You can review and adjust the Fibertracking parameters (if required) in order to optimally track fibers in the image set. Depending on the imported DTI data, the default settings (shown in the image below) may need adjustment.
The FA (fractional anisotropy) value reflects the amount of anisotropy (directionality) in every voxel. The algorithm follows the major diffusion direction path, as long as the FA value is over a certain threshold.
Slide the bar to change the minimum fractional anisotropy.
Lower values allow diffusion in many directions (isotropic) and higher values restrict diffusion along parallel directions (anisotropic).
Slide the bar to set the restriction for the minimum length of the fibers.
Slide the bar to set the angle between two fiber segments and thus to influence the fiber bundle angulation. Higher values allow fiber bundles with greater curvature.
To increase performance and reduce memory consumption, the number of points of a fiber bundle are reduced by employing the “Douglas-Peucker-Algorithm”. This is an algorithm that decimates a curve composed of line segments to a similar curve with fewer points, ensuring that the shape of the fiber is not significantly changed by defining a maximum allowed deviation. This might however result in slightly changed values for average FA and/or minimum length.