Diffusion kurtosis imaging for detecting renal functional changes in glomerulonephritis: a longitudinal experimental study

Glomerulonephritis (GN) is a major contributor to chronic kidney disease, highlighting the need for reliable biomarker to monitor GN. This study aimed to evaluate the potential of diffusion kurtosis imaging (DKI) for dynamic assessment of renal injury in GN. 90 Sprague-Dawley rats were assigned to control and GN groups. After GN induction, renal DKI was performed at multiple time points (days 2, 5, 10, 15; weeks 4, 6, 10, 14, 16). Longitudinal changes in cortical and outer medullary parameters were assessed, and at each time point GN rats were compared with controls. Correlations with serological biomarkers were analyzed, and histopathology served as reference. Cortical and outer medullary mean diffusivity (MD) progressively decreased, whereas mean kurtosis (MK), axial kurtosis (Ka), and radial kurtosis (Kr) increased. Fractional anisotropy (FA) decreased early and rose at later stages. Outer medullary changes were more pronounced than cortical. At 2 days, only cortical FA was reduced; from 5 days onward, significant alterations appeared in outer medullary MD and Ka as well as cortical and outer medullary FA, followed by widespread changes in all DKI parameters. MD was negatively correlated with renal function markers (r = -0.29 to -0.69), while MK, Ka, and Kr were positively correlated (r = 0.31–0.69); FA showed minimal correlation. ROC analysis demonstrated non-significant diagnostic value for outer medullary FA, whereas other parameters achieved AUCs of 0.688–0.976. Delong analysis identified outer medullary MD as the highest diagnostic accuracy. DKI demonstrates high sensitivity in detecting renal microstructural alterations in GN and shows potential for dynamic monitoring of disease progression.