Evaluation Of CI-AKI Induced By Different Contrast Media In Diabetic Nephropathy Rats By IVIM And DKI

【Objective】To investigate the potential of intravoxel incoherent motion-diffusion weighted imaging(IVIM)and diffusion kurtosis imaging(DKI)in monitoring the renal changes after the development of acute kidney injury(CI-AKI)induced by two contrast agents,iso-and low-osmolar,in diabetic nephropathy rat models.【Materials and Methods】Twenty-six Sprague-Dawley(SD)male rats with body weight of 200-250 g were selected and injected intraperitoneally with a small amount of streptozotocin(STZ)for several times to establish the rat model of diabetic nephropathy(DN).They were randomly divided into two groups: Low-osmolar contrast medium(LOCM)group and Iso-osmolar contrast medium(IOCM)group.The contrast agent was injected through the tail vein at the dose of 4 g iodine/kg.The LOCM group was given Iopamidol,and the IOCM group was given Iodixanol.IVIM and DKI images were scanned on a 3.0T scanner at baseline,1 hour,24 hours,48 hours,and 72 hours after contrast agent injection,and inferior venous blood was taken after the scan.The rats were sacrificed to obtain kidney specimens for histology and-SMA evaluation.IVIM and DKI images were postprocessed and analyzed by MITK software,and the true diffusion coefficient(D),pseudo-diffusion coefficient(D*),perfusion fraction(f),mean kurtosis(MK)and mean diffusion rate(MD)of cortex(CO),outer medullary(OM)and inner medullary(IM)were measured.All the results were statistically analyzed.【Results】Compared with the baseline level,D,D* and f values of the kidney anatomical layers in both groups were significantly decreased after the injection of contrast agent.The recovery time of D value in cortex was earlier than that in medulla.The recovery time of D* value is generally earlier than that of f value.The recovery time of D values in cortex,D* values in cortex and outer medulla,and f values in outer medulla and inner medulla in IOCM group was earlier than that in LOCM group.1.Compared with baseline,MK values in the outer medulla of both groups decreased significantly at 1 h after contrast agent injection.24-72 h after the injection of contrast agent,the MK value of each layer in the two groups gradually increased,while the MD value continued to decrease.2.After contrast agent injection,SCr in both groups increased from baseline,and the LOCM group showed a continuous upward trend,while the IOCM group reached the peak at 48 h and decreased at 72 h.After contrast injection,BUN increased in both groups compared with the control group,reaching the peak at 48 h and decreasing at 72 h.3.After contrast injection,renal pathological injury scores in both groups increased from baseline.At 48 h after the injection of contrast agent,the renal pathology score of the LOCM group was higher than that of the IOCM group,and the difference was statistically significant.4.After contrast injection,the expression of α-SMA in the kidneys of both groups increased from baseline.The expression level of α-SMA in the LOCM group was higher than that in the IOCM group 48 h after injection of contrast agent,and the difference was statistically significant.5.There were significant negative correlations between D,D*,f,MD and pathological scores of renal injury and the expression level of α-SMA.【Conclusion】1.For diabetic nephropathy rats,the nephrotoxicity of IOCM was lower than that of LOCM.2.IVIM and DKI imaging can noninvasively identify the changes of renal water diffusion,perfusion and tissue microstructure in diabetic nephropathy rats after CI-AKI.3.The changes of IVIM and DKI were correlated with renal pathophysiology and histological expression of α-SMA.