Quantification of Corticospinal Tract Atrophy Using Diffusion Tensor Imaging: A Potential Diagnostic Tool in Amyotrophic Lateral Sclerosis

Abstract

Amyotrophic Lateral Sclerosis is a rare neurode-generative disease affecting the motor tract pathways. The role of neuroimaging in diagnosing Amyotrophic Lateral Sclerosis is still growing, and no definite technique has been adopted yet. Using an advanced neuroimaging technique, namely Diffusion Tensor Imaging, we propose a novel non-invasive, objective and quantitative technique to help in the diagnosis of Amyotrophic Lateral Sclerosis. Specifically, we collected Fractional Anisotropy and Apparent Diffusion Coefficient measurements at three anatomical sites (Posterior Limb of the Internal Capsule, Anterior Cerebral Peduncle, and Pre-Pyramidal Decussation in the medulla oblongata), where Corticospinal Tracts cross inside the brain and brainstem, in 10 Amyotrophic Lateral Sclerosis patients and 10 healthy controls. Then, we derived Side-to-Side Ratios of the collected Fractional Anisotropy and Apparent Diffusion Coefficient data at every site, and statistically evaluated these data to check for differences between abnormal patients and controls. Our results showed that for Amyotrophic Lateral Sclerosis patients, the Apparent Diffusion Coefficient inter-side difference was $0.4500\times 10^{-10}$, which was more than double the Apparent Diffusion Coefficient inter-side difference in Controls $(0.0212\times 10^{-10})$. The Side-to-Side Ratio of Apparent Diffusion Coefficient at the Posterior Limb of the Internal Capsule was significantly different between abnormal patients and Controls. The Receiver Operating Characteristic curve comparing the Side-to-Side Ratio of Apparent Diffusion Coefficient at the Posterior Limb of the Internal Capsule between abnormal and Control groups showed a sensitivity and specificity of 30% and 90%, respectively, with a likelihood ratio of 3.0 for values <1.017. Our study appeared promising and is the first of its kind in terms of evaluating the diagnostic value of the Side-to-Side Ratios of Fractional Anisotropy and Apparent Diffusion Coefficient measurements at different levels of the central motor pathway in Amyotrophic Lateral Sclerosis patients.