Contrast-enhanced ultrasound (CEUS) in patients with chronic kidney disease (CKD)

Microbubble based contrast-enhanced ultrasound (CEUS) enables the visualization of vascularity given the tendency of microbubbles to function as a blood pooling agent. Using contrast specific ultrasound (US) imaging, it is possible to quantify the kinetics of these agents and derive various perfusion metrics. In this ongoing clinical study, we evaluate the feasibility of using these microbubble based contrast agents (CA) to develop qualitative and quantitative measures of perfusion in patients with chronic kidney disease (CKD). CEUS imaging may provide information about kidney perfusion that will aid in early diagnosis, disease progression and response to therapy. Patients (n = 63) with CKD and 3 healthy controls were imaged using CEUS. Imaging was performed on a Sequoia 512 (Siemens Healthcare) by trained sonographers using a 4C1 transducer (1–4 MHz). Definity (Lantheus Medical Imaging) was administered to the patient as a continuous IV infusion based on recommended dosage guidelines. Multiple sequences of microbubble flash-replenishment were used to generate signal intensity versus time (TIC) curves for specific regions of interest (ROIs). Maximum intensity projections (MIPs) and perfusion maps were also generated based on flash-replenishment cine sequences. Flow rate (β) based on the slope of the TIC was compared with CKD staging to study the correlation between the metrics. Preliminary evaluation of the perfusion maps showed a marked difference between the healthy controls and CKD patients. Significant correlations (r
²
=0.20, p=0.03) and (r
²
=0.16, p<0.01) were found between β and CKD stage by selecting ROIs defined by the whole kidney and in the parenchyma respectively. In this preliminary study, CEUS of CKD patients is shown to be feasible and is able to generate quantitative metrics of perfusion. The diagnostic accuracy of these metrics is yet to be determined.