A comparison of inhomogeneous magnetization transfer, myelin volume fraction, and diffusion tensor imaging measures in healthy children
A comparison of inhomogeneous magnetization transfer, myelin volume fraction, and diffusion tensor imaging measures in healthy children
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DOI：
10.1016/j.neuroimage.2017.09.019
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发表时间：
2018-11-15
期刊：
影响因子：
5.7
通讯作者：
Lebel, Catherine
中科院分区：
文献类型：
--
作者：
Geeraert, Bryce L.;Lebel, R. Marc;Lebel, Catherine
髓鞘的敏感和特异性生物标志物可以帮助定义基线脑健康和发育，识别和监测疾病病理，并评估对髓鞘含量受影响的治疗反应。扩散测量，如径向扩散率（RD）通常用于评估髓鞘含量，但不特定于髓鞘。非均匀磁化传递（ihMT）和多组分驱动的平衡单脉冲观察T1和T2（mcDESPOT）提供了定量参数（qihMT和髓鞘体积分数/VFm，分别），这被认为具有提高的灵敏度髓鞘。我们在一个由23名8-13岁健康儿童组成的队列中比较了RD、qihMT和VFm，以评估这些指标的相似性和差异。所有3个测量值在脑体素中均显著相关，但VFm和qihMT的相关性（qihMT-VFm r = 0.89）显著强于任一测量值与RD的相关性（RD-qihMT r =-0.66，RD-VFm r = -0.74;所有p均< 0.001）。平均参数不同的几个区域，特别是在皮质下灰质。这些差异可能是由每种测量对非髓鞘因素的独特敏感性来解释的，例如交叉纤维几何形状、轴突堆积、纤维取向、神经胶质密度或体素中的磁化传递效应。我们还观察到qihMT在白色物质中的取向依赖性，使得qihMT随着纤维取向从平行到垂直于B-0而降低。所有的措施似乎是敏感的髓鞘含量，虽然qihMT和VFm似乎是更具体的比RD。扫描时间、噪声容限和分辨率要求可以告知研究人员为特定应用选择适当的测量。
Sensitive and specific biomarkers of myelin can help define baseline brain health and development, identify and monitor disease pathology, and evaluate response to treatment where myelin content is affected. Diffusion measures such as radial diffusivity (RD) are commonly used to assess myelin content, but are not specific to myelin. Inhomogeneous magnetization transfer (ihMT) and multicomponent driven equilibrium single-pulse observation of T1 and T2 (mcDESPOT) offer quantitative parameters (qihMT and myelin volume fraction/VFm, respectively) which are suggested to have improved sensitivity to myelin. We compared RD, qihMT, and VFm in a cohort of 23 healthy children aged 8-13 years to evaluate the similarities and differences across these measures. All 3 measures were significantly related across brain voxels, but VFm and qihMT were significantly more strongly correlated (qihMT-VFm r = 0.89) than either measure was with RD (RD-qihMT r = -0.66, RD-VFm r = -0.74; all p < 0.001). Mean parameters differed in several regions, especially in subcortical gray matter. These differences can likely be explained by unique sensitivities of each measure to non-myelin factors, such as crossing fiber geometry, axonal packing, fiber orientation, glial density, or magnetization transfer effects in a voxel. We also observed an orientation dependence of qihMT in white matter, such that qihMT decreased as fiber orientation went from parallel to perpendicular to B-0. All measures appear to be sensitive to myelin content, though qihMT and VFm appear to be more specific to it than RD. Scan time, noise tolerance, and resolution requirements may inform researchers of the appropriate measure to choose for a specific application.