Using intravoxel incoherent motion MR imaging to study the renal pathophysiological process of contrast-induced acute kidney injury in rats: Comparison with conventional DWI and arterial spin labelling

Objectives: To investigate the potential of intravoxel incoherent motion (IVIM) to assess the renal pathophysiological process in contrast-induced acute kidney injury (CIAKI). Methods: Twenty-seven rats were induced with CIAKI model, six rats were imaged longitudinally at 24 h prior to and 30 min, 12, 24, 48, 72 and 96 h after administration; three rats were randomly chosen from the rest for serum creatinine and histological studies. D, f, D* and ADC were calculated from IVIM, and renal blood flow (RBF) was obtained from arterial spin labelling (ASL). Results: A progressive reduction in D and ADC was observed in cortex (CO) by 3.07 and 8.62 % at 30 min, and by 25.77 and 28.16 % at 48 h, respectively. A similar change in outer medulla (OM) and inner medulla (IM) was observed at a later time point (12–72 h). D values were strongly correlated with ADC (r = 0.885). As perfusion measurement, a significant decrease was shown for f in 12–48 h and an increase in 72–96 h. A slightly different trend was found for D*, which was decreased by 26.02, 21.78 and 10.19 % in CO, OM and IM, respectively, at 30 min. f and D* were strongly correlated with RBF in the cortex (r = 0.768, r = 0.67), but not in the medulla. Conclusions: IVIM is an effective imaging tool for monitoring progress in renal pathophysiology undergoing CIAKI. Key Points: • IVIM analysis permits separate quantification of diffusion and perfusion. • IVIM can provide useful biomarkers ifor changes in renal pathophysiology. • IVIM can be useful for monitoring progress in renal pathophysiology undergoing CIAKI.