20 years of ultrasound contrast agent modeling

Faez, Telli; Emmer, Marcia; Kooiman, Klazina; Versluis, Michel; Steen, A.F.W. van der; Jong, Nico de

doi:10.1109/tuffc.2013.2533

Cited by 131 publications

(109 citation statements)

References 106 publications

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“…1 However, thermal damping can be significant for resonant bubbles larger than about 1 lm and is dominant for resonant bubbles larger than $10 lm.…”

Section: B Contributions To Damping Effectsmentioning

confidence: 99%

Impulse response method for characterization of echogenic liposomes

Raymond

Luan²,

Rooij³

et al. 2015

The Journal of the Acoustical Society of America

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An optical characterization method is presented based on the use of the impulse response to characterize the damping imparted by the shell of an air-filled ultrasound contrast agent (UCA). The interfacial shell viscosity was estimated based on the unforced decaying response of individual echogenic liposomes (ELIP) exposed to a broadband acoustic impulse excitation. Radius versus time response was measured optically based on recordings acquired using an ultra-highspeed camera. The method provided an efficient approach that enabled statistical measurements on 106 individual ELIP. A decrease in shell viscosity, from 2.1 Â 10 À8 to 2.5 Â 10 À9 kg/s, was observed with increasing dilatation rate, from 0.5 Â 10 6 to 1 Â 10 7 s À1 . This nonlinear behavior has been reported in other studies of lipid-shelled UCAs and is consistent with rheological shear-thinning. The measured shell viscosity for the ELIP formulation used in this study [j s ¼ (2.1 6 1.0) Â 10 À8 kg/s] was in quantitative agreement with previously reported values on a population of ELIP and is consistent with other lipid-shelled UCAs. The acoustic response of ELIP therefore is similar to other lipid-shelled UCAs despite loading with air instead of perfluorocarbon gas. The methods described here can provide an accurate estimate of the shell viscosity and damping for individual UCA microbubbles.

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“…1 However, thermal damping can be significant for resonant bubbles larger than about 1 lm and is dominant for resonant bubbles larger than $10 lm.…”

Section: B Contributions To Damping Effectsmentioning

confidence: 99%

Impulse response method for characterization of echogenic liposomes

Raymond

Luan²,

Rooij³

et al. 2015

The Journal of the Acoustical Society of America

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“…The ideas of compression-only and expansion-dominated behaviors of microbubbles are widely supported as being the main reason for subharmonic generation from phospholipid coated microbubbles [24]- [26]. Even though the dynamics of subharmonic oscillations are not completely understood, it has been demonstrated that the subharmonic generation of the microbubbles depends on the excitation pressure, waveform, and frequency.…”

Section: A Maximizing the Subharmonic Generation From Ucasmentioning

confidence: 99%

The effect of amplitude modulation on subharmonic imaging with chirp excitation

Harput

Arif

McLaughlan

et al. 2013

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-Subharmonic generation from ultrasound contrast agents depends on the spectral and temporal properties of the excitation signal. The subharmonic response can be improved by using wideband and long duration signals. However, for sinusoidal tone-burst excitation the effective bandwidth of the signal is inversely proportional with the signal duration. Linear frequency modulated (LFM) and nonlinear frequency modulated (NLFM) chirp excitations allow independent control over the signal bandwidth and duration, therefore in this study LFM and NLFM signals were used for the insonation of microbubble populations. The amplitude modulation of the excitation waveform was achieved by applying different window functions. A customized window was designed for the NLFM chirp excitation by focusing on reducing the spectral leakage at the subharmonic frequency and increasing the subharmonic generation from microbubbles.Subharmonic scattering from a microbubble population was measured for various excitation signals and window functions. At a peak-negative pressure of 600 kPa, the generated subharmonic energy by ultrasound contrast agents was 15.4 dB more for NLFM chirp excitation with 40% fractional bandwidth when compared to tone-burst excitation. For this reason, the NLFM chirp with a customized window was used as an excitation signal to perform subharmonic imaging in an ultrasound flow phantom. Results showed that the NLFM waveform with a customized window improved the subharmonic contrast by 4.35 ± 0.42 dB on average over a Hann windowed LFM excitation.

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“…However, phospholipid-encapsulated microbubbles demonstrate large amplitude oscillations at relatively low pressures. 40,41 Recent studies using ultrafast microscopy revealed asymmetric oscillations, compression only behavior, and low subharmonic thresholds, which cannot be explained by assuming constant coating properties for UCA. 40 We have previously observed this discrepancy-the thresholds for subharmonic oscillations predicted by the modified Rayleigh Plesset model were an order of magnitude higher than those observed experimentally.…”

Section: A Modeling the Dynamics Of Ucas: Theory And Implementationmentioning

confidence: 99%

“…42 The change in the effective surface tension during microbubble oscillations causes rapid changes in shell elasticity, which results in a strong nonlinear response at low pressures-a trend that is consistent with experiments. 40 The Marmottant model assumes that the time dependent radial oscillation of a single microbubble is given by…”

Section: A Modeling the Dynamics Of Ucas: Theory And Implementationmentioning

confidence: 99%

The response of phospholipid-encapsulated microbubbles to chirp-coded excitation: Implications for high-frequency nonlinear imaging

Shekhar

Doyley

2013

The Journal of the Acoustical Society of America

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The current excitation strategy for harmonic and subharmonic imaging (HI and SHI) uses short sinebursts. However, alternate pulsing strategies may be useful for enhancing nonlinear emissions from ultrasound contrast agents. The goal of this study was to corroborate the hypothesis that chirp-coded excitation can improve the performance of high-frequency HI and SHI. A secondary goal was to understand the mechanisms that govern the response of ultrasound contrast agents to chirp-coded and sine-burst excitation schemes. Numerical simulations and acoustic measurements were conducted to evaluate the response of a commercial contrast agent (Targestar-P V R ) to chirp-coded and sine-burst excitation (10 MHz frequency, peak pressures 290 kPa). The results of the acoustic measurements revealed an improvement in signal-to-noise ratio by 4 to 14 dB, and a two-to threefold reduction in the subharmonic threshold with chirp-coded excitation. Simulations conducted with the Marmottant model suggest that an increase in expansion-dominated radial excursion of microbubbles was the mechanism responsible for the stronger nonlinear response. Additionally, chirp-coded excitation detected the nonlinear response for a wider range of agent concentrations than sine-bursts. Therefore, chirp-coded excitation could be a viable approach for enhancing the performance of HI and SHI.

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20 years of ultrasound contrast agent modeling

Cited by 131 publications

References 106 publications

Impulse response method for characterization of echogenic liposomes

Impulse response method for characterization of echogenic liposomes

The effect of amplitude modulation on subharmonic imaging with chirp excitation

The response of phospholipid-encapsulated microbubbles to chirp-coded excitation: Implications for high-frequency nonlinear imaging

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