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T 2 ‐weighted 3D fMRI using S 2 ‐SSFP at 7 tesla
Author(s) -
Barth Markus,
Meyer Heiko,
Kannengiesser Stephan A. R.,
Polimeni Jonathan R.,
Wald Lawrence L.,
Norris David G.
Publication year - 2010
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22283
Subject(s) - steady state free precession imaging , nuclear magnetic resonance , voxel , signal (programming language) , physics , sensitivity (control systems) , echo planar imaging , chemistry , magnetic resonance imaging , nuclear medicine , computer science , artificial intelligence , medicine , radiology , electronic engineering , engineering , programming language
In this study, the sensitivity of the S 2 ‐steady‐state free precession (SSFP) signal for functional MRI at 7 T was investigated. In order to achieve the necessary temporal resolution, a three‐dimensional acquisition scheme with acceleration along two spatial axes was employed. Activation maps based on S 2 ‐steady‐state free precession data showed similar spatial localization of activation and sensitivity as spin‐echo echo‐planar imaging (SE‐EPI), but data can be acquired with substantially lower power deposition. The functional sensitivity estimated by the average z‐values was not significantly different for SE‐EPI compared to the S 2 ‐signal but was slightly lower for the S 2 ‐signal (6.74 ± 0.32 for the TR = 15 ms protocol and 7.51 ± 0.78 for the TR = 27 ms protocol) compared to SE‐EPI (7.49 ± 1.44 and 8.05 ± 1.67) using the same activated voxels, respectively. The relative signal changes in these voxels upon activation were slightly lower for SE‐EPI (2.37% ± 0.18%) compared to the TR = 15 ms S 2 ‐SSFP protocol (2.75% ± 0.53%) and significantly lower than the TR = 27 ms protocol (5.38% ± 1.28%), in line with simulations results. The large relative signal change for the long TR SSFP protocol can be explained by contributions from multiple coherence pathways and the low intrinsic intensity of the S 2 signal. In conclusion, whole‐brain T 2 ‐weighted functional MRI with negligible image distortion at 7 T is feasible using the S 2 ‐SSFP sequence and partially parallel imaging. Magn Reson Med 63:1015–1020, 2010. © 2010 Wiley‐Liss, Inc.