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Partial k ‐space reconstruction in single‐shot diffusion‐weighted echo‐planar imaging
Author(s) -
Storey Pippa,
Frigo Fred J.,
Hinks R. Scott,
Mock Bryan J.,
Collick Bruce D.,
Baker Nicole,
Marmurek Jonathan,
Graham Simon J.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21132
Subject(s) - echo (communications protocol) , direct conversion receiver , k space , physics , artifact (error) , planar , echo planar imaging , sampling (signal processing) , truncation (statistics) , homodyne detection , nuclear magnetic resonance , optics , computer vision , computer science , magnetic resonance imaging , fourier transform , detector , medicine , computer network , computer graphics (images) , quantum mechanics , radiology , machine learning
Partial k ‐space sampling is frequently used in single‐shot diffusion‐weighted echo‐planar imaging (DW‐EPI) to reduce the TE and thereby improve the SNR. However, it increases the sensitivity of the technique to bulk rotational motion, which introduces a phase gradient across the tissue that shifts the echo in k ‐space. If the echo is displaced into the high spatial frequencies, conventional homodyne reconstruction fails, causing intensity oscillations across the image. Zero‐padding, on the other hand, compromises the image resolution and may cause truncation artifacts. We present an adaptive version of the homodyne algorithm that detects the location of the echo in k ‐space and adjusts the center and width of the homodyne filters accordingly. The adaptive algorithm produces artifact‐free images when the echo is shifted into the high positive k ‐space range, and reduces to the standard homodyne algorithm in the absence of bulk motion. Magn Reson Med 57:614–619, 2007. © 2007 Wiley‐Liss, Inc.