K-space spatial low-pass filters can increase signal loss artifacts in Echo-Planar Imaging.

Biomedical Signal Processing and Control
Elisabeth C Caparelli, Dardo Tomasi

Abstract

Effective transverse relaxation rate (T(2)*)-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 T(2)* 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.

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Citations

Oct 25, 2012·Translational Psychiatry·S J MoellerR Z Goldstein
Aug 9, 2013·International Journal of Obesity : Journal of the International Association for the Study of Obesity·G-J WangE Dunayevich
Mar 2, 2016·PloS One·Daniele PerroneWilfried Philips
Jun 25, 2013·Medical & Biological Engineering & Computing·Jun Hee HongSung Chan Jun

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