Partner: C.T. Chin |
Recent publications
1. | Postema M.♦, Bouakaz A.♦, Chin C.T.♦, de Jong N.♦, Simulations and Measurements of Optical Images of Insonified Ultrasound Contrast Microbubbles, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2003.1201465, Vol.50, No.5, pp.523-536, 2003 Abstract: Ultrasound contrast agents (UCAs) are used in a clinical setting to enhance the backscattered signal from the blood pool to estimate perfusion and blood flow. The UCAs consist of encapsulated microbubbles, measuring 1–10 m in diameter. Acoustic characterization of UCAs is generally carried out from an ensemble of bubbles. The measured signal is a complicated summation of all signals from the individual microbubbles. Hence, characterization of a single bubble from acoustic measurements is complex.
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2. | Postema M.♦, Bouakaz A.♦, Chin C.T.♦, de Jong N.♦, Optical observations of ultrasound contrast agent destruction, ACTA ACUSTICA UNITED WITH ACUSTICA, ISSN: 1610-1928, Vol.89, pp.728, 2003 |
Conference papers
1. | Postema M.♦, Bouakaz A.♦, Chin C.T.♦, de Jong N.♦, Optically observed microbubble coalescence and collapse, IUS 2002, IEEE Ultrasonics Symposium, 2002-10-08/10-11, Monachium (DE), DOI: 10.1109/ULTSYM.2002.1192681, Vol.2, pp.1900-1903, 2002 Abstract: Understanding the mechanisms of microbubble destruction is needed for the development of ultrasound guided drug and gene delivery methods and for the improvement of diagnostic ultrasonic contrast agent (UCA) detection methods. We performed 482 experiments on the coalescence and collapse mechanisms of a soft- shelled and a hard-shelled contrast agent, by subjecting an experimental lipid-shelled UCA and the hard-shelled UCA QuantisonTM to 500 kHz, high- pressured ultrasound (MI≈1.0), and recording microscopic images of these events with a fast- framing camera. Results showed that bubble fragmentation into smaller bubbles is the primary mechanism for lipid-shelled contrast microbubble destruction during the first cycles after ultrasound arrival. In 28% of our experimental events with a lipid-shelled UCA, we observed bubble coalescence. The coalescence mechanism was observed to be analog to the process desribed for larger gas bubbles. Repetitive coalescence and fragmentation was clearly recorded with a fast-framing camera. We also demonstrated the formation and collapse of large lipid-shelled bubbles and bubble clusters. Furthermore we showed that sonic cracking is feasible for the hard-shelled contrast agent QuantisonTM. Affiliations:
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2. | Postema M.♦, Bouakaz A.♦, Chin C.T.♦, de Jong N.♦, Real-time optical imaging of individual microbubbles in an ultrasound field, IUS 2001, IEEE International Ultrasonics Symposium, 2001-10-07/10-10, Atlanta (US), DOI: 10.1109/ULTSYM.2001.992044, Vol.2, pp.1679-1682, 2001 Abstract: In this study we analyze the behavior of individual experimental ultrasonic contrast bubbles, insonofied by 500 kHz ultrasound, at acoustic pressures between 0.06 and 0.66 MPa. The oscillations were observed under a microscope with a fast framing camera.
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