不同扫描层厚对脑白质纤维束扩散张量成像定量评估的研究

Quantitative Evaluation of Diffusion Tensor Imaging of Cerebral White Matter Fiber Tracts with Different Scanning Layer Thickness

目的探讨扩散张量成像(DTI)中不同扫描层厚的选择对脑白质纤维束各扩散定量评估指标的影响。资料与方法采用不同扫描层厚(分别为3 mm、5 mm、7 mm)对30名健康志愿者在3.0T MR仪上行DTI以及3D T1WI扫描,获得胼胝体压部区域的各向异性分数(FA)、平均扩散率(MD)、轴向扩散(AD)、横向扩散(RD)以及右侧海马区域纤维束数目(FN)、最小纤维束长度(FLmin)、最大纤维束长度(FLmax)等扩散定量评估指标。比较不同扫描层厚下(3 mm组、5 mm组和7 mm组)各扩散定量评估指标,分析扫描层厚与各扩散定量评估指标的相关性。结果 FA、MD、RD、FN、FLmin在各组间、AD在3 mm组与7 mm组以及5 mm组与7 mm组间差异均有统计学意义(P均<0.05),FLmax各组间以及AD在3 mm组与5 mm组间差异无统计学意义(P>0.05)。FA、AD、FN与扫描层厚呈负相关(r=-0.887、-0.316、-0.560,P<0.05),MD、RD、FLmin与扫描层厚呈正相关(r=0.606、0.767、0.501,P<0.05)。FLmax与扫描层厚无相关性(r=0.008,P>0.05)。结论不同扫描层厚对DTI部分扩散定量评估指标有明显影响,数据获取过程中应引起重视。

Purpose To explore the effects of varied scanning layer thicknesses in diffusion tensor imaging(DTI)on quantitative evaluation indicators of diffusions of cerebral white matter fiber tracts.Materials and Methods Thirty healthy volunteers underwent DTI and3D T1WI scanning on3.0T magnetic resonance equipment with varied scanning layer thicknesses(3,5and7mm,respectively)to obtain quantitative evaluation indicators of diffusions of splenium corporis callosi,including fractional anisotropy(FA),mean diffusivity(MD),axial diffusivity(AD),radial diffusivity(RD),fiber numbers(FN)in right hippocampus region,fiber length minimum(FLmin)and fiber length maximum(FLmax).Quantitative evaluation indicators of diffusions with varied scanning layer thicknesses(3mm group,5mm group and7mm group)were compared,the correlation between scanning layer thickness and quantitative evaluation indicators of diffusions was analyzed.Results The differences in FA,MD,RD,FN,FLmin and AD between the3mm group and the7mm group,and that between the5mm group and the7mm group showed statistical significance(P<0.05).FLmax difference between groups and AD difference between the3mm group and the5mm group showed no statistical significance(P>0.05).FA,AD and FN were negatively correlated with scanning layer thickness(r=-0.887,-0.316and-0.560,P<0.05),MD,RD and FLmin positively correlated with scanning layer thickness(r=0.606,0.767and0.501,P<0.05),and FLmax showed no correlation with scanning layer thickness(r=0.008,P>0.05).Conclusion Different scanning layer thicknesses displays obvious influence on DTI partial diffusion quantitative evaluation indicators,which calls for attention in the process of data acquisition.