@article{51477bc55eb640fcb2ebaaed7589decc,
title = "Parallel transmit PUlse design for Saturation Homogeneity (PUSH) for Magnetization Transfer imaging at 7T",
abstract = "Purpose: This work proposes a novel RF pulse design for parallel transmit (pTx) systems to obtain uniform saturation of semisolid magnetization for magnetization transfer (MT) contrast in the presence of transmit field (Formula presented.) inhomogeneities. The semisolid magnetization is usually modeled as being purely longitudinal, with the applied (Formula presented.) field saturating but not rotating its magnetization; thus, standard pTx pulse design methods do not apply. Theory and Methods: Pulse design for saturation homogeneity (PUSH) optimizes pTx RF pulses by considering uniformity of root-mean squared (Formula presented.), (Formula presented.), which relates to the rate of semisolid saturation. Here we considered designs consisting of a small number of spatially non-selective sub-pulses optimized over either a single 2D plane or 3D. Simulations and in vivo experiments on a 7T Terra system with an 8-TX Nova head coil in five subjects were carried out to study the homogenization of (Formula presented.) and of the MT contrast by acquiring MT ratio maps. Results: Simulations and in vivo experiments showed up to six and two times more uniform (Formula presented.) compared to circular polarized (CP) mode for 2D and 3D optimizations, respectively. This translated into 4 and 1.25 times more uniform MT contrast, consistently for all subjects, where two sub-pulses were enough for the implementation and coil used. Conclusion: The proposed PUSH method obtains more uniform and higher MT contrast than CP mode within the same specific absorption rate (SAR) budget.",
keywords = "Magnetization Transfer (MT), parallel transmit (PTx), RF pulse design, B1 inhomogeneity, ultrahigh-field (UHF)",
author = "David Leit{\~a}o and Raphael Tomi-Tricot and Pip Bridgen and Tom Wilkinson and Patrick Liebig and Rene Gumbrecht and Dieter Ritter and Sharon Giles and Ana Baburamani and Jan Sedlacik and Jo Hajnal and Shaihan Malik",
note = "Funding Information: information Engineering and Physical Sciences Research Council, EP/L015226/1; Wellcome Trust, WT 203148/Z/16/Z; Department of Health, EPSRC Centre for Doctoral Training in Medical Imaging, Imperial College London, King's College London, King's College London, Biomedical Research Centre, National Institute for Health Research, Wellcome, Wellcome TrustThis research was funded in whole, or in part, by the Wellcome Trust [WT 203148/Z/16/Z]. For the purpose of open access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. This work was supported by the Wellcome/EPSRC Centre for Medical Engineering [WT 203148/Z/16/Z] and by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London and/or the NIHR Clinical Research Facility, and funded by the King's College London & Imperial College London EPSRC Centre for Doctoral Training in Medical Imaging [EP/L015226/1]. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Funding Information: This research was funded in whole, or in part, by the Wellcome Trust [WT 203148/Z/16/Z]. For the purpose of open access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. This work was supported by the Wellcome/EPSRC Centre for Medical Engineering [WT 203148/Z/16/Z] and by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London and/or the NIHR Clinical Research Facility, and funded by the King's College London & Imperial College London EPSRC Centre for Doctoral Training in Medical Imaging [EP/L015226/1]. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Funding Information: Engineering and Physical Sciences Research Council, EP/L015226/1; Wellcome Trust, WT 203148/Z/16/Z; Department of Health, EPSRC Centre for Doctoral Training in Medical Imaging, Imperial College London, King's College London, King's College London, Biomedical Research Centre, National Institute for Health Research, Wellcome, Wellcome Trust Funding information Publisher Copyright: {\textcopyright} 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.",
year = "2022",
month = jul,
doi = "10.1002/mrm.29199",
language = "English",
volume = "88",
pages = "180--194",
journal = "Magnetic resonance in medicine",
issn = "0740-3194",
publisher = "WILEY-BLACKWELL",
number = "1",
}