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

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 53; no. 1; pp. 126 - 136
• Main Authors: Ammi, A.Y., Cleveland, R.O., Mamou, J., Wang, G.I., Bridal, S.L., O'Brien, W.D.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic emission; Acoustic imaging; Acoustic pulses; Acoustic signal detection; Acoustic transducers; Acoustics; Albumins - analysis; Albumins - radiation effects; Biological and medical sciences; Cardiovascular system; Cavitation; Collapse; Contrast agents; Contrast Media; Cross-disciplinary physics: materials science; rheology; Detectors; Emissions; Exact sciences and technology; Fluorocarbons - analysis; Fluorocarbons - radiation effects; Frequency; Fundamental areas of phenomenology (including applications); Image Interpretation, Computer-Assisted - methods; Inertial; Investigative techniques, diagnostic techniques (general aspects); Materials science; Materials testing; Medical sciences; Microbubbles; Microorganisms; Miscellaneous. Technology; Physics; Pulse duration; Rupture; Signal detection; Sonication; Ultrasonic imaging; Ultrasonic investigative techniques; Ultrasonic transducers; Ultrasonography - methods; Underwater sound; Encapsulation; Acoustic emission testing; Acoustic measurement; Maximal dose; Threshold detection; Measurement sensor; Rupture; Acoustic cavitation; Bubble; Shell; Wide band; Medical imagery; Biological effect; Acoustic image; Non destructive test; Medical application; Contrast media; Acoustic transducer
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2006.1588398

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/spl trade/ 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 /spl mu/s 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.