In vivo Glx and Glu measurements from GABA-edited MRS at 3 T

Research output: Contribution to journalArticlepeer-review

Authors

  • T Bell
  • ES Boudes
  • RS Loo
  • GJ Barker
  • DJ Lythgoe
  • RAE Edden
  • RM Lebel
  • AD Harris

Abstract

In vivo quantification of glutamate (Glu) and γ-aminobutyric acid (GABA) using MRS is often achieved using two separate sequences: a short-echo point resolved spectroscopy (PRESS) acquisition for Glu and a Mescher-Garwood PRESS (MEGA-PRESS) acquisition for GABA. The purpose of this study was to examine the agreement of Glu and Glx (the combined signal of glutamate + glutamine) quantified from two different GABA-edited MEGA-PRESS acquisitions (GABA plus macromolecules, GABA+, T E = 68 ms, and macromolecule suppressed, MMSup, T E = 80 ms) with Glu and Glx quantified from a short-echo PRESS (PRESS-35, T E = 35 ms) acquisition. Fifteen healthy male volunteers underwent a single scan session, in which data were acquired using the three acquisitions (GABA+, MMSup and PRESS-35) in both the sensorimotor and anterior cingulate cortices using a voxel size of 3 × 3 × 3 cm 3. Glx and Glu were quantified from the MEGA-PRESS data using both the OFF sub-spectra and the difference (DIFF) spectra. Agreement was assessed using correlation analyses, Bland–Altman plots and intraclass correlation coefficients. Glx quantified from the OFF sub-spectra from both the GABA+ and MMSup acquisitions showed poor agreement with PRESS-35 in both brain regions. In the sensorimotor cortex, Glu quantified from the OFF sub-spectra of GABA+ showed moderate agreement with PRESS-35 data, but this finding was not replicated in the anterior cingulate cortex. Glx and Glu quantified using the DIFF spectra of either MEGA-PRESS sequence were in poor agreement with the PRESS-35 data in both brain regions. In conclusion, Glx and Glu measured from MEGA-PRESS data generally showed poor agreement with Glx and Glu measured using PRESS-35.

Bibliographic note

© 2020 John Wiley & Sons, Ltd.

Details

Original languageEnglish
Article numbere4245
Number of pages11
JournalNMR in biomedicine
Early online date28 Jan 2020
Publication statusE-pub ahead of print - 28 Jan 2020

Keywords

  • Glx, MEGA-, PRESS, PRESSGABA-edited MRS, glutamate