J-difference editing of gamma-aminobutyric acid (GABA): Simulated and experimental multiplet patterns
Version of Record online: 4 DEC 2012
Copyright © 2012 Wiley Periodicals, Inc.
Magnetic Resonance in Medicine
Volume 70, Issue 5, pages 1183–1191, November 2013
How to Cite
Near, J., Evans, C. J., Puts, N. A. J., Barker, P. B. and Edden, R. A. E. (2013), J-difference editing of gamma-aminobutyric acid (GABA): Simulated and experimental multiplet patterns. Magn Reson Med, 70: 1183–1191. doi: 10.1002/mrm.24572
- Issue online: 25 OCT 2013
- Version of Record online: 4 DEC 2012
- Manuscript Accepted: 26 OCT 2012
- Manuscript Revised: 10 OCT 2012
- Manuscript Received: 13 SEP 2012
- NIH. Grant Numbers: P41 EB015909, R21 NS077300
- J-difference editing
Purpose: To investigate factors that influence the multiplet pattern observed in J-difference editing of gamma-aminobutyric acid (GABA).
Methods: Density matrix simulations were applied to investigate the shape of the 3 ppm GABA multiplet as a function of the editing sequence's slice-selective refocusing pulse properties, in particular bandwidth, transition width, and flip angle. For comparison to the calculations, experimental measurements were also made at 3 T on a 10 mM GABA solution using the MEGA-PRESS sequence at various refocusing pulse flip angles.
Results: Good agreement was found between experiments and simulations. The edited multiplet consists of two outer lines of slightly unequal intensity due to strong coupling, and a smaller central line, the result of the unequal J-couplings between the C4 and C3 protons. The size of the center peak increases with increasing slice-selective refocusing pulse transition width, and deviation of the flip angle from 180°.
Conclusion: The 3 ppm GABA multiplet pattern observed in the MEGA-PRESS experiment depends quite strongly on the properties of the slice-selective refocusing pulses used. Under some circumstance, the central peak can be quite large; this does not necessarily indicate inefficient editing, or a subtraction artifact, but should be recognized as a property of the pulse sequence itself. Magn Reson Med 70:1183–1191, 2013. © 2012 Wiley Periodicals, Inc.