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Proceedings Paper

Effect of third harmonic transmit phasing on second harmonic generation
Author(s): Che-Chou Shen; Yu-Chun Wang
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Paper Abstract

Generation of tissue harmonic signals during acoustic propagation is based on the combined effect of two different spectral interactions of the transmit signal. One produces harmonic whose frequency is the sum of transmit frequencies. The other results in harmonic at difference frequency of the transmit signals. Both the frequency-sum component and the frequency-difference component are sensitive to the phase of their constitutive spectral signals. When the two components are in-phase, enhancement of the native harmonic signal is feasible. Otherwise, they may cancel out each other and result in weak harmonic amplitude. For the frequency-sum component, its phase is solely related to the fundamental signal in the transmit waveform. On the other hand, the phase of the frequency-difference component is determined by the phase difference between the third harmonic signal and the fundamental signal. Results indicate that the relative phasing between the frequency-sum component and the frequency-difference component significantly changes the amplitude of the second harmonic signal. By simultaneously transmitting both fundamental signal and third harmonic signal with proper phases such that the frequency-difference component is in-phase with the frequency-sum component, the amplitude of second harmonic signal can be increased while the lateral harmonic beam pattern remains unchanged as compared to conventional situations. The second harmonic signal could be also reduced significantly when the two components are out of phase. Hence, third harmonic transmit phasing has potential for improving signal-to- noise ratio in tissue harmonic imaging or for enhancing image contrast in contrast agent imaging by suppression of tissue harmonics.

Paper Details

Date Published: 12 March 2007
PDF: 8 pages
Proc. SPIE 6513, Medical Imaging 2007: Ultrasonic Imaging and Signal Processing, 65130T (12 March 2007); doi: 10.1117/12.708390
Show Author Affiliations
Che-Chou Shen, National Taiwan Univ. of Science and Technology (Taiwan)
Yu-Chun Wang, National Taiwan Univ. of Science and Technology (Taiwan)


Published in SPIE Proceedings Vol. 6513:
Medical Imaging 2007: Ultrasonic Imaging and Signal Processing
Stanislav Y. Emelianov; Stephen A. McAleavey, Editor(s)

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