Bates S, Yetkin Z, Jesmanowicz A, Hyde J S, Bandettini P A, Estkowski L, Haughton V M
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226, USA.
J Magn Reson Imaging. 1995 Jul-Aug;5(4):443-5. doi: 10.1002/jmri.1880050413.
Unexpectedly large fluctuations in signal intensity were identified in the functional MRI (FMRI) of normal subjects breathing pure oxygen intermittently. To test the hypothesis that the signal changes were due to fluctuating concentrations of gaseous (paramagnetic) oxygen in the magnetic field, echo planar gradient echo images were acquired of a phantom contiguous to an oxygen mask through which pure oxygen was administered intermittently via plastic tubing. As a control, room air was administered intermittently or oxygen continuously in the same experimental protocol. Signal intensity changes of up to 60% temporally correlated with the administration of oxygen were produced in the phantom. In functional images prepared from the echo planar images, the signal intensity changes resulted in artifacts especially at interfaces in the phantom. The intermittent administration of pure oxygen during acquisition of data for FMRI may produce signal intensity changes that stimulate or obscure function.
在间歇性呼吸纯氧的正常受试者的功能磁共振成像（FMRI）中，发现信号强度出现了意外的大幅波动。为了验证信号变化是由于磁场中气态（顺磁性）氧浓度波动所致的假设，通过塑料管间歇性地输送纯氧，利用与氧气面罩相邻的模型采集了回波平面梯度回波图像。作为对照，在相同的实验方案中，间歇性地输送室内空气或持续输送氧气。模型中产生了高达60%的信号强度变化，且在时间上与氧气的输送相关。在从回波平面图像制备的功能图像中，信号强度变化产生了伪影，尤其是在模型的界面处。在FMRI数据采集过程中间歇性地输送纯氧可能会产生刺激或掩盖功能的信号强度变化。
