兔早期缺血性脑梗死质子磁共振波谱分析

Study on early ischemic cerebral infarction by using proton magnetic resonance spectroscopy in rabbits

目的:分析早期脑梗死质子磁共振波谱(1H MRS)表现。方法:新西兰大白兔36只随机分为对照组8 只,大脑中动脉阻塞(MCAO)组12只,全脑缺血组8只,病理组8只。前3组每只实验动物均于手术后0.5h、1h、2 h、4h、6h、8h、12h和24h进行磁共振扩散加权成像(DWI)和1H MRS检查,测量氮 乙酰天门冬氨酸(Naa)、胆碱 (Cho)、肌酸(Cr)、乳酸(Lac)含量及梗死体积。病理组MCAO后对应于前3组MRS检查的时点取标本分别行光 镜和电镜观察。结果:对照组手术前后各时点Naa、Cho和Cr含量之间差异无统计学意义(P>0.05),且未检出Lac 峰。MCAO组术后0.5hNaa即开始下降,随后6h内Naa在此较低水平保持相对稳定;MCAO后6hNaa再次明显下 降。Cho和Cr在MCAO后24h内也趋于下降,MCAO后0.5h开始出现Lac峰,随梗死时间的延长,Lac持续升高,其 含量与梗死体积呈正相关(r=0.98,P<0.01)。Cho和Lac含量于全脑梗死后24h内无明显变化,而Naa和Cr含量 于全脑梗死后均呈线性持续下降,均与病理学结果相符合。结论:1H MRS可无创性地反映脑梗死后多种代谢物的动 态演变,可用于脑梗死后脑代谢的监测和早期脑梗死的诊断。

Aim: To explore the value of proton magnetic resonance spectroscopy ( 1H-MRS) in early cerebral infarction diagnosis. Methods: A total of 36 New Zealand rabbits were randomly divided assigned into four groups: the middle cerebral artery occlusion(MCAO) group(n=12),control group(n=8), global cerebral ischemia group ( n=8),and pathology group(n=8). In experimental group and pathology group, transorbital electrocoagulation was carried out to occlude the right middle cerebral artery(MCA) whereas the control group was only exposed the right MCA without occlusion.Rabbits of the first three groups underwent DWI and 1H-MRS at 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, and 24 h after operation.The content of Naa,Cho,Cr,Lac,and volume of cerebral infarction were measured. In pathology group, the brain tissue of rabbits after MCAO was obtained at the corresponding time points and observed under light microscope and electron microscope,respectively.Results: In the control group, Naa, Cho,and PCr/Cr waves did not show obvious diversity(P>0.05), and Lac could not be detected. In MCAO group, Naa reduced at 0.5 h, and remained relatively steady within 6 hours. Naa waves dramatically decreased 6 h later. Cho and Cr tended to decrease within 24 h. At 0.5 h after MCAO, Lac was detected and continuously evaluated with time.Cho content and cerebral infarction volume was positively correlated(r=0.98,P<0.01).Cho and Lac level did not change after global cerebral ischemia while Naa and Cr level decreased linearity and continuously.Conclusion: 1H-MRS could noninvasively reflect the dynamic changes of the metabolic materials within the infarct brain tissue, and could be used to investigate changes of the cerebral postinfarction metabolization. It also could be used for early cerebral infarction diagnosis.