Structural insights from high-resolution diffusion tensor imaging and tractography of the isolated rat hippocampus
Structural insights from high-resolution diffusion tensor imaging and tractography of the isolated rat hippocampus
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DOI：
10.1016/j.neuroimage.2006.04.210
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发表时间：
2006-10-01
期刊：
影响因子：
5.7
通讯作者：
Blackband, Stephen J.
中科院分区：
文献类型：
--
作者：
Shepherd, Timothy M.;Ozarslan, Evren;Blackband, Stephen J.
海马体是学习和记忆形成的关键结构，受到癫痫或阿尔茨海默病等多种神经病变的损伤。最近，临床研究尝试使用弥散张量MRI作为海马损伤的更具体的替代标志物。为了更好地了解健康海马区域的组织结构，本研究使用14.1 t磁铁在50 μ m平面图像分辨率下对10只大鼠海马进行了弥散张量成像（DTI）表征。对解剖和拉直的大鼠海马进行化学固定提供了一种简单有效的方法，可以在分割海马区域时减少部分体积效应，并提高单位时间内的平均信噪比（例如，27分钟内b = 1250 s/mm(2)时50.6 +/- 4.4）。与之前的报道相反，水在神经系统中的扩散是均匀的，在分子层和颗粒层的平均扩散率分别为0.238 +/- 0.054和0.318 +/- 0.084 μ m(2)/ms，差异有统计学意义（方差分析，P < 0.05）。不同海马亚区由于结构复杂，其各向异性分数比均匀纤维结构如胼胝体低。dti衍生的彩色纤维取向图和束状图显示了三突触海马内通路的大多数组成部分（例如，孔层分子的取向由穿孔纤维和Schaffer纤维主导），也允许对大鼠海马的连接进行一些评估。(c) 2006爱思唯尔公司版权所有。
The hippocampus is a critical structure for learning and memory formation injured by diverse neuropathologies such as epilepsy or Alzheimer's disease. Recently, clinical investigations have attempted to use diffusion tensor MRI as a more specific surrogate marker for hippocampal damage. To first better understand the tissue architecture of healthy hippocampal regions, this study characterized 10 rat hippocampi with diffusion tensor imaging (DTI) at 50-mu m in-plane image resolution using a 14.1-T magnet. Chemical fixation of the dissected and straightened rat hippocampus provided a simple, effective way to reduce partial volume effects when segmenting hippocampal regions and improved mean signal-to-noise per unit time (e.g. 50.6 +/- 4.4 at b = 1250 s/mm(2) in 27 min). Contrary to previous reports that water diffusion is homogeneous throughout the nervous system, statistically different mean diffusivities were observed (e.g. 0.238 +/- 0.054 and 0.318 +/- 0.084 mu m(2)/ms for the molecular and granule cell layers respectively) (ANOVA, P < 0.05). Different hippocampal subregions had lower fractional anisotropy than uniformly fibrous structures like corpus callosum because of their complex architecture. DTI-derived color fiber orientation maps and tractography demonstrated most components of the trisynaptic intrahippocampal pathway (e.g. orientations in stratum lacunosum-moleculare were dominated by perforant and Schaffer fibers) and also permitted some assessment of connectivity in the rat hippocampus. (c) 2006 Elsevier Inc. All rights reserved.