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政大機構典藏 > 理學院 > 應用物理研究所 > 期刊論文 > Item 140.119/96996

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Title:	Effects of Frequency Drift on the Quantification of Gamma-Aminobutyric Acid Using MEGA-PRES
Authors:	蔡尚岳 Tsai, Shang-Yueh;Fang, Chun-Hao;Wu, Thai-Yu;Lin, Yi-Ru
Contributors:	應物所
Date:	2016-04
Issue Date:	2016-05-30 15:23:03 (UTC+8)
Abstract:	The MEGA-PRESS method is the most common method used to measure γ-aminobutyric acid (GABA) in the brain at 3T. It has been shown that the underestimation of the GABA signal due to B0 drift up to 1.22 Hz/min can be reduced by post-frequency alignment. In this study, we show that the underestimation of GABA can still occur even with post frequency alignment when the B0 drift is up to 3.93 Hz/min. The underestimation can be reduced by applying a frequency shift threshold. A total of 23 subjects were scanned twice to assess the short-term reproducibility, and 14 of them were scanned again after 2–8 weeks to evaluate the long-term reproducibility. A linear regression analysis of the quantified GABA versus the frequency shift showed a negative correlation (P < 0.01). Underestimation of the GABA signal was found. When a frequency shift threshold of 0.125 ppm (15.5 Hz or 1.79 Hz/min) was applied, the linear regression showed no statistically significant difference (P > 0.05). Therefore, a frequency shift threshold at 0.125 ppm (15.5 Hz) can be used to reduce underestimation during GABA quantification. For data with a B0 drift up to 3.93 Hz/min, the coefficients of variance of short-term and long-term reproducibility for the GABA quantification were less than 10% when the frequency threshold was applied.
Relation:	Scientific Reports, Vol.6, pp.24564
Data Type:	article
DOI 連結:	http://dx.doi.org/10.1038/srep24564
DOI:	10.1038/srep24564
Appears in Collections:	[應用物理研究所 ] 期刊論文

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