In neuroscience, tractography is a 3D modeling technique used to visually represent nerve tracts using data collected by diffusion MRI.

The results are presented in two- and three-dimensional images called tractograms.

The existence of these tracts and circuits has been revealed by histochemistry and biological techniques on post-mortem specimens.

Nerve tracts are not identifiable by direct exam, CT, or MRI scans.

This difficulty explains the paucity of their description in neuroanatomy atlases and the poor understanding of their functions.

The most advanced tractography algorithm can produce 90% of the ground truth bundles, but it still contains a substantial amount of invalid results.

This shape is often modeled as an ellipsoid, and the technique is then called diffusion tensor imaging.

Anisotropic diffusion is expected to be increased in areas of high mature axonal order.

Conditions where the myelin or the structure of the axon are disrupted, such as trauma,[5] tumors, and inflammation reduce anisotropy, as the barriers are affected by destruction or disorganization.

Basic colors can tell the observer how the fibers are oriented in a 3D coordinate system, this is termed an "anisotropic map".

The software could encode the colors in this way: The technique is unable to discriminate the "positive" or "negative" direction in the same axis.

Following the Frenet–Serret formulas, we can formulate the space-path of the fiber tract as a parameterized curve: where

By equating the eigenvector corresponding to the largest eigenvalue with the direction of the curve: we can solve for