Effect of myelin water exchange on DTI-derived parameters in diffusion MRI: Elucidation of TE dependence
Effect of myelin water exchange on DTI-derived parameters in diffusion MRI: Elucidation of TE dependence
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DOI：
10.1002/mrm.26812
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发表时间：
2018-03-01
影响因子：
3.3
通讯作者：
Zhong, Jianhui
中科院分区：
文献类型：
--
作者：
Lin, Mu;He, Hongjian;Zhong, Jianhui
脑组织不同神经元间存在水交换，但在大多数扩散模型中往往被忽略。目前的研究的目标是证明扩散测量回声时间（TE）在人脑中的依赖性，并探讨髓鞘水exchanges.MethodsFive健康受试者的潜在影响进行了检查与单次脉冲梯度自旋回波平面成像与固定的持续时间（）和分离（）的扩散梯度脉冲和一组不同的TE。用Monte Carlo模拟研究了细胞内水交换和固有T-2差对TE的影响。结果体内测量和模拟结果均表明，各向异性分数（FA）和轴向扩散系数（AD）与TE呈正相关，而径向扩散系数（RD）与TE呈负相关，这与以前的研究结果一致。模拟结果进一步表明TE依赖性的敏感性的g-ratio.ConclusionThe交换髓鞘和内/外轴突水池之间往往起着不可忽视的作用，在所观察到的TE依赖性的扩散参数，这可能伴随或改变的影响，内在的T-2在造成这种依赖性。TE依赖性可能潜在地用作脱髓鞘过程的生物标志物（例如，多发性硬化症和阿尔茨海默病）。Magn Reson Med 79：1650-1660，2018。(c)2017年国际医学磁共振学会。
PurposeWater exchange exists between different neuronal compartments of brain tissue but is often ignored in most diffusion models. The goal of the current study was to demonstrate the dependence of diffusion measurements on echo time (TE) in the human brain and to investigate the underlying effects of myelin water exchange.MethodsFive healthy subjects were examined with single-shot pulsed-gradient spin-echo echo-planar imaging with fixed duration () and separation () of diffusion gradient pulses and a set of varying TEs. The effects of water exchange and intrinsic T-2 difference in cellular environments were investigated with Monte Carlo simulations.ResultsBoth in vivo measurements and simulations showed that fractional anisotropy (FA) and axial diffusivity (AD) had positive correlations with TE, while radial diffusivity (RD) showed a negative correlation, which is consistent with a previous study. The simulation results further indicated the sensitivity of TE dependence to the change of g-ratio.ConclusionThe exchange between myelin and intra/extra-axonal water pools often plays a non-negligible role in the observed TE dependence of diffusion parameters, which may accompany or alter the effect of intrinsic T-2 in causing such dependence. The TE dependence may potentially serve as a biomarker for demyelination processes (e.g., in multiple sclerosis and Alzheimer's disease). Magn Reson Med 79:1650-1660, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.