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.
Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles
Hong Chen, Andrew A. Brayman, Thomas J. Matula; Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles. Appl. Phys. Lett. 15 October 2012; 101 (16): 163704. https://doi.org/10.1063/1.4761937
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