| Objective: Through the examination of closed loop obstruction(CLO)model of rabbit at different time points by magnetic resonance multi-b value DWI(diffusion weighted imaging,DWI),to analyze the relationship between DWI imaging parameters(ADC value)and pathologic score,and to investigate the diagnostic value of multi-b value DWI in closed loop obstruction of rabbits.Methods: 35 healthy,adult Chinese rabbits,regardless male or female,age 3-4 months,weight 2.4 ± 0.5 kg,randomly selected 20 of them as experimental group(divided into 1h,2h,3h,4h,5h five time points,each time point 4),and the last 15 were selected as control group(correspond with the experimental group,each time point 3).The "U" shape ligation was used to simulate the closed loop obstruction on the experimental group,and the control group only open the abdomen,exposed and turning the small bowel,and did not damage the small bowel.After 1h,2h,3h,4h and 5h,the regular MRI and DWI(b=0?200,400,600,800,1000)scans were respectively done and pathological examination after the scanning.At last,correlational analyses were conducted between the ADC values with the pathological score and the thickness of the looped bowels.Results: 1.Pathological findings: The bowel of the control group were natural meat pink,bowel movements were obvious,no expansion of them,mesenteric artery pulses were obvious.Intestinal wall tissue pathology were normal,organizational structure were integrity.After obstructed for 1 hour,the color of the obstructed bowel was significantly deepened,part of the bowel slightly dilated,the bowel peristalses were weakended than normal bowel,after 3 hour,the obstructed bowel was dark brown,the bowel were significantly dilated,there could seen more bloody effusion of abdominal cavity,bowel peristalses were not obvious,there could smell a little stench.After 5 hours,the bowel stank so much when open the suture line of abdomen,the color of the bowel was purple brown,the bowel were further dilatation and effusion,the near normal bowel dilated a ittle,and the color were slightly deeper.The main performance of experimental group of obstructed bowels were villi necrosis,submucosa edema,hemorrhage,muscle fibers were injury,structure were loose,arrangement were irregular,inflammatory cell were infiltration,and with the extension of time and the pathological changes aggravated gradually.There are significant differences of pathological score between the experimental group and control group(P=0.000);there was no significant difference between the experimental group 1h and 2h,4h and 5h of intestinal injury pathological score(P= 0.107 and 0.318),and the difference of obstruction time of 2 hours and above,intestinal injury scores were difference in pathology(P<0.05).2.DWI parameters measurement results: Using SPSS16.0 software for statistical analysis,the experimental group and the control group of intestinal wall ADC values reduced when the b value is increased.There was no significant difference in ADC value between any two groups at different time points of the control group(P>0.05).There was significant difference in ADC value between any two groups at different time points of the experimental group(P=0.000),there was no significant difference in ADC value of intestinal wall of 2h group when b = 600s/mm2 and b = 800s/mm2 and 4h group when b = 200s/mm2 and b = 400s/mm2(P values were 0.267 and 0.344,respectively),there were significant differences in the ADC values of intestinal wall between diffierent b value of different time points(P=0.000).In the different b value of experimental group,the ADC value of the intestinal wall decreased gradually with the prolongation of time,and the difference was statistically significant(P=0.000).r ADC value increases with the extension of time.The ADC value and the intestinal wall was negatively correlated with the thickness of the intestinal wall(|r|=0.449,P=0.047)in the experimental group of b=800s/mm2.In the experimental group,the ADC value of each group was negatively correlated with the pathological score under different b values,and had a good correlation(|r|>0.8,P=0.000),when b=800s/mm2,the ADC value and the pathology scores have the best correlation(|r|=0.893).Conclusion:1.The ADC value Closed loop of the obstruction and the pathological scores have a good correlation,when b value is 800s/mm2,they have best correlation.2.When the r ADC value is more than 20.86%,indicating that the CLO wall is transmural necrosis.3.Multiple b-value DWI can provide useful diagnostic information for early closed bowel obstruction of rabbit. |
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