Evaluation of renal oxygenation and perfusion in patients with chronic kidney disease: a preliminary prospective study based on functional magnetic resonance.

Background: Renal hypoxia and ischemia significantly contribute to chronic kidney disease (CKD) progression, underscoring the need for noninvasive quantitative assessments. This study employs blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) and arterial spin labeling (ASL) MRI to comprehensively evaluate renal oxygenation and blood flow in CKD patients.

Methods: Forty-two CKD patients across stages 1-5 and ten healthy volunteers underwent simultaneous BOLD-MRI and ASL-MRI. We measured oxygenation (T2* values) and renal blood flow (RBF) in both the renal cortex and medulla, assessing their correlations with estimated glomerular filtration rate (eGFR) and other renal function indicators.

Results: BOLD and ASL revealed higher oxygenation and RBF in the renal cortex than in the medulla. Across CKD stages 2-5, both cortical and medullary oxygenation levels, as well as RBF, were lower than those in the control group and progressively decreased with CKD advancement. Additionally, renal oxygenation and blood flow levels positively correlated with serum creatinine (SCr), cystatin C (Cys C), and blood urea nitrogen (BUN), and negatively correlated with estimated glomerular filtration rate (eGFR) (p < 0.001). However, no significant correlation was observed with uric acid (UA) (p > 0.05). Notably, patients with CKD stages 1-3 exhibited strong correlations between renal oxygenation levels, RBF, and eGFR, while those with CKD stages 4-5 displayed weak correlations.

Conclusion: BOLD-MRI and ASL-MRI effectively measure renal oxygenation and perfusion noninvasively, confirming their utility in tracking CKD progression. These modalities provide accurate assessments of renal function and hypoxic-ischemic injuries across CKD stages, particularly in the early stages.