吸纯氧后脑组织血氧水平依赖功能磁共振成像信号的变化

目的:观察吸纯氧后血氧水平依赖功能磁共振成像(BOLD-fMRI)信号的变化.方法:选择15名健康志愿者(男9,女6),采用GE公司1.5T Singna双梯度超导磁共振仪.采用ORE-EPI序列进行BOLD-fMRI扫描,扫描结果采用SPM2进行统计学处理.观察短时问(15 s)、长时间(6 min)吸纯氧后BOLD-fMRI T2信号的变化.并与吸入正常空气作对比.结果:吸入正常空气后全脑BOLD-fMRI信号未见明显激活;吸纯氧15 s后.全脑信号变化以脑灰质信号下降为主,灰质信号变化约(～0.041±0.31)%,自质约(0.056±0.26)%,与吸入正常空气有统计学差异(P<0.001);吸纯氧6 min后.全脑信号变化以脑白质信号上升为主,白质平均信号变化约(0.14±0.278)%,灰质约(0.015±0.365)%.与吸入正常空气有统计学差异(尸<0.001).结论:吸纯氧不同时间会引起脑组织BOLD-fMRI信号不同的变化,短时间吸纯氧主要引起灰质信号的下降.长时间吸纯氧主要导致白质信号的上升.

Oxygen-induced brain BOLD-fMRI signal change

Objective:To observe the signal changes of blood-oxygen-level-dependent functional MRI (BOLD-fMRI) in brain tissue after inhalation of oxygen. Methods: Fifteen volunteers,9 males and 6 females,were included in the present experiment.The fMRI was conducted using 1.5T Singna Double-gradient Super Conducting Magnetic Resonance Imaging system (GE Inc).Bold-fMRI scanning was conducted using GRE-EPI sequence and data analysis was done using SPM2 software. Meanwhile,the BOLD-fMRI T2 signal changes after 15 s and 6 min inhalation of pure oxygen were observed and compared with those after inhaling normal air.Results: No obvious activation of BOLD-fMRI was observed in the whole brain after inhaling normal air.Fifteen seconds after inhaling pure oxygen,the signal changes in the whole brain mainly manifested as the signal decrease in the gray matter,with average signal change being (-0.041±0.31)% in the gray matter and about (0.056±0.26)% in the white matter; the changes were significantly different from those of the normal air group (P<0.001). Six minutes after inhaling pure oxygen,signal changes in the whole brain mainly manifested as the signal increase in the white matter,with the average signal change being about (0.015±0.365)% in the gray matter and (0.14±0.278)% in the white matter; the changes were significantly different from those of the normal air group (P<0.001).Conclusion: Inhaling oxygen for different time periods can cause different BOLD signal changes in brain tissues. BOLD T2 signal in grey matter is decreased after short-time inhalation and is increased in white matter after long-time inhalation.