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Efficient 1 H to 31 P polarization transfer on a clinical 3T MR system
Author(s) -
Klomp D.W.J.,
Wijnen J.P.,
Scheenen T.W.J.,
Heerschap A.
Publication year - 2008
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.21733
Subject(s) - homonuclear molecule , nuclear magnetic resonance , polarization (electrochemistry) , coupling constant , spins , analytical chemistry (journal) , chemistry , physics , atomic physics , molecule , organic chemistry , particle physics , chromatography , condensed matter physics
31 P MR spectroscopy (MRS) in the detection of phosphocholine (PC), glycerolphosphocholine (GPC), phosphorylelthanolamine (PE), and glycerolphosphoethanolamine (GPE) compounds has shown clinical potential at 1.5T for several human diseases. The use of 1 H to 31 P polarization transfer can improve the sensitivity using a refocused INEPT method with a potential enhancement of 2.4 (γ 1H /γ 31P ). However, in this method the 31 P signals of PE, PC, GPE, and GPC are strongly attenuated (50% or more) due to J‐coupling between 31 P and 1 H that have similar magnitudes for homonuclear J‐coupling constants in those metabolites. A method to cancel the homonuclear J‐coupling effects in polarization transfer experiments is to apply frequency‐selective refocusing pulses, which becomes feasible at 3T due to the increased chemical shift dispersion as compared to 1.5T. In this study, full 1 H to 31 P polarization transfer was realized using chemical shift selective refocusing pulses at 3T. T 1 and T 2 values for 1 H and 31 P spins of PE, PC, GPE, and GPC were measured in the human brain. A more than 2‐fold signal‐to‐noise ratio (SNR) improvement was obtained compared to an optimized direct 31 P MRS method. As shifted RF pulses were used, this method can be applied on a broadband clinical MR system with a single RF system. Magn Reson Med 60:1298–1305, 2008. © 2008 Wiley‐Liss, Inc.