Jezzard P, Clare S
FMRIB Centre, Department of Clinical Neurology, University of Oxford, UK.
Hum Brain Mapp. 1999;8(2-3):80-5. doi: 10.1002/(sici)1097-0193(1999)8:2/3<80::aid-hbm2>3.0.co;2-c.
Functional magnetic resonance image (fMRI) experiments rely on the ability to detect subtle signal changes in magnetic resonance image time series. Any areas of signal change that correlate with the neurological stimulus can then be identified and compared with a corresponding high-resolution anatomical scan. This report reviews some of the several artefacts that are frequently present in fMRI data, degrading their quality and hence their interpretation. In particular, the effects of magnetic field inhomogeneities are described, both on echo planar imaging (EPI) data and on spiral imaging data. The modulation of these distortions as the subject moves in the magnet is described. The effects of gradient coil nonlinearities and EPI ghost correction schemes are also discussed.
功能磁共振成像（fMRI）实验依赖于检测磁共振图像时间序列中细微信号变化的能力。然后可以识别与神经刺激相关的任何信号变化区域，并将其与相应的高分辨率解剖扫描进行比较。本报告回顾了fMRI数据中经常出现的几种伪影，这些伪影会降低数据质量，进而影响其解读。特别描述了磁场不均匀性对回波平面成像（EPI）数据和螺旋成像数据的影响。阐述了受试者在磁体中移动时这些畸变的调制情况。还讨论了梯度线圈非线性和EPI鬼影校正方案的影响。
