Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles

• Published in: Applied physics letters 2012-10, Vol.101 (16), p.163704-163704
• Main Authors: Chen, Hong, Brayman, Andrew A, Matula, Thomas J
• Format: Article
• Language: English
• Subjects: Biophysics and Bio-Inspired Systems
• ISSN: 0003-6951; 1077-3118; 0003-6951
• DOI: 10.1063/1.4761937

Ultrasound-activated microbubbles were used as actuators to deform microvessels for quantifying microvessel relaxation timescales at megahertz frequencies. Venules containing ultrasound contrast microbubbles were insonified by short 1 MHz ultrasound pulses. Vessel wall forced-deformations were on the same microsecond timescale as microbubble oscillations. The subsequent relaxation of the vessel was recorded by high-speed photomicrography. The tissue was modeled as a simple Voigt solid. Relaxation time constants were measured to be on the order of ∼10 μs. The correlation coefficients between the model and 38 data sets were never lower than 0.85, suggesting this model is sufficient for modeling tissue relaxation at these frequencies. The results place a bound on potential numerical values for viscosity and elasticity of venules.