不同数量梯度场方向对正常颈髓弥散张量成像初步探究.doc

不同数量梯度场方向对正常颈髓弥散张量成像初步探究[摘要] 目的：比较数量不同梯度场方向对正常人颈髓弥散张量成像(diffusion tensor imaging, DTI)的影响，探讨正常人颈髓最佳DTI数量梯度场方向。方法：对46名健康志愿者采用GE Signa ExciteⅡ1.5T超导型核磁共振成像系统，在回波平面成像（echo planar imaging, EPI）基础上，分别施加6个和25个方向的扩散敏感梯度磁场，选择b值（0、600 s/mm2），行颈髓DTI成像扫描，分析比较各自影像特点并分别在颈髓相对宽的C2~C3水平、颈髓相对窄的C4~C7水平选择感兴趣区(region of interest, ROI)测量平均表观弥散系数(average apparent diffusion coefficient, ADCav)、部分各向异性（fraction anisotropy, FA）值。结果：在其它参数不变的情况下，6个方向与25个方向相应部位的ADCav值、FA值无显著性差异（P0.05)。结论：磁共振扫描选择扩散张量成像扫描参数时,在不影响各定量值测量的情况下，应尽量减少扫描时间，6个方向是颈髓扩散张量成像的较好选择。 [关键词] 脊髓；磁共振；弥散张量成像；梯度磁场；b值 [中图分类号] R81[文献标识码]A [文章编号]1673-7210（2008）06（b）-015-03 Preliminary study of influence of different directions gradients on diffusion tensor imaging of normal cervical spinal cord ZHAI Feng, FAN Wan-feng, CAO Xin-shan, LIU Quan-yuan, ZHANG Zuo-bing (Department of Radiology, the Affiliated Hospital of Binzhou Medical University, Binzhou 256603, China) [Abstract] Objective: To compare the influence of different directions of gradients on DTI of the nomal cervical cord. Methods:Forty-six healthy volunteers were performed respectively by DTI of cervical cord with MRI scanning(GE Signa Excite Ⅱ 1.5T unit),on the base of using echo planar imaging(EPI) sequence, with 6 directions and 25 directions of gradients and b values（0、600 s/mm2），the images characteristics of cervical spinal cord were compared and analyzed respectively, ADCav values、FAvalues were calculated respectively at the relatively wide cervical cord of C2~C3 level and the more narrow cervical cord of C4~C7 level of Region of interest(ROI) on the images.Results:Without changing of other scan parameters, ADCav values、FAvalues with 6 directions and 25 directions had no significant difference from corresponding position(P0.05). Conclusion:The 6 directions and 25 directions of gradient does not influence measures of FA and ADC of DTI. It is desirable to use 6 directions of measure. [Key words] Spinal cord; MRI; Diffusion tensor imaging; Diffusion sens