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

扩散张量成像（DTI）是一种对水分子迁移方向敏感的磁共振成像技术。DTI有两个特点：扩散各向异性；以及水扩散系数的定向分布。白质表现出较高的扩散各向异性，平行于纤维方向的扩散速度比其他方向快。在一个被称为纤维束成像的过程中，大脑的DTI可以被重建以显示三维宏观纤维束结构。随着主动屏蔽3T磁体和平行成像技术的最新进展，高场磁共振成像已在临床环境中变得实用。在这个项目中，我们已经证明，与1.5 T相比，3T纤维束造影对大多数纤维束的描绘得到了改善（Radiology, 2006;238:668-678）。我们还建立了束造影和术中皮质下运动诱发电位的整合，并证明使用3T MR的皮质脊髓束弥散张量束造影能够提供纤维束的互动信息，描绘手术期间纤维束的过程（放射学，出版）。我们认为，术中皮质下白质刺激和脊髓束造影的互补应用将有助于防止术中皮质脊髓束损伤。这个项目取得的成果将对脑肿瘤患者有益。

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.