The reflection of ultrasound at tissue interfaces mainly depends on differences in what property?

The reflection of ultrasound at tissue interfaces mainly depends on differences in what property?

• A. Acoustic impedance
• B. Density
• C. Viscosity
• D. Temperature

Answer: (A)

Ultrasound reflections at tissue boundaries come from impedance mismatch. Acoustic impedance combines density and the speed of sound in a tissue (Z = ρc). When a wave reaches a boundary where Z changes, part of it reflects and part transmits. The size of the reflected portion depends on how different the impedances are—the bigger the mismatch, the stronger the echo. That’s why acoustic impedance, not density alone, viscosity, or temperature, mainly determines the reflection at interfaces.

Ultrasound reflections at tissue boundaries come from impedance mismatch. Acoustic impedance combines density and the speed of sound in a tissue (Z = ρc). When a wave reaches a boundary where Z changes, part of it reflects and part transmits. The size of the reflected portion depends on how different the impedances are—the bigger the mismatch, the stronger the echo. That’s why acoustic impedance, not density alone, viscosity, or temperature, mainly determines the reflection at interfaces.