Contrast-enhanced Ultrasound for the Evaluation of Complex Renal Cysts

Complex renal cysts are often incidentally detected on imaging. The differential diagnosis of the complex renal cyst includes various benign cystic lesions, which are based on the Bosniak classification scheme. Currently the standard of care in evaluating a complex renal cyst is using a contrast-enhanced computed tomography (CT) scan, or a contrast-enhanced magnetic resonance imaging (MRI) scan. Since both of these modalities present adverse events due to frequent high doses of radiation, a technique such as a contrast-enhanced ultrasound (CEUS) can be used to obtain the same results, without having to impose high doses of radiation upon a patient.

By evaluating complex renal cysts using a contrast-enhanced ultrasound (CEUS), it can be established as to whether or not the results are better, the same, or worse, when compared to CT and/or MRI scans.

A contrast-enhanced ultrasound utilizes intravenous gas-filled microbubbles to enhance visualization in real time.

Complex renal cysts will be classified using the Bosniak classification system for both the CEUS and CT and compared. If surgical removal of a complex cyst is required (Bosniak IIF, III or IV), then the pathology will be evaluated with a single CEUS and a CT (The CEUS will be conducted 14 days within the CT).

If during watchful waiting another CEUS is needed to be done in cases where a CT scan does show change at a follow up visit, then this average percent difference will also be calculated at this point.

Inclusion Criteria: at least 18 years old and capable of giving informed consent all patients undergoing CT evaluation of complex renal cysts at our centre (either initially or in follow-up) A complex renal cyst defined as Bosniak IIF, III or IV Exclusion Criteria: pregnant patients patients with contrast allergies patients with non-cystic, solid renal masses patients with simple cysts (Bosniak class I and II)