Simultaneous in vivo spectral editing and water suppression

M. Mescher, H. Merkle, Jonathan D Kirsch, Michael Garwood, R. Gruetter

Research output: Contribution to journalArticlepeer-review

622 Scopus citations

Abstract

Water suppression is typically performed in vivo by exciting the longitudinal magnetization in combination with dephasing, or by using frequency-selective coherence generation. MEGA, a frequency-selective refocusing technique, can be placed into any pulse sequence element designed to generate a Hahn spin-echo or stimulated echo, to dephase transverse water coherences with minimal spectral distortions. Water suppression performance was verified in vivo using stimulated echo acquisition mode (STEAM) localization, which provided water suppression comparable with that achieved with four selective pulses in 3,1-DRYSTEAM. The advantage of the proposed method was exploited for editing J-coupled resonances. Using a double-banded pulse that selectively inverts a J-coupling partner and simultaneously suppresses water, efficient metabolite editing was achieved in the point resolved spectroscopy (PRESS) and STEAM sequences in which MEGA was incorporated. To illustrate the efficiency of the method, the detection of γ-aminobutyric acid (GABA) was demonstrated, with minimal contributions from macromolecules and overlying singlet peaks at 4 T. The estimated occipital GABA concentration was consistent with previous reports, suggesting that editing for GABA is efficient when based on MEGA at high field strengths.

Original languageEnglish (US)
Pages (from-to)266-272
Number of pages7
JournalNMR in biomedicine
Volume11
Issue number6
DOIs
StatePublished - Oct 1998

Keywords

  • Frequency selective water suppression
  • GABA
  • Human brain
  • In vivo H MRS

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