Chepuri Neeraj B, Yen Yi-Fen, Burdette Jonathan H, Li Hong, Moody Dixon M, Maldjian Joseph A
Department of Radiology, Wake Forest University School of Medicine, Bowman Gray Campus, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
AJNR Am J Neuroradiol. 2002 May;23(5):803-8.
The corpus callosum is a heterogeneous white-matter tract that connects the cerebral hemispheres. The purpose of this investigation was to study its microstructural architecture in normal human adult brains by using diffusion tensor imaging (DTI).
Two hundred consecutive patients referred for brain MR imaging underwent additional DTI with a high gradient field strength applied in six directions. Forty-two patients met the following inclusion criteria: 1) normal brain and 2) age greater than 18 years. Anisotropy maps were generated, and regions of interest were drawn around specified regions within the corpus callosum. Results were stratified by sex and age. In addition, available histologic specimens of the corpus callosum from cadaver brains were analyzed with conventional and specialized vascular staining.
Anisotropy values in the various regions of the corpus callosum differed significantly. Average values of the anisotropy index for the genu, body, and splenium of the corpus callosum were 0.400, 0.456, and 0.539, respectively. The differences between these values are statistically significant (P <.01). Increased anisotropy was present in posterior areas in both sexes and in all three age groups examined.
The results of this investigation show a statistically significant increase in anisotropy of the corpus callosum in its more posterior portions compared with its more anterior portions across sex and age groups. Although the microstructural etiology for this apparent increase in anisotropy is unclear, a number of possible mechanisms are presented.
胼胝体是连接大脑半球的异质性白质束。本研究的目的是通过扩散张量成像（DTI）研究正常成年人大脑中胼胝体的微观结构。
连续200例因脑部磁共振成像就诊的患者接受了额外的DTI检查，在六个方向上施加高梯度场强。42例患者符合以下纳入标准：1）脑部正常；2）年龄大于18岁。生成各向异性图，并在胼胝体内指定区域周围绘制感兴趣区域。结果按性别和年龄分层。此外，对来自尸体大脑的胼胝体可用组织学标本进行常规和特殊血管染色分析。
胼胝体各区域的各向异性值差异显著。胼胝体膝部、体部和压部的各向异性指数平均值分别为0.400、0.456和0.539。这些值之间的差异具有统计学意义（P<.01）。在所有三个年龄组的男性和女性中，后部区域的各向异性均增加。
本研究结果表明，在不同性别和年龄组中，胼胝体后部的各向异性与其前部相比在统计学上有显著增加。虽然这种明显的各向异性增加的微观结构病因尚不清楚，但提出了一些可能的机制。
