How does increased collagen density in tissue affect ultrasound absorption?

• A. Increases
• B. Decreases
• C. No change
• D. Decreases then increases

Answer: (A)

Increasing collagen density raises ultrasound attenuation because the fibrous, collagen-rich tissue creates more acoustic interfaces and viscous losses as the sound wave travels. Those interfaces and the viscoelastic properties of collagen dissipate more of the wave’s energy, boosting both scattering and absorption, especially at diagnostic frequencies. So, with more collagen, more energy is absorbed (and scattered), leading to greater attenuation. The other patterns—less absorption, no change, or a non-monotonic change—don’t align with how dense, collagen-rich tissues interact with ultrasound.