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    題名: Stimulated echo induced misestimates on diffusion tensor indices and its remedy
    作者: 蔡尚岳
    Tsai, Shang-Yueh;Chuang,Tzu-Chao;Wu,Ming-Ting;Huang,Teng-Yi;Lin,Yi-Ru;Chang, Hing-Chiu
    貢獻者: 應物所
    關鍵詞: diffusion-weighted imaging;eddy current;twice-refocused spin-echo;stimulated echo;apparent diffusion coefficient;fractional anisotropy
    日期: 2010.05
    上傳時間: 2014-05-01 17:54:05 (UTC+8)
    摘要: diffusion-weighted imaging;eddy current;twice-refocused spin-echo;stimulated echo;apparent diffusion coefficient;fractional anisotropy
    PURPOSE: To report possible erroneous estimates of diffusion parameters in the twice-refocused spin-echo (TRSE) technique, proposed to eliminate eddy-current-induced geometric distortions in diffusion-weighted echo-planar imaging, when stimulated echo signals are inappropriately included. MATERIALS AND METHODS: Eleven subjects were included for imaging experiments on two 1.5 Tesla systems using the TRSE sequence. Three versions, two with unbalanced crusher gradients inserted to dephase the stimulated echo from the b = 0 images and one with balanced crusher gradients, were implemented. The apparent diffusion coefficients (ADC) and fractional anisotropy (FA) were derived and compared. RESULTS: The ADCs obtained with unbalanced crusher gradients were closer to values reported in the literature. Stimulated echo led to ADC over-estimations by 34.2%, 50.4%, 54.0%, 51.5%, 24.0%, and 41.9% in the genu of corpus callosum, splenium of corpus callosum, bilateral corona radiata, internal capsule, mediofrontal gyrus, and the cuneus, respectively (P < 0.01), with concomitant reduction in FA in highly anisotropic regions. Over-estimations of diffusion coefficients were found to be roughly equal along all directions. CONCLUSION: Formation of stimulated echo in the TRSE technique can lead to erroneous estimations of the diffusion parameters, even if no prominent morphological artifacts are seen.
    關聯: J Magn Reson Imaging, 31(6), 1522-1529
    資料類型: article
    顯示於類別:[應用物理研究所 ] 期刊論文

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