Ultrasonic contrast agent shell rupture detected by inertial cavitation and rebound signals

Azzdine Y. Ammi, Robin O. Cleveland, Jonathan Mamou, Giace I. Wang, S. Lori Bridal, William D. O'Brien

    Research output: Contribution to journalArticle

    76 Scopus citations

    Abstract

    Determining the rupture pressure threshold of ultrasound contrast agent microbubbles has significant applications for contrast imaging, development of therapeutic agents, and evaluation of potential bioeffects. Using a passive cavitation detector, this work evaluates rupture based on acoustic emissions from single, encapsulated, gas-filled microbubbles. Sinusoidal ultrasound pulses were transmitted into weak solutions of Optison™ at different center frequencies (0.9, 2.8, and 4.6 MHz), pulse durations (three, five, and seven cycles of the center frequencies), and peak rarefactional pressures (0.07 to 5.39 MPa). Pulse repetition frequency was 10 Hz. Signals detected with a 13-MHz, center-frequency transducer revealed postexcitation acoustic emissions (between 1 and 5 μs after excitation) with broadband spectral content. The observed acoustic emissions were consistent with the acoustic signature that would be anticipated from inertial collapse followed by "rebounds" when a microbubble ruptures and thus generates daughter/free bubbles that grow and collapse. The peak rarefactional pressure threshold for detection of these emissions increased with frequency (e.g., 0.53, 0.87, and 0.99 MPa for 0.9, 2.8, and 4.6 MHz, respectively; five-cycle pulse duration) and decreased with pulse duration. The emissions identified in this work were separated from the excitation in time and spectral content, and provide a novel determination of microbubble shell rupture.

    Original languageEnglish (US)
    Pages (from-to)126-135
    Number of pages10
    JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
    Volume53
    Issue number1
    DOIs
    StatePublished - Jan 1 2006

    ASJC Scopus subject areas

    • Instrumentation
    • Acoustics and Ultrasonics
    • Electrical and Electronic Engineering

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