Rademacher J, Engelbrecht V, Bürgel U, Freund H, Zilles K
Department of Neurology, Department of Radiology, C. & O. Vogt Institute for Brain Research and Institute of Neuroanatomy, Heinrich-Heine University, D-40225, Düsseldorf, Germany.
Neuroimage. 1999 Apr;9(4):393-406. doi: 10.1006/nimg.1998.0416.
Precise characterization of white matter pathways is important for the understanding of structural-functional relationships in the human brain. While it is known from postmortem studies that the connectivity of cortical areas is conveyed by projection, commissural, and association fibers, most clinical studies disregard useful information about specific fiber tracts. Magnetization transfer (MT) MR detects the relative proportion of free mobile protons and immobile protons bound to macromolecules. MT values correlate with histopathology and it has been proposed that in the white matter, the amount of magnetization transfer correlates with the degree of myelination. Thus, MT-MR provides measures that may reflect more accurately the physiology and natural course of diseases involving the white matter. We applied this quantitative in vivo method to five children at different ages to determine whether the maturational changes of distinct fiber tracts could be measured. All regions of interest were localized by means of Brodmann's original descriptions and the additional use of reconstructed 3D-matched data from 10 myelin-stained human brain specimens. With this atlas-guided approach we localized and measured 26 supratentorial white matter fiber tracts in each hemisphere, connecting to primary as well as association cortices. All fiber tracts showed consistent age-related MT changes and the strongest effects were found in those tracts projecting to the primary cortical areas. These results suggest that our method is suitable for in vivo MT measurements in specific fiber tracts. It can provide data that relate to myelination during ontogenesis or myelination delays in myelin disorders. In the clinical domain, the focus on specific fiber tracts appears to be advantageous over standard approaches, because such system of parcellation is based on the functional anatomy of the white matter. Consequently, it may be especially useful for topical analysis in neurology allowing the assessment of the functional consequences of white matter damage as well as the effectiveness of treatments in patients with any lesion that can be visualized by MRI.
精确描述白质通路对于理解人类大脑的结构-功能关系至关重要。虽然尸检研究表明皮质区域的连接是通过投射纤维、连合纤维和联合纤维来实现的，但大多数临床研究都忽略了有关特定纤维束的有用信息。磁化传递（MT）磁共振成像检测自由移动质子与结合在大分子上的固定质子的相对比例。MT值与组织病理学相关，有人提出在白质中，磁化传递量与髓鞘形成程度相关。因此，MT磁共振成像提供的测量方法可能更准确地反映涉及白质的疾病的生理状况和自然病程。我们将这种定量体内方法应用于五名不同年龄的儿童，以确定是否可以测量不同纤维束的成熟变化。所有感兴趣区域均通过布罗德曼的原始描述以及额外使用来自10个髓鞘染色人脑标本的重建3D匹配数据进行定位。通过这种图谱引导方法，我们在每个半球定位并测量了26条幕上白质纤维束，这些纤维束连接到初级皮质和联合皮质。所有纤维束均显示出与年龄相关的一致MT变化，并且在投射到初级皮质区域的那些纤维束中发现了最强的影响。这些结果表明我们的方法适用于特定纤维束的体内MT测量。它可以提供与个体发育过程中的髓鞘形成或髓鞘疾病中的髓鞘形成延迟相关的数据。在临床领域，关注特定纤维束似乎比标准方法更具优势，因为这种分割系统基于白质的功能解剖结构。因此，它对于神经学中的局部分析可能特别有用，允许评估白质损伤的功能后果以及对任何可通过MRI可视化病变的患者的治疗效果。
