J-difference editing of gamma-aminobutyric acid (GABA): Simulated and experimental multiplet patterns

Research output: Contribution to journalArticle

Abstract

Purpose: To investigate factors that influence the multiplet pattern observed in J-difference editing of gamma-aminobutyric acid (GABA). Methods: Density matrix simulations were applied to investigate the shape of the 3 ppm GABA multiplet as a function of the editing sequence's slice-selective refocusing pulse properties, in particular bandwidth, transition width, and flip angle. For comparison to the calculations, experimental measurements were also made at 3 T on a 10 mM GABA solution using the MEGA-PRESS sequence at various refocusing pulse flip angles. Results: Good agreement was found between experiments and simulations. The edited multiplet consists of two outer lines of slightly unequal intensity due to strong coupling, and a smaller central line, the result of the unequal J-couplings between the C4 and C3 protons. The size of the center peak increases with increasing slice-selective refocusing pulse transition width, and deviation of the flip angle from 180°. Conclusion: The 3 ppm GABA multiplet pattern observed in the MEGA-PRESS experiment depends quite strongly on the properties of the slice-selective refocusing pulses used. Under some circumstance, the central peak can be quite large; this does not necessarily indicate inefficient editing, or a subtraction artifact, but should be recognized as a property of the pulse sequence itself. Magn Reson Med 70:1183-1191, 2013. © 2012 Wiley Periodicals, Inc.

Original languageEnglish (US)
Pages (from-to)1183-1191
Number of pages9
JournalMagnetic resonance in medicine
Volume70
Issue number5
DOIs
StatePublished - Nov 1 2013

Keywords

  • GABA
  • J-difference editing
  • MEGA-PRESS
  • pseudo-doublet

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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