Development of MRI techniques for the assessment of chronic kidney disease

It is well established that patients with Chronic Kidney Disease (CKD) are more susceptible to develop cardiovascular disease in comparison to the healthy population. This thesis aims to develop and apply MRI techniques to assess the human heart and kidney in patients with chronic kidney disease (CKD). Magnetic resonance imaging (MRI) can be used to inform on structure, function, perfusion and blood flow, without the need for ionizing radiation. In order to assess blood flow using MRI, gadolinium based contrast agents are often used. Patients with compromised kidney function are contraindicated to these contrast agents and so it is necessary to develop imaging techniques that can be used without a contrast agent. Arterial spin labelling (ASL) is an MRI technique that provides a non-contrast enhanced method to assess tissue perfusion using the intrinsic signal from the water in the body. ASL is now becoming a well-established technique in the brain, however applications of ASL in the body are currently limited. In this work, a cardiac ASL technique is developed using a modified Look-Locker scheme to study the myocardium of the heart. This technique is then applied in patients with CKD Stage 3 and age-matched healthy control subjects to assess the changes in myocardial perfusion during a handgrip exercise challenge. MRI measurements of cardiac index and stroke volume index, global and regional contractile function (myocardial strain), coronary artery flow and myocardial perfusion using ASL are applied to assess changes in cardiac function in CKD Stage 5 patients during dialysis treatment. The measures are performed in a randomised design to assess the cardiovascular effects in patients undergoing both haemodialysis and haemodiafiltration. Finally, a comparison of 2D readout schemes for renal ASL is performed. Gradient and spin echo based readout schemes for multi-slice ASL of the kidney at 3 T are evaluated and directly compared in terms of temporal SNR, image SNR, spatial coverage, perfusion quantification and variability across slices/subjects. This work aims to determine the optimal readout scheme for pulsed ASL (PASL) of the kidneys at 3 T in healthy volunteers with normal renal function. In future work this could be applied to patients with compromised renal function where a robust imaging technique is needed. Finally, a summary of the key findings of this thesis and an outline of the potential future directions of this work is provided