Understanding tests after your visit.

A detailed look at the brain's structure

A brain MRI creates detailed pictures of the brain. It can show changes in brain volume, disease in small or large blood vessels, old or recent strokes, bleeding, a buildup of fluid, tumors, and other structural findings. If an older scan is available, comparing the two can be especially helpful.

MRI uses a strong magnetic field and radio waves rather than X-rays. During the scan, you lie on a table that moves into the scanner and remain still while the images are collected. The machine is loud. Many brain MRIs do not require contrast, although contrast is useful for some questions.

Before the scan, tell the imaging team about implanted devices, metal in your body, kidney disease, pregnancy, or claustrophobia. This allows them to decide whether the scan can be performed safely and whether any preparation is needed.

What an MRI can and cannot tell us

An MRI may reveal a pattern that fits the symptoms, or it may point to another condition that needs attention. It is particularly useful for understanding the contribution of strokes and blood-vessel disease and for excluding certain structural causes of cognitive change.

An MRI does not directly show amyloid plaques or tau tangles. It cannot, by itself, establish that Alzheimer's disease or another neurodegenerative disease is the cause of someone's symptoms. A normal MRI does not rule those conditions out. Common age-related or vascular changes on a scan are not always the reason a person is having difficulty.