Myelin and iron concentration in the human brain: A quantitative study of MRI contrast
Myelin and iron concentration in the human brain: A quantitative study of MRI contrast
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DOI：
10.1016/j.neuroimage.2014.02.026
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发表时间：
2014-06-01
期刊：
影响因子：
5.7
通讯作者：
Turner, Robert
中科院分区：
文献类型：
--
作者：
Stueber, Carsten;Morawski, Markus;Turner, Robert
在过去的五年里，超高场磁共振成像（MRI）为活体人类大脑提供了前所未有的视角。已知大多数MRI序列中的脑组织对比度主要反映髓鞘和铁的空间分布。这些分布已经被证明在许多大脑区域，特别是在皮层中明显重叠。它是越来越感兴趣的区分和识别皮质区的外观在MRI中，这已被证明是可行的，在体内。通过量化铁和髓磷脂对MRI对比度的独立贡献，可以极大地提高分割效果。最近的研究使用磁化率映射声称，允许这样的分离髓鞘和铁在MRI中的作用。我们使用死后人脑组织证明，这一目标是可以实现的。MRI扫描后，块适当的T-1映射和T-2* 加权序列，我们部分块和应用一种新的技术，质子诱导X射线发射（PIXE），空间映射铁，磷和硫元素的浓度，同时与1 μ m的空间分辨率。因为大多数脑磷位于髓磷脂中，所以利用硫的元素图的校准步骤能够实现髓磷脂浓度的半定量离体映射。将铁和髓鞘浓度的结果结合在线性模型中，我们准确地建模了MRI组织对比度。相反，铁和髓磷脂浓度现在可以通过适当的MRI测量来估计死后大脑样本。(C)2014爱思唯尔公司All rights reserved.
During the last five years ultra-high-field magnetic resonance imaging (MRI) has enabled an unprecedented view of living human brain. Brain tissue contrast in most MRI sequences is known to reflect mainly the spatial distributions of myelin and iron. These distributions have been shown to overlap significantly in many brain regions, especially in the cortex. It is of increasing interest to distinguish and identify cortical areas by their appearance in MRI, which has been shown to be feasible in vivo. Parcellation can benefit greatly from quantification of the independent contributions of iron and myelin to MRI contrast. Recent studies using susceptibility mapping claim to allow such a separation of the effects of myelin and iron in MRI. We show, using post-mortem human brain tissue, that this goal can be achieved. After MRI scanning of the block with appropriate T-1 mapping and T-2* weighted sequences, we section the block and apply a novel technique, proton induced X-ray emission (PIXE), to spatially map iron, phosphorus and sulfur elemental concentrations, simultaneously with 1 mu m spatial resolution. Because most brain phosphorus is located in myelin phospholipids, a calibration step utilizing element maps of sulfur enables semi-quantitative ex vivo mapping of myelin concentration. Combining results for iron and myelin concentration in a linear model, we have accurately modeled MRI tissue contrasts. Conversely, iron and myelin concentrations can now be estimated from appropriate MRI measurements in post-mortem brain samples. (C) 2014 Elsevier Inc. All rights reserved.