Brain MRI Report Explained
Plain-language explanations of common terms found on a brain MRI report
You Just Had a Brain MRI — What Do These Terms Mean?
If you have recently had a brain MRI, opening the radiology report can be an unsettling experience. Reports are written in dense medical language for other doctors, not for patients, and it is very easy to read an unfamiliar term — "white matter changes," "gliosis," "arachnoid cyst," "empty sella" — and assume the worst before you have even had a chance to discuss it with a doctor.
The reality is that radiology reports use a standardized vocabulary to describe absolutely everything the radiologist sees on the scan, including many findings that are extremely common, frequently related to normal aging, and often entirely incidental — meaning they were never the reason you had the scan and have nothing to do with whatever symptom prompted it. A report that runs to a full page of findings can still add up to "a normal brain for your age" once a doctor reviews it in context.
This page explains, in plain language, what the most commonly seen terms on a brain MRI report actually mean, which ones are usually nothing to worry about, and which ones genuinely warrant a neurosurgical opinion. It is written for patient education and general understanding — it is not a substitute for having your own specific report reviewed by a doctor who can see your actual images and correlate them with your symptoms.
Incidental Findings — Common and Usually Not Dangerous
The findings below are among the most frequent things patients search for after reading their own MRI report. They are grouped together here because they share an important feature: they are largely age-related or vascular in nature, and are usually followed by your treating physician or a neurologist rather than a neurosurgeon. They are not typically things that need an operation.
White Matter Changes / White Matter Hyperintensities
Small bright spots seen on certain MRI sequences (usually T2/FLAIR) within the brain's white matter. These become progressively more common with age and are usually related to the health of the brain's smallest blood vessels — often described as "microvascular" or "chronic small vessel ischemic changes." They are far more relevant to cardiovascular risk factors such as blood pressure, cholesterol, blood sugar, and smoking than to anything a neurosurgeon treats. Your treating doctor or neurologist can advise on any follow-up needed, usually centred on managing these vascular risk factors.
Gliosis
Gliosis describes an area where scar-like tissue (formed by supportive brain cells called glial cells) has replaced normal brain tissue following some earlier injury — this could be an old, often unnoticed small vascular event, a past head injury, or an area of prior inflammation. Gliosis itself is not a disease; it is a description of a healed change. Isolated gliosis findings, especially in older patients, are common and usually followed by your physician or neurologist rather than requiring neurosurgical treatment.
Lacunar Infarct / Old Infarct
A lacunar infarct is a small area of the brain that experienced a temporary loss of blood supply at some point in the past, often small enough that it caused no symptoms noticeable at the time. Finding one on a scan today is a marker of small-vessel disease and vascular risk, and it is generally addressed by your treating physician or neurologist through blood pressure, diabetes, and cholesterol management, along with lifestyle measures, rather than by neurosurgery.
Cerebral Atrophy
Atrophy simply means a loss of brain volume. Nearly everyone's brain loses some volume gradually with age, and mild, age-appropriate atrophy on a report is a normal, expected finding rather than a disease. Atrophy that appears more pronounced than expected for a person's age, or that comes with memory or thinking changes, is worth discussing with your physician or a neurologist, who are best placed to assess cognitive findings — this is not typically something a neurosurgeon manages.
Microvascular Ischemic Changes
This term describes the same family of small-vessel findings as white matter changes above — subtle evidence that the brain's tiniest blood vessels have been affected by long-term factors like high blood pressure, diabetes, high cholesterol, or smoking. These findings are a prompt to focus on cardiovascular health with your treating physician, and are not a neurosurgical finding.
Findings That May Need Neurosurgical Input
The findings below are the ones that genuinely fall within neurosurgical territory. Even among these, most are found incidentally, are small, and never require any treatment — but they are worth having formally reviewed by a neurosurgeon so that size, location, and any change over time can be properly assessed.
Meningioma
A tumor arising from the membranes covering the brain, most often benign and slow-growing. Many are found incidentally and simply monitored with periodic MRI; others need surgical removal depending on size, location, and growth. Read our full guide to meningioma →
Pituitary Lesion / Empty Sella
A pituitary lesion or adenoma is an abnormal growth of the pituitary gland and may need evaluation of hormone levels and, in some cases, surgery. This is different from an "empty sella," which describes the sella turcica (the bony space housing the pituitary gland) appearing partly filled with cerebrospinal fluid and the gland looking smaller or flattened as a result. An empty sella is usually a normal anatomical variant that needs no treatment at all — it should not be confused with an actual pituitary tumor. Read our full guide to pituitary tumors →
Arachnoid Cyst
A fluid-filled sac between the brain and one of its covering membranes. The great majority are congenital (present from birth), asymptomatic, and stable, and are simply left alone once identified. A small minority — larger cysts, or ones associated with symptoms such as headaches, seizures, or pressure effects on nearby brain tissue — are assessed for possible treatment.
Pineal Cyst
A fluid-filled cyst in the pineal gland, a small structure deep in the brain. This is one of the most frequently seen incidental findings on brain MRI and is almost always harmless, small, and stable over time. Large or symptomatic pineal cysts are uncommon and would be assessed individually.
Chiari Malformation / Low-Lying Cerebellar Tonsils
A structural finding where the lowest part of the cerebellum extends slightly below the base of the skull into the spinal canal. Many cases are mild and incidental; others cause a characteristic headache pattern worsened by coughing or straining and may benefit from decompression surgery. Read our full guide to Chiari malformation →
Hydrocephalus
An abnormal build-up of cerebrospinal fluid within the brain's ventricles, which can cause pressure symptoms such as headache, nausea, vision changes, or gait and balance problems. This is a genuinely neurosurgical finding that needs formal evaluation and, in many cases, treatment. Read our full guide to hydrocephalus →
Sinus-Related Findings
Because the sinuses sit right next to the base of the skull, a brain MRI very often incidentally captures part of them, and reports frequently mention things like "mucosal thickening" in the sinuses or a small amount of fluid within a sinus cavity. These are almost always ear-nose-throat (ENT) findings related to sinus lining changes, allergies, or a recent cold — not a neurosurgical issue. If a report mentions a sinus finding, it is usually enough to simply note it to your physician, who can refer you to an ENT specialist if it is relevant to any nasal or sinus symptoms you may have.
The Finding Alone Doesn't Tell the Whole Story
A radiology report describes what your MRI shows — it doesn't, by itself, tell you whether any treatment is needed. What actually matters is correlating the finding with your real symptoms, its exact size and location, and whether it is changing when compared with any previous scans. The same word on two different reports — "cyst," "lesion," "changes" — can mean something completely different in size, risk, and next steps for two different patients. This is exactly why a formal review by a neurosurgeon, rather than reading the report in isolation, is the safest way to know what your result actually means for you.
Frequently Asked Questions
What does white matter changes on MRI mean?
Is gliosis on a brain MRI serious?
What is an arachnoid cyst and is it dangerous?
What does empty sella mean on a brain MRI?
Should I worry about a pineal cyst?
What is cerebral atrophy?
What is a lacunar infarct on MRI?
Can I get a second opinion on my brain MRI report?
Want Your MRI Report Explained Clearly?
Consult Dr. Waqas Mehdi for a plain-language explanation of your brain MRI findings and clear advice on whether any follow-up is needed. MidCity Hospital, Lahore — Mon to Sat, 6–8 PM.
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