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Frequency difference mapping applied to the corpus callosum at 7T

PURPOSE: Frequency difference mapping (FDM) is a phase processing technique which characterizes the nonlinear temporal evolution of the phase of gradient echo (GE) signals. Here, a novel FDM‐processing algorithm is introduced, which is shown to reveal information about white matter microstructure. U...

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Autores principales: Tendler, Benjamin C., Bowtell, Richard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6492142/
https://www.ncbi.nlm.nih.gov/pubmed/30582226
http://dx.doi.org/10.1002/mrm.27626
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author Tendler, Benjamin C.
Bowtell, Richard
author_facet Tendler, Benjamin C.
Bowtell, Richard
author_sort Tendler, Benjamin C.
collection PubMed
description PURPOSE: Frequency difference mapping (FDM) is a phase processing technique which characterizes the nonlinear temporal evolution of the phase of gradient echo (GE) signals. Here, a novel FDM‐processing algorithm is introduced, which is shown to reveal information about white matter microstructure. Unlike some other phase‐processing techniques, the FDM algorithm presented here does not require the use of phase unwrapping or sophisticated image processing. It uses a series of scaled complex divisions to unwrap phase and remove background fields. METHODS: Ten healthy subjects underwent a series of single‐slice, sagittal multi‐echo GE scans at 7T with the slice positioned at the midline. Phase data were processed with the novel FDM algorithm, and the temporal evolution of the magnitude signal and frequency difference was examined in 5 regions of the corpus callosum (CC; genu, anterior body, middle body, posterior body, and splenium). RESULTS: Consistent frequency difference contrast relative to surrounding tissue was observed in all subjects in the CC and in other white matter regions where the nerve fibers run perpendicular to [Formula: see text] , such as the superior cerebellar peduncle. Examination of the frequency difference curves shows distinct variations over the CC, with the genu and splenium displaying larger frequency differences than the other regions (in addition to a faster decay of signal magnitude). CONCLUSION: The novel FDM algorithm presented here yields images sensitive to tissue microstructure and microstructural differences over the CC in a simple manner, without the requirement for phase unwrapping or sophisticated image processing.
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spelling pubmed-64921422019-05-06 Frequency difference mapping applied to the corpus callosum at 7T Tendler, Benjamin C. Bowtell, Richard Magn Reson Med Full Papers—Imaging Methodology PURPOSE: Frequency difference mapping (FDM) is a phase processing technique which characterizes the nonlinear temporal evolution of the phase of gradient echo (GE) signals. Here, a novel FDM‐processing algorithm is introduced, which is shown to reveal information about white matter microstructure. Unlike some other phase‐processing techniques, the FDM algorithm presented here does not require the use of phase unwrapping or sophisticated image processing. It uses a series of scaled complex divisions to unwrap phase and remove background fields. METHODS: Ten healthy subjects underwent a series of single‐slice, sagittal multi‐echo GE scans at 7T with the slice positioned at the midline. Phase data were processed with the novel FDM algorithm, and the temporal evolution of the magnitude signal and frequency difference was examined in 5 regions of the corpus callosum (CC; genu, anterior body, middle body, posterior body, and splenium). RESULTS: Consistent frequency difference contrast relative to surrounding tissue was observed in all subjects in the CC and in other white matter regions where the nerve fibers run perpendicular to [Formula: see text] , such as the superior cerebellar peduncle. Examination of the frequency difference curves shows distinct variations over the CC, with the genu and splenium displaying larger frequency differences than the other regions (in addition to a faster decay of signal magnitude). CONCLUSION: The novel FDM algorithm presented here yields images sensitive to tissue microstructure and microstructural differences over the CC in a simple manner, without the requirement for phase unwrapping or sophisticated image processing. John Wiley and Sons Inc. 2018-12-23 2019-05 /pmc/articles/PMC6492142/ /pubmed/30582226 http://dx.doi.org/10.1002/mrm.27626 Text en © 2019 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Full Papers—Imaging Methodology
Tendler, Benjamin C.
Bowtell, Richard
Frequency difference mapping applied to the corpus callosum at 7T
title Frequency difference mapping applied to the corpus callosum at 7T
title_full Frequency difference mapping applied to the corpus callosum at 7T
title_fullStr Frequency difference mapping applied to the corpus callosum at 7T
title_full_unstemmed Frequency difference mapping applied to the corpus callosum at 7T
title_short Frequency difference mapping applied to the corpus callosum at 7T
title_sort frequency difference mapping applied to the corpus callosum at 7t
topic Full Papers—Imaging Methodology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6492142/
https://www.ncbi.nlm.nih.gov/pubmed/30582226
http://dx.doi.org/10.1002/mrm.27626
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