Prediction of Renal Functional Outcome after Revascularization with Magnetic Resonance Imaging in Atheromatous Renovascular Disease

Abstract

Atheromatous renovascular disease (ARVD) is an increasingly significant cause of chronic kidney disease and hypertension. Renal revascularization procedures, with angioplasty and stenting, are often undertaken for significant renal artery stenosis (RAS) lesions. However, only 25% of patients manifest an improvement in renal function post revascularization; the procedure itself is not without risk to the patient. Selecting patients likely to benefit is a considerable challenge. No technique has thus far been able to effectively predict a patient's response to revascularization.Magnetic resonance imaging (MRI) allows detailed assessment of renal morphology. Nephrogenic systemic fibrosis (NSF) is a new condition associated with gadolinium contrast enhanced (CE)- MRI. MRI calculated renal parenchymal volume (PV) does not require gadolinium and is the best correlate of isotopic single-kidney glomerular filtration rate (isoSK-GFR) in ARVD.The aim of this research project was fourfold. Firstly, critically analyse the existing literature on NSF. This was combined with our centre's experience in CE- MRI, multiple centres involved in the ASTRAL trial and a large London hospital. This led to development of an imaging protocol for this study. Secondly, identify kidney sub-groups which do improve renal function post renal revascularization. This involved prospective validation of pilot study findings that kidneys with a disproportionately larger PV: isoSK-GFR ratio were likely to improve renal function post revascularization. A control group were recruited for comparison purposes. Thirdly, explore a second non-CE-MRI method, called BOLD R2* imaging as a complementary predictive imaging tool. Lastly, to extrapolate the PV: isoSK-GFR findings and analyse the peri-revascularization changes of a patient with acute flash pulmonary oedema in more detail. This included analysis of cardiac MRI and serum biomarkers collected peri-revascularization.Adjustments were made to the MRI protocol ensuring maximal safety for the patients imaged. Both stented and contralateral kidneys with a disproportionately larger PV: isoSK-GFR ratio improved renal function post revascularization (p = 0.002 and p = 0.006 respectively). This ratio was thought to represent the presence of 'hibernating parenchyma' which has the potential to recover renal function. Patients with disproportionately larger BOLD R2* measurements in relation to isoSK-GFR were also more likely to improve renal function post revascularization. These non-invasive MRI methods provide a potentially highly important one-stop investigative tool to predict renal functional response to revascularization. In so doing, sub-groups which benefit from revascularization can be better identified, and those which are unlikely to benefit can avoid a procedure which may potentially carry risks.

Date of Award	1 Jan 1824
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Philip Kalra (Supervisor)