摘要
目的 探索不同b值和扩散张量成像参数的定量关系。方法 对 12例正常成人进行扩散张量磁共振扫描 ,测量多个灰白质感兴趣区的表观扩散系数 (ADC)、指数表观扩散系数 (EADC)、最大特征值、各向异性比率 (FA)、各向异性指数 (AI)和相对各向异性 (RA)等参数 ,分析这些参数随着b值的变化趋势。结果 FA和RA的平均值、中位数、标准差以及变异系数都不随b值变化 (P >0 5 ) ;而ADC、EADC及最大特征值受b值的影响 (P <0 0 1) ,随b值的增加而降低 ;AI的平均值、中位数、标准差及变异系数在不同被试者间差异存在显著性意义 (P <0 0 5 )。结论 b值确实影响多个扩散张量成像的导出量。在临床应用中当比较不同被试者 ,或者不同组织结构时 ,应尽量选择同样的成像参数 ,特别是b值 ,同时选择不受b值影响的参数 ,如FA和RA。
Objective To investigate the relationship between various b values and the anisotropy index in diffusion tensor imaging (DTI) Methods The apparent diffusion coefficient (ADC), exponent ADC (EADC), maximum eigenvalue, fractional anisotropy (FA), anisotropy index (AI), and relative anisotropy (RA) with various b values from region of interest (ROI) in human brain were measured using spin echo EPI pulse sequence with diffusion gradients in 12 healthy adults The images were analyzed with AW workstation offline Results The mean, median, standard deviation (SD), and the coefficients of variation (CV) of FA and RA were b value independent( P >0 5), but the mean, SD, and CV of ADC, EADC, and maximum eigenvalue were affected by the strength of b value( P <0 01) The mean, median, SD, and CV of AI had significant difference between subjects Conclusion The strength of b value does influence measures of DTI and anisotropy It is desirable to use the same experimental parameters for anisotropy diffusion quantification and DTI index unaffected by the strength of b value (such as FA and RA) when comparing between different subjects and regions of interest
出处
《中华放射学杂志》
CAS
CSCD
北大核心
2004年第12期1238-1242,共5页
Chinese Journal of Radiology
基金
国家自然科学基金项目 (10 2 75 0 0 3 )
国家重点基础研究发展规划项目 (973 ) (G19990 5 40 0 6)
