基于不同FA模板的全脑体素分析方法可靠性的研究

Reliability Study of Voxel-Based Analysis Based on Two Different FA Templates

比较基于两种不同FA模板的全脑体素分析(VBA)方法的结果,了解该方法的可靠性,以期为脑白质的功能研究和相关疾病的诊治提供基础信息。选择27例健康成年志愿者,分为青年组(14例)和老年组(13例),行磁共振弥散张量成像扫描。首先使用DTIStudio软件对图像进行自动配准和张量计算,获取部分各向异性(FA)图,然后利用统计参数图(SPM8)软件对FA图进行配准、归一化、平滑等预处理,最后分别基于SPM8软件下产生的专用FA模板和本实验室自主开发的正常中国人FA模板,对两组间的脑白质FA值进行全脑体素分析比较。以纤维束示踪的空间统计学(TBSS)方法和相关文献结果为标准,对以上比较结果进行验证。在基于SPM8产生的专用FA模板下,与青年组对比,老年组的双侧内囊前、后肢,左外囊,左额上回,左枕叶,右放射冠,右大脑脚底,右额中、下回,右小脑中脚的FA值显著下降(P<0.05,簇错误率校正);在基于正常中国人FA模板下,老年组的左内囊后肢,左外囊,左额上回,左颞中回,左枕叶,右放射冠,右内囊前、后肢,右大脑脚底,右额中、下回和胼胝体膝部的FA值相对于青年组显著下降(P<0.05,簇错误率校正);两种模板结果的不一致区域共有4个,即:左内囊前肢、右小脑中脚和左颞中回、胼胝体膝部,前两个区域出现在第一个模板中,后两个区域出现在第二个模板中,根据TBSS方法的激活区结果可得出左内囊前肢、右小脑中脚是假阳性,TBSS方法和相关文献结果支持第二个模板的结论。在采用VBA方法对脑白质进行分析时,基于正常中国人FA模板有助于提高结果的客观性和可靠性。

The aim of this work is to compare the results of voxel-based analysis（VBA） based on two different fractional anisotropy（FA） templates and examine the reliability of this method.The study is expected to provide basic information of white matter in brain function and in diagnosis of the related diseases.Healthy volunteers of 27 were divided into two groups,one was young group with 14 subjects,and the other was old group with 13 subjects.Diffusion tensor imaging scans were conducted with the two groups.In the automatic image registration,tensor calculation was performed in DTIStudio software.Next,the FA maps acquired from the first step were coregistered,normalized and smoothed using SPM8 software package.And then voxel-based analysis between the two groups’ FA were studied based on two FA templates separately with SPM8.The first template was the study-specific FA template produced in SPM8,the other was our self-created Chinese normal FA template.In addition,the tract-based spatial statistic（TBSS） method and related literatures were applied to validate the different results from two kinds of FA templates.As to the study-specific template,compared with the young group,the old group’s white matter FA significantly decreased in bilateral anterior and posterior limbs of internal capsule,left external capsule,left superior frontal gyrus,left occipital lobe,right corona radiata,right cerebral peduncle,right middle,inferior frontal gyros,right middle cerebellar peduncle（P 〈0.05,FWE corrected）.In normal Chinese FA template,the significantly decreased areas of FA were distributed in left posterior limb of internal capsule,left external capsule,left superior frontal gyrus,left middle temporal gyrus,left occipital lobe,right corona radiata,right anterior and posterior limbs of internal capsule,right cerebral peduncle,right middle,inferior frontal gyri,genu of corpus callosum（P〈0.05,FWE corrected）.There were four different areas in the two templates.Left anterior limb of internal capsule and right middle cerebellar peduncle belonged to the first template,while left middle temporal gyrus,genu of corpus callosum shown up on the second template.From the active areas of TBSS,we could conclude that both left anterior limb of internal capsule and right middle cerebellar peduncle were false positive.The results of TBSS and related literatures were mostly in accordance with those in our Chinese normal FA template.When it comes to voxel-based analysis of brain white matter,our self-created Chinese normal FA template may play an important role in improving the objectivity and reliability of the results.