Utility of axial and radial diffusivity from diffusion tensor MRI as markers of neurodegeneration in amyotrophic lateral sclerosis

The asymmetry of neural symptoms in Wilson's disease patients detecting by diffusion tensor imaging, resting‐state functional MRI, and susceptibility‐weighted imaging

“…DTI metrics include fractional anisotropy (FA), axial diffusivity (λ1), and radial diffusivity (λ2, λ3) . (Metwalli et al., 2010) FA and λ values are thought to reflect the condition of axons and myelin (Maija et al., 2013). DTI fiber tracking (FT) can show individual fiber tracts of the brain (Coenen, Mädler, Schiffbauer, Urbach, & Allert, 2011; Mark et al., 2011).…”

Widespread Microstructural White Matter Involvement in Amyotrophic Lateral Sclerosis: A Whole-Brain DTI Study

“…2 DTI is a relatively new method for structural neuroimaging, which allows visualizing the orientation of the fiber tracts and assessing their integrity in the WM by measuring anisotropic water diffusion properties of the brain with MR imaging. 3 DTI has already produced promising results in assessing UMN pathology in patients with ALS, 2,[4][5][6][7][8][9] suggesting that FA, the most sensitive DTI measure, is reduced along the CSTs due to axonal degeneration and loss of fiber integrity, 2,4-6 though AD, MD, and RD changes along the CSTs and other WM structures may also be indicative of degenerative injury. 8,9 Significant correlations of diffusion parameters with duration, progression, and severity of the disease also have been reported in some previous studies.…”

“…3 DTI has already produced promising results in assessing UMN pathology in patients with ALS, 2,[4][5][6][7][8][9] suggesting that FA, the most sensitive DTI measure, is reduced along the CSTs due to axonal degeneration and loss of fiber integrity, 2,4-6 though AD, MD, and RD changes along the CSTs and other WM structures may also be indicative of degenerative injury. 8,9 Significant correlations of diffusion parameters with duration, progression, and severity of the disease also have been reported in some previous studies. 2,[9][10][11][12] Even if the clinical signs of ALS consist of motor impairments, recent evidence suggests that ALS is not an isolated motor neuron disorder 13 and that the variability in the location and extension of FA reduction in patients with ALS is such that relying on a priori ROIs to assess DTI changes may not give a consistent and complete picture of ALS neurodegeneration.…”

“…Therefore, a novel approach based on whole-brain DTI analysis may result in improved accuracy in detecting subclinical microstructural disease-related WM changes. Previous whole-brain DTI analyses reported regions of WM damage in ALS via voxel-based 6,11,14,15 and TBSS 8,[16][17][18][19] techniques. Most of these studies reported changes of FA and MD mainly in the CSTs, but also in the CC 6,8,15,[17][18][19] and the frontal and temporal lobes.…”

Complex regional pain syndrome: The matter of white matter?

“…However, the interpretations of the altered DTI parameters are not straightforward because the underlying cellular‐level pathophysiology is incompletely understood (for a review, see e.g., Concha, 2014). For example, increased AD combined with increased RD has been found in several neurological diseases such as multiple sclerosis (Roosendaal et al., 2009), Alzheimer's disease (Acosta‐Cabronero et al., 2010), and amyotrophic lateral sclerosis (Metwalli et al., 2010) with otherwise separate and distinctive pathophysiology.…”