Multiparametric MR Imaging for Evaluating Renal Function and Microstructure.

Chronic kidney disease (CKD) is a major global health burden, encompassing a heterogeneous group of disorders with diverse etiologies and pathophysiological mechanisms. Conventional biomarkers such as serum creatinine, estimated glomerular filtration rate (eGFR), and proteinuria are indispensable for detection and staging, yet they may be insensitive to early CKD including diabetic kidney disease (DKD) and can be discordant with underlying structural damage. Over the past 15 years, functional renal MRI has gained attention as a promising noninvasive approach to quantify complementary domains of renal pathology without ionizing radiation or gadolinium-based contrast agents, enabling repeated assessments even in patients with impaired renal function. This review provides a comprehensive overview of multiparametric MRI techniques for evaluating renal microstructure and physiology across CKD, including T1 and T2 mapping for interstitial expansion and inflammatory activity, blood oxygenation level dependent MRI for oxygenation and corticomedullary gradients, diffusion-based methods (apparent diffusion coefficient [ADC], diffusion tensor imaging, intravoxel incoherent motion) for microstructural injury and microvascular components, and arterial spin labeling for perfusion. Corticomedullary differentiation (CMD) is highlighted as an integrative feature across modalities, including signal-intensity-based CMD using noncontrast steady-state free precession (SSFP) with spatially selective inversion recovery and individualized optimal inversion time (multi-TI). Across CKD populations, many MRI-derived metrics correlate with contemporaneous kidney function, and diffusion-derived indices-particularly cortical ADC-have been associated with subsequent eGFR decline, suggesting potential value for progression-risk assessment. DKD is discussed as an important illustrative subtype in which complex pathophysiology may highlight the added value of multiparametric approaches. Clinical translation will depend on standardized acquisition, quality control, and multicenter validation to establish reproducibility and outcome-based thresholds.