Insights into brain microstructure from the T2 distribution
Insights into brain microstructure from the T2 distribution
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DOI：
10.1016/j.mri.2005.12.037
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发表时间：
2006-05-01
影响因子：
2.5
通讯作者：
M채dler, B
中科院分区：
文献类型：
--
作者：
MacKay, A;Laule, C;M채dler, B
T-2加权对广泛的脑病理特别敏感，但众所周知是非特异性的。然而，仔细测量和分析的T2衰减曲线从脑组织承诺提供更好的病理特异性。体内T2测量需要精确的180个脉冲和适当的刺激回波操作;最常见的方法是从单个切片采集多个回波。T2分布是分量幅度作为T2的函数的曲线图，可以使用能够拟合多指数T2衰减的算法来估计，而无需关于指数分量数量的先验假设。来自正常脑的T2分布显示来自髓磷脂水、细胞内/细胞外水和脑脊液的峰;它们可用于提供总水含量（T2分布下的总面积）和髓磷脂水分数（MWF，髓磷脂水峰下的分数面积）的估计，这是一种被认为与髓磷脂含量相关的量度。牛脑的实验表明，水池间的磁化交换对T2分布的影响较小，不同的白色物质结构具有不同的MWF。在正常白色物质（NWM）中，MAT与磁化传递比（MTR）或扩散张量分数各向异性（FA）无关;因此它提供了有关大脑微观结构的独特信息。多发性硬化症（MS）脑内外观正常的白色物质（NAWM）比对照组具有更高的含水量和更低的MWF，与组织病理学结果一致。多发性硬化病变表现出极大的异质性MWF，可能是由于不同的髓鞘内容物的这些局灶性区域的病理。与对照组相比，患有精神分裂症的受试者发现在胼胝体的小钳和小钳中MAT显著减少，这表明额叶髓鞘形成减少在精神分裂症中起作用。在正常对照组中，额叶髓鞘形成与年龄和受教育程度呈正相关;而在精神分裂症患者中未观察到这一结果。在福尔马林固定的脑中观察到MWF与髓鞘的luxol固蓝组织学染色光密度之间的强相关性，支持MWF作为体内髓鞘标记物的使用。(c)2006年爱思唯尔公司All rights reserved.
T-2 weighting is particularly sensitive, but notoriously unspecific, to a wide range of brain pathologies. However, careful measurement and analysis of the T2 decay curve from brain tissue promise to provide much improved pathological specificity. In vivo T2 measurement requires accurate 180 pulses and appropriate manipulation of stimulated echoes; the most common approach is to acquire multiple echoes from a single slice. The T2 distribution, a plot of component amplitude as a function of T2, can be estimated using an algorithm capable of fitting a multi-exponential T2 decay with no a priori assumptions about the number of exponential components. T2 distributions from normal brain show peaks from myelin water, intra/extracellular water and cerebral spinal fluid; they can be used to provide estimates of total water content (total area under the T2 distribution) and myelin water fraction (MWF, fractional area under the myelin water peak), a measure believed to be related to myelin content. Experiments on bovine brain suggest that magnetization exchange between water pools plays a minor role in the T2 distribution.Different white matter structures have different MWFs. In normal white matter (NWM), MAT is not correlated with the magnetization transfer ratio (MTR) or the diffusion tensor fractional anisotropy (FA); hence it provides unique information about brain microstructure. Normal-appearing white matter (NAWM) in multiple sclerosis (MS) brain possesses a higher water content and lower MWF than controls, consistent with histopathological findings. Multiple sclerosis lesions demonstrate great heterogeneity in MWF, presumably due to varying myelin contents of these focal regions of pathology. Subjects with schizophrenia were found to have significantly reduced MAT in the minor forceps and genu of the corpus callosum when compared to controls, suggesting that reduced frontal lobe myelination plays a role in schizophrenia. In normal controls, frontal lobe myelination was positively correlated with both age and education; this result was not observed in subjects with schizophrenia.A strong correlation between MWF and the optical density from the luxol fast blue histological stain for myelin was observed in formalin-fixed brain, supporting the use of the MWF as an in vivo myelin marker. (c) 2006 Elsevier Inc. All rights reserved.