Nonlinear coded excitation method for ultrasound contrast imaging.

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Acoustics

Background:

• Coded excitation with compression on receive is a technique used in medical ultrasound (US) imaging.
• It aims to improve signal-to-noise ratio (SNR) and penetration depth.
• Contrast agent imaging in US seeks to enhance visualization and diagnostic accuracy.

Purpose of the Study:

• To investigate the application of chirped pulse excitation in ultrasound contrast agent imaging.
• To assess the potential of chirped pulses to increase SNR and contrast-to-tissue ratio (CTR).
• To evaluate the impact on contrast agent destruction and tissue harmonic generation.

Main Methods:

• A computer simulation study was conducted.
• Chirped pulse excitation was compared to a Gaussian pulse (9.4-µs duration, 2-MHz center frequency, 45% relative bandwidth).
• A novel nonlinear compression technique selectively compressing the second harmonic component was proposed and utilized.

Main Results:

• Chirped pulse excitation demonstrated an increase in resonant bubble response of 10–13 dB for peak pressures between 50 and 300 kPa.
• The axial resolution after compression was comparable to conventional imaging methods.
• The observed enhancement was relatively insensitive to peak excitation pressure and maximized for bubbles resonant near the excitation center frequency.

Conclusions:

• Chirped pulse excitation offers significant improvements in SNR and CTR for ultrasound contrast agent imaging.
• The proposed nonlinear compression technique effectively enhances harmonic components while preserving axial resolution.
• This approach holds promise for reducing contrast agent dose and minimizing tissue harmonic interference in US imaging.