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Interleaved snapshot echo planar imaging of mouse brain at 7.0 T
Author(s) -
Guilfoyle David N.,
Hrabe Jan
Publication year - 2006
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1009
Subject(s) - snapshot (computer storage) , shim (computing) , computer science , image quality , artificial intelligence , computer vision , medicine , erectile dysfunction , image (mathematics) , operating system
Single‐shot echo planar imaging (EPI) of a mouse brain at high field is very challenging. Large susceptibility‐induced gradients affect much of the brain volume, causing severe image deformations and signal loss. Segmented EPI and other conventional multi‐shot approaches alleviate these problems but suffer from lower temporal resolution and motion artifacts. We demonstrate that interleaved snapshot EPI represents a simple and robust alternative approach and one that is particularly suitable for high‐field T 2 *‐weighted functional imaging of a mouse brain. Similarly to segmented multi‐shot techniques, it significantly reduces the susceptibility‐related artifacts. At the same time, it preserves the high temporal resolution and the snapshot capability of a conventional EPI by acquiring entire image within a single TR period. We discuss implementation details of the interleaved snapshot EPI sequence and the trade‐offs involved between the imaging efficiency, the number of interleaved excitation‐acquisition blocks and the artifact reduction. To document the sequence utility, murine brain in vivo imaging with the interleaved snapshot EPI method was compared with a conventional EPI. We found that at least five interleaved blocks were necessary to restore the signal in most cortical areas. We also show that a standard global shimming procedure provides sufficient homogeneity for multi‐slice interleaved snapshot EPI acquisition. In contrast, the conventional EPI of comparable image quality would be limited to a single slice with highly optimized local shim. Finally, an in vitro comparison with turbo FLASH acquisition shows the interleaved snapshot EPI to have superior time resolution and signal‐to‐noise ratio. Copyright © 2006 John Wiley & Sons, Ltd.