Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6027255 | NeuroImage | 2014 | 9 Pages |
Abstract
A whole brain, multiband spin-echo (SE) echo planar imaging (EPI) sequence employing a high spatial (1.5Â mm isotropic) and temporal (TR of 2Â s) resolution was implemented at 7Â T. Its overall performance (tSNR, sensitivity and CNR) was assessed and compared to a geometrically matched gradient-echo (GE) EPI multiband sequence (TR of 1.4Â s) using a color-word Stroop task. PINS RF pulses were used for refocusing to reduce RF amplitude requirements and SAR, summed and phase-optimized standard pulses were used for excitation enabling a transverse or oblique slice orientation. The distortions were minimized with the use of parallel imaging in the phase encoding direction and a post-acquisition distortion correction. In general, GE-EPI shows higher efficiency and higher CNR in most brain areas except in some parts of the visual cortex and superior frontal pole at both the group and individual-subject levels. Gradient-echo EPI was able to detect robust activation near the air/tissue interfaces such as the orbito-frontal and subcortical regions due to reduced intra-voxel dephasing because of the thin slices used and high in-plane resolution.
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Authors
Rasim BoyacioÄlu, Jenni Schulz, Nils C.J. Müller, Peter J. Koopmans, Markus Barth, David G. Norris,