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Hippocampal single-voxel MR spectroscopy with a long echo time at 3 T using semi-LASER sequence

Gajdošík, Martin ; Landheer, Karl ; Swanberg, Kelley M LU orcid ; Adlparvar, Fatemeh ; Madelin, Guillaume ; Bogner, Wolfgang ; Juchem, Christoph and Kirov, Ivan I (2021) In NMR in Biomedicine 34(8).
Abstract

The hippocampus is one of the most challenging brain regions for proton MR spectroscopy (MRS) applications. Moreover, quantification of J-coupled species such as myo-inositol (m-Ins) and glutamate + glutamine (Glx) is affected by the presence of macromolecular background. While long echo time (TE) MRS eliminates the macromolecules, it also decreases the m-Ins and Glx signal and, as a result, these metabolites are studied mainly with short TE. Here, we investigate the feasibility of reproducibly measuring their concentrations at a long TE of 120 ms, using a semi-adiabatic localization by adiabatic selective refocusing (sLASER) sequence, as this sequence was recently recommended as a standard for clinical MRS. Gradient offset-independent... (More)

The hippocampus is one of the most challenging brain regions for proton MR spectroscopy (MRS) applications. Moreover, quantification of J-coupled species such as myo-inositol (m-Ins) and glutamate + glutamine (Glx) is affected by the presence of macromolecular background. While long echo time (TE) MRS eliminates the macromolecules, it also decreases the m-Ins and Glx signal and, as a result, these metabolites are studied mainly with short TE. Here, we investigate the feasibility of reproducibly measuring their concentrations at a long TE of 120 ms, using a semi-adiabatic localization by adiabatic selective refocusing (sLASER) sequence, as this sequence was recently recommended as a standard for clinical MRS. Gradient offset-independent adiabatic refocusing pulses were implemented, and an optimal long TE for the detection of m-Ins and Glx was determined using the T2 relaxation times of macromolecules. Metabolite concentrations and their coefficients of variation (CVs) were obtained for a 3.4-mL voxel centered on the left hippocampus on 3-T MR systems at two different sites with three healthy subjects (aged 32.5 ± 10.2 years [mean ± standard deviation]) per site, with each subject scanned over two sessions, and with each session comprising three scans. Concentrations of m-Ins, choline, creatine, Glx and N-acetyl-aspartate were 5.4 ± 1.5, 1.7 ± 0.2, 5.8 ± 0.3, 11.6 ± 1.2 and 5.9 ± 0.4 mM (mean ± standard deviation), respectively. Their respective mean within-session CVs were 14.5% ± 5.9%, 6.5% ± 5.3%, 6.0% ± 3.4%, 10.6% ± 6.2% and 3.5% ± 1.4%, and their mean within-subject CVs were 17.8% ± 18.2%, 7.5% ± 6.3%, 7.4% ± 6.4%, 12.4% ± 5.3% and 4.8% ± 3.0%. The between-subject CVs were 25.0%, 12.3%, 5.3%, 10.7% and 6.4%, respectively. Hippocampal long-TE sLASER single voxel spectroscopy can provide macromolecule-independent assessment of all major metabolites including Glx and m-Ins.

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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Adult, Algorithms, Computer Simulation, Female, Hippocampus/diagnostic imaging, Humans, Magnetic Resonance Spectroscopy, Male, Metabolome, Time Factors
in
NMR in Biomedicine
volume
34
issue
8
article number
e4538
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85105209462
  • pmid:33956374
ISSN
0952-3480
DOI
10.1002/nbm.4538
language
English
LU publication?
no
id
02dd852f-efd6-487f-9ecf-62c6b1834ad1
date added to LUP
2023-09-18 14:59:58
date last changed
2024-04-19 01:21:13
@article{02dd852f-efd6-487f-9ecf-62c6b1834ad1,
  abstract     = {{<p>The hippocampus is one of the most challenging brain regions for proton MR spectroscopy (MRS) applications. Moreover, quantification of J-coupled species such as myo-inositol (m-Ins) and glutamate + glutamine (Glx) is affected by the presence of macromolecular background. While long echo time (TE) MRS eliminates the macromolecules, it also decreases the m-Ins and Glx signal and, as a result, these metabolites are studied mainly with short TE. Here, we investigate the feasibility of reproducibly measuring their concentrations at a long TE of 120 ms, using a semi-adiabatic localization by adiabatic selective refocusing (sLASER) sequence, as this sequence was recently recommended as a standard for clinical MRS. Gradient offset-independent adiabatic refocusing pulses were implemented, and an optimal long TE for the detection of m-Ins and Glx was determined using the T2 relaxation times of macromolecules. Metabolite concentrations and their coefficients of variation (CVs) were obtained for a 3.4-mL voxel centered on the left hippocampus on 3-T MR systems at two different sites with three healthy subjects (aged 32.5 ± 10.2 years [mean ± standard deviation]) per site, with each subject scanned over two sessions, and with each session comprising three scans. Concentrations of m-Ins, choline, creatine, Glx and N-acetyl-aspartate were 5.4 ± 1.5, 1.7 ± 0.2, 5.8 ± 0.3, 11.6 ± 1.2 and 5.9 ± 0.4 mM (mean ± standard deviation), respectively. Their respective mean within-session CVs were 14.5% ± 5.9%, 6.5% ± 5.3%, 6.0% ± 3.4%, 10.6% ± 6.2% and 3.5% ± 1.4%, and their mean within-subject CVs were 17.8% ± 18.2%, 7.5% ± 6.3%, 7.4% ± 6.4%, 12.4% ± 5.3% and 4.8% ± 3.0%. The between-subject CVs were 25.0%, 12.3%, 5.3%, 10.7% and 6.4%, respectively. Hippocampal long-TE sLASER single voxel spectroscopy can provide macromolecule-independent assessment of all major metabolites including Glx and m-Ins.</p>}},
  author       = {{Gajdošík, Martin and Landheer, Karl and Swanberg, Kelley M and Adlparvar, Fatemeh and Madelin, Guillaume and Bogner, Wolfgang and Juchem, Christoph and Kirov, Ivan I}},
  issn         = {{0952-3480}},
  keywords     = {{Adult; Algorithms; Computer Simulation; Female; Hippocampus/diagnostic imaging; Humans; Magnetic Resonance Spectroscopy; Male; Metabolome; Time Factors}},
  language     = {{eng}},
  number       = {{8}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{NMR in Biomedicine}},
  title        = {{Hippocampal single-voxel MR spectroscopy with a long echo time at 3 T using semi-LASER sequence}},
  url          = {{http://dx.doi.org/10.1002/nbm.4538}},
  doi          = {{10.1002/nbm.4538}},
  volume       = {{34}},
  year         = {{2021}},
}