Noninvasive evaluation of renal oxygenation by blood oxygenation level-dependent magnetic resonance imaging in patients with primary aldosteronism

This study investigated renal oxygenation status in primary aldosteronism (PA) patients using blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI), with comparative analysis against healthy controls and correlation assessments with biochemical markers of renal function. A total of 48 patients and 27 healthy controls were enrolled. All participants underwent renal BOLD-MRI with a 3 T MRI scanner. The R2* values were measured in the renal cortex and medulla of the bilateral kidneys using the region of interest method. Paired-sample t tests and independent-samples t tests were used. Pearson correlation analysis examined the relationship between R2* values and clinical indicators, and ROC curve analysis evaluated the performance of R2* values in distinguishing PA patients from healthy controls. The cortical R2* values were significantly lower than the medullary R2* values for all participants. For PA patients, left kidney cortical and medullary R2* values were significantly higher than those of the right kidney. Left kidney cortical R2* values in PA patients were significantly higher than in healthy controls. Medullary R2* values positively correlated with blood urea nitrogen (r = 0.408, p = 0.005). The optimal threshold for left cortical R2* in discriminating PA patients from healthy controls was 18.955 Hz, yielding a sensitivity of 75.5% and a specificity of 63.0%, with an AUC of 0.717 (95% CI, 0.593-0.841). BOLD-MRI can detect renal hypoxia in patients with PA, suggesting its potential as a noninvasive tool for renal assessment. Specifically, the cortical R2* value in the left kidney demonstrated a moderate ability (AUC = 0.717) to distinguish PA patients from healthy controls.