Time and pressure dependence of acoustic signals radiated from microbubbles

Ganor, Yaniv; Adam, Dan; Kimmel, Eitan

doi:10.1016/j.ultrasmedbio.2005.06.014

Cited by 21 publications

(20 citation statements)

References 20 publications

(21 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While this relatively small change in static pressure is not expected to have a substantial effect on the BB thresholds (Bader et al, 2012), Dave et al (2013) found subharmonic emissions decreased linearly with increasing ambient pressure. Ganor et al (2005) concluded that this change in subharmonic emission was due in part to the reduction in steady-state bubble radius as a result of a higher compression force. UH emissions have also been found to decrease with increasing static pressure (Sun et al, 2012) although the strength of the dependence varies with insonifying frequency.…”

Section: E Limitations Of the Studymentioning

confidence: 99%

Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

Gruber

Bader

Holland

2014

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity V R ) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540-900 kHz) and a broad frequency bandwidth (0.54-1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 6 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.

show abstract

Section: E Limitations Of the Studymentioning

confidence: 99%

Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

Gruber

Bader

Holland

2014

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

“…However, the experimental setup was plagued by acquisition problems (employing 2 single element transducers held together with duct tape and no imaging capabilities [13]), which is clearly not clinically acceptable. Other studies have explored SHAPE in vitro [14][15][16][17][18], but without flow dynamics i.e., under static conditions. The objective of this work was to evaluate the use of microbubbles to track dynamic pressures in a continuous flow environment and to develop a SHAPE application using a commercially available ultrasound scanner and an existing ultrasound contrast agent.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive estimation of dynamic pressures in vitro and in vivo using the subharmonic response from microbubbles

Dave

Halldorsdottir

Eisenbrey

et al. 2011

2011 IEEE International Ultrasonics Symposium

View full text Add to dashboard Cite

In this work, the development of subharmonic emission based noninvasive pressure estimation technique is presented. In vitro, ambient pressures were varied (between 0 and 120 mmHg) in a closed-loop flow system circulating 0.2 ml Sonazoid microbubbles (GE Healthcare, Oslo, Norway) suspended in 750 ml of isotonic diluent and recorded by a Millar pressure catheter as the reference standard. Simultaneously, a SonixRP ultrasound scanner (Ultrasonix Medical Corp., Richmond, BC, Canada) operating in pulse inversion mode (f transmit : 2.5 MHz) was used to acquire unprocessed RF data at five different incident acoustic pressures (from 76 kPa to 897 kPa; n=3). The subharmonic data for each pulse was extracted using band-pass filtering with averaging, and subsequently, processed to eliminate noise. The incident acoustic pressure most sensitive to ambient pressure fluctuations was determined; then the ambient pressure was tracked over 20 seconds. Regression analysis compared subharmonic and catheter pressure values. In vivo validation of this technique was performed noninvasively for tracking left ventricular (LV) pressures of two canines using similar post processing as in vitro. The subharmonic signal tracked ambient pressures with r 2 = 0.922 for 20 seconds in vitro. In vivo the subharmonic signal tracked the LV pressures with r 2 > 0.790. Maximum errors in estimating clinically relevant systolic and diastolic pressures ranged from 0.22 to 2.84 mmHg using this subharmonic technique relative to Millar catheter pressures. Clinical validation and real time implementation of this technique may ultimately lead to the first noninvasive cardiac pressure monitoring tool.

show abstract

“…In order to correctly estimate the micro bubble concentration in perfused tissues, the non linear behaviour of micro bubbles regarding the insonating pressure has to be characterized and modelled. The deviation of the bubble response from the one of a linear scatterer is complex and subject to many parameters [1][2] [3], and has been explored in many different approaches and ranges [1] [4] [5] [6] [7][8] [9]. However an accurate method of measuring the bubble concentration has not been developed.…”

Section: Introductionmentioning

confidence: 99%

A non-linear ultrasonic scattering approach for micro bubble concentration quantification

Mari¹,

Hibbs²,

Tang³

2007

2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

View full text Add to dashboard Cite

Ultrasonic imaging of microbubble contrast agents and their concentration quantification is an ongoing problem, complicated by the lack of accurate attenuation compensation (TGC) algorithms and by the complex behaviour of microbubbles. Indeed the ultrasound contrast agents behave non linearly in the power range for medical imaging, while the biological tissues behave mainly linearly. Such quantification is required to allow the physicians to estimate the local blood perfusion in the biological tissues. But the different imaging methods developed to distinguish the agent from the surrounding tissues do not give an accurate representation of local agent concentration, which therefore has to be qualitatively estimated by the physicians. In this paper, we expand an existing automatic attenuation compensation algorithm by introducing a nonlinear relationship between insonating power and scattering when medium acoustic pressure is used (0.33 MI - 0.52 MI at 3MHz), and model amplitude modulation (AM). An acquisition system is set up to allow acquisitions of radio frequency data from Sonovue suspension with a programmable ultrasound scanner and a sectorial probe. Results show that the behaviour of microbubble clouds with pressure and concentration follow the evolution expected from the assumptions formulated to be able to develop the model. In particular, the proposed equations for concentration estimation correctly predict the true concentration in the range [0-228]microL/L.

show abstract

Time and pressure dependence of acoustic signals radiated from microbubbles

Cited by 21 publications

References 20 publications

Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

Noninvasive estimation of dynamic pressures in vitro and in vivo using the subharmonic response from microbubbles

A non-linear ultrasonic scattering approach for micro bubble concentration quantification

Contact Info

Product

Resources

About