Lee Joon Woo, Kim Jae Hyung, Kang Heung Sik, Lee Jong Sea, Choi Ja-Young, Yeom Jin-Sup, Kim Hyun-Jib, Chung Hye Won
Department of Radiology, Seoul National University Bundang Hospital, Gyeongi-Do, Korea.
Invest Radiol. 2006 Jul;41(7):553-9. doi: 10.1097/01.rli.0000221325.03899.48.
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.
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; 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.
In step 1, DTIs using a b-value of 900 seconds/mm 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 4 mm.
Optimal parameters for DTI in the cervical spinal cord included a b-value of 900 seconds/mm, 15 diffusion gradient directions, 5 excitations, and a slice thickness of 4mm.
本研究旨在利用最近开发的敏感性编码（SENSE）成像技术优化颈脊髓扩散张量成像（DTI）的成像参数，该技术可大幅减少磁化率伪影。
对40名正常志愿者的颈脊髓进行了120组DTI检查，采用基于SENSE的回波平面成像技术，逐步改变不同参数（b值、扩散梯度方向数、激励次数和层厚）。第一步，对颈脊髓进行不同b值（500、700、900秒/平方毫米）的DTI检查；第二步，采用不同的扩散梯度方向数（6、15、32）；第三步，采用不同的激励次数（1、3、5）；第四步，采用不同的层厚（2、3、4毫米）。在每一步中，从10名志愿者中获取30组DTI数据。为确定最佳成像参数，3名放射科医生通过视觉分析评估了分数各向异性（FA）图和彩色FA图的质量。测量重建纤维的数量以进行定量分析。所有定性和定量比较均采用Friedmann检验和Wilcoxon符号秩检验进行统计学分析。
在第一步中，使用900秒/平方毫米b值的DTI显示重建纤维数量最多，FA图和彩色图的图像质量最佳。在第二步中，使用15或32个方向的DTI质量优于6个方向。15个方向和32个方向的DTI质量之间无显著差异。15个方向的DTI扫描时间比32个方向短。在第三步中，随着激励次数增加，重建纤维数量显著增加，FA图和彩色图的图像质量显著提高。在第四步中，层厚为4毫米时重建纤维数量显著最多。
颈脊髓DTI的最佳参数包括900秒/平方毫米的b值、15个扩散梯度方向、5次激励和4毫米的层厚。
