CT imaging for the assessment of kidney injury distal to renal artery stenosis

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DESCRIPTION (provided by applicant): The impact of vascular disease on morbidity and mortality is on the rise in the Western world. Atherosclerotic renal artery stenosis (ARAS), a common etiology of chronic kidney disease, amplifies deterioration of renal function and attenuates its recovery following intervention. However, the mechanisms leading to these grave outcomes are yet to be identified, partly due to the lack of techniques capable of studying the kidney distal to ARAS, and of suitable experimental models of ARAS. The hypothesis underlying this proposal is that atherosclerosis blunts the recovery of the stenotic ARAS kidney following intervention by impairing renal function and exacerbating oxidative stress, inflammation, and fibrosis, and that high-resolution computed tomography (CT) techniques would be useful to explore and characterize renal injury and response to revascularization. This hypothesis will be tested in a novel pig model of unilateral ARAS that we have developed and characterized, using unique imaging approaches that we have refined to study single-kidney function and structure. Electron beam CT (EBCT) will quantify in vivo, in the stenotic kidney of pigs undergoing percutaneous transluminal renal angioplasty, the reversibility of alterations in renal regional volume, perfusion, GFR, segmental tubular function, and response to challenge. Micro-CT will be subsequently used to assess in situ renal microvascular remodeling, a hallmark of atherosclerosis. The imaging studies will be correlated with in vitro studies of renal redox status, inflammation, and fibrosis. Furthermore, the impact of preexisting renal injury on the response to revascularization will be explored by superimposing ARAS on tubulointerstitial injury or glomerulosclerosis. The effect of attenuation of renal injury will be studied using chronic supplementation of statins, drugs that decrease oxidative stress, inflammation, and fibrosis, and might improve renal outcomes before as well as after intervention. Moreover, renal alterations will be correlated with renal recovery, and potential predictors of interventional success will be determined. The proposed studies may greatly advance our understanding of the pathogenesis of renal injury in ARAS, and assist in development of imaging strategies to detect injury markers and identify predictors of renal viability. Thus, these studies may contribute towards management of patients with renovascular disease.