| Autor: |
Storey P; Radiology Department, Evanston Northwestern Healthcare, Evanston, Illinois 60201, USA. pstorey@enh.org, Frigo FJ, Hinks RS, Mock BJ, Collick BD, Baker N, Marmurek J, Graham SJ |
| Jazyk: |
angličtina |
| Zdroj: |
Magnetic resonance in medicine [Magn Reson Med] 2007 Mar; Vol. 57 (3), pp. 614-9. |
| DOI: |
10.1002/mrm.21132 |
| Abstrakt: |
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. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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