Knight R A, Dereski M O, Helpern J A, Ordidge R J, Chopp M
Department of Neurology, Henry Ford Hospital, Detroit, MI 48202.
Stroke. 1994 Jun;25(6):1252-61; discussion 1261-2. doi: 10.1161/01.str.25.6.1252.
This study was performed to document the progression of ischemic brain damage after middle cerebral artery occlusion in the rat using magnetic resonance imaging and histopathologic methods.
Cerebral ischemia was induced through permanent tandem occlusion of ipsilateral middle cerebral and common carotid arteries. The evolution of magnetic resonance imaging and histopathologic parameter changes was studied, both short term (1.5 to 8 hours) and long term (24 to 168 hours), in five specific brain regions within the middle cerebral artery territory.
Significant changes in proton nuclear magnetic resonance spin-lattice and spin-spin relaxation times and the "apparent" diffusion coefficient of water could be detected within hours after the onset of permanent focal cerebral ischemia, whereas significant alterations in proton spin-density ratios were not apparent until approximately 48 hours. Histological changes were evident within 12 hours, with a significant loss of neurons seen in the most severely damaged regions at 7 days. Diffusion-weighted imaging was the most sensitive technique for visualizing acute ischemic alterations. The water diffusion coefficient was the only magnetic resonance imaging parameter studied to indicate significant alterations within the first 4 hours after arterial occlusion in all five brain regions.
The degree of change for a particular magnetic resonance imaging parameter appeared to be related to the location and extent of neuronal injury, with the most dramatic changes occurring within the areas displaying the most severe histological damage. These results indicate that complete specification of all brain regions affected by ischemic brain injury may require a combination of imaging strategies applied over a period of days and suggest the possibility of using magnetic resonance imaging to distinguish between permanent and reversible cell damage.
本研究旨在运用磁共振成像和组织病理学方法记录大鼠大脑中动脉闭塞后缺血性脑损伤的进展情况。
通过永久性结扎同侧大脑中动脉和颈总动脉诱导脑缺血。在大脑中动脉供血区域内的五个特定脑区，对短期（1.5至8小时）和长期（24至168小时）的磁共振成像和组织病理学参数变化演变进行了研究。
在永久性局灶性脑缺血发作后的数小时内，即可检测到质子核磁共振自旋晶格和自旋 - 自旋弛豫时间以及水的“表观”扩散系数的显著变化，而质子自旋密度比的显著改变直到约48小时才明显。组织学变化在12小时内明显可见，在7天时，在受损最严重的区域可见神经元大量丢失。扩散加权成像是观察急性缺血性改变最敏感的技术。水扩散系数是所研究的唯一在动脉闭塞后的前4小时内，在所有五个脑区均显示出显著变化的磁共振成像参数。
特定磁共振成像参数的变化程度似乎与神经元损伤的位置和范围有关，最显著的变化发生在组织学损伤最严重的区域。这些结果表明，要全面明确受缺血性脑损伤影响的所有脑区，可能需要在数天内应用多种成像策略，并提示了利用磁共振成像区分永久性和可逆性细胞损伤的可能性。
