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Lin Y.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Lin L.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Wei Z.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Chen Z.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance
Magnetic Resonance in Medicine | Year: 2015

Purpose: To acquire single voxel localized one-dimensional 1H magnetic resonance spectroscopy (MRS) without J coupling modulations, free from amplitude and phase distortions. Methods: A pulse sequence, named PRESSIR, is developed for volume localized MRS without J modulations at arbitrary echo time (TE). The J coupling evolution is suppressed by the J-refocused module that uses a 90° pulse at the midpoint of a double spin echo. Results: The localization performance of the PRESSIR sequence was tested with a two-compartment phantom. The proposed sequence shows similar voxel localization accuracy as PRESS. Both PRESSIR and PRESS sequences were performed on MRS brain phantom and pig brain tissue. PRESS spectra suffer from amplitude and phase distortions due to J modulations, especially under moderate and long TEs, while PRESSIR spectra are almost free from distortions. Conclusion: The PRESSIR sequence proposed herein enables the acquisition of single voxel in-phase MRS within a single scan. It allows an enhanced signal intensity of J coupling metabolites and reducing undesired broad resonances with short T2s while suppressing J modulations. Moreover, it provides an approach for direct measurement of nonoverlapping J coupling peaks and of transverse relaxation times T2s. © 2015 Wiley Periodicals, Inc.


Chen Y.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Zhang Z.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Lin Y.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | Cai C.,Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance | And 2 more authors.
Molecular Physics | Year: 2014

A new pulse sequence based on Hadamard encoding technique, dubbed as Hadamard encoded localised correlation spectroscopy (HLCOSY) was devised to speed up the acquisition of localised two-dimensional (2D) nuclear magnetic resonance (NMR) correlation spectroscopy (LCOSY). Direct frequency-domain (F2) excitation with an array of different radiofrequencies has been used to speed up 2D NMR experiments by a large factor. Multiplex excitation in the indirect frequency (F1) dimension is restricted to the signal-bearing regions and is encoded according to a Hadamard matrix of order N, where N is a relatively small number. The detected signals are decoded by reference to the same Hadamard matrix. An HLCOSY spectrum of a two-compartment phantom was obtained with a total acquisition time of 32 s, with its volume localisation confirmed. The success in achieving 2D LCOSY spectrum of pig marrow within 40 s shows the feasibility of HLCOSY for the detection of biological tissues. It may provide a promising way for in vivo and in vitro NMRs. © 2014 Taylor & Francis.

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