What do we call ultrasound images that have clear outlines and well-defined borders?

The term that accurately describes ultrasound images with clear outlines and well-defined borders is "homogeneous." In ultrasound imaging, homogeneous textures indicate that the tissues have a uniform appearance, which results in distinct delineation of structures. This uniformity allows for better visibility of the edges and contours of the organs or anomalies being examined.

In contrast, hypoechoic structures appear darker on the ultrasound image compared to surrounding tissues, which can sometimes obscure clear outlines. Isoechoic structures blend in with the surrounding tissue, making it difficult to distinguish their borders. While the term "well-defined" does suggest clarity, it is more of a qualitative description rather than a technical term used in ultrasound imaging, which is why "homogeneous" is the most precise choice here.