Division of Pediatric and Neonatal Intensive Care, University Hospital of Geneva, Geneva, Switzerland.
Magn Reson Med. 2011 Sep;66(3):839-45. doi: 10.1002/mrm.22869. Epub 2011 Mar 9.
To identify quantitative MRI indices of injury in the brain following neonatal hypoxic-ischemic brain injury, we subjected mouse pups to hypoxia-ischemia on postnatal day 7 and obtained conventional and diffusion-weighted in vivo images of the brain 24 h later followed by histological assessment. T(2)-weighted images showed increased signal intensity in the CA1 and CA2 regions of the hippocampus ipsilateral to the injury and adjacent white matter. In contrast, diffusion imaging showed reduced apparent diffusion coefficient (ADC) values in CA1 and CA2, but increased values in the adjacent white matter. Histological analysis showed widespread gliosis with degenerating oligodendrocytes in the ipsilateral hippocampus. In addition, white matter areas that were abnormal by MRI showed an increase in the number of activated microglia (CD45 positive cells). Activated caspase-3 immunostaining showed a marked increase in neurons in the hippocampal regions corresponding to those with reduced ADC, and a quantitative measure of staining showed a statistically significant correlation with the ADC. In contrast, ADC was higher in adjacent white matter, where histology showed activation of microglia and reactive oligodendrocytes but not caspase-3 activation. These results suggest that the ADC response differs between areas of neuronal injury as compared with those showing glial changes without marked cell death.
为了确定新生儿缺氧缺血性脑损伤后脑损伤的定量 MRI 指标，我们在出生后第 7 天对幼鼠进行缺氧缺血处理，24 小时后获得大脑的常规和扩散加权活体图像，并进行组织学评估。T2 加权图像显示损伤对侧和相邻白质的海马 CA1 和 CA2 区信号强度增加。相比之下，扩散成像显示 CA1 和 CA2 的表观扩散系数 (ADC) 值降低，但相邻白质的 ADC 值升高。组织学分析显示同侧海马广泛性胶质增生，少突胶质细胞变性。此外，MRI 异常的白质区域显示活化的小胶质细胞（CD45 阳性细胞）数量增加。活化的 caspase-3 免疫染色显示与 ADC 值降低相对应的海马区域的神经元明显增加，并且染色的定量测量与 ADC 呈统计学显著相关。相比之下，ADC 在相邻白质中较高，其中组织学显示小胶质细胞和反应性少突胶质细胞激活，但 caspase-3 激活不明显。这些结果表明，与没有明显细胞死亡的胶质变化区域相比，ADC 反应在神经元损伤区域有所不同。
