不同弥散梯度编码方向对胼胝体弥散张量成像的影响分析  

The influence of different diffusion gradient encoding directions on parameter measurements of corpus callosum at MR diffusion tensor imaging

作　　者：赵雅琴[1] 杨军乐[1] 贺长安[1] 高燕军[1] 徐敏[1] 马鸣岳[1] 

机构地区：[1]西安交通大学医学院附属西安市中心医院影像中心,陕西西安710003

出　　处：《实用放射学杂志》2011年第9期1416-1419,共4页Journal of Practical Radiology

基　　金：陕西省科技厅攻关项目（编号：2008K11-02）.

摘　　要：目的探讨胼胝体1．5T磁共振弥散张量成像（DTI）较合理的弥散梯度编码方向。方法连续采集30例健康成人志愿者，男女分别为16例、14例。分别施加15、25、39个弥散梯度磁场方向，行DTI扫描，3个不同弥散梯度磁场方向扫描时间分别为108s、168S、252S。观察不同弥散梯度方向DTI的图像质量，在FA图上分别测量胼胝体膝部及压部的FA值，对测量值进行统计学分析。结果所有FA图像均可清楚显示大脑白质纤维束，纤维束边缘显示清楚且能分辨出不同纤维束的解剖结构细节，与灰质形成鲜明对比。自15个弥散梯度磁场方向至25个、39个弥散梯度磁场方向，随着梯度磁场方向数量的增加，所得FA图示各部位白质纤维束边缘更加清楚、锐利，白质纤维束细节显示更加清晰。计算机重建的白质纤维束成像图（DTT图）也更加清晰丰富。15、25、39个弥散梯度磁场方向测量的胼胝体膝部FA值（F=0．772，P=0．465）及压部FA值（F=1．804，P=0．171）之间差异均无统计学意义，3个方向上胼胝体压部FA值均高于胼胝体膝部FA值。结论对胼胝体纤维束的显示25个弥散梯度磁场方向扫描时间合理，既可保证扫描成功率，又可得到高质量的FA图像，实际应用意义较大。Objective To study the reasonable diffusion gradient encoding directions in diffusion tensor imaging（DTI） for corpus callosum at 1.5T MR scanner. Methods 30 healthy adult volunteers （16 men and 16 women） continuously underwent DTI with 15, 25 and 39 diffusion gradient encoding direction,respectively. The DTI scan time was 108 s, 168 s and 252 s respectively. The frac- tional anisotropy （FA} values of the genu and splenium of the corpus callosum were measured on FA map. The FA values were ana- lyzed. Results The white matter fiber tracts were distinct on all FA maps. The margin of the white matter fiber tracts became more clear and sharp with the increasing of diffusion gradient encoding directions from 15 to 25 to 39. The detail of white matter fiber tract was more clear, and the diffusion tensor tractography by reconstruction was more distinct and abundant. The FA values of genu（F = 0. 772,P= 0. 465}and splenium（F= 1. 804, P=0. 171）among 15, 25 and 39 diffusion gradient encoding directions were no of statistical difference. The FA value of splenium was higher than that in genu. Conclusion 25 diffusion gradient encoding direction is more practical importance with reasonable time and higher clear image.

关 键 词：脑 胼胝体 弥散张量成像 磁共振成像 

分 类 号：R322.81[医药卫生—人体解剖和组织胚胎学] R445.2[医药卫生—基础医学]