Nakane M, Tamura A, Miyasaka N, Nagaoka T, Kuroiwa T
Department of Neurosurgery, Teikyo University School of Medicine, Tokyo, Japan.
AJNR Am J Neuroradiol. 2001 Apr;22(4):660-3.
Focal cerebral ischemia results in neuronal changes in remote areas that have fiber connections with the ischemic area. We reported previously that a high-signal-intensity lesion was observed in the substantia nigra after striatal infarction on T2-weighted MR images in both clinical and experimental cases. However, the origin of these changes in signal intensity remains unclear. The aim of this study was to investigate the nigral changes by examining the correlation between the apparent diffusion coefficient (ADC) and the tissue structure.
Sprague-Dawley rats were subjected to middle cerebral artery occlusion. Four days after the occlusion, when T2-weighted images revealed the presence of an area of high signal intensity in the ipsilateral substantia nigra, diffusion-weighted imaging was performed using a 4.7-T superconductive MR unit, and the ADCs were calculated and imaged. Histopathologic examination by both light and electron microscopy was performed on day 4 after surgery.
Diffusion-weighted images showed an area of high signal intensity in the ipsilateral substantia nigra, and the ADC map revealed uniform reduction of the ADC in this area. Swelling of astrocytic end-feet was observed, especially in the pars reticulata.
These findings suggest that MR changes in the ipsilateral substantia nigra after striatal injury consist mainly of swelling in the astrocytic end-feet.
局灶性脑缺血会导致与缺血区域有纤维连接的远隔区域发生神经元变化。我们之前报道过，在临床和实验病例中，纹状体梗死后在T2加权磁共振图像上黑质出现高信号强度病变。然而，这些信号强度变化的起源仍不清楚。本研究的目的是通过检查表观扩散系数（ADC）与组织结构之间的相关性来研究黑质的变化。
将Sprague-Dawley大鼠进行大脑中动脉闭塞。闭塞后4天，当T2加权图像显示同侧黑质存在高信号强度区域时，使用4.7-T超导磁共振单元进行扩散加权成像，并计算和成像ADC值。术后第4天进行光镜和电镜组织病理学检查。
扩散加权图像显示同侧黑质有高信号强度区域，ADC图显示该区域ADC值均匀降低。观察到星形胶质细胞终足肿胀，尤其是在黑质网状部。
这些发现表明，纹状体损伤后同侧黑质的磁共振变化主要由星形胶质细胞终足肿胀组成。
