How to Understand Your Brain MRI Results

By Margaret O. Johnson, MD, Evan Calabrese, MD, PhD, and Daniel S. Rudd, RN

September 16, 2026

How to Understand Your Brain MRI Results: A Guide for Patients With Brain Cancer

Originally published Dec. 2025, updated August 2026.

Getting a brain MRI can be an important part of diagnosing and monitoring brain cancer, but reading the resulting report can be overwhelming. Radiology reports often contain terms such as lesion, enhancement, edema, mass effect, necrosis, and progression that may sound alarming when you first see them.

The most important thing to remember is that an MRI report is not a diagnosis by itself. Your care team interprets the findings alongside your symptoms, neurological examination, previous MRI scans, treatment history, biopsy or surgical results, and overall health. A finding that sounds concerning in a report does not necessarily mean that your brain tumor has grown or that treatment is not working.

Key Takeaways: Understanding Brain MRI Results

A brain MRI provides detailed images of the brain and can help doctors detect and monitor tumors.
MRI reports use specialized medical terminology that may not have the same meaning to patients that it does to physicians.
One MRI scan does not tell the entire story; doctors compare current and previous scans to identify meaningful changes.
Contrast enhancement, edema, necrosis, and other findings do not automatically mean that a brain tumor is growing.
Treatment effects such as pseudoprogression can sometimes make an MRI appear worse even when treatment is working.
BT-RADS may be used to standardize how brain tumor MRI findings are categorized.
Your neuro-oncology team should interpret your MRI results in the context of your complete medical history.

What Does a Brain MRI Show?

A brain MRI uses magnets and radio waves to create detailed images of the brain without using ionizing radiation. For patients with brain cancer, MRI can help doctors locate a tumor, measure changes over time, evaluate surrounding brain tissue, assess treatment response, and identify changes such as swelling or bleeding.

MRI is particularly valuable because physicians can compare images from multiple scans to determine whether an abnormal area is stable, changing, or responding to treatment.

Your doctor may recommend periodic MRIs throughout your care. These scans can help the treatment team make decisions about surgery, radiation therapy, chemotherapy, immunotherapy, or continued monitoring.

What Your MRI Can Help Doctors Evaluate

A brain MRI may provide information about:

The location of a tumor
The size and shape of a tumor
Changes compared with previous scans
Swelling around a tumor
Bleeding or other structural changes
How a tumor responds to treatment
Possible tumor recurrence
Changes following surgery or radiation therapy

The MRI is one part of the diagnostic process rather than a standalone answer.

How Do Doctors Interpret Brain MRI Results?

Doctors interpret MRI results by looking at the current scan, previous scans, your symptoms, treatment history, and other clinical information together.

This is especially important for patients undergoing brain cancer treatment. An area that looks different from a previous scan may represent tumor growth, but it could also reflect inflammation, swelling, scar tissue, or another treatment-related change.

Your care team may consider:

What the previous MRI showed
Whether the tumor has changed in size
Whether new areas of enhancement have appeared
Whether your symptoms have changed
What treatment you have recently received
Results from surgery or biopsy
Your neurological examination

This broader context is why reading an MRI report on your own can sometimes create unnecessary anxiety. The radiologist describes what is visible on the images, while your oncology team combines those findings with the rest of your clinical picture.

Common Brain MRI Terms Explained

MRI reports are written primarily for communication between medical professionals. Understanding some of the most common terminology can make your report easier to discuss with your care team.

Lesion or Mass

A lesion or mass generally refers to an area of tissue that appears abnormal on an imaging study.

Seeing the word "lesion" does not automatically tell you whether the area is cancerous, whether it is growing, or whether treatment is working.

Additional information from imaging, previous scans, pathology, and your clinical history is needed to determine what the finding represents.

Tumor Size and Measurements

MRI reports may include measurements such as 2.4 cm x 1.9 cm.

What It Means

These measurements describe the dimensions of the area being evaluated. Your doctor will compare measurements from different scans to determine whether a meaningful change has occurred.

Reports may describe a finding as:

Stable: No significant change
Increased: The measured area is larger
Decreased: The measured area is smaller

Small differences between measurements do not necessarily mean that a tumor has meaningfully grown or shrunk. The overall pattern across multiple scans is often more informative than one measurement.

Enhancement

Enhancement describes how an area of the brain appears after contrast material is administered during an MRI.

Enhancement does not automatically mean that a brain tumor is growing.

Different tumors can enhance differently, and treatment itself can change how an area appears on an MRI. Your doctor considers enhancement alongside other imaging findings and your clinical history before determining what it means.

Edema

Edema is swelling caused by excess fluid in or around brain tissue.

Brain tumor-related edema can develop around a tumor and may contribute to symptoms such as:

Headaches
Nausea
Vision changes
Weakness
Other neurological symptoms

Depending on the circumstances, doctors may use medications such as corticosteroids to reduce swelling.

For more information, patients can also learn about what happens when the brain swells from cancer.

Midline Shift

A midline shift occurs when pressure from swelling, a tumor, or another mass pushes brain structures away from their normal central position.

The significance of a midline shift depends on its severity, underlying cause, symptoms, and other MRI findings. Your care team will determine whether it requires treatment or additional monitoring.

Necrosis

Necrosis means that tissue has died.

In patients receiving cancer treatment, necrosis can sometimes occur when tumor cells or surrounding tissue are damaged by treatment. Although the term can sound alarming, necrosis does not automatically mean that cancer is progressing.

Your physicians may need to consider the location, appearance, timing, treatment history, and other imaging findings to determine what the necrosis represents.

Does a Brain MRI Show If a Tumor Is Growing?

An MRI can show changes that may suggest tumor growth, but a change on one scan does not always mean that the tumor is progressing.

Doctors generally compare the newest MRI with previous scans to identify trends. They may look at:

Changes in tumor size
New areas of enhancement
Changes in surrounding edema
Changes in tumor appearance
New abnormalities
Your symptoms and neurological function

This comparison is particularly important after treatment because radiation, chemotherapy, and immunotherapy can cause temporary changes that resemble tumor progression.

Why One Brain MRI Does Not Tell the Whole Story

An MRI is essentially a snapshot of what is happening in your brain at one point in time. Your physician needs additional information to determine what those images mean for your individual situation.

Your MRI results should always be interpreted in context, not in isolation.

Two patients can have similar-looking MRI findings but receive different recommendations because their:

Tumor types differ
Treatment histories differ
Symptoms differ
Previous scans differ
Molecular tumor characteristics differ
Overall health differs

This is particularly important when an MRI shows a new or enlarged area after treatment.

What Is Pseudoprogression on a Brain MRI?

Pseudoprogression is a treatment-related change that makes a brain tumor appear to have grown on an MRI even though the cancer may not actually be progressing.

Pseudoprogression can occur when treatment causes inflammation, swelling, or tissue changes around the tumor. These changes can make an MRI look worse temporarily even when the treatment is having the intended effect.

Pseudoprogression is particularly important to understand after radiation therapy and certain cancer treatments.

Doctors may respond by:

Comparing the scan with previous MRIs
Monitoring symptoms
Scheduling another MRI
Using advanced imaging techniques
Evaluating the patient's neurological condition
Considering the timing of treatment

In some cases, additional time and imaging are needed before doctors can determine whether an apparent change represents true tumor progression or a treatment effect.

Understanding BT-RADS: What Does Your MRI Score Mean?

You may see a BT-RADS (Brain Tumor Reporting and Data System) score in your MRI report. BT-RADS is a standardized system that helps radiologists describe changes seen on MRI scans for patients with brain tumors and communicate whether those changes appear stable, improved, or potentially concerning.

BT-RADS provides your medical team with a structured way to evaluate changes between MRI scans, but your score should always be interpreted alongside your symptoms, treatment history, and previous imaging.

BT-RADS Categories Explained

The BT-RADS system includes several categories that describe what your imaging may show:

BT-RADS 1: Imaging Improved

This category indicates that the imaging has improved, such as when a tumor has become smaller or is no longer visible.

BT-RADS 2: Imaging Stable

A stable scan means there has been no significant change compared with the previous imaging.

For many patients, a stable MRI is reassuring because it indicates that there is no clear evidence of tumor progression at that point in time.

BT-RADS 3: Imaging Changes of Unclear Significance

A BT-RADS 3 finding means that an imaging change has occurred, but it is not clear whether the change represents tumor growth or a treatment-related effect.

Depending on the specific findings, the radiologist may consider the change more likely to represent treatment effects, may be uncertain about its significance, or may have greater concern for tumor progression.

Additional monitoring or another MRI may be recommended to determine what is happening over time.

BT-RADS 4: Likely Tumor Growth or Recurrence

This category indicates that the MRI findings are concerning for tumor growth or recurrence.

A BT-RADS 4 finding does not, by itself, determine your next treatment. Your oncology team will consider the MRI alongside your symptoms, previous scans, treatment history, and other clinical information before making recommendations.

What Does "Progression" Mean on a Brain MRI?

The word progression can be particularly concerning when patients read their MRI reports. In general, progression refers to evidence suggesting that a tumor has increased or that there are new findings consistent with tumor activity.

A report mentioning possible progression does not necessarily mean that your doctors have confirmed that the cancer is growing.

Radiologists may use cautious language such as:

"Concerning for progression"
"Findings suggest progression"
"Cannot exclude progression"
"Interval increase"
"New enhancement"

These phrases communicate what the images appear to show. Your oncology team then determines how those findings fit into the larger clinical picture.

What Does "Stable" Mean on an MRI?

A report describing a brain tumor as stable generally means there has not been a significant change compared with the previous scan.

A stable MRI is often a reassuring finding because it suggests that the tumor has not demonstrated significant radiographic progression since the prior examination.

However, stable does not necessarily mean that a tumor has disappeared. It means that the imaging findings have remained sufficiently similar over the period being evaluated.

Your care team may recommend continued treatment or monitoring depending on your diagnosis and treatment plan.

What If Your MRI Report Says "Worsening"?

Words such as "worsening," "increased," or "concerning" can understandably cause anxiety.

MRI findings that appear worse do not always mean that a brain tumor is growing.

Changes can result from:

Tumor progression
Inflammation
Treatment effects
Swelling
Scar tissue
Radiation-related changes
Immune system activity

This is why your oncologist may recommend comparing several MRI scans rather than making a treatment decision based solely on one report.

What Is Immunotherapy-Related Pseudoprogression?

Patients receiving immunotherapy may encounter another term: immune-related pseudoprogression.

Immunotherapy can cause inflammation around a tumor that temporarily makes the tumor appear larger or more prominent on MRI, even when the treatment may be working.

Immunotherapy stimulates the immune system to attack cancer cells. As immune cells enter the tumor area, they can cause:

Increased inflammation
Swelling
More contrast enhancement
A temporary increase in the apparent size of the lesion

On an MRI, these changes can resemble tumor growth.

When immunotherapy-related pseudoprogression is possible, your care team may monitor your symptoms, compare additional scans, and consider the timing of treatment before deciding whether the cancer is actually progressing.

How Should You Read the "Impression" Section of Your MRI Report?

The impression is usually one of the most important sections of a radiology report. It summarizes the radiologist's interpretation of the most significant findings.

The impression provides a concise medical interpretation of the MRI, but it should not be treated as a standalone diagnosis.

The impression may mention:

Whether the tumor appears stable
Changes compared with previous imaging
New or increased enhancement
Swelling or edema
Possible progression
Treatment-related changes
Recommendations for additional imaging

If the wording is unclear, ask your doctor to explain exactly what the findings mean for your diagnosis and treatment plan.

What Questions Should You Ask After a Brain MRI?

It can be difficult to remember everything discussed during an appointment, especially when you're processing a new diagnosis or waiting for an important treatment decision.

Writing down questions before your appointment can help you understand your MRI results and participate more confidently in decisions about your care.

Consider asking:

Has my tumor changed since my previous MRI?
Is the tumor stable, shrinking, or growing?
What does the enhancement on my MRI mean?
Could these changes be caused by treatment rather than tumor growth?
Could pseudoprogression be a possibility?
Does my MRI change my current treatment plan?
Do I need another MRI or additional imaging?
What symptoms should I watch for?
When should I have my next MRI?
Can you show me the area you're discussing on my MRI images?

Asking your physician to pull up the actual images can also be helpful. Seeing what your doctor is describing can make unfamiliar terminology easier to understand.

Can You Understand Your MRI Results Without a Doctor?

Patients can learn what common MRI terms mean, but they should not attempt to diagnose themselves from a radiology report.

Your MRI report can provide useful information, but only your healthcare team can put those findings into the context of your complete medical history and treatment.

Radiologists focus on interpreting medical images and communicating their findings to the rest of the care team. Your oncologist and other specialists combine that information with your symptoms, examination, pathology, treatment history, and previous imaging.

If your report contains a phrase that worries you, bring it to your doctor rather than assuming the most concerning interpretation.

How MRI Results Guide Brain Tumor Treatment

MRI findings can influence many aspects of brain tumor care.

Doctors use MRI results to help determine whether to continue, modify, or further investigate a patient's treatment plan.

Depending on the findings, your care team may recommend:

Continuing the current treatment
Additional monitoring
A repeat MRI
Advanced imaging
Surgery
Radiation therapy
Chemotherapy
Immunotherapy
Another treatment approach
Participation in a clinical trial

The appropriate next step depends on your specific diagnosis and the reason for the imaging change.

What to Remember About Your Brain MRI Results

Receiving a brain MRI report filled with unfamiliar terminology can be stressful, but an individual word or phrase does not necessarily tell the whole story.

A finding described as "enhancement," "edema," "necrosis," or even "possible progression" needs to be interpreted in context. Your physicians consider the current MRI alongside previous scans, your symptoms, treatment history, and other diagnostic information before determining what the findings mean.

The most useful question is often not simply, "What does my MRI say?" but rather, "What does this MRI mean in the context of my treatment and previous scans?"

If you are unsure about your results, ask your care team to walk through the report and images with you. Understanding your imaging can help you feel more informed and prepared as you make decisions about your care.

Understanding Your Brain MRI at Duke

At The Preston Robert Tisch Brain Tumor Center at Duke, specialists from multiple disciplines work together to interpret brain imaging and develop individualized treatment plans. Our team of radiologists, neurosurgeons, neuro-oncologists, radiation oncologists, and other specialists can evaluate imaging findings alongside a patient's symptoms, pathology, treatment history, and previous scans.

This multidisciplinary approach is particularly important when MRI findings are difficult to interpret or when treatment-related changes may resemble tumor progression. Patients can benefit from specialized expertise throughout diagnosis, treatment, follow-up, and long-term care.

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FAQs: How to Understand Your Brain MRI Results

How can I understand my brain MRI results?

Start by looking at the impression section of the report, which summarizes the radiologist's most important findings. However, MRI terminology can be difficult to interpret without medical context, and a single finding does not necessarily indicate tumor growth or treatment failure. Your oncology team can explain how the current scan compares with previous images and what the findings mean for your individual treatment plan.

What does it mean if my brain MRI is stable?

A stable brain MRI generally means that there has not been a significant change compared with the previous scan. For many patients receiving brain tumor treatment, stability can be a reassuring finding because there is no clear radiographic evidence of progression. Your doctor will determine what stability means for you based on your tumor type, treatment, symptoms, and overall clinical picture.

Does MRI enhancement mean my brain tumor is growing?

Not necessarily. Enhancement can occur for several reasons, including tumor activity, inflammation, and treatment-related changes. Your doctors consider enhancement alongside previous scans, symptoms, treatment timing, and other MRI findings before determining whether it represents tumor progression.

What is pseudoprogression on a brain MRI?

Pseudoprogression is a treatment-related imaging change that can make a tumor appear to have grown even when the cancer may not actually be progressing. It can occur because treatment causes inflammation, swelling, or changes in tissue around the tumor. Doctors may use additional imaging and follow-up scans to determine whether an apparent change represents true progression or a treatment effect.

Should I be worried if my MRI report says "concerning for progression"?

Not necessarily. This wording means the imaging contains findings that could represent tumor progression, but it does not necessarily establish that the tumor is growing. Your oncologist will compare the scan with previous imaging and consider your symptoms, treatment history, and other clinical information before determining what the finding means.

How often will I need a brain MRI?

The frequency of MRI scans depends on your diagnosis, treatment plan, and how your tumor responds to treatment. Some patients may have scans every few months during active treatment, while others may have longer intervals between scans during ongoing surveillance. Your care team will establish an imaging schedule based on your individual circumstances.