扩散张量成像技术及各指标的初步应用与评价

The preliminary application and assessment of MR diffusion tensor imaging technique and metrics

目的 探讨正常脑组织及脑肿瘤的扩散张量 (DTI)成像技术及各种评价指标的变化规律及临床应用价值。方法 10例正常志愿者和 19例脑肿瘤患者进行常规MRI和DTI扫描并重建参数图 ,测量正常志愿者脑组织各主要白质束和神经核团的部分各向异性值 (FA)、各向同性值 (Iso)、衰减指数值 (ExAt)和容积比异向性值 (VrA) ,肿瘤患者测量受累白质束及对侧正常白质束的上述各参数 ,取值并进行统计学分析 ,包括配对t检验 ,相关性分析及方差分析。结果 DTI图上 ,正常脑组织FA、Iso、ExAt、VrA值按组织结构呈规律分布 ;脑肿瘤病例则清楚显示肿瘤对周围结构的破坏、占位效应及水肿所致的改变。各指标中 ,患、健侧间差异有显著性意义 (FA组 :t=9 12 5 ,P <0 0 0 1;Iso组 :t= 5 5 37,P <0 0 0 1;ExAt组 :t=7 16 8,P <0 0 0 1;Vra组 :t=7 12 8,P <0 0 0 1) ,FA与VrA的患侧测量值之间相关性较高 (r=0 92 2 ,P <0 0 0 1) ,其他各指标间无显著相关性 ,单因素方差分析 4种指标变化幅度 [|(患侧 -健侧 ) |/健侧 ) ]的差异具有显著性意义 (F =2 0 4 30 ,P <0 0 0 1) ,FisherLSD检验显示Vra的变化幅度与另 3种指标间差异有显著性意义 (P <0 0 0 1)。另外 ,FA与Iso比较 ,P =0 0 0 6 ,其他无显著性意义。

Objective To discuss the values of imaging technique of diffusion tensor imaging (DTI) used in normal volunteers and brain tumor patients, and to assess the changing regularity of several evaluating metrics of DTI Methods Ten volunteers and nineteen brain tumor patients underwent routine and DTI scan and then the parametric maps were reconstructed In ten volunteers, the values of FA, Iso, VrA, and ExAt of the main white matter bundles and nerve nucleus were measured; In nineteen patients, the data gathered from damaged white matter and contralateral intact areas were analyzed statistically, including paired T test, correlation analysis, and analysis of variance Results In normal brain DTI maps, the values of each metrics distributed regularly according to tissues structure; In brain tumor patients, the destroys of surrounding tissues and other various changes caused by tumors, mass effect, and edema could be clearly demonstrated For each metric, the difference between lesion group and intact group was significant ( P <0 001), and there was good correlation between FA values and VrA values in lesions ( r =0 922, P <0 001) The changing magnitude of VrA in lesions compared with others metrics had significant meanings ( P <0 001), so VrA could be the most sensitive metric Conclusion DTI can clearly depict the characteristic of normal brain, demonstrate and assess quantitatively the conditions caused by tumors, and instruct pre operation plan and post operation assessment, so the technique has great clinic values