@article{fed241900b984291acb6ef2c8e19c168,
title = "Whole-brain 3D FLAIR at 7T using direct signal control",
abstract = "PURPOSE: Image quality obtained for brain imaging at 7T can be hampered by inhomogeneities in the static magnetic field, B0, and the RF electromagnetic field, B1. 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.",
keywords = "direct signal control, dynamic RF shimming, FLAIR, parallel transmission, RF shimming, ultrahigh field, Direct signal control",
author = "Arian Beqiri and Hans Hoogduin and Alessandro Sbrizzi and Hajnal, {Joseph V} and Malik, {Shaihan J}",
note = "Funding Information: This work was funded by the EPSRC (EP/L00531X/1) and the Medical Research Council (MR/K006355/1). The research was also supported by the Wellcome/EPSRC Centre for Medical Engineering at King's College London (WT 203148/Z/16/Z) and the National Institute for Health Research Biomedical Research Centre based at Guy's and St Thomas' National Health Service Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the National Health Service, the National Institute for Health Research, or the Department of Health. Funding Information: Grant sponsor: funded by the EPSRC (EP/L00531X/1) and the Medical Research Council (MR/K006355/1). The research was also supported by the Wellcome/EPSRC Centre for Medical Engineering at King{\textquoteright}s College London (WT 203148/Z/16/Z) and the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas{\textquoteright} NHS Foundation Trust and King's College London Funding Information: This work was funded by the EPSRC (EP/L00531X/1) and the Medical Research Council (MR/K006355/1). The research was also supported by the Wellcome/EPSRC Centre for Medical Engineering at King{\textquoteright}s College London (WT 203148/Z/16/Z) and the National Institute for Health Research Biomedical Research Centre based at Guy{\textquoteright}s and St Thomas{\textquoteright} National Health Service Foundation Trust and King{\textquoteright}s College London. The views expressed are those of the author(s) and not necessarily those of the National Health Service, the National Institute for Health Research, or the Department of Health. Publisher Copyright: {\textcopyright} 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine",
year = "2018",
month = oct,
day = "1",
doi = "10.1002/mrm.27149",
language = "English",
volume = "80",
pages = "1533--1545",
journal = "Magnetic Resonance in Medicine",
issn = "0740-3194",
publisher = "John Wiley & Sons Inc.",
number = "4",
}