不同参数条件下巴马小型猪腰椎神经根扩散张量成像的比较研究

Comparative Study of Diffusion Tensor Imaging with Different Parameters of Bama Minipig Lumbar Nerve Roots

目的比较1.5T磁共振不同参数条件下的巴马小型猪腰椎神经根扩散张量成像(Diffusion Tensor Imaging,DTI)序列的图像质量,优选最佳扫描参数。方法采用不同的层厚、扫描野、矩阵组合对10头小型猪各进行3次腰椎DTI扫描,由3名高年资放射科医师完成图像信噪比的测量和扩散张量纤维示踪图(Diffusion Tensor Tractography,DTT)的重建,并对DTT显示效果进行评分,采用方差检验对评分结果进行统计学分析。结果体素大小相近时,不同参数条件下(层厚不同或FOV不同)DTI图像信噪比间的差异无统计学意义(P>0.05),不同FOV的DTT图像质量评分之间的差异有统计学意义(P<0.05),相对小FOV的序列DTT图像质量评分较高。结论体素大小取决于层厚、扫描野及矩阵,过大或过小的体素均导致图像质量下降。相对小扫描野(110 mm×110 mm)结合使用小矩阵(72 mm×72 mm)扫描,扩散张量纤维示踪成像可重建出更多的神经纤维、完整性更好,是用于巴马小型猪腰椎神经根DTI相关评价的理想选择。

Objective To summarize the optimal sequence parameters,we compared the image quality ofdiffusion tensor imaging(DTI)with different sequence parameters in lumbar nerve roots of Bama minipigat1.5T.Methods We performed lumbar DTI scan on10pigs for3times based on different combinationsof slice thickness,view field and matrix.The signal to noise ratio and reconstructed diffusion tensortractography(DTT)were measured by3experienced radiologists,then the DTT images were evaluatedand scored.Scoring results were analyzed statistically with the statistical analysis.Results There wasno significant differences in the SNR among different DTI images(P>0.05)when the voxel size weresimilar,whereas the slice thickness and FOV were different.The difference of DTI image score wasstatistically significant among the different sequences of FOV(P<0.05).The relative smaller FOVsequence had relative higher DDT image score.Conclusion Voxel size depends on slice thickness,viewfield and matrix,either too large or too small voxel can cause poor image quality.The DTT images showmore nerve fibers and better continuity when use the small view field(72mm×72mm)in combinationwith small matrix.Therefore,this combination is a good choice for DTI evaluation of lumbar nerve rootin miniature pigs.