Renal hypoxia plays a key role in the pathophysiology of several diseases and has been implicated in acute kidney injury and in the initiation and progression of chronic kidney disease. The ability to non-invasively assess renal hypoxia can be an important tool for assessing a subject's renal health early and initiating targeted treatment that can slow disease progression, reduce complications of the decreased glomerular filtration rate and improve quality of life. MRI sequences based on the blood oxygen level-dependent (BOLD) contrast mechanism have been used for following changes in renal oxygenation. However, recent studies have shown that these measurements are sensitive to other confounding factors in addition to oxygenation. There still exists a need for a reliable, quantitative and non-invasive measure of renal oxygenation. In this proposal, we will investigate the use of R2' as a BOLD MRI parameter and validate it against independent measures of blood and tissue oxygen by invasive phosphorimetry. Furthermore, we will explore alternative methods for analyzing BOLD MRI parametric maps to minimize subjectivity and hence allow for comparing data across laboratories. Our overall hypothesis is that methods that can directly probe renal oxygenation, without influences from confounding factors, along with an objective analysis of the parametric maps, will provide for widespread utility of these measurements both in pre-clinical and clinical settings.
Healthy kidney function is highly dependent on sufficient levels of oxygen delivery, with regions actually operating at severely reduced oxygen levels which can be further decreased by disease. This spatial variation makes imaging an ideal candidate for oxygen assessment. The goal of this project is to develop and validate a quantitative method for estimating kidney oxygenation.
