What does the term "hypoechoic" describe in ultrasound imaging?

The term "hypoechoic" in ultrasound imaging refers to areas that reflect fewer sound waves compared to surrounding tissues and thus appear darker on the ultrasound image. This characteristic indicates that the tissue has a lower echogenicity, which can be associated with fluid-filled structures, some types of masses, or certain pathological conditions. Understanding the echogenicity of tissues is crucial for interpreting ultrasound images accurately, as it helps identify differences in tissue composition and guides clinical evaluations. For example, a hypoechoic lesion can suggest the presence of a cyst or tumor, prompting further investigation.