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 language | English (US) |
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Pages (from-to) | 628-634 |
Number of pages | 7 |
Journal | Journal of Magnetic Resonance Imaging |
Volume | 25 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2007 |
Keywords
- Bipolar disorder
- Brain
- LFA
- Large flip angle
- P-MRS
- PME
- Phosphomonoesters
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging