Application of Coherence Analysis Method on fMRI and Resting-state fMRI

• Main Authors: Chia-Fang Chen, 陳家芳
• Other Authors: Jyh-Horng Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/44616099874473461448

碩士 === 國立臺灣大學 === 電機工程學研究所 === 92 === A new direction in studying interregional functional connectivity using magnetic resonance imaging (fMRI) in addition to structure connectivity and effective connectivity. The basic hypothesis of functional connectivity is the high linear temporal relationship in the relevant information about the interactions of brain regions at the same time. The relevant brain regions with high linear temporal relationship induce the result that synchronicity of low frequency fluctuations in functional related regions. Using functional connectivity MR(fcMR) imaging‚research workers identified very low frequency (<0.1 Hz) fluctuations in the signal of the resting brain‚revealing a high degree of temporal correlation‚and is a evidence of the existence of neuronal connections characterizing a widespread cortical network. By adopting relationship in frequency domain‚ coherence analysis method is presented on the thesis for conventional fMRI and resting-state fMRI. Otherwise‚ I use cross spectral density function in the coherence analysis method to discuss the phase delay and phase lead. The thesis adopts phantom tests with ROC (Receiver operating characteristic) curve analysis to compare cross correlation analysis method with coherence analysis method on Bruker MedSpec 3T system‚ and according to the advantage of coherence analysis method to analysis conventional fMRI and resting-state fMRI. This reseach designed a phase delay fMRI experiment‚ and used coherence analysis method to find the phase delay. This thesis successfully discover the coherence maps and phase maps on the different frequency (0.025Hz and 0.08Hz), and the result shows different frequency in the very low frequency (<0.1Hz) perform distinct maps. Recently for the purpose of excluding physiological noise aliasing to the low frequency signals which we want to observe‚ TR(repetition time) should be shortened to the value under 400ms (effective frequency band is 1.25Hz). This will lead to not enough special resolution which is an essential topic for future study.