Investigating the effect of phase cycling schemes on the measurement of GABA using MEGA-PRESS

• Main Authors: Chih-Ling Liang, 梁芷綾
• Other Authors: Yi-Ru Lin
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/22460233389435104490

碩士 === 國立臺灣科技大學 === 電子工程系 === 104 === GABA (γ-Aminobutyric acid) as a major inhibitory neurotransmitter in human brain plays an important role in central nervous system. Proton Magnetic Resonance Spectroscopy (1H MRS) is a non-invasively tool that provides measurement of in vivo metabolic concentrations. However, GABA is only present in human brain at millimolar levels and its resonance frequency overlaps with other metabolites having over 100 times higher signals than GABA. The most common method used to detect GABA is MEshcher–GArwood Point RESolved Spectroscopy (MEGA-PRESS) which is a spectral editing MRS method. In this study, we compared the spectral quality of GABA using 4 kinds of phase cycling schemes (w/o PC, PC4, PC16 and Inter4) in dorsal lateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). In conclusions, our results showed that phase cycling is necessary for MEGA-PRESS to ensure stable GABA shape. However, subtraction artifacts may occur at the presence of frequency drift between edit on and edit off spectra, so lower phase cycling steps are suggested to ensure GABA spectral quality and to avoid subtraction artifacts