Introduction:

The prevalence of chronic kidney disease (CKD) in the United States is estimated to be over 14%. One particular difficulty, among the many issues that arise when caring for these patients, is accurate diagnosis of renal lesions without the use of intravenous contrast. Contrast Enhanced Renal Ultrasound (CERUS) is a diagnostic tool with the potential to allow for more precise imaging without the nephrotoxic effects of standard contrast in patients with indeterminate renal lesions and CKD.

Methods:

A retrospective chart review of patients who underwent CERUS from 2014 to 2015 was performed at a single institution with data collection focused on renal function, prior imaging of renal lesions, and final clinical and pathological diagnoses. The main imaging modalities patients underwent prior to CERUS included Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and non-contrast enhanced ultrasound. Patients were separated into two cohorts based on renal function with an eGFR<60 defining the CKD cohort. Comparisons were made between the two cohorts based on the results and findings of prior imaging modalities and follow-up CERUS performed.

Results:

A total of 169 patients had a CERUS completed from 2014 to 2015 at a single academic institution. There were 104 patients with eGFR<60 who were classified as having CKD. A comparative analysis of categorical variables was done using chi-squared and Fisher’s exact test. CERUS provided specific diagnosis, new diagnosis and/or confirmed diagnosis of previously labeled “indeterminant renal lesions” by other imaging modalities in 41 (39.4%) of the CKD patients compared to 13 patients (20.0%) with normal renal function (p=0.0084). CERUS also resulted in a change in Bosniak classification of cysts in 2 (4.3%) of CKD patients compared to 8 (22.8%) patients with normal renal function (p=0.017). Finally, CERUS resulted in a change in the number of lesions in 2 (1.9%) CKD patients compared to 5 (7.7%) patients with normal renal function (p=0.11).

Conclusion:

CERUS can be used to diagnose and follow renal lesions in patients with CKD who otherwise may not be able to undergo imaging with various forms of nephrotoxic contrast. Though US has its limitations, CERUS can help differentiate and further classify indeterminate renal lesions that may be concerning for malignancy. Perhaps patients with normal renal function have better complex cystic lesion characterization and detection of otherwise occult renal lesions based on improved blood flow characteristics. Further studies are necessary to validate these findings and further elucidate the mechanisms for the findings to optimize imaging selection in patients with compromised renal function.

Funding: UAB-UCSD O'Brien Center for Kidney Injury Research Summer Program