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MRI · Brain

What a brain MRI shows, and what the report means

Read Your Scan Editorial Team·Last updated

Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →

The short answer

A brain MRI shows the substance of the brain, the fluid-filled ventricles, the coverings and the blood vessels, in far more detail than a CT and without radiation. It is used for headaches, neurological symptoms, suspected stroke, and to characterise anything a CT found.

A brain MRI (magnetic resonance imaging) uses a strong magnet and radio waves — no X-rays — to make detailed pictures of the brain. This page explains what it looks at and what terms on the report can mean.

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What a brain MRI shows, and what the report means

What this scan shows

A brain MRI shows the brain tissue in fine detail, along with the fluid spaces, blood vessels, and surrounding structures. Doctors order it to look into headaches, dizziness, memory changes, weakness, seizures, or to follow up on other tests. MRI is especially good at showing soft tissue. Many findings it describes are common, age-related, or minor — the report describes what the pictures show, and your doctor interprets what it means for you.

Brain MRI — What this scan shows
A real exam, not a drawing. Openly licensed — 511KeV · CC BY-SA 4.0

Common findings, in plain words

White matter hyperintensities

Small bright spots in the brain’s wiring seen on certain images. They are very common, especially with age, and are often related to normal aging or blood-vessel health. Your doctor considers them alongside your symptoms and history.

Atrophy

A description of the brain appearing slightly smaller or with a bit more space around it. Some volume change is a normal part of aging. It is one observation among many your doctor weighs.

Ischemia / small vessel changes

Signs relating to blood flow in small vessels. These are frequently seen and are usually described so your doctor can consider your overall vascular health.

Sinus or mastoid changes

Fluid or thickening in the sinuses or the air spaces near the ear, often noticed incidentally. These are common and frequently unrelated to the reason for the scan.

Mass or lesion

A general term for an area that looks different from the surrounding tissue. Many are benign or harmless. The report describes it so your doctor can decide whether anything further is helpful.

Incidental cyst

A fluid-filled pocket found by chance. Most brain cysts are harmless and stable. Your doctor decides whether it needs any monitoring.

Terms you might see

Hyperintensity
An area that appears brighter than the surrounding tissue on a particular MRI image. It describes appearance, not a specific diagnosis.
Lesion
A general word for any area that looks different from normal tissue. It does not, on its own, say whether something is serious.
Contrast (gadolinium)
A dye sometimes given through a vein to make certain areas stand out. Not every brain MRI uses it.
Ventricles
The normal fluid-filled spaces inside the brain. Their size is often noted as part of a routine description.
FLAIR
A common MRI image setting that makes some changes in brain tissue easier to see. You may see it named in the report.
Basal ganglia
A group of structures deep in the centre of the brain involved in movement and habit. Reports mention them because small changes there are common with age and with blood-pressure related vessel change.
Report glossary, A–Z →

Questions to ask your doctor

  • 1.What prompted this MRI, and did the images address that concern?
  • 2.Are any of the findings expected for my age, or do any stand out?
  • 3.Do any findings need a follow-up scan, and if so, when?
  • 4.Should these results be discussed with a specialist?
  • 5.Is there anything I can do to support my brain and vascular health?

See these findings on your own scan

Upload your scan (de-identified in your browser) and your radiologist’s report, and every finding is mapped onto the images, explained in plain language and scored — free, no card needed. Informational only — not a diagnosis.

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FAQ

What do white spots on a brain MRI mean?
Small bright spots (white matter hyperintensities) are very common, especially as we get older, and are often linked to normal aging or blood-vessel health. Your doctor reads them together with your symptoms rather than in isolation.
Does an MRI use radiation?
No. MRI uses a strong magnet and radio waves, not X-rays. That is one reason it is often chosen for imaging the brain and other soft tissues.
Why did my scan use contrast dye?
Contrast can make certain areas easier to see, such as when looking more closely at a specific finding. Whether it is used depends on the clinical question, and your care team can explain why for your scan.

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Go deeper

What “clinical correlation is recommended” means on your reportThe sentence is addressed to your doctor, not to you. What a radiologist means by it, the three different jobs it does, and when it is worth asking about.What “unremarkable” means on a medical reportUnremarkable means normal — nothing worth remarking on. Why the best news in a radiology report is written in its flattest word, and what "grossly" adds.What “no acute intracranial abnormality” means on a head CTThe standard conclusion of a normal head CT. What the scan was actually looking for, why "acute" is the key word, and what a normal CT does not rule out.T2/FLAIR hyperintensities: the bright spots on a brain MRIThe bright spots on your brain MRI, what the report calls them, why "small vessel ischemic disease" sounds worse than it usually is, and how they are graded.What “mucosal thickening” means on a sinus CT or MRIWhy "mucosal thickening" turns up on scans done for something else entirely, what mild versus severe means, and when a sinus finding is worth acting on.What “encephalomalacia” means on a brain scanAn area where brain tissue was lost and never came back. Why it is almost always old, what gliosis beside it means, and why it is not a progressive disease.What a pineal cyst means on a brain MRIA fluid-filled sac in a gland at the centre of the brain. Why most are found by accident, why size alone is not the issue, and when one is actually followed up.What “cavum septum pellucidum” means on a brain scanA small fluid space between two membranes at the centre of the brain. Why it is a normal variant in adults, and why it is looked for on a fetal scan.What “small vessel ischemic changes” means on a brain MRIWhite spots in the brain’s white matter, reported as small vessel disease or chronic microvascular change. Why they are so common after 50 and what the wording is actually claiming.What “concha bullosa” means on a sinus CTAn air pocket inside one of the structures in your nose. Why it is classed as a normal variant found in a third of people, and when it is worth doing anything about.How to read a radiology reportA radiology report has five parts and only one is the answer. What each section means, which sentence to read first, and what the hedging words are doing.MRI vs CT scan: what each one showsMRI and CT answer different questions. What each physically detects, which tissues it sees well, how long it takes, and why your doctor chose one.How to read a brain CT scanWhat a radiologist checks on a head CT and in what order: windows, symmetry, grey-white contrast, ventricles, cisterns — and what an early scan misses.How to read a brain MRIA brain MRI is several scans of the same head. What T1, T2, FLAIR, DWI and post-contrast each reveal, and how a radiologist compares them.MRI sequences explainedWhy one MRI produces many different image sets, what each sequence is sensitive to, and how to tell fat from fluid from blood by comparing them.Contrast on a CT or MRI, explainedWhat contrast dye does, why iodine is used for CT and gadolinium for MRI, why some scans are done both with and without, and what the safety checks are for.How long do scan results take?The images are ready in minutes; the report is not. Why routine scans wait, what urgent changes, and why the portal shows it before your doctor calls.

Sources

  1. Patient-facing procedure descriptions (MRI, CT, X-ray, ultrasound)RadiologyInfo.org — Radiological Society of North America & American College of Radiology
  2. MRI scan — overview, how it is performed and resultsNHS (United Kingdom)
  3. ACR Appropriateness Criteria and practice parameters for reportingAmerican College of Radiology

Read Your Scan is informational only — not a medical diagnosis, and not a substitute for a licensed radiologist or your doctor. If you have urgent symptoms, seek care.

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