In vivo 1H MR spectroscopy with J-refocusing

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Abstract

Purpose: The goal of this study was to propose a novel localized proton MR spectroscopy (MRS) sequence that reduces signal loss due to J-modulation in the rat brain in vivo. Methods: Sprague-Dawley rats were studied at 9.4 T. A semi-LASER sequence with evenly distributed echo-time (TE) was used, and a 90° J-refocusing pulse was inserted at TE/2. Proton spectra were acquired at two TEs (30 and 68 ms), with and without the J-refocused pulse. Data were processed in MATLAB and quantified with LCModel. Results: The J-refocused spectrum acquired at TE = 30 ms did not show any signal losses due to J-modulation and had comparable spectral pattern to the one acquired with semi-LASER using the minimum achievable TE. Higher signal amplitudes for glutamine, γ-aminobutyric acid and glutathione led to more reliable quantification precision for these metabolites. The refocused signal intensities at TE = 68 ms were also unaffected by J-modulation but were smaller than the signals at TE = 30 ms mainly due to transverse T2 relaxation of metabolites. Conclusion: The proposed localized MRS sequence will be beneficial in both animal and human MRS studies when using ultra-short TE is not possible while also providing more reliable quantification precision for J-coupled metabolites.

Original languageEnglish (US)
Pages (from-to)2957-2965
Number of pages9
JournalMagnetic resonance in medicine
Volume86
Issue number6
Early online dateJul 26 2021
DOIs
StatePublished - Dec 2021

Bibliographical note

Funding Information:
The authors thank Lynn Utecht for expert technical assistance. J.D.W. acknowledges support from the National Science Foundation under grant CHE‐1807724. This work was supported by NIH grants P41 EB027061 and P30 NS076408.

Publisher Copyright:
© 2021 International Society for Magnetic Resonance in Medicine

Keywords

  • 9.4 T
  • GABA
  • J-coupled metabolites
  • brain
  • glutamine
  • glutathione
  • semi-LASER

Center for Magnetic Resonance Research (CMRR) tags

  • SMCT
  • P41

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