کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
558313 | 874896 | 2008 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: k-Space spatial low-pass filters can increase signal loss artifacts in echo-planar imaging k-Space spatial low-pass filters can increase signal loss artifacts in echo-planar imaging](/preview/png/558313.png)
Effective transverse relaxation rate (T2*)-weighted echo-planar imaging (EPI) is extensively used for functional magnetic resonance imaging (fMRI), because of its high speed and good sensitivity to the blood oxygenation level-dependent (BOLD) signal. Nevertheless, its use is limited in areas with severe static magnetic field inhomogeneities that cause frequency shifts and T2* relaxation-related distortions of the MR signal along the time-domain (k-space) trajectory, resulting in disperse time-domain signals and generating susceptibility-induced signal losses. Echo planar images are commonly smoothed with k-space spatial low-pass filters to improve the signal-to-noise ratio (SNR) and reduce reconstruction artifacts. Here, we show that when such filters are applied to the dispersed echo-signals (not perfectly centered in k-space), part of the image information from the object is removed, thereby enhancing signal-loss artifacts in the images. To avoid this artifact, the dispersed echo signal has to be refocused before k-space filtering.
Journal: Biomedical Signal Processing and Control - Volume 3, Issue 1, January 2008, Pages 107–114