Dynamic changes in MRI of cerebral edema in rats after experimental cerebral infarction and intervention effect of mild hypotherma on them

[Objective]To study the intervention effect of mild hypotherrnia on cerebral edema in rats after cerebral infarction.[Methods]Twelve male SD rats were randomized into control group (n--6) and mild hypotherma treatment group (n=6).The rat models of focal cerebral infarction were established with obstructing the middle cerebral artery of rats by suture emboli.Rats of the mild hypotherma treatment group were treated by mild hypotherm for 3 h after the models were established.MRI was performed at 6 h,and 1,3,5 and 7 d after the success of model making.Cerebral infarction volume,absorption rate of edema,and signal intensity ratios (SIRs) ofTIWl,T2WI,FLAIR and DWI sequencas in the infarction zones,and relative variance ratio of SIR (△SIR) were measured and calculated.[Results] In the mild hypotherma treatment group,the cerebral infarction volumes 3,5 and 7 d after the models were established were significantly decreased as compared with those in the control group (P＜0.05);the absorption rate of edema (the 7th d against the 3th d of infarction) in the the mild hypotherma treatment group was significantly higher than that in the control group (P＜0.05).Three,5 and 7 d after infarction,the SIRs of TIWI were all obviously higher than those in the control group,and the SIRs of T2WI and FLAIR were all significantly lower than those in the control group (P＜0.05).The SIR of DWI in the mild hypotherma treatment group was obviously lower than that in the control group 7 d after infarction (P＜0.05).The △SIRs of T2Wl,FLAIR and DWI in the mild hypotherma treatment group were significantly higher than those in the control group (P＜0.05).[Conclusion] Mild hypothermia has a significant inhibition effect on cerebral edema in rats after cerebral infarction. Key words: Cerebral infarction; Cerebral edema; Mild hypothermia; Magnetic resonance imaging; Model, animal