What is hypoechoic?

In medical imaging, the term "hypoechoic" refers to an area or structure that appears darker or less echogenic compared to its surrounding tissues when visualized through ultrasound examination. It is used to describe the relative echogenicity or reflectivity of sound waves in ultrasound images.

When sound waves emitted by an ultrasound transducer encounter different tissues or structures within the body, they create echoes based on their acoustic properties. Dense or solid tissues with high acoustic impedance reflect the sound waves strongly, resulting in brighter or "hyperechoic" areas on the ultrasound image. In contrast, tissues with lower acoustic impedance, such as fluid-filled cysts or soft tissues, tend to scatter or absorb the sound waves rather than reflecting them effectively. This leads to darker or "hypoechoic" areas on the image.

Hypoechoic regions can often help radiologists in identifying certain abnormal tissue changes, such as cysts, tumors, or areas of inflammation, which may have lower density or different acoustic characteristics compared to the surrounding normal tissues. It is important to note that hypoechogenicity alone does not definitively indicate a specific pathology, and further evaluation such as biopsies or additional imaging studies may be needed for an accurate diagnosis.