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Spatial effects in the detection of γ‐aminobutyric acid: Improved sensitivity at high fields using inner volume saturation
Author(s) -
Edden Richard A.E.,
Barker Peter B.
Publication year - 2007
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.21383
Subject(s) - saturation (graph theory) , sensitivity (control systems) , nuclear magnetic resonance , volume (thermodynamics) , chemistry , physics , mathematics , thermodynamics , combinatorics , electronic engineering , engineering
The MEGA‐PRESS‐IVS method has been developed, which combines MEGA (a frequency‐selective editing technique) editing with the point‐resolved spectroscopy sequence (PRESS) and inner volume saturation (IVS) localization, reducing the deleterious effects of spatial variation in coupling evolution. The IVS method has been previously described for improved efficiency of lactate detection. The current study demonstrates that the combination of MEGA‐PRESS with IVS results in increased sensitivity for edited single‐voxel measurements of glutamate and γ‐aminobutyric acid (GABA). A four‐compartment model of coupling evolution is investigated through simple product operators and full spin‐system simulations and the predicted pattern of signal evolution is demonstrated through MEGA‐PRESS‐MRSI. MEGA‐PRESS‐IVS is then compared to MEGA‐PRESS in a phantom and an average signal increase of 24% is demonstrated in five healthy volunteers. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.