Resonance frequency of microbubbles in small blood vessels: a numerical study

Sassaroli, E.; Hynynen, Kullervo

doi:10.1088/0031-9155/50/22/006

Cited by 97 publications

(70 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They used a nonlinear lumped parameter model of the surrounding vessel and tissue as a boundary condition on the outer surface of the viscous, incompressible liquid, modeled with finite elements. Their predicted bubble natural frequency agrees with the one-dimensional cylindrical bubble model (Sassaroli and Hynynen, 2005) when the tube is rigid, however, the frequency increases as the vessel rigidity index, accounting for vessel thickness as well as stiffness, decreases.…”

Section: Introductionsupporting

confidence: 56%

“…This spherically symmetric model can be used to approximate the behavior of a bubble in a vessel only if the bubble radius is much smaller than the vessel radius. For the opposite extreme, if the bubble radius is comparable to the vessel radius, a one-dimensional linear model of a cylindrical bubble can be used to approximate the behavior of the bubble in a rigid tube (Oguz and Prosperetti, 1998;Sassaroli and Hynynen, 2004;Sassaroli and Hynynen, 2005). Oguz and Prosperetti (1998) present simulation results using a boundary integral method for a bubble in a rigid tube that indicates that the large bubble approximation accurately predicts the bubble's natural frequency when the ratio of bubble radius to tube radius is greater than 0.2.…”

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

Jang

Zakrzewski

Rossi

et al. 2011

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Motivated by various clinical applications of ultrasound contrast agents within blood vessels, the natural frequencies of two bubbles in a compliant tube are studied analytically, numerically, and experimentally. A lumped parameter model for a five degree of freedom system was developed, accounting for the compliance of the tube and coupled response of the two bubbles. The results were compared to those produced by two different simulation methods: (1) an axisymmetric coupled boundary element and finite element code previously used to investigate the response of a single bubble in a compliant tube and (2) finite element models developed in COMSOL Multiphysics. For the simplified case of two bubbles in a rigid tube, the lumped parameter model predicts two frequencies for in-and out-of-phase oscillations, in good agreement with both numerical simulation and experimental results. For two bubbles in a compliant tube, the lumped parameter model predicts four nonzero frequencies, each asymptotically converging to expected values in the rigid and compliant limits of the tube material.

show abstract

Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 95%

Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

Jang

Zakrzewski

Rossi

et al. 2011

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

“…The vibration frequencies used in our study are several orders of magnitude lower than those that have been shown in animal experiments to induce gas bubble growth from micronuclei ( 1,35 ) and are substantially lower than the resonance frequency of microbubbles in blood vessels ( 34 ). Therefore, a purely resonance effect on micronuclei by these lowfrequency vibrations is unlikely.…”

Section: Discussionmentioning

confidence: 64%

Pre-Dive Vibration Effect on Bubble Formation After a 30-m Dive Requiring a Decompression Stop

Germonpré¹,

Pontier²,

Gempp³

et al. 2009

aviat space environ med

View full text Add to dashboard Cite

G ERMONPRE P, PONTIER J-M, GEMPP E, BLATTEAU J-E, DENEWETH S, LAFÉRE P, MARRONIIntroduction: The preconditioning of divers to reduce post-dive decompression sickness (DCS) has gained increased interest in diving medical research over the last few years. The benefi cial effects of physical exercise, oxygen breathing, hyperbaric exposure, heat exposure, hyperhydration, or nitroglycerin administration before the dive are only a few examples of ongoing research. In this work, we investigated the effects of pre-dive whole-body vibration on post-dive bubble formation. Methods: Following French Navy standard dive procedures, 14 healthy male military divers performed 2 identical dives 1 wk apart to 30 m of seawater (msw) for 30 min. One of the dives was randomly preceded by a 30-min whole-body vibration session (frequencies 35-40 Hz) 1 h before the dive. Post-dive bubbles were measured precordially 30, 60, and 90 min after the dive and were graded according to the Kissman Integrated Severity Score (KISS) protocol, with and without knee fl exing. Arterial endothelial function was measured before and after vibration using fl ow mediated dilation (FMD) measurement. Results: A signifi cant reduction in bubble scores was observed after the " vibration " dive. Conclusion: As there was no observed change in FMD after vibration, we do not believe a nitric oxide mediated mechanism is involved; rather, a mechanical dislodgement or enhanced lymphatic elimination of gas nuclei is hypothesized.

show abstract

“…1972) on the curve l, (5) The volume variance of the bubble is compensated by the vessel's deformation and after subtracting the scattered wave from the microbubble, the liquid at the end of the vessel can be considered to be undisturbed, as considered in Sassaroli and Hynynen (2005). Since the acoustic impedances of the microvessel, blood pool and surrounding tissue are similar, the boundary conditions at the microvessel ends are approximated as: (6) We found that a vessel length of 100μm is sufficiently long to obtain precise results within the typical computational interval of 5μs.…”

Section: Methodsmentioning

confidence: 99%

Acoustic response of compliable microvessels containing ultrasound contrast agents

2006

View full text Add to dashboard Cite

The existing models of the dynamics of ultrasound contrast agents (UCAs) have largely been focused on an UCA surrounded by an infinite liquid. Preliminary investigations of a microbubble's oscillation in a rigid tube have been performed using linear perturbation, under the assumption that the tube diameter is significantly larger than UCA size. In the potential application of drug and gene delivery, it may be desirable to fragment the agent shell within small blood vessels and in some cases to rupture the vessel wall, releasing drugs and genes at the site. The effect of a compliant small blood vessel on the UCA's oscillation and the microvessel's acoustic response are unknown. The aim of this work is to propose a lumped-parameter model to study the interaction of a microbubble oscillation and compliable microvessels. Numerical results demonstrate that in the presence of UCAs, the transmural pressure through the blood vessel substantially increases and thus the vascular permeability is predicted to be enhanced. For a microbubble within an 8 to 40 micron vessel with a peak negative pressure of 0.1MPa and a center frequency of 1MHz, small changes in the microbubble oscillation frequency and maximum diameter are observed. When the ultrasound pressure increases, strong nonlinear oscillation occurs, with an increased circumferential stress on the vessel. For a compliable vessel with the range of diameters considered in this work, 0.2 MPa PNP at 1 MHz is predicted to be sufficient for microbubble fragmentation regardless the vessel diameter, however, for a rigid vessel 0.5 MPa PNP at 1 MHz may not be sufficient to fragment the bubbles. For a center frequency of 1MHz, a peak negative pressure of 0.5 MPa is predicted to be sufficient to exceed the stress threshold for vascular rupture in a small (diameter less than 15 μm) compliant vessel. As the vessel or surrounding tissue becomes more rigid, the UCA oscillation and vessel dilation decrease, however the circumferential stress is predicted to increase. Decreasing the vessel size or the center frequency increases the circumferential stress. For the two frequencies considered in this work, the circumferential stress does not scale as the inverse of the square root of the acoustic frequency v a as in the Mechanical Index, but rather has a stronger frequency dependence, 1/v a .

show abstract

Resonance frequency of microbubbles in small blood vessels: a numerical study

Cited by 97 publications

References 39 publications

Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

Pre-Dive Vibration Effect on Bubble Formation After a 30-m Dive Requiring a Decompression Stop

Acoustic response of compliable microvessels containing ultrasound contrast agents

Contact Info

Product

Resources

About