Application of noninvasive functional imaging to monitor the progressive changes in kidney diffusion and perfusion in contrast-induced acute kidney injury rats at 3.0 T

Abstract

Contrast-induced acute kidney injury is a prevalent cause of renal failure, and the noninvasive tools to monitor its progress are lacking. We applied intravoxel incoherent motion (IVIM) DWI to measure the progressive changes in kidney diffusion and perfusion of CI-AKI. Twenty-four rats received Iopromide (370mg/ml, 1600mg iodine/kg) to induce CI-AKI. IVIM DWI was performed on rats (n=6) at 24h prior to and 12, 24, 48, 72, and 96h after the injection using a 3.0T MRI scanner. The progressive changes in the diffusion (D) and perfusion parameters (D* and f) were studied in the cortex (CO), outer medulla (OM), and inner medulla (IM). For the histology group (n=18), three rats were sacrificed at each time point. In the CO, D reduced progressively from 24 to 48h (P<0.001) and increased starting from 72h (P<0.001). However, D decreased until to 72h in the medulla (P<0.001) and increased starting from 96h (P<0.001). D* decreased to the bottom at 24h in the cortex and medulla (P=0.037) and started to recover at 48h (P=0.007). f decreased in the cortex and medulla in an early stage (12h) (P=0.035) of CI-AKI and then ascended in the later stage (72h) (P=0.017). The H & E staining showed different degrees of serial pathological change including cloudy swelling, atrophy, even necrosis, and interstitial vasodilation of tubule epithelial cells and glomerulus cells. Our study demonstrates the feasibility of using IVIM DWI to monitor the progress of CI-AKI, implying that IVIM DWI is a useful biomarker in the staging of CI-AKI.