What does “FLAIR” mean on a radiology report?
Fluid-attenuated inversion recovery: an MRI sequence that darkens normal brain fluid so that changes in brain tissue stand out as bright areas.
How "FLAIR" is used in radiology reports
FLAIR stands for fluid-attenuated inversion recovery. It is a type of T2-weighted MRI sequence with one important change: the signal from free fluid, such as the cerebrospinal fluid around and inside the brain, is suppressed so it looks dark. Without that suppression, bright fluid sits right next to the brain and makes small changes in brain tissue hard to see.
With the fluid darkened, areas of brain tissue that hold extra water stand out as bright. Reports describe these as "FLAIR hyperintensities" or "T2/FLAIR hyperintense foci". They are very commonly seen in the white matter of older adults, where they are often attributed to changes in the small blood vessels. They are also seen in multiple sclerosis, after injury or infection, and with migraine, which is why the pattern and location matter more than the presence of a bright spot.
FLAIR is one of several sequences in a brain MRI; the radiologist reads them together. A finding on FLAIR alone is a description of signal, and the Impression section is where they say what they think it represents.
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General explanations of common wording, not advice about your own scan. Ask the doctor who ordered it what your results mean for you.
Does this mean something is wrong?
Not on its own. A radiology report describes what the images show, in language written for the doctor who ordered the scan. One term is rarely the whole picture — what it means for you depends on why you were scanned and what else the report says.
If the report worries you, the person who can actually answer that is the doctor who referred you. Understanding the words first usually makes that conversation a better one.
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One term is a start. Radily reads your full report and explains it in plain English — and can talk you through it on video, so you are not reading medical language alone.
Other technical terms
- ArtifactAn abnormal appearance on an image caused by the scanning process, not actual anatomy.
- AttenuationHow much X-rays are absorbed by tissue. Dense tissue (bone) shows high attenuation (bright), while air shows low attenuation (dark).
- AxialCross-sectional images taken in a horizontal plane, like slicing bread.
- ContrastA dye injected or swallowed to make certain tissues show up better on imaging.
- CoronalImages taken from front to back, dividing the body into front and back portions.
- DensityHow solid or compact tissue appears on imaging. High density = bright (bone), low density = dark (air).
This explains a term as it is commonly used in radiology reports. It is not a diagnosis and not medical advice. Discuss your own results with your doctor.