Multiparametric MRI for Early Chronic Kidney Disease Detection: Insights Into Renal Microcirculation.

Chronic kidney disease (CKD) is a major health burden. Intrarenal microcirculation impairment occurs early in CKD and precedes measurable declines in renal function. We investigated whether contrast-free multiparametric MRI (mp-MRI) can characterize intrarenal microcirculation alterations and improve early CKD detection. This retrospective study included 54 patients with pathology-confirmed CKD (25 mild and 29 moderate-severe by the Katafuchi system) and 20 age- and sex-matched healthy controls (HCs) enrolled between March 2020 and August 2022. All participants underwent an mp-MRI protocol comprising arterial spin labeling (ASL), intravoxel incoherent motion imaging (IVIM), blood oxygen level-dependent (BOLD) imaging, and quantitative susceptibility mapping (QSM). Renal biopsy served as the reference standard, with estimated glomerular filtration rate and serum creatinine as clinical comparators. Group differences in MRI metrics were assessed, correlations with histopathology were evaluated, and multivariable logistic regression models were constructed to distinguish CKD (and mild CKD) from healthy controls. Renal blood flow, diffusion and microperfusion metrics (D, D*, f), BOLD-derived R2*, and susceptibility values differed significantly across groups, and each MRI parameter and clinical biomarker correlated with histopathological severity (|r| = 0.33-0.97). A mp-MRI model integrating RBFCortex, D*Cortex, fCortex, and R2*Cortex achieved excellent discrimination for CKD versus HCs (AUC = 0.976; 95% confidence interval [CI]: 0.949-1.000; p < 0.001) and for mild CKD versus HCs (AUC = 0.948; 95% CI: 0.891-1.000; p < 0.001). These findings support a pathophysiology-driven, contrast-free mp-MRI framework for noninvasive assessment of renal microcirculation and early CKD detection.