Which term describes echo-free tissue that appears dark on ultrasound?

Which term describes echo-free tissue that appears dark on ultrasound?

• A. Hyperechoic
• B. Isoechoic
• C. Hypoechoic
• D. Anechoic

Answer: (D)

Anechoic describes echo-free tissue that appears dark on ultrasound. Echo-free means there are no internal echoes within the structure, so the sound is not reflected back to the transducer. Fluids, such as a simple cyst or urine in a dilated duct, are classic examples. Because fluids transmit sound readily, you’ll often see posterior acoustic enhancement—brighter appearance behind the fluid. Other terms describe tissues with varying amounts of echoes: hypoechoic is darker than surrounding tissue but not completely black; isoechoic is similar in brightness to surrounding tissue; hyperechoic is brighter than surrounding tissue due to strong reflections.

Anechoic describes echo-free tissue that appears dark on ultrasound. Echo-free means there are no internal echoes within the structure, so the sound is not reflected back to the transducer. Fluids, such as a simple cyst or urine in a dilated duct, are classic examples. Because fluids transmit sound readily, you’ll often see posterior acoustic enhancement—brighter appearance behind the fluid. Other terms describe tissues with varying amounts of echoes: hypoechoic is darker than surrounding tissue but not completely black; isoechoic is similar in brightness to surrounding tissue; hyperechoic is brighter than surrounding tissue due to strong reflections.