Deelchand DK, Walls JD, Marjańska M. In vivo
1 H MR spectroscopy with J-refocusing.
Magn Reson Med 2021;
86:2957-2965. [PMID:
34309065 DOI:
10.1002/mrm.28936]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/07/2021] [Accepted: 07/02/2021] [Indexed: 11/11/2022]
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 TE s (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.
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