Diffusion-tensor fiber tractography in patients with brain tumor using 1.5T and 3T MR systems

扩散张量成像（DTI）是一种磁共振（MR）成像技术，对水分子的迁移率方向敏感。DTI揭示了两个具体的特点：扩散各向异性和水扩散率的方向性分布。白色物质显示出高的扩散各向异性，因为平行于纤维方向的扩散比其他方向的扩散快。脑的DTI可以被重建以显示3D宏观纤维束结构，该过程被称为纤维束成像。随着主动屏蔽3 T磁体和并行成像技术的最新进展，高场MR成像在临床环境中已变得实用。在这个项目中，我们已经证明，与1.5 T纤维束成像相比，3 T纤维束成像对大多数纤维束的描绘得到了改善（Radiology，2006;238：668-678）。我们还建立了纤维束成像和术中皮质下运动诱发电位的整合，并证明了使用3 T MR的皮质脊髓束扩散张量纤维束成像能够提供有关纤维束的交互信息，描绘手术过程中的功能性纤维束（放射学，出版中）。我们相信，术中皮质下白色物质刺激和纤维束成像的互补使用将有助于防止术中皮质脊髓束的损伤。本课题的研究成果对脑肿瘤患者的治疗具有一定的参考价值。

Diffusion tensor imaging (DTI) is a magnetic resonance (MR) imaging technique that is sensitive to orientation of mobility in water molecules. DTI reveals two specific characteristics : diffusion anisotropy ; and directional distribution of water diffusivity. White matter shows high diffusion anisotropy, because diffusion is faster in parallel to fiber direction than in other directions. DTI of the brain can be reconstructed to display 3D macroscopic fiber tract architecture, in a process known as fiber tractography. With recent advances in actively shielded 3T magnets and parallel imaging techniques, high-field MR imaging has become practical in clinical settings. In this project, we have demonstrated that depiction of most fiber tracts was improved on 3T tractography compared to 1.5 T (Radiology, 2006;238:668-678). We have also established an integration of tractography and intraoperative subcortical motor-evoked potential, and demonstrated that diffusion tensor tractography of the corticospinal tract using 3T MR was able to provide interactive information on fiber tracts, depicting the course of eloquent fiber tracts during an operation (Radiology, in press). We believe that complementary use of intraoperative subcortical white matter stimulation and tractography will contribute to preventing intraoperative damage of the corticospinal tract. The accomplishments achieved in this project will be beneficial for patients with brain tumor.