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Whole‐brain 3 D FLAIR at 7 T using direct signal control
Author(s) -
Beqiri Arian,
Hoogduin Hans,
Sbrizzi Alessandro,
Hajnal Joseph V.,
Malik Shaihan J.
Publication year - 2018
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.27149
Subject(s) - fluid attenuated inversion recovery , signal (programming language) , computer science , magnetic resonance imaging , neuroimaging , image quality , nuclear magnetic resonance , physics , nuclear medicine , neuroscience , medicine , artificial intelligence , radiology , image (mathematics) , psychology , programming language
Purpose Image quality obtained for brain imaging at 7T can be hampered by inhomogeneities in the static magnetic field, B 0 , and the RF electromagnetic field, B 1 . In imaging sequences such as fluid‐attenuated inversion recovery (FLAIR), which is used to assess neurological disorders, these inhomogeneities cause spatial variations in signal that can reduce clinical efficacy. In this work, we aim to correct for signal inhomogeneities to ensure whole‐brain coverage with 3D FLAIR at 7T. Methods The direct signal control (DSC) framework was used to optimize channel weightings applied to the 8 transmit channels used in this work on a pulse‐by‐pulse basis through the echo train in the FLAIR sequences. 3D FLAIR brain images were acquired on 5 different subjects and compared with imaging using a quadrature‐like mode of the transmit array. Precomputed “universal” DSC solutions calculated from a separate set of 5 subjects were also explored. Results DSC consistently enabled improved imaging across all subjects, with no dropouts in signal seen over the entire brain volume, which contrasted with imaging in quadrature mode. Further, the universal DSC solutions also consistently improved imaging despite not being optimized specifically for the subject being imaged. Conclusion 3D FLAIR brain imaging at 7T is substantially improved using DSC and is able to recover regions of low signal without increasing imaging time or interecho spacing.