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In vivo 31 P spectroscopy by fully adiabatic extended image selected in vivo spectroscopy: A comparison between 3 T and 7 T
Author(s) -
Bogner W.,
Chmelik M.,
Andronesi O. C.,
Sorensen A. G.,
Trattnig S.,
Gruber S.
Publication year - 2011
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.22897
Subject(s) - spectroscopy , nuclear magnetic resonance , imaging phantom , pulse sequence , physics , nuclear magnetic resonance spectroscopy , voxel , reproducibility , isotropy , chemistry , optics , computer science , artificial intelligence , quantum mechanics , chromatography
An improved image selected in vivo spectroscopy (ISIS) sequence for localized 31 P magnetic resonance spectroscopy at 7 T was developed. To reduce errors in localization accuracy, adiabatic excitation, gradient offset independent adiabatic inversion pulses, and a special extended ISIS ordering scheme were used. The localization accuracy of extended ISIS was investigated in phantoms. The possible spectral quality and reproducibility in vivo was explored in a volunteer (brain, muscle, and liver). A comparison between 3 T and 7 T was performed in five volunteers. Adiabatic extended ISIS provided high spectral quality and accurate localization. The contamination in phantom experiments was only ∼5%, even if a pulse repetition time ∼ 1.2· T 1 was chosen to maximize the signal‐to‐noise ratio per unit time. High reproducibility was found in the calf muscle for 2.5 cm isotropic voxels at 7 T. When compared with 3 T, localized 31 P magnetic resonance spectroscopy in the human calf muscle at 7 T provided ∼3.2 times higher signal‐to‐noise ratio (as judged from phosphocreatine peak amplitude in frequency domain after matched filtering). At 7 T, extended ISIS allowed the performance of high‐quality localized 31 P magnetic resonance spectroscopy in a short measurement time (∼3 to 4 min) and isotropic voxel sizes of ∼2.5 to 3 cm. With such short measurement times, localized 31 P magnetic resonance spectroscopy has the potential to be applied not only for clinical research but also for routine clinical practice. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.