Infarct

What it means

Brain cells need a constant supply of oxygen and sugar from the blood. When a small artery is blocked — by a clot, a piece of plaque, or a narrowing — the tissue downstream stops getting what it needs and begins to fail within minutes. On a CT scan, a recent area of tissue death shows up as a darker, softer-looking patch; on MRI it stands out clearly on certain sequences, sometimes within the first hour.

Why it appears on a CT or MRI report

The radiologist describes the location (which lobe or which artery's territory), the size, and how old the change looks. Reports often distinguish acute (new, within hours to a day or two), subacute (days to weeks old), and chronic (older, healed) changes, because each looks different on imaging and means something different clinically. You may also see notes about swelling around the area, any bleeding into it, or other older changes that suggest previous events.

What it usually means

The seriousness depends mostly on three things: how new the finding is, how big the affected area is, and which part of the brain is involved. A small, old, healed area in a person without symptoms may simply be evidence of a past silent event and prompts a search for risk factors — high blood pressure, irregular heart rhythm, diabetes, high cholesterol, smoking. A new finding is treated as an emergency because the surrounding tissue may still be salvageable in the first hours, and rapid treatment with clot-busting medication or a procedure to remove the clot can make a real difference. The team will also look for the source of the block, often with scans of the neck arteries and the heart, and start medications to reduce the risk of another event.

When to follow up

If this is a new finding on an emergency scan, the stroke team is already moving. If you see it on an outpatient report, contact your doctor the same day to discuss next steps and prevention. Call emergency services immediately for the FAST warning signs: Face drooping on one side, Arm weakness, Speech that is slurred or strange, Time to call for help. Sudden vision loss, severe dizziness, or a sudden very bad headache also need urgent attention.

A plain-language way to picture it

Think of the brain as a city with a network of small water pipes feeding every neighbourhood. If one pipe gets blocked, the gardens and lawns it served start to wilt within minutes and, if the block is not cleared, eventually dry out for good. On the scan, the radiologist is pointing at the dried patch. How big the patch is, and which neighbourhood it covers, tells the team how much trouble was caused.