超急性脑梗塞的磁共振波谱分析

Analysis of magnetic resonance spectroscopy in superacute cerebral infarction in the rabbit

目的 :探讨超急性脑梗塞的代谢特点及演变规律 ,为超急性期溶栓治疗和神经保护剂的使用提供病理生理学依据。方法 :健康家兔 12只 ,随机分成假手术组 5只 ,大脑中动脉闭塞 (MCAO)组 7只 ,采用 1.5T超导MR成像仪 ,Probe 2 0 0 0多体素MRS软件包进行扫描。MCAO组 ,选取缺血后 0 .5h、1h、2h、3h、4h和 6h时间点对梗塞区及其镜像区进行磁共振波谱(MRS)分析。结果 :(1)假手术组 :双侧代谢物对称分布 ,两侧氮 -乙酰门冬氨酸 /胆碱类复合物 (NAA/Cho) ,磷酸肌酸和肌酸/胆碱类复合物 (Pcr+Cr/Cho)没有显著差别 (P >0 .0 5 )。 (2 )MCAO组 :Lac在缺血 0 .5h时即可在梗塞区检测到 ,随缺血时间的延长呈上升趋势。NAA和Pcr+Cr在缺血 2h后各时间点与相应镜像区比较均出现降低 (P <0 .0 5或 >0 .0 1。Cho在缺血3h内保持稳定 ,4h和 6h时间点出现降低 (P <0 .0 5 )。结论 :梗塞区脑组织无氧代谢在超急性期持续存在 ,神经元损伤及能量代谢障碍始于缺血后 2h ,细胞膜及髓鞘的破坏始于缺血后 4h。提示对脑梗塞干预治疗 (包括溶栓和神经保护剂的使用 )

Objective:To explore the metabolic characteristics and the changes with lapse of time in superacute cerebral infarction in order to provide pathophysiological evidences for thrombolytic therapy and the use of neuroprotective drugs in superacute stage.Methods:12 healthy rabbits were randomly divided into two groups:sham operative group (5 rabbits)and occlusion of middle cerebral artery (MCAO) group (7 rabbits).The rabbits with MCAO were scanned with 1.5T MRI unit.The infarct regions and their mirror image regions were analyzed by probe 2000 software package of multi-voxel ~1 H magnetic resonance spectroscopy (~1H-MRS) at 0.5,1,2,3,4 and 6 hours respectively after MCAO.Results:(1)sham operative group:bilateral metabolites were symmetrically distributed,and N-acetylaspartate (NAA)/choline containing compounds (Cho),phosphocreatine and creatine(Pcr+cr)/Oho showed no significant difference(P<0.05).(2)MCAO group:Lactate(Lac) was detected in the infarct region at 0.5 hours after ischemia,which kept increasing during first 6 hours.NAA and Pcr+Cr showed no obvious changes from O.5 to 1 hours while began to decrease after 2 hours,as compared with the mirror image regions(P<0.05 or 0.01).Cho was relatively stable within 3 hours and showed a reduction at 4 and 6 hours(P<0.05).Conclusion:The brain tissue in the infarct regions carried on anaerobic glycolysis continuously under local hypoxic conditions in the superacute stage after ischemia.The neuronal damage and the obstacle of energy metabolism begins at 2 hours and the breakdown of nerve cell membrane and myelin sheath at 4 hours.Above results suggest that the earlier the thrombolysis and the use of neuroprotective drugs for cerebral infarction begins, the better the effect of treatment may be.