Gamma‐aminobutyric acid edited echo‐planar spectroscopic imaging (EPSI) with MEGA‐sLASER at 7T

Peter O. Magnusson*, Vincent O. Boer, Anouk Marsman, Olaf B. Paulson, Lars G. Hanson, Esben Thade Petersen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Purpose: For rapid spatial mapping of gamma‐aminobutyric acid (GABA) at the
increased sensitivity and spectral separation for ultra‐high magnetic field strength (7
tesla [T]) an accelerated edited magnetic resonance spectroscopic imaging technique
was developed and optimized for the human brain at 7 T.
Methods: A MEGA‐sLASER sequence was used for GABA editing and volume
selection to maximize editing efficiency and minimize chemical shift displacement
errors. To accommodate the high bandwidth requirements at 7 T, a single‐shot echo
planar readout was used for rapid simultaneous encoding of the temporal dimension
and 1 spatial. B0 and B1 field aspects specific for 7 T were studied together with correction
procedures, and feasibility of the EPSI MEGA‐sLASER technique was tested
in vivo in 5 healthy subjects.
Results: Localized edited spectra could be measured in all subjects giving spatial
GABA signal distributions over a central brain region, having 45‐ to 50‐Hz spatial
intervoxel B0 field variations and up to 30% B1 field deviations. MEGA editing was
found unaffected by the B0 inhomogeneities for the optimized sequence. The correction
procedures reduced effects of intervoxel B0 inhomogeneities, corrected for spatial
editing efficiency variations, and compensated for GABA resonance phase and
frequency shifts from subtle motion and acquisition instabilities. The optimized oscillating
echo‐planar gradient scheme permitted full spectral acquisition at 7 T and
exhibited minimal spectral‐spatial ghosting effects for the selected brain region.
Conclusion: The EPSI MEGA‐sLASER technique was shown to provide time‐efficient
mapping of regional variations in cerebral GABA in a central volume of interest
with spatial B1 and B0 field variations typical for 7 T.
Original languageEnglish
JournalMagnetic Resonance in Medicine
Volume81
Issue number2
Pages (from-to)773-780
ISSN0740-3194
DOIs
Publication statusPublished - 2018

Keywords

  • 7T
  • Edited MRSI
  • EPSI
  • GABA

Cite this

Magnusson, Peter O. ; Boer, Vincent O. ; Marsman, Anouk ; Paulson, Olaf B. ; Hanson, Lars G. ; Petersen, Esben Thade. / Gamma‐aminobutyric acid edited echo‐planar spectroscopic imaging (EPSI) with MEGA‐sLASER at 7T. In: Magnetic Resonance in Medicine. 2018 ; Vol. 81, No. 2. pp. 773-780.
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abstract = "Purpose: For rapid spatial mapping of gamma‐aminobutyric acid (GABA) at theincreased sensitivity and spectral separation for ultra‐high magnetic field strength (7tesla [T]) an accelerated edited magnetic resonance spectroscopic imaging techniquewas developed and optimized for the human brain at 7 T.Methods: A MEGA‐sLASER sequence was used for GABA editing and volumeselection to maximize editing efficiency and minimize chemical shift displacementerrors. To accommodate the high bandwidth requirements at 7 T, a single‐shot echoplanar readout was used for rapid simultaneous encoding of the temporal dimensionand 1 spatial. B0 and B1 field aspects specific for 7 T were studied together with correctionprocedures, and feasibility of the EPSI MEGA‐sLASER technique was testedin vivo in 5 healthy subjects.Results: Localized edited spectra could be measured in all subjects giving spatialGABA signal distributions over a central brain region, having 45‐ to 50‐Hz spatialintervoxel B0 field variations and up to 30{\%} B1 field deviations. MEGA editing wasfound unaffected by the B0 inhomogeneities for the optimized sequence. The correctionprocedures reduced effects of intervoxel B0 inhomogeneities, corrected for spatialediting efficiency variations, and compensated for GABA resonance phase andfrequency shifts from subtle motion and acquisition instabilities. The optimized oscillatingecho‐planar gradient scheme permitted full spectral acquisition at 7 T andexhibited minimal spectral‐spatial ghosting effects for the selected brain region.Conclusion: The EPSI MEGA‐sLASER technique was shown to provide time‐efficientmapping of regional variations in cerebral GABA in a central volume of interestwith spatial B1 and B0 field variations typical for 7 T.",
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author = "Magnusson, {Peter O.} and Boer, {Vincent O.} and Anouk Marsman and Paulson, {Olaf B.} and Hanson, {Lars G.} and Petersen, {Esben Thade}",
year = "2018",
doi = "10.1002/mrm.27450",
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Gamma‐aminobutyric acid edited echo‐planar spectroscopic imaging (EPSI) with MEGA‐sLASER at 7T. / Magnusson, Peter O.; Boer, Vincent O.; Marsman, Anouk; Paulson, Olaf B.; Hanson, Lars G. ; Petersen, Esben Thade.

In: Magnetic Resonance in Medicine, Vol. 81, No. 2, 2018, p. 773-780.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Gamma‐aminobutyric acid edited echo‐planar spectroscopic imaging (EPSI) with MEGA‐sLASER at 7T

AU - Magnusson, Peter O.

AU - Boer, Vincent O.

AU - Marsman, Anouk

AU - Paulson, Olaf B.

AU - Hanson, Lars G.

AU - Petersen, Esben Thade

PY - 2018

Y1 - 2018

N2 - Purpose: For rapid spatial mapping of gamma‐aminobutyric acid (GABA) at theincreased sensitivity and spectral separation for ultra‐high magnetic field strength (7tesla [T]) an accelerated edited magnetic resonance spectroscopic imaging techniquewas developed and optimized for the human brain at 7 T.Methods: A MEGA‐sLASER sequence was used for GABA editing and volumeselection to maximize editing efficiency and minimize chemical shift displacementerrors. To accommodate the high bandwidth requirements at 7 T, a single‐shot echoplanar readout was used for rapid simultaneous encoding of the temporal dimensionand 1 spatial. B0 and B1 field aspects specific for 7 T were studied together with correctionprocedures, and feasibility of the EPSI MEGA‐sLASER technique was testedin vivo in 5 healthy subjects.Results: Localized edited spectra could be measured in all subjects giving spatialGABA signal distributions over a central brain region, having 45‐ to 50‐Hz spatialintervoxel B0 field variations and up to 30% B1 field deviations. MEGA editing wasfound unaffected by the B0 inhomogeneities for the optimized sequence. The correctionprocedures reduced effects of intervoxel B0 inhomogeneities, corrected for spatialediting efficiency variations, and compensated for GABA resonance phase andfrequency shifts from subtle motion and acquisition instabilities. The optimized oscillatingecho‐planar gradient scheme permitted full spectral acquisition at 7 T andexhibited minimal spectral‐spatial ghosting effects for the selected brain region.Conclusion: The EPSI MEGA‐sLASER technique was shown to provide time‐efficientmapping of regional variations in cerebral GABA in a central volume of interestwith spatial B1 and B0 field variations typical for 7 T.

AB - Purpose: For rapid spatial mapping of gamma‐aminobutyric acid (GABA) at theincreased sensitivity and spectral separation for ultra‐high magnetic field strength (7tesla [T]) an accelerated edited magnetic resonance spectroscopic imaging techniquewas developed and optimized for the human brain at 7 T.Methods: A MEGA‐sLASER sequence was used for GABA editing and volumeselection to maximize editing efficiency and minimize chemical shift displacementerrors. To accommodate the high bandwidth requirements at 7 T, a single‐shot echoplanar readout was used for rapid simultaneous encoding of the temporal dimensionand 1 spatial. B0 and B1 field aspects specific for 7 T were studied together with correctionprocedures, and feasibility of the EPSI MEGA‐sLASER technique was testedin vivo in 5 healthy subjects.Results: Localized edited spectra could be measured in all subjects giving spatialGABA signal distributions over a central brain region, having 45‐ to 50‐Hz spatialintervoxel B0 field variations and up to 30% B1 field deviations. MEGA editing wasfound unaffected by the B0 inhomogeneities for the optimized sequence. The correctionprocedures reduced effects of intervoxel B0 inhomogeneities, corrected for spatialediting efficiency variations, and compensated for GABA resonance phase andfrequency shifts from subtle motion and acquisition instabilities. The optimized oscillatingecho‐planar gradient scheme permitted full spectral acquisition at 7 T andexhibited minimal spectral‐spatial ghosting effects for the selected brain region.Conclusion: The EPSI MEGA‐sLASER technique was shown to provide time‐efficientmapping of regional variations in cerebral GABA in a central volume of interestwith spatial B1 and B0 field variations typical for 7 T.

KW - 7T

KW - Edited MRSI

KW - EPSI

KW - GABA

U2 - 10.1002/mrm.27450

DO - 10.1002/mrm.27450

M3 - Journal article

VL - 81

SP - 773

EP - 780

JO - Magnetic Resonance in Medicine

JF - Magnetic Resonance in Medicine

SN - 0740-3194

IS - 2

ER -