Partial k-space reconstruction in single-shot diffusion-weighted echo-planar imaging

✍ Scribed by Pippa Storey; Fred J. Frigo; R. Scott Hinks; Bryan J. Mock; Bruce D. Collick; Nicole Baker; Jonathan Marmurek; Simon J. Graham

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 967 KB
• Volume: 57
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.21132

✦ Synopsis

Abstract

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.