Purpose: To examine the T 2 -normal appearing spinal cord of patients with multiple sclerosis (MS) using diffusion tensor imaging.
Materials and Methods:Diffusion tensor images of the spinal cord were acquired from 21 healthy subjects, 11 MS patients with spinal cord lesions, and 10 MS patients without spinal cord lesions on the T 2 -weighted MR images. Different diffusion measures were evaluated using both a region of interest (ROI) -based and a diffusion tensor tractography-based segmentation approach.Results: It was observed that the FA, the transverse diffusivity Ќ , and the ratio of the longitudinal and transverse diffusivities ( / Ќ ) were significantly lower in the spinal cord of MS patients with spinal cord lesions compared with the control subjects using both the ROI method (P ϭ 0.014, P ϭ 0.028, and P ϭ 0.039, respectively) and the tractography-based approach (P ϭ 0.006, P ϭ 0.037, and P ϭ 0.012, respectively). For both image analysis methods, the FA and the / Ќ values were significantly different between the control group and the MS patient group without T 2 spinal cord lesions (P ϭ 0.013).
Conclusion:Our results suggest that the spinal cord may still be affected by MS, even when lesions are not detected on a conventional MR scan. In addition, we demonstrated that diffusion tensor tractography is a robust tool to analyze the spinal cord of MS patients.