Time-dependent ultrasound echo changes occur in tendon during viscoelastic testing

Area of Science:

• Biomechanics
• Biomaterials Science
• Medical Imaging

Background:

• Tendon viscoelasticity is crucial for mechanical function but challenging to measure in vivo.
• Previous work established a link between ultrasound echo intensity and tendon stress/strain in vitro.
• The viscoelastic properties and time-dependent echo intensity changes in tendons remained unverified.

Purpose of the Study:

• To investigate if ultrasound echo intensity changes reflect the viscoelastic behavior of tendons.
• To determine if these echo intensity changes are repeatable and predictable during viscoelastic testing.
• To explore the potential of ultrasound acoustoelasticity for in vivo tendon characterization.

Main Methods:

• Porcine flexor tendons were subjected to relaxation and cyclic loading tests.
• Ultrasound echo intensity (B-mode brightness) was recorded concurrently with mechanical testing.
• Analysis focused on the relationship between time-dependent mechanical properties and echo intensity variations.

Main Results:

• Ultrasonic echo intensity changes were found to manifest time- and strain history-dependent mechanical properties.
• Echo intensity patterns did not directly mirror load changes but exhibited repeatable and predictable behavior.
• This suggests that echo intensity changes correlate with viscoelastic phenomena in tendons.

Conclusions:

• Ultrasound echo intensity changes can anticipate tendon viscoelastic behavior.
• The repeatable nature of these changes opens possibilities for predicting in vivo tissue mechanics.
• This ultrasound-based acoustoelasticity method holds potential for enhanced noninvasive characterization of tendon viscoelasticity.