中文摘要：

目的 评价外标准法MRS结合LCModel软件绝对定量测量急性缺氧缺血脑损伤猪脑N-乙酰天冬氨酸（NAA）、肌酸（Cr）和乳酸（Lac）浓度变化的价值.方法 8头7日龄健康猪麻醉后未作任何处理（正常组）,麻醉清醒后1 d制成缺氧缺血性脑病（HIE）模型（HIE组）,先后与内含已知浓度物质的外标准模型一起行1H-MRS检查,数据采集完毕后用LCModel软件定量分析测量NAA、Cr、Lac浓度,HIE前、后猪脑代谢物NAA、Cr、Lac间比较采用多元方差分析,并对2头HIE猪缺氧缺血0、2 h脑代谢物动态变化情况作初步观察.结果 l头猪因麻醉过深死亡而剔除,最后统计数据为7头.小猪急性缺氧缺血前脑NAA、Cr、Lac分别为（6.86±0.49）、（4.65±0.73）、0.00 mmol/kg,缺氧缺血后即刻脑NAA、Cr、Lac分别为（5.73±0.88）、（4.40±0.80）、（0.43±0.39）mmol/kg.急性缺氧缺血后即刻猪脑NAA浓度下降,差异有统计学意义（F=8.608,P=0.013）;Cr浓度有所下降,但差异无统计学意义（F=0.379,P=0.550）;Lac浓度升高,差异有统计学意义（F=8.600,P=0.013）.初步观察脑代谢物动态变化见HIE后即刻出现Lac峰,2 h Lac峰下降.结论 外标准法MRS结合LCModel定量分析软件能方便准确地定量测量脑内代谢物,NAA与Lac浓度的改变均能敏感地反映急性缺氧缺血脑损伤早期改变,且以NAA浓度的改变稍敏感.

英文摘要：

Objective To evaluate the absolute quantification of brain metabolites concentrations using external standard MRS in acute hypoxia ischemia encephalopathy （HIE） piglet model. Method Eight 7-day-old healthy piglets were subjected to insult of hypoxia ischemia （HI）. The animals and an external standard phantom containing detectable metabolites of known concentrations were studied on a 1.5 T GE Signa scanner. The single-voxel proton magnetic resonance spectroscopy （1H-MRS） data were processed using LCModel software, and the quantification of N-acetylaspartate （ NAA）, creatine （Cr） and lactate （Lac） were accomplished. Multivariate analysis of variance was performed to compare the NAA, Cr, Lac concentration differences in the brains of piglets pre- and post-HI （0h）. In addition, the dynamic changes of brain metabolites concentrations of 2 HIE piglets were observed at the time points of 0 h and 2 h. Results One piglet was excluded because it was over anesthetized to death. Seven piglets＇ data were analyzed. The concentrations of NAA pre- and post-HI were （ 6. 86 ± 0. 49 ） mmol/kg and （ 5.73 ± 0. 88 ） mmol/kg respectively, they were （ 4. 65 ± 0. 73 ） mmol/kg and （ 4. 40 ± 0. 80 ） mmol/kg for Cr; and were 0. 00 mmol/kg and （0. 43 ± 0. 39） mmol/kg for Lac. After HI, decreased NAA concentration immediately was observed, and it was of statistical significance （ F = 8. 608, P = 0. 013 ）. The concentration of Cr was insignificantly decreased （ F = 0. 379, P = 0. 550）. The concentration of Lac was increased, and the difference was of statistical significance （ F = 8. 600 ,P = 0. 013 ）. Dynamic observation showed a Lac peak immediately after HI and it decreased after 2 h post-HI. Conclusions External standard MRS using LCModel has great value in the quantitative analysis of brain metabolites. The changes of NAA and Lac concentrations are sensitive to reflect the early metabolic change of acute HIE.