Finding the right tests…
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Finding the right tests…
MRI
Diffusion tensor imaging (DTI) maps the nerve fiber tracts that carry signals through your brain's white matter, by tracking the direction water molecules move along those fibers. Where fibers are tightly bundled and organized, water moves mainly in one direction, and DTI turns that pattern into a three-dimensional map of the tracts themselves, not just the brain's outer shape. Neurosurgeons use this map before operating on a brain tumor, to see how close it sits to pathways controlling movement, sensation, or language, so they can plan an approach that removes as much tumor as possible while avoiding those tracts. It's also studied in traumatic brain injury.
DTI produces fractional anisotropy values, a measure of how organized fiber tracts are in a given area, along with 3D tractography images showing the path of major white matter bundles relative to a lesion. Your doctor and the treating surgeon use this to plan the surgical approach.
Inside organized white matter, water molecules diffuse more easily along the length of a nerve fiber than across it. DTI measures this directional pattern throughout the brain and reconstructs it into visible tracts, a process called tractography.
- It shows whether a tumor is pushing a critical tract aside, growing into it, or has already damaged it - It helps identify tracts that control movement, sensation, vision, and language, so surgeons can plan around them - It can be combined with intraoperative navigation, so the surgical team has this map available in the operating room - Research suggests using DTI in planning is linked to more complete tumor removal with better preservation of function afterward
DTI is also studied in traumatic brain injury, where it can pick up changes in white matter that don't always show on a standard MRI. This use is more established in research settings than in routine day-to-day diagnosis, so your doctor will explain what a DTI scan can and can't tell you in your specific situation.
A standard MRI shows brain structures and any visible lesions. DTI adds a map of the nerve fiber tracts running through the white matter, based on how water moves along them.
It helps the surgeon see how close a tumor sits to tracts controlling movement, sensation, or language. That can change how the surgery is planned to protect those functions.
No. It's a type of MRI, so it uses magnetic fields and radio waves rather than X-rays.
No. You lie in the scanner as you would for any MRI. It may take longer than a routine MRI, since more data is being captured.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Yes, it's also studied in traumatic brain injury and some other neurological conditions. Its use there is more research-focused than routine, though, so your doctor will explain what it can offer in your case.
Yes, DTI tractography is typically shared with the treating neurosurgeon as part of surgical planning. It's reviewed together with your other scans before the operation.
It's considered a useful planning tool, but it's an estimate based on water movement, not a direct picture of nerve fibers. Your doctor interprets it alongside your other clinical information.