正常人颈髓扩散张量成像最佳参数研究

The optimal parameters of diffusion tensor imaging for normal cervical spinal cord:apreliminary study

目的:比较不同b值、不同数量扩散梯度方向(NDGDs)3.0T磁共振(MRI)扩散张量成像(DTI)对正常人颈髓成像的影响;探讨颈髓最佳DTI参数。方法:随机选取健康志愿者20例,进行颈髓矢状面DTI扫描,选用b值分别为0、200、400、600、800、1000s/mm2,NDGDs选择6、12、20。分别在不同b值、不同NDGDs条件下,分析图像质量以及颈髓各向异性(FA)值、表观扩散系数(ADC)值。结果:当NDGDs不变(20),随b值增加图像信噪比及质量指数递减(F=28.694、30.272,P<0.05),且不同b值条件下FA、ADC值无组间差异性(F=0.495、0.359,P>0.05)。当b值不变(600s/mm2),随NDGDs增加图像质量评分递增(F=11.927,P<0.05),不同NDGDs条件下FA、ADC值无组间差异性(F=0.08、0.583,P>0.05),但NDGDs为20与6、12分别两两比较,FA值之间差异有统计学意义(P<0.05)。结论:使用西门子3.0T磁共振DTI技术,选取b值为600s/mm2,NDGDs为20的条件下,得到最佳的颈髓DTI图像。

Objective：To compare the effects of different b values and different numbers of diffusion gradient direc-tions （NDGDs）of MR diffusion tensor imaging （DTI）with 3T MR scanner for normal cervical spinal cord,and to assess the most optimal DTI parameters.Methods：20 healthy volunteers were recruited randomly,cervical spinal cord sagittal DTI scanning were performed with different b values （0,200,400,600,800,1000s/mm2 ）and different NDGDs （6,12,20）.The image quality,fractional anisotropy （FA）and apparent diffusion coefficient （ADC）were analyzed with different b values and different NDGDs,respectively.Results：With the constant NDGD as 20,the signal-to-noise ratio （SNR）and image qual-ity index decreased with the increasing of b values （F =28.694,30.272,P 〈0.05）,there was no significant difference of FA and ADC between different groups of b value （F =0.495,0.359,P 〉0.05）.With the constant b value as 600s/mm2 ,the im-age quality score increased with the increasing of NDGD （F =11.927,P 〈0.05）,there was no significant difference of FA and ADC between different groups of NDGD （F =0.08,0.583,P 〉0.05）,yet there was significant difference between FA values when comparing NDGD as 20 with that as 6 and 12 （P 〈0.05）.Conclusion：The optimal DTI image of cervical spinal cord could be obtained with the parameters including the b value as 600s/mm2 and NDGD as 20 using a Siemens 3.0T MR scanner.