Which tissue type has relatively little effect on ultrasound propagation?

Which tissue type has relatively little effect on ultrasound propagation?

• A. Adipose tissue
• B. Bone
• C. Muscle
• D. Nerve

Answer: (A)

Ultrasound propagation depends on how easily a tissue compresses and how much energy it absorbs or scatters as the sound wave travels. Tissues with large acoustic impedance differences or high attenuation will alter the beam more, causing reflections, refraction, and rapid energy loss. Adipose tissue is relatively soft, has low density differences with surrounding soft tissues, and exhibits low attenuation (speed around 1450 m/s and attenuation roughly 0.5–0.6 dB per MHz per cm). This means the ultrasound energy passes through fat with minimal absorption and scattering, so the beam is less distorted and reflects fewer echoes compared with tougher, denser tissues. In contrast, bone has a big impedance mismatch and high attenuation, producing strong reflections and shadowing, while muscle attenuates more than fat but less than bone. Therefore adipose tissue has relatively little effect on ultrasound propagation.

Ultrasound propagation depends on how easily a tissue compresses and how much energy it absorbs or scatters as the sound wave travels. Tissues with large acoustic impedance differences or high attenuation will alter the beam more, causing reflections, refraction, and rapid energy loss. Adipose tissue is relatively soft, has low density differences with surrounding soft tissues, and exhibits low attenuation (speed around 1450 m/s and attenuation roughly 0.5–0.6 dB per MHz per cm). This means the ultrasound energy passes through fat with minimal absorption and scattering, so the beam is less distorted and reflects fewer echoes compared with tougher, denser tissues. In contrast, bone has a big impedance mismatch and high attenuation, producing strong reflections and shadowing, while muscle attenuates more than fat but less than bone. Therefore adipose tissue has relatively little effect on ultrasound propagation.