Diffusion Tensor Tractography of the Corticospinal and Medial Lemniscus Pathways in Healthy Adults

Abstract

Objective: This study aims to visualize major brainstem white matter pathways in vivo through MR tractography, with a specific focus on the corticospinal tract (CST) and medial lemniscus (ML), which are essential motor and sensory tracts in healthy individuals. Methods: Twenty right-handed healthy adults (10 females, 10 males; mean age: 29.95 ± 8.77 years) with normal brain MRI findings were included. DTI was acquired using a 3T MRI scanner. For each participant, CST and ML tracts were reconstructed bilaterally by placing regions of interest (ROIs) at anatomically defined points within the internal capsule and brainstem. Tracts fractional anisotropy (FA) values were calculated for quantitative assessment, and tract visual quality was scored independently by two observers using a 5-point scale. Results: Tract reconstruction was successful in all participants. CSTs demonstrated consistently higher FA values and clearer anatomical delineation compared to ML tracts. Visual quality was independently rated by two experts using a 5-point scale. Mean CST scores were significantly higher than ML scores (p < 0.001), and inter-observer consistency was strong. Conclusion: This study demonstrated that the CST and ML pathways can be reliably and anatomically accurately visualized in healthy individuals using ROI-based tractography. Establishing normative data for these vital brainstem tracts may serve as a valuable reference, particularly for neurological disorders or neurosurgical planning in which these pathways are likely to be affected.

Keywords

• Diffusion tensor imaging (DTI)
• Tractography
• Corticospinal tract (CST)
• Medial lemniscus (ML)

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