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Magn Reson Med. 2010 Apr;63(4):959-69. doi: 10.1002/mrm.22222.

Improvements in parallel imaging accelerated functional MRI using multiecho echo-planar imaging.

Author information

1
Lucas Center, Department of Radiology, Stanford University, Stanford, California, USA.

Abstract

Multiecho echo-planar imaging (EPI) was implemented for blood-oxygenation-level-dependent functional MRI at 1.5 T and compared to single-echo EPI with and without parallel imaging acceleration. A time-normalized breath-hold task using a block design functional MRI protocol was carried out in combination with up to four echo trains per excitation and parallel imaging acceleration factors R = 1-3. Experiments were conducted in five human subjects, each scanned in three sessions. Across all reduction factors, both signal-to-fluctuation-noise ratio and the total number of activated voxels were significantly lower using a single-echo EPI pulse sequence compared with the multiecho approach. Signal-to-fluctuation-noise ratio and total number of activated voxels were also considerably reduced for nonaccelerated conventional single-echo EPI when compared to three-echo measurements with R = 2. Parallel imaging accelerated multiecho EPI reduced geometric distortions and signal dropout, while it increased blood-oxygenation-level-dependent signal sensitivity all over the brain, particularly in regions with short underlying T*(2). Thus, the presented method showed multiple advantages over conventional single-echo EPI for standard blood-oxygenation-level-dependent functional MRI experiments.

PMID:
20373397
PMCID:
PMC2906757
DOI:
10.1002/mrm.22222
[Indexed for MEDLINE]
Free PMC Article
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