assessed with CEUS and stratified into either benign (Bosniak I, II, IIF) or suspicious for malignancy (Bosniak III, IV or hypervascular solid lesions). Diagnostic accuracy was determined by comparing these findings to subsequent histological diagnoses, temporal change after at least 20 months follow-up or after a diagnostic computer tomography / magnetic resonance imaging study. Results: CEUS correctly identified 49/52 (94.2%) of benign lesions and 21/22 (95.5%) of malignant lesions, resulting in a sensitivity of 95.5% (95% CI 77.2-99.9%), specificity of 94.2% (95% CI 84.1-98.8%), positive predictive value (PPV) 87.5% (95% CI 67.6-97.3) and negative predictive value (NPV) 98.0% (95% CI 89.4-100%). Conclusion: CEUS has high diagnostic performance in predicting the benignity of a renal lesion in patients with renal impairment, showing sensitivity and NPV approaching 100%