Establishing a New Ultrasound Technique to Improve Assessment of Chronic Kidney Disease.

Renal perfusion, the delivery of oxygenated blood to kidney tissues, is relevant to a number of acute and chronic kidney diseases. Despite this, we do not have methods in current clinical practice to measure renal perfusion and monitor the response to supportive treatments in real time. This is a major barrier to investigation and management of acute kidney injury (AKI) and chronic kidney disease (CKD). The current non-invasive gold standard technique for renal perfusion measurement is arterial-spin labelling magnetic resonance imaging (ASL-MRI), which has been validated against other measures of perfusion, including contrast agent-based methods. However, MRI has limitations including high cost, and logistical barriers. Therefore, validation of a bed-side measurement tool for renal perfusion would be of significant clinical importance. This proposal aims to validate CEUS renal cortical perfusion measurement by comparison with quantifiable ASL-MRI parameters of renal microvascular perfusion in individuals with CKD. TRIAL REGIMEN All interventions outlined below are for the purposes of research, not usual care. Study day: All participants will attend fasted for preceding 2 hours. Demographic details and medical history will be recorded. The patient's concomitant medications which form part of their usual care will be recorded. These will not be adjusted. Results of blood and urine tests that are collected as part of clinical care will be recorded. Participants will undergo two scanning sessions, the first using renal MRI at the Sir Peter Mansfield Imaging Centre (SPMIC) to provide a quantitative measure of renal perfusion, and the second to provide the comparator measure of renal perfusion using CEUS performed at Royal Derby Hospital. Outcomes: MRI derived perfusion variables: peak time, and peak signal intensity (SI) will be obtained from time intensity curves. Mean flow velocity (cm/s), cross-sectional area of the lumen (mm2), and hence bulk renal blood flow (ml/s) CEUS derived perfusion parameters: acoustic index (AU); mean transit time (seconds); perfusion index, which is the ratio of AI to mTT; and wash-in rate (seconds)