脑功能MR成像的信号机理

The Mechanism of Brain Functional MR Signal

目的 回顾了脑功能磁共振成像中功能信号产生的机理。方法 对大脑皮层功能活跃可引起的功能区代谢变化和血液动力学改变 ,以及这些改变对MR信号的影响进行了总结。结果 脑功能磁共振信号的产生主要与功能区血氧含量的改变、动脉血供增加引起的流入效应等因素有关 ,主要表现为功能区信号增高。结论 通过功能活动可以使皮层功能区的MR信号出现改变 ,通过选择适当的脉冲序列和扫描方法可以检出功能信号改变。

Objective To review the mechanism of brian functional MR signal.Methods The metabolic and hemodynamic changes induced by the functional activities in brain cortex and the relationship between these changes with the local MR signal were summarized.Results The changes in blood oxygen level and the increased artial inflow result in the brain cortex functional MR signal, which displayed as slightly increased signal intensity in the active cortex.Conclusion Functional activities induce the corresponding MR signal changes in brain cortex. The functional signal of brain cortex can be detected by carefully designing the pulse sequences and scan method.