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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, 2003Streszczenie: 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.
In this study, 583 optical observations of freely flowing, oscillating, individual microbubbles from an experimental UCA were analyzed. The excursions during ultra- sound exposure were observed through a microscope. Images were recorded with a high frame rate camera operating at 3 MHz. Microbubbles on these images were measured off-line, and maximal excursions were determined. A technique is described to determine the diameters of the bubbles observed. We compared the maximal excursions of microbubbles of the same initial size in an ultrasound field with a 500 kHz center frequency at acoustic amplitudes ranging from 0.06 MPa to 0.85 MPa.
It was concluded that maximal excursions of identical bubbles can differ by 150% at low acoustic pressures (mechanical index or MI 0.2). At a high acoustic pressure (MI = 1.2) an image sequence was recorded on which a bubble collapsed, but an apparently identical bubble survived. Afiliacje autorów:
Postema M. | - | inna afiliacja | Bouakaz A. | - | Université François Rabelais (FR) | Chin C.T. | - | inna afiliacja | de Jong N. | - | inna afiliacja |
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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 | |