Frequency-dependent diffusion kurtosis imaging in the human brain using an oscillating gradient spin echo sequence and a high-performance head-only gradient.
Frequency-dependent diffusion kurtosis imaging in the human brain using an oscillating gradient spin echo sequence and a high-performance head-only gradient.
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DOI：
10.1016/j.neuroimage.2023.120328
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发表时间：
2023-10-01
期刊：
影响因子：
5.7
通讯作者：
Mcnab, Jennifer A.
中科院分区：
文献类型：
--
作者：
Dai, Erpeng;Zhu, Ante;Yang, Grant K.;Quah, Kristin;Tan, Ek T.;Fiveland, Eric;Foo, Thomas K. F.;Mcnab, Jennifer A.
关键词：
测量磁共振扩散成像的时间/频率相关性是区分不同组织微环境的一种很有前途的方法，如膜限制、组织异质性和隔室水交换。在这项研究中，我们使用高性能、仅限头部的Magnus梯度系统，结合b值、振荡频率(F)和回声时间，在人脑中使用振荡梯度扩散编码波形和扩散峰度成像(DKI)模型测量扩散率(D)和峰度(K)的频率依赖性，这在以前的人类研究中尚未实现。在整体和局部白质(WM)和灰质(GM)区域观察到扩散系数和峰度的频率依赖性，并用幂定律模型~Λ*fθ进行表征。扩散系数和峰度的频率依赖关系(包括fmin和fmax、Λ和θ之间的变化)在不同的WM和Gm区域上不同，表明区域之间潜在的微结构差异。在活体人类大脑中，成功地捕捉到了在短时间内峰度随频率降低的趋势。研究并修正了梯度非线性(GNL)对频率相关扩散系数和峰度测量的影响。我们的结果表明，全球大气环流对测量的扩散系数值有显著的标度效应(全球WM相差3.5~5.5%，全球皮层相差6~8%)，进而影响相应的幂定律参数(Λ，θ)，而对测量的峰度值(<；0.05%差)和幂定律参数(Λ，θ)影响不大。这项研究扩展了以往的OGSE研究，进一步证明了频率相关的扩散率和峰度测量对人脑的可译性，这可能为探索健康和疾病中的人脑微结构提供新的机会。
Measuring the time/frequency dependence of diffusion MRI is a promising approach to distinguish between the effects of different tissue microenvironments, such as membrane restriction, tissue heterogeneity, and compartmental water exchange. In this study, we measure the frequency dependence of diffusivity (D) and kurtosis (K) with oscillating gradient diffusion encoding waveforms and a diffusion kurtosis imaging (DKI) model in human brains using a high-performance, head-only MAGNUS gradient system, with a combination of b-values, oscillating frequencies (f), and echo time that has not been achieved in human studies before. Frequency dependence of diffusivity and kurtosis are observed in both global and local white matter (WM) and gray matter (GM) regions and characterized with a power-law model ~Λ*fθ. The frequency dependences of diffusivity and kurtosis (including changes between fmin and fmax, Λ, and θ) vary over different WM and GM regions, indicating potential microstructural differences between regions. A trend of decreasing kurtosis over frequency in the short-time limit is successfully captured for in vivo human brains. The effects of gradient nonlinearity (GNL) on frequency-dependent diffusivity and kurtosis measurements are investigated and corrected. Our results show that the GNL has prominent scaling effects on the measured diffusivity values (3.5~5.5% difference in the global WM and 6~8% difference in the global cortex) and subsequently affects the corresponding power-law parameters (Λ, θ) while having a marginal influence on the measured kurtosis values (<0.05% difference) and power-law parameters (Λ, θ). This study expands previous OGSE studies and further demonstrates the translatability of frequency-dependent diffusivity and kurtosis measurements to human brains, which may provide new opportunities to probe human brain microstructure in health and disease.
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