Evolution of magnetic resonance imaging changes associated with cerebral hypoxia-ischemia and a relatively selective white matter injury in neonatal rats
Evolution of magnetic resonance imaging changes associated with cerebral hypoxia-ischemia and a relatively selective white matter injury in neonatal rats
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DOI：
10.1203/01.pdr.0000203099.40643.84
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Tuor, UI
中科院分区：
文献类型：
--
作者：
Meng, SZ;Qiao, M;Tuor, UI
我们假设，在最近建立的7d龄大鼠单侧轻度脑缺氧缺血模型中，结合定量磁共振成像(Mri)序列将检测到与灰质相比，白质中缺氧缺血变化的不同进化。采用单侧颈总动脉结扎后低氧45~50min的模型，分别于缺血前、缺血后1、24、48h和7d分别测得水的表观弥散系数(ADC)、T-1、T-2和脑血流量(CBF)图，并进行组织学观察。缺氧缺血后1h，缺血缺血侧脑白质MRI改变不如灰质明显。而脑白质内T-1、T-2和ADC值的升高以及脑血流量的下降随着时间的推移而增强，在缺氧缺血后48h变化最大，而皮质灰质的变化在这段时间内趋于正常。到缺氧缺血7d时，尽管缺氧缺血侧脑白质发生了组织学变化，包括胶质细胞增殖和反应性增加，髓鞘碱性蛋白减少，细胞死亡增加，但大脑半球之间的ADC值、T-1、T-2和CBF没有差异。结果表明，在缺氧缺血后亚急性观察到的ADC和T-2的增加与选择性脑白质损伤有关，提示婴儿弥漫性白质高信号和ADC增加是缺氧缺血后的一过性MRI改变。
We hypothesized that a combination of quantitative magnetic resonance imaging (MRI) sequences would detect a differential evolution of hypoxic-ischemic changes in white matter compared with gray matter in a recently developed model of unilateral mild cerebral hypoxia-ischemia in the 7-d-old rat. Using this model, which involved unilateral carotid artery Occlusion and exposure to hypoxia for 45-50 min, maps of apparent diffusion coefficients of water (ADC), T-1, T-2, and cerebral blood flow (CBF) were acquired either before hypoxia-ischemia or at 1, 24, or 48 h and at 7 d post-hypoxia-ischemia followed by brain processing for histology. At 1 h post-hypoxia-ischemia, MRI changes in white matter ipsilateral to the hypoxia-ischemia were not as pronounced as those in gray matter. However, increases in T-1, T-2 and ADC and decreases in CBF within white matter enhanced over time, with changes being maximal at 48 h post-hypoxia-ischemia, whereas changes in the cortical gray matter normalized over this time. By 7 d post-hypoxia-ischemia, there were no differences in ADC, T-1, T-2, or CBF between hemispheres despite there being histologic changes in white matter within the hypoxic-ischemic hemisphere including increased glial proliferation and reactivity, reduced myelin basic protein, and increased cell death. The results demonstrate that increases in ADC and T-2 observed subacutely in the days following hypoxia-ischemia are associated with rather selective white matter damage and suggest that diffuse white matter hyperintensities and increased ADC reported in infants are transient MRI changes post-hypoxia-ischemia.