De Santis Silvia, Assaf Yaniv, Jeurissen Ben, Jones Derek K, Roebroeck Alard
CUBRIC, School of Psychology, Cardiff University, Cardiff CF24 4HQ,UK; Maastricht University, Maastricht, The Netherlands.
Department of Neurobiology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Neuroimage. 2016 Nov 1;141:133-142. doi: 10.1016/j.neuroimage.2016.07.037. Epub 2016 Jul 19.
A comprehensive tract-based characterisation of white matter should include the ability to quantify myelin and axonal attributes irrespective of the complexity of fibre organisation within the voxel. Recently, a new experimental framework that combines inversion recovery and diffusion MRI, called inversion recovery diffusion tensor imaging (IR-DTI), was introduced and applied in an animal study. IR-DTI provides the ability to assign to each unique fibre population within a voxel a specific value of the longitudinal relaxation time, T1, which is a proxy for myelin content. Here, we apply the IR-DTI approach to the human brain in vivo on 7 healthy subjects for the first time. We demonstrate that the approach is able to measure differential tract properties in crossing fibre areas, reflecting the different myelination of tracts. We also show that tract-specific T1 has less inter-subject variability compared to conventional T1 in areas of crossing fibres, suggesting increased specificity to distinct fibre populations. Finally we show in simulations that changes in myelination selectively affecting one fibre bundle in crossing fibre areas can potentially be detected earlier using IR-DTI.
对白质进行全面的基于纤维束的特征描述应包括能够量化髓鞘和轴突属性，而不论体素内纤维组织的复杂性如何。最近，一种结合反转恢复和扩散磁共振成像的新实验框架——反转恢复扩散张量成像（IR-DTI）被引入并应用于一项动物研究中。IR-DTI能够为体素内每个独特的纤维群体赋予纵向弛豫时间T1的特定值，T1是髓鞘含量的一个替代指标。在此，我们首次将IR-DTI方法应用于7名健康受试者的活体人脑。我们证明该方法能够测量交叉纤维区域的不同纤维束特性，反映纤维束不同的髓鞘形成情况。我们还表明，在交叉纤维区域，与传统T1相比，特定纤维束的T1在受试者间的变异性较小，这表明对不同纤维群体的特异性增加。最后，我们在模拟中表明，使用IR-DTI可能能够更早地检测到在交叉纤维区域选择性影响一个纤维束的髓鞘形成变化。
