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Effect of strong homonuclear proton coupling on localized 13 C detection using PRESS
Author(s) -
Yahya and Atiyah,
Allen Peter S.
Publication year - 2005
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.20725
Subject(s) - homonuclear molecule , proton , nuclear magnetic resonance , coupling (piping) , physics , chemistry , nuclear physics , materials science , molecule , quantum mechanics , metallurgy
The effect of strong homonuclear proton coupling on 13 C incorporation measurements by either indirect or direct means was investigated (and illustrated with glutamate) both numerically and experimentally at 3.0 T. In particular, two sequences were considered, each using a proton PRESS sequence for localization. The indirect 13 C detection method incorporated the POCE (proton observe carbon edited) technique onto PRESS, and for direct 13 C detection a DEPT (distortionless enhancement by polarization transfer) sequence was appended to the PRESS localization. Both analysis and experiment demonstrate that when strong homonuclear coupling of protons is additional to heteronuclear coupling with 13 C spins, the 13 C measures derived from either the indirect PRESS‐POCE sequence or the direct‐but‐enhanced PRESS‐DEPT sequence are significantly modified. Specifically, the MR lineshapes of both 13 C‐bonded and nonbonded protons are changed during 13 C incorporation, giving rise, for example, to a potential cross‐contamination of ≤30% between glutamate 13 C 3 and 13 C 4 measures from the PRESS‐POCE indirect method. During direct‐but‐enhanced detection, the DEPT enhancement is reduced for glutamate 13 C 2 , 13 C 3 , and 13 C 4 but not equally, and the reduction is further exacerbated by proton PRESS localization, which gives rise to enhancements that are strong functions of PRESS TE 1 and TE 2 . Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.