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Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging
Published on: December 4, 2016
The effect of third harmonic transmit phasing on contrast agent responses for CTR improvement
Che-Chou Shen1, Chih-Kuang Yeh, Wen-Shiang Chen
1Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan. Choushen@mail.ntust.edu.tw
Physics in Medicine and Biology
|October 16, 2008
Summary
Third harmonic (3f(0)) transmit phasing improves contrast-to-tissue ratio (CTR) in ultrasound imaging by suppressing tissue harmonics. However, contrast agent signals require different phasing, limiting CTR gains and necessitating multi-pulse sequences for optimal results.
Area of Science:
- Medical imaging
- Ultrasound technology
- Acoustics
Background:
- Harmonic detection in ultrasound imaging is limited by background tissue harmonic signals, reducing contrast-to-tissue ratio (CTR).
- Third harmonic (3f(0)) transmit phasing offers a method to suppress tissue harmonic amplitudes by canceling frequency components.
Purpose of the Study:
- To investigate the efficacy of third harmonic (3f(0)) transmit phasing for improving CTR in ultrasonic contrast imaging.
- To analyze the nonlinear responses of microbubbles under 3f(0) transmit phasing and compare them to tissue harmonic behavior.
Main Methods:
- Utilizing third harmonic (3f(0)) transmit phasing to generate cancellation of tissue harmonic signals.
- Analyzing the nonlinear responses of microbubbles and tissue harmonic signals at the third harmonic frequency.
- Selecting 3f(0) transmit phase for maximal tissue suppression to optimize CTR.
Main Results:
- Microbubble nonlinear responses in 3f(0) transmit phasing differ significantly from tissue harmonic behavior.
- The suppression phase for contrast microbubbles deviates from that of tissue, reducing achievable contrast harmonic signal suppression.
- Optimal CTR improvement is achieved by selecting the 3f(0) transmit phase for maximal tissue suppression.
Conclusions:
- Third harmonic (3f(0)) transmit phasing can enhance CTR in ultrasound contrast imaging, but gains are limited by differing microbubble and tissue responses.
- Spectral leakage can compromise CTR improvement; multi-pulse sequences like pulse inversion are recommended for mitigation.
- Further research into advanced phasing techniques is warranted for maximizing CTR in contrast-enhanced ultrasound.
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