Kidney Stiffness Measured in an Animal Model of Unilateral Renal Arterial Stenosis Using 2D MR Elastography

Introduction: Renal arterial stenosis (RAS) is a narrowing of the renal artery, usually due to arthrosclerosis, which often diminishes the blood supply to the kidneys and leads to irreversible tissue fibrosis. We have previously shown in a swine model that by six weeks of RAS the stenotic kidney exhibits moderate but significant interstitial fibrosis [5]. Fibrosis threatens the viability of the kidney, and may ultimately lead to kidney failure [1]. In addition, the kidney is normally richly perfused, and its distension (and in turn stiffness) may be determined by renal perfusion pressure, blood flow, and filtrate volume, which together sustain around 25% of renal volume. Both fibrosis and turgor may affect the mechanical properties of tissues, which have been investigated by several newly emerging imaging techniques [2-3], such as MR Elastography (MRE) [4]. However, renal tissue elasticity in RAS remains uncharacterized. The goal of this study was to quantitatively determine in vivo the effect of RAS on the mechanical properties the swine kidney.