What does a DTI map show?
Some clinics offer DTI after a concussion, crash, sports injury, normal CT, or normal MRI. In studies, some injured groups show average white-matter differences, mainly after more serious injury. One person's colored map or FA number is harder to read because movement, age, sex, scanner settings, software, and the comparison group can change it.
DTI output
DTI estimates the direction of water movement
Common results include FA, MD, other water-movement numbers, and brain-path maps made by software.
Established planning use
A known brain target may need a surgery map
A tract map may help locate brain paths near a tumor or epilepsy target when used with standard MRI and specialist mapping.
One unusual number has many causes
A difference cannot show when or why it began
An unusual result may come from injury, another illness, normal differences, movement, the scanner, the comparison group, or the software.
Symptoms can be serious even when CT, standard MRI, and DTI look normal. After checks for urgent problems, assess headache, balance, vision, sleep, mood, neck, medicines, thinking, and activity.
Save this test
Save DTI as an imaging report, not a damage score
Save each tract or number with the scanner, software, comparison data, standard MRI, symptom timeline, specialist opinion, and decision it changed.
My Fog keeps the report and questions you enter for your appointment.
Children, pregnancy, men and women, older adults, injury severity, and surgical planning
Brain growth, aging, pregnancy, sex, blood-vessel health, movement in the scanner, and the reason for the scan can change DTI results. There is no single normal map for every group.
Children and teenagers
White matter changes as a child grows, so adult comparison data do not apply. CDC says scans should not be used as a routine test for mild brain injury in children. Young children may also need sedation to lie still, which adds risk.
Pregnancy and breastfeeding
MRI does not use X-ray radiation. Tell the clinician and scan center if you are or may be pregnant. Pregnant people usually don't get MRI dye unless they need it. DTI often needs no dye, but another part of the MRI may use it.
Men and women
One FA value cannot prove injury in a man or woman. A 2026 review found that sex changed the size of group differences. The comparison group should therefore match the person, but there is no injury cutoff for each sex.
Older adults
Aging, small blood-vessel disease, an old stroke, brain disease, falls, medicines, and heart risks can change white matter and symptoms. Blood thinners can make a new injury more urgent. Standard CT or MRI comes before calling one DTI number an old injury.
Brain tumor or epilepsy surgery
With a known tumor or epilepsy target, tract maps may help show where movement, speech, or vision paths run before surgery. A tumor, swelling, crossing fibers, and brain movement during surgery can change the map. It is one part of the plan.
Before a DTI MRI appointment
Ask what the full MRI order includes. DTI is usually added to a standard brain MRI. It doesn't replace the images used to look for bleeding, stroke, tumor, multiple sclerosis, or other changes in brain structure.
Ask what the DTI part will change. Mapping a brain pathway before surgery is one clear use. An old mild brain injury, recovery forecast, symptom explanation, legal claim, or rehab choice raises different questions.
Complete the MRI safety form. Bring the maker, model, and implant card for a pacemaker, hearing implant, aneurysm clip, nerve stimulator, pump, metal fragment, surgery hardware, medicine patch, or other device. The center must check any unknown implant.
Tell the center about pregnancy, kidney disease, a past reaction to MRI dye, or fear of closed spaces. Also mention pain, movements you cannot control, trouble lying flat, hearing needs, or a need for sedation. DTI itself often needs no dye, but another part of the MRI may use it.
Follow the center's food and medicine rules, especially if you're having dye or sedation. Do not fast, stop medicine, or take a sedative on your own.
Bring the injury date, emergency records, older CT and MRI images, symptom timeline, nerve exam, and any thinking tests. Ask what insurance will cover and what you will pay before buying a scan package.
Remove metal and electronics as directed. Tell the staff if noise, a closed space, pain, dizziness, or symptoms may keep you from lying still. Movement can change DTI numbers.
After a new injury, get urgent help for a worsening headache, repeated vomiting, a seizure, or growing confusion or sleepiness. Weakness, numbness, slurred speech, unequal pupils, fainting, or fast-worsening nerve signs also need urgent help. Do not wait for a DTI visit.
Write down why you need the scan
Record whether DTI is mapping brain paths before surgery, adding information to a standard MRI, or being used after a concussion. These uses have different evidence.
Keep the standard MRI with it
Save the standard MRI findings, images for blood and stroke, any dye used, and the radiologist's main result. A tract map is only one part of the scan.
Ask how the numbers were made
Ask for the scanner strength, scan settings, movement fixes, software, brain map or tracts, comparison group, cutoff, and whether the reader used images, numbers, or both.
Ask what the report changes
The report should change a clear surgery, scan, rehab, or symptom-care decision. If every result leads to the same treatment sold by the clinic, ask an independent brain radiologist or neurologist.
How to read a DTI MRI or tractography report
Start with the reason for the scan, injury date and severity, and the standard MRI. Then check the scanner settings, movement fixes, software, comparison group, brain area, cutoff, and scan limits. Ask which care decision the result should change.
No reportable DTI abnormality
No reportable diffusion or tract abnormality on a technically adequate study, with no concerning finding on the conventional MRI
The scan did not find a DTI or standard MRI change that the radiologist could report. A past concussion or ongoing symptoms can still need care based on the history and exam.
Isolated or uncertain quantitative difference
A small, isolated, asymmetric, or statistically flagged difference with unclear technical quality, reference data, symptom match, or conventional MRI correlate
Check movement, scan quality, scanner and software, brain area, comparison group, and how many areas were tested. Ask whether an independent brain radiologist gets the same result.
Reproducible finding tied to a known lesion or defined question
A reproducible diffusion difference or displaced tract reported in a named region, interpreted with a known lesion, standard MRI, examination, and a defined clinical question
The finding may help plan surgery or a wider check. A specialist must match it to the standard MRI, exam, and symptoms before deciding what it means or what to do.
There is no personal DTI cutoff for concussion
The 2026 mild-TBI review included 325 studies and 26,287 participants. Lower FA was the most common group finding, but results were less consistent than in more severe injury and links with symptoms were mixed. That's useful research evidence, not a test that can prove why one person has brain fog.
See research details
These notes explain head-injury guidance, recent reviews, scanner effects, and use before brain surgery.
Ask whether the clinical question needs acute CT, standard MRI, vascular imaging, susceptibility imaging, or another defined study before paying for advanced diffusion analysis.
The scale of the literature supports continued research. It does not create a universal FA cutoff or let one scan prove that a past injury caused one person's current symptoms.
These findings can guide research questions. They do not show that DTI can identify the cause of symptoms in every person or improve care when used as a retail confirmation test.
Do not use one team's research pipeline as a universal return-to-play, prognosis, or permanent-damage test. Clinical recovery and graded return decisions require the athlete's symptoms and examination.
A published group difference can't serve as one person's normal range. The report needs demographic, scanner, injury-severity, and analysis context.
For a repeat or comparison, ask whether the scanner, acquisition, processing, atlas, and reference data match. Another clinic's methods may change the result even if the brain hasn't.
This supports selected specialist planning around a known lesion. It does not validate individual concussion diagnosis, symptom attribution, or a treatment sold from an isolated FA map.
What can you do before follow-up?
Keep treating the symptoms while deciding whether DTI would change care. You do not need a colored tract map for a clinician to take the symptoms seriously.
Build a dated injury and symptom record
Write the injury date, any fainting or memory gap, emergency results, recovery, and setbacks. Track headache, dizziness, vision, sleep, mood, neck pain, exercise, attention, memory, school or work, and what helps or worsens each symptom.
Get help for the symptom that is present
Ask for care that matches the problem, such as headache, balance, vision, sleep, mood, neck, medicine, thinking, or step-by-step activity care. DTI should not delay care based on symptoms and the exam.
Ask for an independent read before buying treatment
Be cautious if a clinic compares you with its own database and then sells rehab, neurofeedback, injections, supplements, or repeat scans. Ask an independent brain radiologist or specialist whether the method is proven and whether the result changes care.
Keep activity guidance tied to recovery, not a colored map
After urgent danger has passed, follow a step-by-step return plan based on symptoms, the exam, school or work, and the injury. Do not use a tract map alone to return to contact sports, driving, heavy work, or another risky activity.
Do not buy supplements, peptides, hyperbaric oxygen, neurofeedback, a strict diet, injections, or costly rehab to change FA, MD, tract count, or a colored map. Do not use DTI alone to return to sports or stop medicine. New or worse nerve warning signs need urgent care.
What to save before the next appointment
Keep these together
- Reason for imaging, injury date and severity if relevant, symptoms, neurologic examination, and the decision the scan was expected to change.
- Complete MRI protocol, standard sequences, contrast use, scanner manufacturer and field strength, diffusion directions and b-values if reported, and technical-quality notes.
- Motion and distortion correction, analysis software and version, atlas or tracts, comparison database, matched age and sex information, statistical threshold, and any correction for multiple comparisons.
- FA, MD, axial or radial diffusivity, z-score or asymmetry only with the named region, unit, reference, and interpretation. Do not save a detached number as a diagnosis.
- Save the full radiology report, original images and tract maps, and any earlier CT or MRI. Add cognitive or symptom testing, an independent review, coverage or cost, and the next medical or surgical step.
Question for the visit
“Is the scan clear and the finding specific? Does an independent reader get the same result? Does it match the standard MRI and exam, and will it change treatment or surgery?”
Sources for DTI MRI (Diffusion Tensor Imaging)
Guide sections: Current head-trauma guidance separates DTI from ordinary MRI; Older adults
Guide sections: Current head-trauma guidance separates DTI from ordinary MRI; Ask for an independent read before buying treatment
Guide sections: Build a dated injury and symptom record; Get help for the symptom that is present
Guide sections: Children and teenagers; Get help for the symptom that is present; Keep activity guidance tied to recovery, not a colored map
What patients should know before having an MRI exam.
Guide sections: Children and teenagers
Guide sections: Pregnancy and breastfeeding
Reference listed in this guide.
The second decade of DTI in TBI part 1: a systematic review of mild TBI.
Diffusion MRI of white matter alterations in chronic traumatic brain injury: a systematic review and meta-analysis.
Predictive Utility of Diffusion MRI After Mild Traumatic Brain Injury in Civilian Populations: A Systematic Review.
Clinical utility of diffusion tensor imaging in sport-related concussion: a systematic review.
The use of intraoperative tractography in brain tumor and epilepsy surgery: a systematic review and meta-analysis.
Harmonization of multi-site diffusion tensor imaging data.
See each claim's sources
procedure
DTI applies diffusion-sensitive gradients in multiple directions to model water-diffusion direction, then derives metrics such as FA and MD and may be used for tractography.limitation
Current head-trauma guidance does not support routine MRI with DTI as an individual concussion diagnosis or treatment selector, while standard MRI may be useful for persistent unexplained neurologic deficits.interpretation
Across the second decade of mild-TBI DTI research, the direction of diffusion findings varied and links with post-concussion symptoms were inconsistent, so group results cannot be treated as a personal diagnostic cutoff.interpretation
Chronic-TBI diffusion effects differ with injury severity and are influenced by age, sex, and magnetic field strength, which limits direct comparison between studies and people.limitation
FA and MD are affected by scanner and site, so comparison across systems requires acquisition and analysis context and may require harmonization.indication
Diffusion tractography may support selected tumor and epilepsy surgical planning, which is a different use from diagnosing mild TBI or attributing brain-fog symptoms.safety
MRI does not use ionizing radiation but requires implant and metal screening, hearing protection, stillness, and separate review of any sedation or gadolinium contrast.