What it means
Ultrasound makes pictures from sound waves that bounce back from tissues. Tissues that reflect a lot of sound look bright, and those that reflect less look darker. Hypoechoic means an area sends back fewer echoes than its surroundings, so it looks darker gray. It describes how the area looks, not what it is. An area that is completely black is called anechoic instead.
When it matters
Many hypoechoic findings are harmless, such as fibroadenomas (common breast lumps that are not cancer), normal lymph nodes and many thyroid nodules. Some cancers are hypoechoic too, so the radiologist weighs other features: shape, edges, size and blood flow. Scoring systems such as BI-RADS for the breast and TI-RADS for the thyroid combine these. Next steps range from no action to a follow-up scan or a needle biopsy (a small tissue sample).
Questions to ask your doctor
- Is the hypoechoic area solid or filled with fluid?
- What do its shape, edges and blood flow suggest?
- Does it have a risk score, such as BI-RADS or TI-RADS?
