Engelhardt Eliasz, Moreira Denise Madeira, Laks Jerson
Coordinator, Cognitive and Behavioral Neurology Unit - INDC/UFRJ, Rio de Janeiro RJ, Brazil.
Coordinator, Neuroimaging Unit - INDC/UFRJ, Rio de Janeiro RJ, Brazil.
Dement Neuropsychol. 2009 Jul-Sep;3(3):228-233. doi: 10.1590/S1980-57642009DN30300009.
To study the integrity of hemispheric subcortical white matter by comparing normal young and elderly subjects using quantitative fractional anisotropy (DTI-FA).
Subjects of two different age groups (young=12, elderly=12) were included. MR - GE Signa Horizon - 1.5T scans were performed. Cases with Fazekas scores =3 were assessed on FLAIR sequence. Standard parameters for DTI-FA were used. ROIs were placed at various sites of the subcortical white matter, and the genu and splenium of the midline corpus callosum. Analysis was performed using Functool. Statistics for anterior and posterior white matter, as well as the genu and splenium were compared between the groups. The study was approved by the Ethics Committee of IPUB-UFRJ and informed consent obtained.
DTI-FA showed lower anisotropy values in the anterior region (subcortical white matter and genu), but not in the posterior region (subcortical white matter and splenium), in elderly normal subjects compared to young subjects.
The results may represent loss of integrity of anterior (frontal) white matter fibers in the elderly subjects. These fibers constitute important intra- and inter-hemispheric tracts, components of neural networks that provide cognitive, behavioral, motor and sensory integration. The loss of integrity of the anterior segments of the studied fiber systems with ageing, represents a disconnection process that may underlie clinical manifestations found in elderly subjects such as executive dysfunction.
通过使用定量分数各向异性（DTI-FA）比较正常年轻人和老年人，研究半球皮质下白质的完整性。
纳入两个不同年龄组的受试者（年轻人=12名，老年人=12名）。进行了MR - GE Signa Horizon - 1.5T扫描。对Fazekas评分为3分的病例在FLAIR序列上进行评估。使用DTI-FA的标准参数。将感兴趣区（ROI）放置在皮质下白质的各个部位以及胼胝体中线的膝部和压部。使用Functool进行分析。比较两组之间前、后白质以及膝部和压部的统计数据。该研究获得了IPUB-UFRJ伦理委员会的批准并取得了知情同意。
与年轻受试者相比，老年正常受试者的DTI-FA在前部区域（皮质下白质和膝部）显示出较低的各向异性值，但在后部区域（皮质下白质和压部）则没有。
这些结果可能代表老年受试者前部（额叶）白质纤维的完整性丧失。这些纤维构成重要的半球内和半球间传导束，是神经网络的组成部分，提供认知、行为、运动和感觉整合。随着年龄增长，所研究纤维系统前部节段的完整性丧失代表了一种断开连接的过程，这可能是老年受试者中发现的如执行功能障碍等临床表现的基础。
