Value and pathological change of three MRI methods for early diagnosis of cerebral infarction

Objective: To compare the value and pathological change of three MRI methods for early diagnosis of cerebral infarction.Methods: Right middle cerebral artery occlusion(MCAO) model was established by suture method.A total of 42 rats were randomly divided into 7 groups: control group,15 min occlusion group,30 min occlusion group,1 h occlusion group,2 h occlusion group,4 h occlusion group,and 6 h occlusion group(n=6).Diffusion weighted imaging(DWI),T-2FLAIR and conventional T-2WI were employed.Appearance time of high signal at right basal ganglia and relative area of high signal at different time points were recorded.Pathological changes of corresponding brain tissues were also observed.Results:No abnormal signal was observed in three MRI sequences of control group,and high signal area appeared 15 min after occlusion in DWI(6/6).The area and density of high signal increased gradually,and the increase was significant in 2 h,which was significant different from T-2FLAIR and T-2WI(t=25.76,P0.01).The high signal area was increased gradually in 4-6 h,with unclear infarction boundary and incorrect anatomical position.High signal area appeared in most T-2FLAIR imaging 2 h after occlusion(4/6),and the area was significant different from T-2WI(t=10.86,P0.05),and ischemia area could be observed.High signal area also appeared T-2 WI imaging of 4 rats,and there was no significant difference in density of high signal(F=26.12,P0.05).Conclusions:DWI signal can reflect the degree of intracellular edema,T-2FLAIR can reflect mixture cerebral edema,and T-2WI can only show vascular edema and tissue necrosis.DWI is first imaging method for early diagnosis of cerebral infarction,followed by T-2FLAIR.Three methods should be used to detect comprehensive situation of ischemia area.