Nonlinear propagation delay and pulse distortion resulting from dual frequency band transmit pulse complexes

Area of Science:

• Medical imaging
• Acoustics
• Biomedical engineering

Background:

• Medical ultrasound is a crucial diagnostic tool.
• Current ultrasound methods face limitations in diagnostic capabilities.
• Advanced signal processing techniques can potentially enhance ultrasound performance.

Purpose of the Study:

• To introduce and describe a novel acoustic imaging method called second-order ultrasound field imaging.
• To explore the potential of this method to improve diagnostic capabilities in medical ultrasound.
• To investigate the nonlinear propagation effects in this dual-frequency ultrasound technique.

Main Methods:

• Utilizing dual-frequency band pulse complexes with overlapping high-frequency (HF) and low-frequency (LF) pulses.
• Employing HF pulses for image reconstruction.
• Using LF pulses to manipulate the elastic properties of the medium during HF imaging.

Main Results:

• Observed nonlinear propagation effects of HF imaging pulses due to LF manipulation pulses.
• Demonstrated nonlinear HF propagation delay and HF pulse distortion with large frequency separation (e.g., 1:10).
• Identified nonlinear aberration when using different transmit foci for HF and LF pulses.

Conclusions:

• Second-order ultrasound field imaging offers a new approach to enhance medical ultrasound.
• Nonlinear propagation effects, including delay and distortion, are significant with dual-frequency pulses.
• This method shows promise for improving diagnostic accuracy in ultrasound applications.