实验性缺氧缺血性脑病的~1H-MRS及病理学研究

Experimental Study on Hypoxic Ischemic Encephalopathy with ~1H Spectroscopy and Correlating with Pathology

目的：探讨早期新生猪缺氧缺血性脑病（HIE）的^1H—MRS波峰变化规律及其与病理学改变的关系。方法：选取40只7日龄健康新生猪，随机分为：正常对照组（n=5只）、假手术组（n=5只）及缺氧缺血组（n=30只）。1．5T磁共振^1H MRS测定脑内代谢产物。观察每组新生猪脑组织的病理变化情况。结果：①造模后0～24h，NAA峰明显下降，Lac峰呈典型的双峰状显著升高，NAA／Cho、Lac／NAA、Lac／Cr、Lac／Cho和Lac／（Cr＋Cho）比值逐渐降低，HI后3h，NAA／Or、NAA／（Cr＋Cho）比值升高，然后逐渐降低，G1x峰和mI峰无明显变化。②造模后0～24h随着时间延长脑水肿逐渐加重，24h出现坏死灶。结论：①NAA／Cho、Lac／NAA、Lac／Cr、Lac／Cho和Lac／（Cr＋Cho）是定量反映脑缺氧缺血生化改变的最敏感指标；②早期缺氧缺血后脑NAA、Lac与病理学的变化一致。

Objective：To investigate the peak alteration tendency regularity of ^1H magnetic resonance spectroscopy （^1H MRS）and the relationship between the findings of ^1H MRS and those of pathology in the brains of neonatal piglet models with hypoxic ischemic encephalopathy （HIE）. Methods：40 of 7 day old healthy neonatal piglets were randomly divided into 3 groups：control group （n= 5）,sham operation group （n= 5） and HIE group （n= 30）. The metabolites of the brain were detected with ^1 H MRS in a 1.5T scanner. Ratios of the metabolites were calculated. Using HE stain method, the pathological changes of the specimens of the brains in the all groups were observed. Results： ①The peak of NAA was declining,while that of Lac presented typical double peak appearance and elevated from 0 hour to 24 hour post-HI. The ratios of NAA/Cho, Lac/Cr, Lac/NAA, Lac/Cho, Lac/（Cr＋ Cho） declined gradually. The ratios of NAA/Cr and NAA/（ Cr ＋ Cho） elevated at 3 hours post-HI and then gradually decreased. The changes of Glx and MI peaks were not obvious. ②Pathological results showed cerebral edema and cellular necrosis aggravated gradually from 0 hour to 24 hour post HI,and multiple focal necrotic lesions presented at 24 hour post HI. Conclusion： ① the ratios of NAA/Cho, Lac/NAA, I.ac/Cr, Lac/Cho, Lac/（Cr＋Cho） were the most sensitive indicators of HIE, they quantitatively reflected the biochemical alterations of cerebral hypoxic ischemic injury. ②The changes of NAA and Lac were unanimously correlated to the pathological findings in early HIE.