Which ultrasound term describes structures that appear completely black on the image and are typically fluid-filled?

Which ultrasound term describes structures that appear completely black on the image and are typically fluid-filled?

• A. Hypoechoic
• B. Anechoic
• C. Artifacts
• D. Acoustic Shadowing

Answer: (B)

On grayscale ultrasound, echogenicity describes how bright a structure appears. Anechoic means there are no internal echoes—fluid-filled structures reflect almost none of the sound, so they look completely black on the image. Classic examples are simple cysts and the bladder. You often also see posterior acoustic enhancement behind an anechoic area, since the fluid transmits sound with little attenuation, making the behind-tissue appear brighter. The other terms describe different appearances: hypoechoic areas are darker than surrounding tissue but still produce echoes, while artifacts and acoustic shadowing refer to echo patterns not representing true tissue, such as false echoes or shadows beyond dense objects.

On grayscale ultrasound, echogenicity describes how bright a structure appears. Anechoic means there are no internal echoes—fluid-filled structures reflect almost none of the sound, so they look completely black on the image. Classic examples are simple cysts and the bladder. You often also see posterior acoustic enhancement behind an anechoic area, since the fluid transmits sound with little attenuation, making the behind-tissue appear brighter. The other terms describe different appearances: hypoechoic areas are darker than surrounding tissue but still produce echoes, while artifacts and acoustic shadowing refer to echo patterns not representing true tissue, such as false echoes or shadows beyond dense objects.