Optimization of acquisition parameters of diffusion-tensor magnetic resonance imaging in the spinal cord
Optimization of acquisition parameters of diffusion-tensor magnetic resonance imaging in the spinal cord
复制标题
DOI：
10.1097/01.rli.0000221325.03899.48
复制
发表时间：
2006-07-01
影响因子：
6.7
通讯作者：
Chung, Hye Won
中科院分区：
文献类型：
--
作者：
Lee, Joon Woo;Kim, Jae Hyung;Chung, Hye Won
目的：本研究的目的是使用最近开发的灵敏度编码（SENSE）成像技术优化颈髓扩散张量成像（DTI）的成像参数，该技术可以大大减少磁敏感伪影。材料和方法：对40例正常志愿者进行了120组颈髓DTI检查，使用基于SENSE的回波平面成像技术，在逐步方法中具有不同的参数（b值、扩散梯度方向的数量、激励的数量和切片厚度）。在步骤1中，使用不同b值500、700、900秒/mm（2）对颈髓进行DTI;然后在步骤2中使用不同数量的扩散梯度方向6、15、32;在步骤3中使用不同数量的激励1、3、5;在步骤4中使用不同的切片厚度2、3、4 mm。在每个步骤中，从10名志愿者中获得30组DTI。为确定最佳成像参数，3名放射科医师通过视觉分析评价分数各向异性（FA）图和彩色FA图的质量。测量重构纤维的数量以进行定量分析。结果：在第1步中，b值为900 s/mm（2）的DTI显示出最高的重建纤维数和最好的FA图和彩色图图像质量。在第2步中，使用15或32个方向比使用6个方向表现出更好的DTI质量。15个方向与32个方向的DTI图像质量差异无统计学意义。15个方向的DTI扫描时间明显短于32个方向。在步骤3中，随着激发次数的增加，重建纤维的数量显著增加，FA图和彩色图的图像质量显著改善。结论：采用b值900 s/mm（2）、15个扩散梯度方向、5个激励、层厚4 mm的层厚，可以获得最佳的颈髓DTI参数。
Objective: The purpose of this study was to optimize imaging parameters for diffusion tensor imaging (DTI) of the cervical spinal cord using a recently developed sensitivity-encoded (SENSE) imaging technique, which can substantially reduce susceptibility artifacts.Materials and Methods: One hundred twenty sets of DTIs were performed of the cervical spinal cord in 40 normal volunteers, using a SENSE-based echo-planar imaging technique with different parameters (b-values, numbers of diffusion gradient directions, number of excitations, and slice thickness) in a stepwise approach. In step 1, DTI was performed of the cervical spinal cord with different b-values 500, 700, 900 seconds/mm(2); then with different numbers of diffusion gradient directions 6, 15, 32 in step 2; different number of excitations 1, 3, 5 in step 3; and different slice thicknesses 2, 3, 4 mm in step 4. In each step, 30 sets of DTIs were obtained from 10 volunteers. To determine the optimal imaging parameters, 3 radiologists evaluated the qualities of fractional anisotropy (FA) maps and color FA maps by visual analysis. The number of reconstructed fibers was measured for quantitative analysis. All qualitative and quantitative comparisons were analyzed by statistical methods using the Friedmann test and the Wilcoxon signed rank test.Results: In step 1, DTIs using a b-value of 900 seconds/mm(2) showed the highest number of reconstructed fibers and the best image quality of FA map and color map. In step 2, the use of 15 or 32 directions demonstrated better quality DTIs than 6 directions. No significant difference was evident between the quality of DTI with 15 directions and that with 32 directions. The scan time of DTI with 15 directions was shorter than with 32 directions. In step 3, as the number of excitations increased, the number of reconstructed fibers increased significantly and the image quality of the FA map and the color map improved significantly. In step 4, the numbers of reconstructed fibers were significantly the highest with a slice thickness of 4mm.Conclusion: Optimal parameters for DTI in the cervical spinal cord included a b-value of 900 seconds/mm(2), 15 diffusion gradient directions, 5 excitations, and a slice thickness of 4mm.