Multiparametric Determination of Renal Hemodynamics and Oxygenation using Non‐Invasive Magnetic Resonance Imaging in Healthy Volunteers

Abstract

PurposeDue to the risks associated with using contrast media in patients with impaired renal function there is clearly a need for non‐invasive techniques measuring renal blood flow (RBF) and oxygenation. Current techniques include arterial spin labelling (ASL), blood oxygen level‐dependent (BOLD) magnetic resonance imaging (MRI) and phase contrast (PC). In addition to needing thorough validation, it is also important to know if RBF and oxygenation are influenced by circadian rhythm. Therefore, we determined total and regional RBF and regional oxygenation in healthy volunteers as a function of time of day using these MRI.Methods and MaterialsTotal RBF was determined by PC in renal arteries, regional RBF by ASL and regional oxygenation by BOLD in 6 healthy volunteers every fourth hour for a total of 24 hours resulting in 6 repeated measurements in each individual.ResultsAverage total RBF was 898±10 ml/min and 893±27 ml/min for right and left kidney, respectively, with a drop during evening‐night but with significant individual variations. Average cortical RBF was 289±7 and 274±8 ml/min/100g for right and left kidney, respectively, with highest values during the day and lowest values during the evening‐night. Cortical oxygenation was 52±1 and 49±1 ms for right and left kidney, respectively, with minimal circadian variation.ConclusionNon‐invasive MRI is able to quantify also substile changes in RBF. Furthermore, these results demonstrate that RBF is influenced by circadian variations which should be considered when designing future studies in order to elucidate the role of deranged RBF regulation for the development of kidney disease.