Evaluation Of IVIM-DWI On Rabbit Small Intestine Ischemia-reperfusion Injury

Objective:IVIM-DWI imaging and pathological examination were performed on the rabbit model of intestinal ischemia-reperfusion injury（IRI）,and the correlation between imaging parameters and pathological scores was observed and analyzed.To explore the value of IVIM-DWI imaging technology in evaluating small bowel IRI.Methods:Sixty-four adult New Zealand white rabbits were randomly divided into experimental group（n=60）and control group（n=4）.The experimental group was divided into three subgroups for 1h,2h and 3h ischemia（n=20 in each group）,and each subgroup was reperfused for 1h,2h,3h,4h and 5h（n=4 Per reperfusion time）,respectively.Intestinal ischemia-reperfusion injury model was made by separating and clamping the main superior mesenteric artery（SMA）with non-invasive arterial clips in the experimental group,the control group only opened the abdomen and separated the SMA without clamping.Routine MRI scan and IVIM-DWI were performed at each reperfusion time point after the model was completed,and measure the intestinal wall thickness and IVIM-DWI parameter values at each time point,and take the corresponding small intestine tissue for pathological examination.One-way ANOVA was used to compare the intestinal wall pathological score,intestinal wall thickness and IVIM-DWI parameter values at each time point.Pearson correlation analysis was used to compare the correlation between IVIM-DWI parameter values and intestinal wall thickness and pathological score in the experimental group.Results:（1）Intestinal wall thickness and IVIM-DWI parameter values:There were extremely significant differences in intestinal wall thickness and IVIM-DWI parameter value between the experimental group and the control group（P<0.001）.In the experimental group,the ADC value,D value,and f value of the intestinal wall at the same ischemic time point gradually decreased as the reperfusion time prolonged,and the D*value of the intestinal wall gradually increased,and the intestinal wall gradually thickened.The difference was extremely significant（P<0.001）.Among them,the ADC value and D value of the intestinal wall increased slightly at 4h and 5h after 1h of ischemia and reperfusion（relative to 3h of reperfusion）,and the D*value decreased slightly;The ADC value,D value and f value of the intestinal wall at the same reperfusion time point gradually increased as the time of ischemia prolonged,and the D*value of the intestinal wall gradually decreased,and the intestinal wall gradually thickens.The difference was extremely significant（P<0.001）.When the duration of ischemia and reperfusion injury are equal,the longer the ischemic time,the lower the ADC value,D value,and f value of the intestinal wall,the higher the D*value,the thicker the intestinal wall,and the difference is statistically significant（P<0.05）.（2）Pathological results:In the control group,the intestine wall was ruddy in color,with good blood supply,and the structure of each layer of the intestinal wall was clearly displayed.Pathological scores at each time point were not statistically significant（P>0.05）.In the experimental group,the color of the intestinal wall was dark red after 1 hour of ischemia and reperfusion for 1-5 hours,the peristalsis of the bowel was weakened,and the damage was mainly in the mucosa and submucosa.The most severe injury was 3 hours after reperfusion,the lamina propria capillaries were exposed and ulcers formed under the microscope,the intestinal wall injury was slightly reduced after 4 hours and 5 hours after reperfusion,and the mucosal epithelium was repaired early.The color of the intestinal wall is generally dark red after 2 hours of ischemia and reperfusion for 1-5 hours,the intestinal spasm is obvious,and the effusion of intestinal dilatation is progressively aggravated.The damage extends to the crypt layer,and the mucosal epithelium is repaired early.After 3hours of ischemia and reperfusion for 1-5 hours,the intestinal wall was purple-red,and gradually turned into charcoal black,and the intestinal tube had persistent spasm.The injury involves the muscle layer,and the intestinal wall was irreversibly damaged after 4 hours of reperfusion.The comparison between the experimental group and the control group is extremely significant（P<0.001）.The correlation results show that each parameter value of IVIM-DWI has a good correlation with intestinal wall thickness and pathological scores.Among them,the D value has the strongest correlation with the two（r₁=-0.890;r₂=-0.907）.Conclusion:（1）IVIM-DWI imaging technology can indirectly reflect the pathological changes of small intestine IRI,and can be used as a non-invasive imaging technology to evaluate small intestine IRI;（2）Irreversible damage to the intestinal wall occurred after 3hours of small intestine ischemia and 4 hours of reperfusion,which is the upper limit of intestinal wall survival of rabbit small intestine IRI;（3）The value of D in IVIM-DWI parameters is of greater value in diagnosing small bowel IRI.When r D value≥32.82%,it suggested that the intestinal wall has irreversible reperfusion injury.