Which tissue exhibits the highest rate of attenuation for an ultrasound wave?

Which tissue exhibits the highest rate of attenuation for an ultrasound wave?

• A. Liver
• B. Fat
• C. Fluid
• D. Lung

Answer: (D)

Attenuation is the loss of ultrasound energy as it travels through tissue, due to absorption, scattering, and reflection. Tissues with many interfaces and gas content cause much more energy to be expelled from the wave. The lungs are full of air, creating countless air–tissue interfaces and a large impedance mismatch. Because of these interfaces, most of the wave’s energy is reflected and scattered, so the amplitude drops quickly as it moves through lung tissue. In contrast, fluid, fat, and liver lack that level of gas-related scattering and interface disruption, so their attenuation is much lower. That’s why the highest attenuation occurs in the lung.

Attenuation is the loss of ultrasound energy as it travels through tissue, due to absorption, scattering, and reflection. Tissues with many interfaces and gas content cause much more energy to be expelled from the wave. The lungs are full of air, creating countless air–tissue interfaces and a large impedance mismatch. Because of these interfaces, most of the wave’s energy is reflected and scattered, so the amplitude drops quickly as it moves through lung tissue. In contrast, fluid, fat, and liver lack that level of gas-related scattering and interface disruption, so their attenuation is much lower. That’s why the highest attenuation occurs in the lung.