Enhanced ambient pressure sensitivity of the subharmonic signal from ultrasound contrast microbubbles

Microbubbles are considered a promising tool for noninvasive estimation of local blood pressure. It is reported that the subharmonic scattering amplitude of microbubbles decreases by 9 to 12 dB when immersed in the media under an ambient pressure variation from 0 to 180 mmHg. However, the pressure sensitivity still needs to be improved to satisfy clinical diagnostic requirements. Here, we investigated the effects of acoustic parameters on the pressure sensitivity of microbubbles through measuring the acoustic attenuation and scattering properties of commercially available SonoVue microbubbles. Our results showed that the first harmonic, subharmonic, and ultraharmonic amplitudes of microbubbles were reduced by 6.6 dB, 10.9 dB, and 9.3 dB at 0.225 mechanical index (MI), 4.6 dB, 19.8 dB, and 12.3 dB at 0.25 MI, and 18.5 dB, 17.6 dB, and 12.6 dB at 0.3 MI, respectively, when the ambient pressure increased from 0 to 180 mmHg. Our finding revealed that a moderate MI (0.25–0.4) exciting microbubbles could significantly improve their sensitivities to detect ambient pressure.

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Ambient pressure dependence of the ultra-harmonic response from contrast microbubbles

The Journal of the Acoustical Society of America ◽

10.1121/1.4707512 ◽

2012 ◽

Vol 131 (6) ◽

pp. 4358-4364 ◽

Cited By ~ 14

Author(s):

Tao Sun ◽

Nan Jia ◽

Dong Zhang ◽

Di Xu

Keyword(s):

Pressure Dependence ◽

Ambient Pressure ◽

Harmonic Response ◽

Contrast Microbubbles

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Effects of ambient pressure variation on the subharmonic response from contrast microbubbles

The Journal of the Acoustical Society of America ◽

10.1121/1.4877609 ◽

2014 ◽

Vol 135 (4) ◽

pp. 2309-2309

Author(s):

NIma Mobadersany ◽

Amit Katiyar ◽

Kausik Sarkar

Keyword(s):

Ambient Pressure ◽

Pressure Variation ◽

Subharmonic Response ◽

Contrast Microbubbles

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Real-Time Excitation-Enhanced Ultrasound Contrast Imaging

Ultrasonic Imaging ◽

10.1177/016173460502700201 ◽

2005 ◽

Vol 27 (2) ◽

pp. 65-74 ◽

Cited By ~ 2

Author(s):

Flemming Forsberg ◽

William T. Shi ◽

Michael K. Knauer ◽

Anne L. Hall ◽

Chris Vecchio ◽

...

Keyword(s):

Real Time ◽

Imaging Modality ◽

Surrounding Tissue ◽

Contrast Imaging ◽

Maximum Enhancement ◽

Ultrasound Contrast ◽

Ultrasound Contrast Imaging ◽

Contrast Microbubbles

A new nonlinear contrast specific imaging modality, excitation-enhanced imaging (EEI) has been implemented on commercially-available scanners for real-time imaging. This novel technique employs two acoustic fields: a low-frequency, high-intensity ultrasound field (the excitation field) to actively condition contrast microbubbles, and a second lower-intensity regular imaging field applied shortly afterwards to detect enhanced contrast scattering. A Logiq 9 scanner (GE Healthcare, Milwaukee, WI) with a 3.5C curved linear array and an AN2300 digital ultrasound engine (Analogic Corporation, Peabody, MA) with a P4-2 phased array transducer (Philips Medical Systems, Bothell, WA) were modified to perform EEI on a vector-by-vector basis in fundamental and pulse inversion harmonic grayscale modes. Ultrasound contrast microbubbles within an 8 mm vessel embedded in a tissue-mimicking flow phantom (ATS Laboratories, Bridgeport, CT) were imaged in vitro. While video intensities of scattered signals from the surrounding tissue were unchanged, video intensities of echoes from contrast bubbles within the vessel were markedly enhanced. The maximum enhancement achieved was 10.4 dB in harmonic mode (mean enhancement: 6.3 dB; p=0.0007). In conclusion, EEI may improve the sensitivity of ultrasound contrast imaging, but further work is required to assess the in vivo potential of this new technique.

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