| Objective:Through the IVIM-DWI examination of rabbit models of renal ischemia-reperfusion injury at different reperfusion time points,to explore the value of The value of IVIM-DWI in evaluating the effect of dexamethasone preconditioning on renal ischemia-reperfusion injury in rabbits.Methods:50 healthy male New Zealand white rabbits were divided into the following groups by simple random sampling method:(1)Sham operation group(Sham group),including sham operation+normal saline group(Sham+Veh group),sham operation+dexamethasone group(Sham+Dexa group),5 in each group;(2)Ischemia-reperfusion group(RIRI group),including ischemia-reperfusion injury+normal saline group(RIRI+Veh group)and ischemia-reperfusion injury+dexamethasone group(RIRI+Dexa group),20rabbits in each group,5 rabbits at each time of reperfusion(1h,12h,24h,48h).The Sham+Dexa group and RIRI+Dexa group were given intraperitoneal injection of 4mg/kg dexamethasone 1 hour before ischemia,while Sham+Veh group and RIRI+Veh group were given 0.9%sodium chloride intraperitoneal injection 1 hour before ischemia.The left renal artery was reversibly cut off for 60 minutes in the RIRI group,but not in the Sham group.MRI scans(T1WI,T2WI,IVIM-DWI)were performed at the corresponding time points before and after modeling.After the end of scanning at each time point in the RIRI group and the last scan in the Sham group,blood samples from left renal vein were taken under anesthesia for detection of serum creatinine and urea nitrogen,and the left kidney was taken for pathological examination,and the IVIM-DWI parameter value(D value,f value,D~*value,ADC value)of left kidney extramedullary layer was measured.The IVIM-DWI parameters,values of serum creatinine and blood urea nitrogen,pathological score were statistically analyzed.Results:In Sham group,there was no significant difference in D value,f value,D~*value and ADC value at different time points after operation with that before operation.In theRIRI group,the D value,f value and ADC value of the extramedullary layer of the left kidney showed similar changes at different time points after operation,that is,the D value decreased gradually from 1 h,decreased sharply at 1 h,increased at 12 h,decreased gradually at 24 h and 48 h.There was significant difference in D~*only at 1 h in RIRI+Veh group and 12 h in RIRI+Dexa group,but there was no statistical difference at other time points.The D and ADC values of the extramedullary layer of the left kidney in the RIRI+Veh group were lower than those in the RIRI+Dexa group at each time point after operation,and the f values at 1 h and 24 h were lower than those in the RIRI+Dexa group,but there was no statistical difference among the others.At 48h,the serum creatinine and urea nitrogen of RIRI group were higher than those of corresponding Sham group.There was significant difference in serum creatinine and blood urea nitrogen between RIRI groups at 48h,but there was no significant difference at other time points.The injury of the intramedullary layer of the left kidney in the RIRI group aggravated with the passage of time,and significantly relieved in the RIRI+Dexa group,and the pathological score increased with the passage of time,and the pathological score in the RIRI+Veh group was higher than that in the RIRI+Dexa group at the same time point.There is a very high negative correlation between D value and pathological integral of extramedullary layer of left kidney,a high negative correlation between ADC value and pathological integral,and a moderate negative correlation between f value and pathological integral,and the correlation between D value and pathological integral was the best.The number of groups with D value to distinguish different pathological integral groups was the most,followed by ADC value,and the f value was the least.Conclusion:(1)IVIM-DWI parameter can detect rabbit RIRI earlier than serum creatinine and blood urea nitrogen.(2)The D value,ADC value and f value of IVIM-DWI parameters can reflect the pathological changes of early RIRI.The correlation between D value and pathological integral is the best,and the number of groups to distinguish pathological integral group is the most.(3)IVIM-DWI can be used as a non-invasive method to evaluate the protective effect of dexamethasone preconditioning on RIRI. |
