Diffusion MRI tractography estimates the course of white-matter pathways in the living brain. In epilepsy surgery it can help surgeons plan routes and treatment boundaries that reduce the risk of damaging critical visual, language and motor connections.
Why white matter matters
Epilepsy surgery is not only about avoiding eloquent cortex. Damage to connecting white-matter tracts can also cause permanent neurological deficits.
Tractography provides a patient-specific estimate of where those pathways may run.
The optic radiation is a classic example
Anterior temporal lobe surgery can injure Meyer’s loop, part of the optic radiation, producing a superior visual-field defect.
DTI tractography has been studied as a way to estimate the pathway preoperatively and adapt the surgical approach.
Other pathways can also be mapped
Depending on the operation, tractography may be used to estimate corticospinal, language-related and other association pathways.
The clinically relevant tract depends on the planned resection or ablation.
It is a model, not a photograph of axons
Tractography reconstructs probable pathways from patterns of water diffusion.
Crossing fibres, distortion, acquisition quality and algorithm choices can produce false-positive and false-negative streamlines.
Recent evidence is encouraging but not epilepsy-specific enough to overstate
A 2025 systematic review/meta-analysis across intracranial surgery found tractography-assisted approaches associated with fewer postoperative neurological deficits.
However, only a subset of the evidence came from epilepsy surgery, so the result should not be interpreted as proof for every epilepsy procedure.
Intraoperative integration is developing
Tractography can be incorporated into neuronavigation and combined with direct electrical stimulation or functional mapping.
Brain shift during open surgery can reduce the accuracy of preoperative images, which is one reason intraoperative updating remains an area of development.
Best used as one safety layer
Tractography can help visualise risk, but direct functional mapping remains the reference standard in many situations.
The safest planning combines anatomy, function and the individual surgical hypothesis.
Related reading
Sources and further reading
- Diffusion MRI tractography to reduce postoperative neurological deficits — 2025 meta-analysis
- Intraoperative tractography in brain tumour and epilepsy surgery — systematic review/meta-analysis
- Optic-radiation tractography in anterior temporal lobe resection
Evidence checked: September 2026.