Watts Richard, Liston Conor, Niogi Sumit, Uluğ Aziz M
Departments of Radiology, Psychiatry and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021, USA.
Ment Retard Dev Disabil Res Rev. 2003;9(3):168-77. doi: 10.1002/mrdd.10077.
Diffusion tensor imaging is unique in its ability to noninvasively visualize white matter fiber tracts in the human brain in vivo. Diffusion is the incoherent motion of water molecules on a microscopic scale. This motion is itself dependent on the micro-structural environment that restricts the movement of the water molecules. In white matter fibers there is a pronounced directional dependence on diffusion. With white matter fiber tracking or tractography, projections among brain regions can be detected in the three-dimensional diffusion tensor dataset according to the directionality of the fibers. Examples of developmental changes in diffusion, tracking of major fiber tracts, and examples of how diffusion tensor tractography and functional magnetic resonance imaging can be combined are provided. These techniques are complimentary and allow both the identification of the eloquent areas of the brain involved in specific functional tasks, and the connections between them. The noninvasive nature of magnetic resonance imaging will allow these techniques to be used in both longitudinal developmental and diagnostic studies. An overview of the technique and preliminary applications are presented, along with its current limitations.
扩散张量成像的独特之处在于其能够在活体状态下无创地可视化人类大脑中的白质纤维束。扩散是水分子在微观尺度上的非相干运动。这种运动本身取决于限制水分子运动的微观结构环境。在白质纤维中，扩散存在明显的方向依赖性。通过白质纤维追踪或纤维束成像，可以根据纤维的方向性在三维扩散张量数据集中检测脑区之间的投射。文中提供了扩散的发育变化示例、主要纤维束的追踪示例，以及扩散张量纤维束成像与功能磁共振成像如何结合的示例。这些技术相辅相成，既能识别参与特定功能任务的大脑明确区域，又能确定它们之间的连接。磁共振成像的无创特性将使这些技术可用于纵向发育研究和诊断研究。本文介绍了该技术的概述、初步应用及其当前局限性。
