What it means
On MRI, brightness is usually described by comparing one tissue with another. Isointense means a spot gives off about the same signal as the tissue it is compared with. The two look alike on that image. Reports often name the reference, such as isointense to muscle or to the liver. The same spot can look brighter or darker on another sequence (image type).
When it matters
Isointense is neutral: it says the spot blends in on that image, not what it is. A spot that blends in can be hard to see. Radiologists then rely on its shape, its effect on nearby tissue and the other sequences. Images after contrast dye often help. Many isointense findings are harmless. The impression, the summary at the end of the report, matters more than this one word.
Questions to ask your doctor
- What tissue is the spot being compared with?
- Does it look different on other sequences or after contrast?
- Does the overall pattern suggest something harmless?
