Delineation of relationship between brain tumor and the white matter tracts by means of 3-dimenitional anisotropy contrast imaging and diffusion tensor analysis

目的：为评价三维各向异性对比(3DAC)成像和扩散张量分析在显示脑肿瘤与白质束关系中的作用，我们对5名正常志愿者(1岁)和19例幕上脑肿瘤患者进行了3DAC成像。方法：在3个正交方向上应用运动探测梯度(MPG)获得的彩色编码扩散加权图像(DWI)进行3DAC成像。用MPG在6个不同方向上获得的弥散张量进行扩散张量分析。利用这些数据集，我们得到了分数各向异性(FA)、表观扩散系数(ADC)轨迹和扩散本征值的图像。FA是反映弥散各向异性的指标之一。结果：1)3DAC成像结果：在对正常受试者的分析中，所有病例的3DAC图像均清晰地显示了白质束。然而，在I…中，图像往往很差在脑肿瘤病例中，我们利用3DAC图像对肿瘤与锥体束的关系进行了评价。2)弥散张量分析结果首先比较了5例正常人和4例脑肿瘤患者的弥散张量分析(FA)和常规3正交扩散成像(FA-3)测量弥散各向异性的准确性。在对健康受试者的分析中，FA-3的不对称性明显高于FA。在一例脑肿瘤压迫锥体束的病例中，FA-3被显著低估，导致错误的结论。测量锥体束的FA、ADC轨迹和特征值。这些指标反映了锥体束受压和/或T2高的情况。结论3DAC成像和弥散张量分析可以提供更多关于脑白质束的有用信息，这可能有助于脑肿瘤的手术计划。较少

PURPOSE : To evalutate the usefulness of 3-dimentional anisotropy contrast (3DAC) imaging and diffusion tensor analysis for delineation of relationship between brain tumor and the white matter tracts, we applied these technique to 5 normal volunteers (first year) and 19 patients with a supratentorial brain tumor.METHODS : 3DAC imaging was performed by synthesizing color-coded diffusion-weighted images (DWI) which were obtained by applying motion probing gradient (MPG) in 3-orthogonal directions. Diffusion tensor analysis was performed using DWIs obtained by applying MPG in 6 different directions. Using this data sets, we obtained images of fractional anisotorpy (FA), apparent diffusion coefficient (ADC) trace and diffusion eigenvalues. The FA is one of the indicies representing diffusion anisotorpy.RESULTS :1) Results of 3DAC imagingIn the analysis of the normal subjects, the 3DAC images delineated the white matter tracts clearly in all cases. However, the images tended to be poor in i … More nfratentorial region due to susceptiblity artifacts, which made it almost impossible to evaluation of the fiber tracts in some cases.In the cases with brain tumor, we evaluated the relationship between a tumor and the pyramidal tract by 3DAC images. In all cases, 3DAC images could clearly show the relationship ; the tumor just compressed the tracts or the tumor/perifocal edema involved the tracts.2) Results of diffusion tensor analysisAt first, we compared the accuracy of the measurement of diffusion anisotropy between diffusion tensor analysis (FA) and conventional 3-orthogonal diffusion imaging (FA-3) in 5 normal subjects and 4 patients with brain tumor. In the analysis of healthy subjects, FA-3 was significantly more asymmetric than FA.In one case with a brain tumor compressing the pyramidal tract, FA-3 showed markedly underestimated, which led erroneous conclusion.Then, we investigated the diffusion characteristics of the pyramidal tract in cases with brain tumor. The FA, ADC trace and eigenvalues of the pyramidal tracts were measured. These indices reflected condition of pyramidal tract, being compressed and/or being T2-high. Estimation of eigenvalues, in addition to the FA and the trace, should provide more detailed information.CONCLUSION3DAC imaging and diffusion tensor analysis may provide additional useful information about the white matter tracts, which may be helpful for surgical planning of brain tumors. Less