Nov 1, 2021 · Some of the most commonly used approaches to date for studies of WM microstructure have been based on DTI, which provides general information on the local orientation of white matter fibres as well as metrics describing the fractional anisotropy (FA) and mean diffusivity (MD).

By using constrained spherical deconvolution (CSD) with a single fiber orientation as a basis function, we can resolve the signal measured within a voxel into its constituent fibers, or fiber orientation distributions (FODs).

Here we perform a 2-step threshold to identify template white matter fixels to be included in the analysis. Fixels in the template fixel analysis mask are also used to identify the best fixel correspondence across all subjects (i.e. match fixels across subjects within a voxel).

Nov 4, 2021 · Fixel-based analysis (FBA) and free water corrected DTI (fwcDTI) have recently emerged as useful techniques to quantify abnormalities in WM. Here, we sought to evaluate FBA and fwcDTI metrics between HIV+ and healthy controls (HIV−) individuals.

Nov 1, 2021 · Diffusion MRI has provided the neuroimaging community with a powerful tool to acquire in-vivo data sensitive to microstructural features of white matter, up to 3 orders of magnitude smaller than typical voxel sizes. The key to extracting such valuable information lies in complex modelling techniques …

Jan 28, 2022 · Fixel-based analysis (FBA) is a novel framework that addresses the shortcomings of DTI and estimates microstructural changes of individual populations of specific white matter...

Jan 1, 2017 · Fixels are colour-coded by family-wise error (FWE) corrected p-values and overlaid on the total voxel-wise FD map. As shown by the zoomed in region, fixel-based analysis enables fibre tract-specific inference by attributing p-values to …

May 4, 2023 · The goal of Fixel-Based Analysis is to compare groups and determine which fixels show a difference in fiber density, cross-section, or a combination of the two (referred to as Fiber Density & Cross-Section, or FDC).

Most prior studies of age differences in WM have used diffusion tensor imaging (DTI), but typical DTI metrics (e.g., fractional anisotropy; FA) can reflect multiple neurobiological features, making interpretation challenging.

Dec 20, 2024 · Diffusion Tensor Imaging (DTI) (Basser et al., 1994) is a single fiber method traditionally used to estimate properties of the fixels, averaging the diffusion properties of all the fixels within a voxel.