播散性皮层抑制猫脑模型的磁共振功能成像研究

目的：用血氧水平依赖性磁共振功能成像（BOLD-fMRI）技术研究KCl诱导猫脑模型的播散性皮层抑制（SCD）。方法：雌猫6只,双侧额窦开颅并充填琼脂糖凝胶,两侧上侧裂回上方开颅,以备分别注入KCl凝胶和生理盐水凝胶。在1.5T场强下分别行静息期、KCl刺激期及对侧生理盐水刺激期BOLD-fMRI采集。结果：KCl刺激区上侧裂回及邻近边缘回脑皮层可见脑功能激活区者5例,并播及到同侧边缘回后部,而对侧大脑半球均无脑激活区。感兴趣区时间-信号强度曲线显示注入KCl后,fMRI信号立即显著增高,并维持于高水平较长时间。结论：BOLD-fMRI能准确检测出SCD伴发的神经血管耦联现象—脑血流量的变化,是研究SCD的可靠方法。

Experimental study an spreading cortical depression in cat model using functional MRI

Objective： To study the brain functional activation of cat model with spreading cortical depression （SCD） induced by KCl stimulation using blood oxygenation level dependent functional magnetic resonance imaging（BOLD-fMRI）. Methods： Six adult female cats were anesthetized with ketamine （25mg/kg, i.m.） and chlorpromazine （10mg/kg, i.m.）. Craniotomies were performed in both frontal sinuses, which were then filled with agar （2% in sterile saline） to reduce image susceptibility effects between brain and adjacent tissue. A second craniotomy with durectomy 5mm lateral to the midline and 5mm posterior to the bregma exposed the surface of the suprasylvian gyri for were acquired using a 1.5T super-conducting magnet （Siemens KCl/agar and sterile saline/agar application respectively. Images Vision 1.5T）. The functional imaging of brain cortex by BOLD technique was obtained in resting phase, KCI stimulated phase and sterile saline stimulated phase respectively. Results： The activated regions included the local areas which contacted KCl of the suprasylvian gyrus and adjacent areas of the marginal gyrus, and spread to posterior part of the marginal gyrus, but there were no activated regions on the opposite hemisphere. The signal of fMRI increased significantly in the local activated areas immediately after the application of KCl and sustained thereafter, showed on time-signal intensity curve. In contrast, the application of sterile saline did not cause the signal of fMRI increase. Conclusion： BOLD-fMRI is reliable in detecting the changes of cerebral blood flow （CBF） associated with SCD and is valuable for evaluating SCD.