Understanding Your MRI Scan Results: A Patient's Plain-English Guide

Receiving an MRI scan report can be unsettling, particularly when the document is full of unfamiliar medical terminology. Unlike blood test results, where a number sits next to a reference range, MRI reports are written in descriptive radiology language that can be difficult to interpret without medical training. This guide explains how MRI scans work, how to read a typical report, and what common findings mean.

How Does an MRI Scan Work?

MRI (Magnetic Resonance Imaging) uses powerful magnetic fields and radio waves — not radiation — to create detailed images of the inside of your body. It is particularly good at imaging soft tissues: the brain, spinal cord, joints, muscles, tendons, and organs. Different tissue types appear in different shades on the scan, allowing radiologists to distinguish normal from abnormal structures.

MRI Sequences: T1, T2, and FLAIR

MRI can produce several different types of images (called sequences or weightings) of the same body area. You may see these mentioned in your report:

• T1-weighted images: Fat appears bright (white); fluid appears dark. Good for showing anatomy and structure. With contrast (gadolinium injection), areas of abnormal blood vessel permeability (such as tumours or inflammation) appear bright.
• T2-weighted images: Fluid appears bright (white). Excellent for detecting oedema (swelling), inflammation, and most abnormalities, which tend to contain more water than surrounding tissue.
• FLAIR (Fluid Attenuated Inversion Recovery): Similar to T2 but with the fluid signal suppressed — making it easier to see abnormalities near fluid-filled spaces, such as the brain's ventricles. Commonly used in brain MRI for detecting white matter changes, multiple sclerosis lesions, and stroke.
• DWI (Diffusion-Weighted Imaging): Measures the movement of water molecules. Restricted diffusion (appearing bright on DWI) is a hallmark of acute stroke and some tumours.

Understanding the Structure of an MRI Report

A radiology report typically has the following sections:

• Clinical information: The reason for the scan as stated by the referring doctor, which guides the radiologist's interpretation.
• Technique: What was scanned, which sequences were used, and whether contrast was given.
• Findings: A systematic description of what the radiologist observed in each region of the scan.
• Impression / Conclusion: A summary of the most important findings and their likely significance — this is the most important section for patients to read.

Common MRI Terms Explained

Signal Intensity

Radiologists describe abnormalities by how they appear on different sequences — whether they appear brighter (hyperintense) or darker (hypointense) than surrounding tissue. For example: "a T2 hyperintense lesion" appears brighter than normal tissue on T2-weighted images, suggesting it contains more water — consistent with oedema, inflammation, or some tumours.

Lesion

A "lesion" simply means an area of abnormality seen on the scan. It is a non-specific term and does not imply cancer or any specific diagnosis. A lesion requires interpretation in context — many are benign (harmless).

Oedema

Swelling caused by excess fluid. In the brain, oedema appears as T2/FLAIR hyperintensity and can surround tumours, areas of infarction, or inflammation. In joints and soft tissues, oedema indicates recent injury or inflammation.

Enhancement

When contrast (gadolinium) is given intravenously, areas with disrupted or abnormal blood vessel permeability "enhance" — meaning they appear brighter on post-contrast T1 images. Enhancement is seen in active inflammation, infection, some tumours, and recent areas of brain injury.

Atrophy

Loss of tissue volume. Cerebral atrophy refers to shrinkage of brain tissue, which can be age-related or associated with neurological conditions. Muscle atrophy refers to reduced muscle bulk, often from disuse or nerve damage.

Herniation (Disc Prolapse)

In spine MRI, disc herniation (also called a prolapsed disc or "slipped disc") refers to the displacement of intervertebral disc material beyond its normal boundary. You may see terms such as:

• Bulge: The disc extends slightly beyond normal but the outer fibres (annulus) are intact.
• Protrusion: The disc material extends further but has a narrower base than the extent of protrusion.
• Extrusion: The disc material has broken through the outer fibres.
• Sequestration: A fragment of disc has broken completely free.

Importantly, many people with disc herniations on MRI have no symptoms at all. The clinical significance depends on whether the herniation is pressing on a nerve root or the spinal cord, and whether this matches your symptoms.

Stenosis

Narrowing of a space. Spinal stenosis refers to narrowing of the spinal canal, which may compress the spinal cord or nerve roots. Foraminal stenosis refers to narrowing of the openings (foramina) through which nerve roots exit the spine.

Degenerative Changes / Spondylosis

These terms describe normal age-related wear and tear in the spine — disc dehydration, facet joint arthrosis, and osteophyte (bone spur) formation. These findings are extremely common, increase with age, and are often asymptomatic. Finding degenerative changes on MRI does not automatically explain back or neck pain.

Incidental Finding

An abnormality discovered that was not related to the original reason for scanning. Many incidental findings (such as small cysts on the kidney, liver, or ovary) are benign and require no treatment, but some may require further investigation to confirm they are harmless.

Common Brain MRI Findings

• White matter hyperintensities (WMH): Small bright areas on T2/FLAIR images. Very common, especially in older adults or those with hypertension, migraine, or small vessel disease. Often described as "non-specific" — they reflect minor damage to small blood vessels but usually do not indicate serious disease in isolation.
• Infarct: An area of brain tissue that has died due to loss of blood supply (stroke). Old infarcts appear as areas of loss of brain tissue on T1 and bright areas on T2/FLAIR.
• Arachnoid cyst: A benign fluid-filled sac between brain tissue and the arachnoid membrane. Usually an incidental finding requiring no treatment.

What Should I Do With My Results?

You should always discuss your MRI results with the clinician who arranged the scan. They will:

• Explain what the findings mean in the context of your symptoms
• Decide whether further imaging or tests are needed
• Arrange specialist referral if required
• Advise on management and treatment

If you are worried about your results before your appointment, HealthLens can help you understand the terminology in your report so you can ask more informed questions at your consultation.