Abstract

Measurement of Subharmonics in Liquid Containing Encapsulated Microbubbles

X.F.Gong, R.R.Lu, J.F.Yu (State Key Lab, Institute of Acoustics, Nanjing University, Nanjing, China); W.T.Shi (Department of Radiology and Jefferson Ultrasound Research and Education Institute, Thomas Jefferson University, PA, USA)

e-mail: zligong@nju.edu.cn

The gasfilled microbubbles existed in liquid are the strong scatters of the sound propagation. A liquid containing microbubbles is used as an effective contrast agent in biomedical ultrasound diagnosis in order to improve the quality of the images. However, due to existence of microbubbles in liquid, a series of harmonics will be generated. Bubbles insonified at frequency f have been shown to produce not only high harmonics, but also subharmonics at f/2, f/3, etc. In this paper, the subharmonics in contrast agent Sonazoid (Nycomed, Norway) containing encapsulated microbubbles with diameter in average 3.0 micrometers are studied. The experimental results of acoustic nonlinear behavior of this bubbly liquid and the dependence of received first, second harmonic and subharmonic amplitudes on the sound pressure are presented. Results indicate that the subharmonic generation obviously depends on the applied sound pressure and the existence of a threshold is observed in the measurement. This result is in agreement with the results reported for other kind of ultrasound contrast agents. (Supported by the Natural Science Foundation of China No.10074033)

Section : 5