Selective maximization of 31P MR spectroscopic signals of in vivo human brain metabolites at 3T

Rose Ann M. Blenman, John D. Port, Joel P. Felmlee

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Purpose: To develop a short TR, short TE, large flip angle (LFA), in vivo 31P MR spectroscopy (MRS) technique at 3T that selectively maximizes the signal-to-noise ratio (SNR) of long T1 human brain metabolites implicated in bipolar disorder. Materials and Methods: Two pulse sequences were evaluated for efficiency. Slice profiles acquired with the scaled, sinc-shaped, radiofrequency (RF) LFA pulses were compared to those acquired with Shinnar-Le Roux (SLR) RF LFA pulses. The SLR-based LFA pulse sequence was used to maximize the inorganic phosphate signal in a phantom, after which volunteer metabolite signals were selectively maximized and compared to their correlates acquired with conventional spin-echo methods. Results: The comparison of slice profiles acquired with sinc-shaped RF LFA pulses vs. SLR RF LFA pulses showed that SLR-based pulse sequences, with their improved excitation and slice profiles, yield significantly better results. In vivo LFA spin-echo MRS implemented with SLR pulses selectively increased the 31P MRS signal, by as much as 93%, of human brain metabolites that have T1 times longer than the TR of the acquisition. Conclusion: The data show that the LFA technique can be employed in vivo to maximize the signal of long T1 31P brain metabolites at a given TE and TR. LFAs ranging between 120° and 150° are shown to maximize the 31P signal of human brain metabolites at 3T.

Original languageEnglish (US)
Pages (from-to)628-634
Number of pages7
JournalJournal of Magnetic Resonance Imaging
Volume25
Issue number3
DOIs
StatePublished - Mar 1 2007

Keywords

  • Bipolar disorder
  • Brain
  • LFA
  • Large flip angle
  • P-MRS
  • PME
  • Phosphomonoesters

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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