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Scalar coupling and zero‐quantum coherence relaxation in STEAM: Implications for spectral editing of lactate
Author(s) -
Kingsley Peter B.
Publication year - 1994
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.1910310311
Subject(s) - coherence (philosophical gambling strategy) , amplitude , physics , scalar (mathematics) , chemistry , pulse sequence , coherence time , quantum , nuclear magnetic resonance , relaxation (psychology) , atomic physics , quantum mechanics , analytical chemistry (journal) , mathematics , psychology , social psychology , geometry , chromatography
Accurate values were obtained for the lactate zero‐quantum coherence frequency, ω ZQ = ω i ‐ω s = CH 3 –CH chemical shift difference, and scalar coupling constant, J, by using the methyl signal's amplitude modulation during the TM period of a STEAM sequence, 90°– TE /2–90°–TM–90°– TE /2‐ Acquire. Although most previous work has used J = 7.35 Hz, or 1/ J = 136 ms, the actual value is J = 6.93 ± 0.05 Hz or 1/ J = 144.3 ± 1 ms. In addition, the CH 3 –CH chemical shift difference = 2.7956 ± 0.0005 ppm, and the relaxation time for zero‐quantum coherence, T ZQ , was much shorter than either T 2 or T 1 for the methyl resonance. A small component of the signal with TE = 144 ms, which was not modulated at the zero‐quantum coherence frequency or by scalar coupling, was assigned to longitudinal two‐spin order magnetization (I z S z ) created by imperfect radio frequency pulse profiles. This information will allow improved editing of the lactate signal and more accurate quantitation of lactate concentrations.