Which of the following is a non-thermal effect of ultrasound?

Which of the following is a non-thermal effect of ultrasound?

• A. Alter cell membrane permeability
• B. Increased blood flow
• C. Increased collagen extensibility
• D. Decreased pain

Answer: (A)

Non-thermal ultrasound works through mechanical effects like cavitation and acoustic streaming that occur without significant heating. These mechanical interactions can increase cell membrane permeability, allowing ions, nutrients, and signaling molecules to move more readily in and out of cells, which can kick-start healing processes. The other options are more closely tied to heating: warming tissue can raise collagen extensibility, vasodilation and increased blood flow often follow thermal delivery, and pain reduction can happen with heat as well as other mechanisms. So the direct non-thermal effect described here is the alteration of cell membrane permeability.

Non-thermal ultrasound works through mechanical effects like cavitation and acoustic streaming that occur without significant heating. These mechanical interactions can increase cell membrane permeability, allowing ions, nutrients, and signaling molecules to move more readily in and out of cells, which can kick-start healing processes. The other options are more closely tied to heating: warming tissue can raise collagen extensibility, vasodilation and increased blood flow often follow thermal delivery, and pain reduction can happen with heat as well as other mechanisms. So the direct non-thermal effect described here is the alteration of cell membrane permeability.