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Minimum echo time PRESS ‐based proton observed carbon edited ( POCE ) MRS in rat brain using simultaneous editing and localization pulses
Author(s) -
Kumaragamage Chathura,
Madularu Dan,
Mathieu Axel P.,
Lupinsky Derek,
Graaf Robin A.,
Near Jamie
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27119
Subject(s) - sequence (biology) , chemistry , in vivo , ex vivo , pulse sequence , nuclear magnetic resonance , physics , biochemistry , in vitro , biology , microbiology and biotechnology
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/J HC . 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 C 2 ‐Glc infusion, and on a microwave fixed rat brain following a 2‐hour [1,6‐ 13 C 2 ]‐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.