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Exchange kinetics by inversion transfer: Integrated analysis of the phosphorus metabolite kinetic exchanges in resting human skeletal muscle at 7 T
Author(s) -
Ren Jimin,
Yang Baolian,
Sherry A. Dean,
Malloy Craig R.
Publication year - 2015
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.25256
Subject(s) - magnetization transfer , chemistry , magnetization , nuclear magnetic resonance , kinetic energy , metabolite , skeletal muscle , kinetics , relaxation (psychology) , analytical chemistry (journal) , biophysics , magnetic field , biochemistry , magnetic resonance imaging , physics , anatomy , biology , medicine , quantum mechanics , chromatography , neuroscience , radiology
Purpose To develop an inversion pulse‐based, chemical exchange saturation transfer‐like method for detection of 31 P magnetization exchanges among all nuclear magnetic resonance visible metabolites suitable for providing an integrated kinetic analysis of phosphorus exchange reactions in vivo. Methods The exchange kinetics by inversion transfer (EKIT) sequence includes application of a frequency‐selective inversion pulse arrayed over the range of relevant 31 P frequencies, followed by a constant delay and a hard readout pulse. A series of EKIT spectra, each given by a plot of Z ‐magnetization for each metabolite of interest versus frequency of the inversion pulse, can be generated from this single data set. Results EKIT spectra reflect chemical exchange due to known biochemical reactions, cross‐relaxation effects, and relayed magnetization transfers due to both processes. The rate constants derived from EKIT data collected on resting human skeletal muscle were: ATP synthesis via ATP synthase (0.050 ± 0.016 s −1 ), ATP synthesis via creatine kinase (0.264 ± 0.023 s −1 ), and cross‐relaxation between neighboring spin pairs within ATP (0.164 ± 0.022 s −1 ). Conclusion EKIT provides a simple, alternative method to detect chemical exchange, cross relaxation, and relayed magnetization transfer effects in human skeletal muscle at 7 T. Magn Reson Med 73:1359–1369, 2015. © 2014 Wiley Periodicals, Inc.