MEGA-PRESS of GABA+: Influences of acquisition parameters

Research output: Contribution to journalArticle

Abstract

γ-aminobutyric acid (GABA) was the first molecule that was edited with MEGA-PRESS. GABA edited spectroscopy is challenged by limited selectivity of editing pulses. Coediting of resonances from macromolecules (MM) is the greatest single limitation of GABA edited spectroscopy. In this contribution, relative signal contributions from GABA, MM and homocarnosine to the total MEGA-PRESS edited signal at ~3 ppm, i.e., GABA+, are simulated at 3 tesla using several acquisition schemes. The base scheme is modeled after those currently supplied by vendors: it uses typical pulse shapes and lengths, it minimizes the first echo time (TE), and the delay between the editing pulses is kept at TE/2. Edited spectra are simulated for imperfect acquisition parameters such as incorrect frequency, larger chemical shift displacement, incorrect transmit B1-field calibration for localization and editing pulses, and longer TE. An alternative timing scheme and longer editing pulses are also considered. Additional simulations are performed for symmetric editing around the MM frequency to suppress the MM signal. The relative influences of these acquisition parameters on the constituents of GABA+ are examined from the perspective of modern experimental designs for investigating brain GABA concentration differences in healthy and diseased humans. Other factors that influence signal contributions, such as T1 and T2 relaxation times are also considered.

Original languageEnglish (US)
Article numbere4199
JournalNMR in biomedicine
DOIs
StateAccepted/In press - Jan 1 2019

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gamma-Aminobutyric Acid
Macromolecules
Spectrum Analysis
Spectroscopy
Aminobutyrates
Chemical shift
Design of experiments
Relaxation time
Calibration
Brain
Research Design
Molecules

Keywords

  • editing
  • GABA
  • homocarnosine
  • lysine
  • macromolecules
  • magnetic resonance spectroscopy

PubMed: MeSH publication types

  • Journal Article

Cite this

MEGA-PRESS of GABA+ : Influences of acquisition parameters. / Deelchand, Dinesh K.; Marjańska, Małgorzata; Henry, Pierre Gilles; Terpstra, Melissa.

In: NMR in biomedicine, 01.01.2019.

Research output: Contribution to journalArticle

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