Quantitative BOLD MRI for Estimating Intra-renal Oxygen Availability: Are Kidneys Hypoxemic in CKD?

Kidney BOLD MRI measurements are not specific to oxygen availability especially when comparing different cohorts because R2* also depends on fractional blood volume (fBV) and hematocrit (Hct). In this study, we have estimated fBV using ferumoxytol and Hct by blood sampling. Using these we show Quantitative BOLD MRI can characterize oxygen availability in quantitative terms. For the first time, we show that kidney cortex is normoxemic in healthy controls while moderately hypoxemic in CKD. Medulla is mildly hypoxemic in controls while moderately hypoxemic in CKD.