Premium
Versatile pulse sequence device to conserve hyperpolarization for NMR and MRI studies
Author(s) -
Ghosh Rajat K.,
Kuzma Nicholas N.,
Kadlecek Stephen J.,
Rizi Rahim R.
Publication year - 2016
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.25679
Subject(s) - pulse sequence , singlet state , excitation , hyperpolarization (physics) , adiabatic process , scalar (mathematics) , polarizer , polarization (electrochemistry) , population , nuclear magnetic resonance , computational physics , physics , chemistry , atomic physics , nuclear magnetic resonance spectroscopy , optics , mathematics , quantum mechanics , birefringence , demography , sociology , geometry , excited state
Purpose Levitt and co‐workers have described the M2S pulse sequence which transfers between longitudinal and singlet spin order. Building on this work, we describe the construction of a portable M2S pulse sequence generator to increase the relaxation time of polarized compounds. Additionally, we investigate the efficiency of spin order transfer under conditions where physical parameters of the system are not known precisely. Theory and Methods A portable M2S generator is built. Longitudinally polarized N 2 O is converted to the singlet state by both adiabatic transfer and by the M2S sequence. Density matrix simulations are used to model the effects of mismatched chemical shift, flip angle, and scalar couplings. Results Density matrix simulations suggest that to convert 95% of the longitudinal m = 1 triplet state population to the singlet order we must match the Larmor precession frequency to the excitation radiofrequency field by 10%, the scalar couplings must be determined to better than 0.6%, and the flip angle must be calibrated to better than 2%. Conclusion The sequence is robust against many mismatched physical parameters of the species we are converting. Additionally, the instrument's portability allows for the conversion of hyperpolarized species near a polarizer. The lifetime is increased by ∼12‐fold. This is highly advantageous in systems where the hyperpolarized media relax rapidly. Magn Reson Med 75:1822–1830, 2016. © 2015 Wiley Periodicals, Inc.