Which material yields the greatest attenuation?

Which material yields the greatest attenuation?

• A. Bone
• B. Muscle
• C. Fat
• D. Water

Answer: (A)

Attenuation grows with how dense and absorptive a tissue is, plus how much it scatters the sound. Bone is highly dense and mineralized, so it absorbs and scatters ultrasound energy far more than soft tissues. That combination causes the largest loss of signal per centimeter, making bone the tissue with the greatest attenuation. Water attenuates very little, fat attenuates more than water but less than muscle, and muscle attenuates more than fat but far less than bone. Also, attenuation increases with frequency, so at typical diagnostic frequencies bone’s attenuation is especially pronounced, leading to strong signal loss and shadowing behind it.

Attenuation grows with how dense and absorptive a tissue is, plus how much it scatters the sound. Bone is highly dense and mineralized, so it absorbs and scatters ultrasound energy far more than soft tissues. That combination causes the largest loss of signal per centimeter, making bone the tissue with the greatest attenuation. Water attenuates very little, fat attenuates more than water but less than muscle, and muscle attenuates more than fat but far less than bone. Also, attenuation increases with frequency, so at typical diagnostic frequencies bone’s attenuation is especially pronounced, leading to strong signal loss and shadowing behind it.