Pressure dependence of subharmonic signals from contrast microbubbles

Shi, W.T.; Forsberg, Flemming; Raichlen, JoelS; Needleman, Laurence; Goldberg, Barry

doi:10.1016/s0301-5629(98)00163-x

Cited by 214 publications

(238 citation statements)

References 25 publications

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“…In the same interval, the energy of the subharmonic component is reduced by 9.2 dB. Both these observations correspond well to the results presented in [6] and [14]. However, the fluctuating nature and the overall decrease in energy seen in Fig.…”

Section: Resultssupporting

confidence: 90%

“…The subharmonic component seems to drop from the beginning of the experiment to the end. According to Shi and colleagues [6], [14], this was expected for the first six measurement points. But the fact that the energy continues to drop for at least the next two measurement points (p ov = [20 15] kPa) could indicate that the bubbles are being dissolved.…”

Section: Resultsmentioning

confidence: 82%

“…Despite successful in vitro experiments and suggestions for further sensitivity improvements, no in vivo results or further investigations using this approach have been presented yet. Around the same time, Shi et al [6] observed from experiments, using two single element transducers, that the subharmonic component of Levovist is highly sensitive to ambient pressure changes compared to the fundamental and the second harmonic component. They reported a 9.9 dB linear decrease of the peak amplitude of the subharmonic component when increasing the ambient pressure from 0 to 24.8 kPa (1 kPa = 7.5 mmHg).…”

Section: Introductionmentioning

confidence: 95%

“…Because of the high compressibility of gas, microbubbles containing air or gas can be used as local pressure sensors [4], [5], [6]. The idea of using an ultrasound contrast agent (UCA) to measure the cardiac pressure noninvasively was first proposed by Fairbank and Scully [4] in 1977.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

In vitro measurement of ambient pressure changes using a realistic clinical setup

Andersen

Jensen

2008

2008 IEEE Ultrasonics Symposium

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

In vitro measurement of ambient pressure changes using a realistic clinical setup

Andersen

Jensen

2008

2008 IEEE Ultrasonics Symposium

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“…Current investigations in this field use the assumption that changes of the ambient pressure alter significantly the bubble dimensions; consequently their resonant frequency is changed, resulting in changes in the characteristics of backscattered signal. Using harmonic and sub-harmonic frequencies instead of resonant original frequency, allows to exclude artifacts from the surrounding media and to improve signal-to-noise ratio [3].The current paper conducts comparative analysis of the pressure sensitivity of some UCA, using computer simulation. It also evaluates the parameter best correlated to the ambient pressure, using both computer simulation and 'in-vitro' experiments.…”

mentioning

confidence: 99%

Study of pressure dependence of signals from ultrasound contrast agents

Adam

Burla

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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-Noninvasive pressure estimation within the heart cavities or coronary arteries is essential for providing information on blood perfusion and viability of the organ. Some ultrasound contrast agents (UCA) are particularly well suited for pressure measurements because pressure changes affect the reflectivity of the microbubbles after their injection. In-vitro experiments were conducted with UCA (Optison) using 2.0 MHz ultrasound pulses. Preliminary results indicate that, over the pressure range of 0-210 mmHg, the rate (slope) of decline as a function of time, of the amplitudes of the first and second harmonics and that of the sub-harmonic, may be a suitable parameter for estimation of the hydrostatic pressure changes. The difference between the amplitude of the first harmonic and that of the sub-harmonic stays almost constant throughout specific time window, thus demonstrating a good and stable correlation with the hydrostatic pressure.Keywords -Noninvasive, Hydrostatic pressure, Ultrasound, Contrast agent I. INTRODUCTIONThe problem of noninvasive pressure estimation using ultrasound contrast agents (UCA) is studied here. The blood pressure measurement in heart cavities, in internal organs or in the peripheral vascular system is very important because these are the locations where the pressure needs to be known. It also allows calculation of the flow through valves, stenosed arteries, etc., and it provides essential information about the blood perfusion of the given organ. Currently such pressure measurements are invasive. The possibility of exploiting particular properties of UCA as a tool for noninvasive pressure estimation seems to be promising [1], [2]. Current investigations in this field use the assumption that changes of the ambient pressure alter significantly the bubble dimensions; consequently their resonant frequency is changed, resulting in changes in the characteristics of backscattered signal. Using harmonic and sub-harmonic frequencies instead of resonant original frequency, allows to exclude artifacts from the surrounding media and to improve signal-to-noise ratio [3].The current paper conducts comparative analysis of the pressure sensitivity of some UCA, using computer simulation. It also evaluates the parameter best correlated to the ambient pressure, using both computer simulation and 'in-vitro' experiments. The particular problem discussed here is how to avoid the UCA backscatter time dependence, so that hydrostatic pressure can be estimated. II. METHODSThe aim of the current work was to assess the sensitivity of different UCA to ambient pressure changes and determine the particular properties that may make the UCA perform as 'pressure sensors'. 1) Simulation studies4 kinds of UCA micro-bubbles (air, Albunex, octafluoropropane, Optison) were compared for their pressure sensitivity, by studying the following features: frequency shift, first harmonic amplitude, second harmonic amplitude, the sub-harmonic amplitude and its threshold, "sub-harmonic to the first harmonic" and "sub-harmonic ...

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Three‐Dimensional Subharmonic Aided Pressure Estimation for Assessing Arterial Plaques in a Rabbit Model

Nam

Liu

Eisenbrey

et al. 2018

J of Ultrasound Medicine

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Objectives-To investigate 3-dimensional subharmonic aided pressure estimation (SHAPE) for measuring intraplaque pressure and the pressure gradient across the plaque cap as novel biomarkers for potentially predicting plaque vulnerability.Methods-Twenty-seven rabbits received a high-cholesterol diet for 2 weeks before a balloon catheter injury to denude the endothelium of the aorta, followed by 8 to 10 weeks of the high-cholesterol diet to create arteriosclerotic plaques. SHAPE imagings of the resulting plaques were performed 12, 16, and 20 weeks after injury using a LOGIQ 9 scanner with a 4D10L probe (GE Healthcare, Milwaukee, WI) before and during an infusion of Definity (Lantheus Medical Imaging, North Billerica, MA) and Sonazoid (GE Healthcare, Oslo, Norway). The ratios of the maximum subharmonic magnitudes at baseline and during the infusion were correlated with the intraplaque pressure and pressure gradient across the plaque cap obtained from direct measurements.Results-Ten rabbits died prematurely after the balloon injury procedure or due to toxicity from the high-cholesterol diet, whereas 2 rabbits were excluded for other conditions. Five rabbits were scanned in the 12-, 16-, and 20-week groups, respectively. Even after 20 weeks, the plaques that developed were very small (mean AE SD, 0.9 AE 0.4 × 0.14 AE 0.05 cm). Definity performed better than Sonazoid in this application but still only achieved a moderate correlation with pressure across the plaque cap (Definity, r = -0.40; Sonazoid, r = 0.22) and intraplaque pressure (Definity, r = -0.19; Sonazoid, r = -0.11).Conclusions-Initial findings from plaque pressure estimation using 3-dimensional SHAPE technique showed only moderate correlations with reference standards, but that may be have been due to weaknesses in the animal model studied.

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Pressure dependence of subharmonic signals from contrast microbubbles

Cited by 214 publications

References 25 publications

In vitro measurement of ambient pressure changes using a realistic clinical setup

In vitro measurement of ambient pressure changes using a realistic clinical setup

Study of pressure dependence of signals from ultrasound contrast agents

Three‐Dimensional Subharmonic Aided Pressure Estimation for Assessing Arterial Plaques in a Rabbit Model

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