期刊
MAGNETIC RESONANCE IN MEDICINE
卷 63, 期 4, 页码 959-969出版社
WILEY
DOI: 10.1002/mrm.22222
关键词
fMRI; parallel imaging; multiecho EPI; temporal SNR; image distortions; signal dropout
资金
- National Institutes of Health [R01EB002711, R01NS047607, R01NS34866, P41RR09784]
- Lucas Foundation
- Oak Foundation
- August-Karolus-Fund ETH Zurich
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. Thus, the presented method showed multiple advantages over conventional single-echo EPI for standard blood-oxygenation-level-dependent functional MRI experiments. Magn Reson Med 63:959-969, 2010. (C) 2010 Wiley-Liss, Inc.
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