| Objective: Based on the animal model of renal ischemia-reperfusion injury(RIRI),CEST technology was used to non-invasively diagnose early acute kidney injury(AKI),and to evaluate and monitor the changes of renal function.Materials and methods: 35 C57BL/6N male mice were purchased,and the mice were divided into an experimental group and a blank control group.After the renal artery of the mice in the experimental group was clamped for 30 minutes,the hemostatic clip was opened and the wound was sutured.MRI scans were performed on days 1,4,7,and 14 after model construction,respectively.After scanning,blood was collected to measure blood data,such as(BUN,CRE),and then the kidney tissue was taken out for pathological examination.All mice were scanned on a9.4T small animal MRI system.Finally,the imaging data,pathological and blood results of each group were statistically analyzed at each time node.Results: In vitro experiments showed that the synthesized CEST contrast agent Hy SA not only had good water solubility but also had a deterministic CEST signal at 6.6 ppm and 9.6 ppm,it showed sensible p H dependence in the range of p H 6.0～7.5.After the successful establishment of the mouse renal ischemia-reperfusion injury model,In vivo experiments showed that BUN,CRE values of the experimental group mice were statistically different from the control group(p<0.05)in the three time nodes of Day 1、Day 4、Day 7.Among them,The difference of the right kidney DAY 1 is significant and statistically significant(p<0.001),and the DAY14 p H is higher(p> 0.05).The mice in the Day 1 group showed signs of injury,but there was no statistical difference in the renal tubular score and inflammation score(p>0.05).The differences of the renal tubular score and inflammation score between Day 4,Day 7,and Day 14 groups are statistically significant(p<0.05).The renal tubular epithelial tissue of the right kidney of the mice in the Day4 group was swollen,the renal tubules were significantly dilated,and the interstitial inflammation was significantly increased.The right kidney hyaline casts of the mice in the Day 7 group were significantly reduced,and the inflammatory cells were reduced.Most of the right kidney tubules of the 14 groups of mice returned to normal shape,and inflammatory cells were rare.The p H value of CEST-MRI showed that there were significant differences in these time nodes of Day 1,Day 4,and Day 7 of both kidneys(p<0.05).The renal metabolism of the mice in the Day14 group was recovered and the renal function was improved,so the difference was not statistically significant(p>0.05).CEST MRI semiquantitative parameters representing bilateral renal perfusion,showed differences in right renal perfusion in mice on Day 4,Day 7,and Day 14 after RIRI compared to baseline perfusion(p<0.05),and the compensatory perfusion of the left kidney increased on Day4 and Day 7.Conclusion: In vitro experiment showed that the CEST contrast agent has high sensitivity and specificity,and can be used for the determination of p H value of living tissue.In vivo imaging confirmed that CEST MRI can reflect the changes of renal blood perfusion and p H in RIRI model mice,so as to evaluate the renal metabolic environment and the changes of renal function after AKI,so it can be used as a non-invasive method to monitor the changes of renal function. |
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