Segmentation of the white matter in MRI scans of the rat brain presents a significant challenge due to the low contrast. Existing anatomical reference maps of rat brain are usually constructed from fixed tissue, which may suffer from geometrical distortions due to fixation/processing. To significantly increase the in vivo contrast between white and gray matter in the rat brain we used a known neurotoxicant hexachlorophene, which produces selective white matter damage. This model was used to map white matter in the rat brain and estimate the partial white matter content in any given imaging voxel. Hexachlorophene was administered to rats at a dose of 30 mg/kg orally once a day over five consecutive days. A significant white matter changes were observed using quantitative T maps, from which the partial white matter content throughout the whole rat brain was derived. Several assumptions were made: hexachlorophene affects T relaxation only in the white matter; T of gray matter is relatively uniform in the brain; apparent T value in a given voxel is a combination of Ts from white and gray matter portions of that voxel, hexachlorophene affects nearly 100 % of white matter. The partial white matter map of the rat brain was constructed with the resolution of 0.2 × 0.2 × 1.0 mm per voxel. This map could be adjusted for segmentation of the brain tissue with preset threshold of the white matter content, or to establish the tissue composition in any region of interest among other applications.

中文翻译：

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使用六氯酚诱导的神经毒性模型绘制大鼠脑部分白质含量的体内图谱

由于对比度低，对大鼠大脑 MRI 扫描中的白质分割提出了重大挑战。现有的大鼠大脑解剖参考图通常是由固定组织构建的，这些组织可能会因固定/处理而遭受几何变形。为了显着增加大鼠大脑白质和灰质之间的体内对比度，我们使用了一种已知的神经毒剂六氯酚，它会产生选择性的白质损伤。该模型用于绘制大鼠大脑中的白质图并估计任何给定成像体素中的部分白质含量。连续五天向大鼠口服六氯酚，剂量为 30 mg/kg，每天一次。使用定量 T 图观察到显着的白质变化，从中得出整个大鼠大脑的部分白质含量。做出了几个假设：六氯酚仅影响白质中的 T 弛豫；大脑中灰质的T值比较均匀；给定体素中的表观 T 值是该体素的白质和灰质部分的 T 值的组合，六氯酚几乎影响 100% 的白质。以每体素 0.2 × 0.2 × 1.0 mm 的分辨率构建了大鼠大脑的部分白质图。可以调整该图以使用预设的白质含量阈值来分割脑组织，或者在其他应用中建立任何感兴趣区域的组织成分。