Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, E7 3424, Waterloo, Ontario, N2L 3G1, Canada.
Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Ave, S621, Toronto, Ontario, M4N 3M5, Canada.
Neuroradiology. 2021 Mar;63(3):373-380. doi: 10.1007/s00234-021-02635-9. Epub 2021 Jan 14.
Neuroimaging provides great utility in complex spinal surgeries, particularly when anatomical geometry is distorted by pathology (tumour, degeneration, etc.). Spinal cord MRI diffusion tractography can be used to generate streamlines; however, it is unclear how well they correspond with white matter tract locations along the cord microstructure. The goal of this work was to evaluate the spatial correspondence of DTI tractography with anatomical MRI in healthy anatomy (where anatomical locations can be well defined in T1-weighted images).
Ten healthy volunteers were scanned on a 3T system. T1-weighted (1 × 1 × 1 mm) and diffusion-weighted images (EPI readout, 2 × 2 × 2 mm, 30 gradient directions) were acquired and subsequently registered (Spinal Cord Toolbox (SCT)). Atlas-based (SCT) anatomic label maps of the left and right lateral corticospinal tracts were identified for each vertebral region (C2-C6) from T1 images. Tractography streamlines were generated with a customized approach, enabling seeding of specific spinal tract regions corresponding to individual vertebral levels. Spatial correspondence of generated fibre streamlines with anatomic tract segmentations was compared in unseeded regions of interest (ROIs).
Spatial correspondence of the lateral corticospinal tract streamlines was good over a single vertebral ROI (Dice's similarity coefficient (DSC) = 0.75 ± 0.08, Hausdorff distance = 1.08 ± 0.17 mm). Over larger ROI, fair agreement between tractography and anatomical labels was achieved (two levels: DSC = 0.67 ± 0.13, three levels: DSC = 0.52 ± 0.19).
DTI tractography produced good spatial correspondence with anatomic white matter tracts, superior to the agreement between multiple manual tract segmentations (DSC ~ 0.5). This supports further development of spinal cord tractography for computer-assisted neurosurgery.
神经影像学在复杂的脊柱手术中具有很大的实用性，尤其是在解剖几何结构因病变（肿瘤、退化等）而扭曲时。脊髓 MRI 扩散轨迹可以用来生成流线；然而，它们与脊髓微观结构中沿脊髓的白质束位置的对应程度尚不清楚。本工作的目的是评估 DTI 轨迹与健康解剖结构中解剖 MRI 的空间对应关系（在 T1 加权图像中可以很好地定义解剖位置）。
对 10 名健康志愿者在 3T 系统上进行扫描。采集 T1 加权（1×1×1mm）和扩散加权图像（EPI 读出，2×2×2mm，30 个梯度方向），并随后进行配准（脊髓工具箱（SCT））。从 T1 图像中，为每个椎骨区域（C2-C6）确定基于图谱（SCT）的左侧和右侧皮质脊髓束的解剖标签图。使用定制的方法生成轨迹流线，能够在对应于各个椎骨水平的特定脊髓束区域播种。在未播种的感兴趣区域（ROI）中比较生成的纤维流线与解剖束分割的空间对应关系。
单个椎骨 ROI 中皮质脊髓束流线的空间对应关系良好（Dice 相似性系数（DSC）=0.75±0.08，Hausdorff 距离=1.08±0.17mm）。在更大的 ROI 中，轨迹和解剖标签之间达到了良好的一致性（两个水平：DSC=0.67±0.13，三个水平：DSC=0.52±0.19）。
DTI 轨迹与解剖白质束具有良好的空间对应关系，优于多个手动轨迹分割之间的一致性（DSC~0.5）。这支持了脊髓轨迹用于计算机辅助神经外科的进一步发展。
