Contrast-enhanced ultrasound (CEUS) as a new technique to characterize suspected renal transplant malignancies in renal transplant patients in comparison to standard imaging modalities.

Background: Renal transplant patients have a higher risk for malignancies of the renal transplant. In most cases suspected renal malignancies will be detected during the regular ultrasound follow-up and will require cross-sectional imaging to rule out a malignant aetiology. But it is well known that contrast agents for computed tomography or magnetic resonance imaging are critical in patients with limited renal function.

Objective: This study aims to compare the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and gold standard imaging modalities in characterizing suspected renal transplant malignancies in renal transplant patients.

Methods: A total of 22 renal transplant patients who underwent one or more CEUS examinations and at least one standard imaging modality (CT or MRI) between 2005 and 2017 were included. Patient ages ranged from 28.2 years to 74.6 (mean age 55.7 years; SD±13.0 years). CEUS of 22 patients was correlated with a standard imaging modality, CT (15 out of 22) or MRI (7 out of 22), serving as gold standard.

Results: CEUS showed a sensitivity of 100%, a specificity of 94.4%, a positive predictive value (PPV) of 80%, and a negative predictive value (NPV) of 100%.

Conclusions: CEUS is an eligible method to help characterizing suspected renal malignancies in renal transplant patients compared to the well-established imaging modalities CT and MRI. As an imaging modality with no nephrotoxic effects CEUS can be used repeatedly even in patients with limited renal function.