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Magn Reson Med. 2018 Oct;80(4):1279-1288. doi: 10.1002/mrm.27119. Epub 2018 Feb 9.

Minimum echo time PRESS-based proton observed carbon edited (POCE) MRS in rat brain using simultaneous editing and localization pulses.

Author information

1
Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada.
2
Brain Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.
3
Department of Psychiatry, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
4
Center for Translational NeuroImaging, Northeastern University, Boston, Massachusetts, USA.
5
Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut, USA.

Abstract

PURPOSE:

Indirect 13 C MRS by proton-observed carbon editing (POCE) is a powerful method to study brain metabolism. The sensitivity of POCE-MRS can be enhanced through the use of short TEs, which primarily minimizes homonuclear J-evolution related losses; previous POCE-MRS implementations use longer than optimal echo times due to sequence limitations, or short TE image selected in vivo spectroscopy-based multi-shot acquisitions for 3D localization. To that end, this paper presents a novel single-shot point resolved spectroscopy (PRESS)-localized POCE-MRS sequence that involves the application of simultaneous editing and localization pulses (SEAL)-PRESS, allowing the TE to be reduced to a theoretically optimal value of ∼ 1/JHC .

METHODS:

The optimized SEAL-PRESS sequence was first evaluated in simulation and in phantom; next, the sequence was validated with dynamic in vivo POCE-MRS performed in a rat preparation during a 1,6-13 C2 -Glc infusion, and on a microwave fixed rat brain following a 2-hour [1,6-13 C2 ]-Glc infusion. POCE spectra from the SEAL-PRESS sequence were compared against a previously described 12.6-ms PRESS-POCE sequence utilizing a classical carbon editing scheme.

RESULTS:

The SEAL-PRESS sequence provides > 95% editing efficiency, optimal sensitivity, and localization for POCE MRS with an overall sequence TE of 8.1 ms. Signal amplitude of 13 C-labeled metabolites Glu-H4, Gln-H4, Glx-H3, Glc-H6 +Glx-H2, and Asp-H2 were shown to be improved by >17% relative to a 12.6-ms PRESS-POCE sequence in vivo.

CONCLUSION:

We report for the first time, a single-shot PRESS-localized and edited 8.1-ms TE POCE-MRS sequence with optimal sensitivity, editing efficiency, and localization.

KEYWORDS:

1H-[13C] MRS; POCE; SEAL-PRESS; [1,6-13C2] glucose infusion; localized 13C edited MRS; short TE

PMID:
29427395
DOI:
10.1002/mrm.27119

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