Which statement about ultrasound modes is true?

Which statement about ultrasound modes is true?

• A. Continuous mode provides heating to deep tissues
• B. Pulsed mode provides mechanical benefits with minimal heating
• C. Ultrasound is effective on all tissues equally
• D. Collagen-based structures respond best and less well on muscle

Answer: (D)

Tissue response to ultrasound depends on what the tissue is made of. Tissues rich in collagen, such as tendons, ligaments, fascia, and scar tissue, absorb more energy from ultrasound. That higher energy absorption leads to heating and mechanical effects that stimulate collagen remodeling and improve fiber alignment, so these structures respond well to ultrasound. Muscle, by contrast, has less collagen and more water, so it absorbs less energy and experiences less heating and fewer mechanical changes. That's why collagen-based structures tend to respond best, while muscle responds less well. The other statements are less accurate because they oversimplify or misstate how ultrasound works: continuous mode does cause heating, but depth and extent of heating depend on frequency and tissue properties; pulsed mode reduces heating and emphasizes mechanical effects but doesn’t eliminate heating entirely; and ultrasound is not equally effective in all tissues due to varying absorption.

Tissue response to ultrasound depends on what the tissue is made of. Tissues rich in collagen, such as tendons, ligaments, fascia, and scar tissue, absorb more energy from ultrasound. That higher energy absorption leads to heating and mechanical effects that stimulate collagen remodeling and improve fiber alignment, so these structures respond well to ultrasound. Muscle, by contrast, has less collagen and more water, so it absorbs less energy and experiences less heating and fewer mechanical changes. That's why collagen-based structures tend to respond best, while muscle responds less well.

The other statements are less accurate because they oversimplify or misstate how ultrasound works: continuous mode does cause heating, but depth and extent of heating depend on frequency and tissue properties; pulsed mode reduces heating and emphasizes mechanical effects but doesn’t eliminate heating entirely; and ultrasound is not equally effective in all tissues due to varying absorption.