Evaluation of chirp reversal power modulation sequence for contrast agent imaging

Area of Science:

• Ultrasound imaging
• Medical imaging physics
• Contrast-enhanced ultrasound

Background:

• Chirp sequences enhance contrast-to-noise ratio (CNR) in ultrasound imaging.
• Chirp reversal (CR) improves contrast detection by amplifying non-linear microbubble responses.

Purpose of the Study:

• Evaluate contrast enhancement of chirped imaging sequences with power modulation (PM) and pulse inversion (PI).
• Assess the impact of chirp compression filters on non-linear microbubble responses.

Main Methods:

• Implemented and tested various chirped imaging sequences on a programmable open scanner.
• Utilized a tissue-mimicking flow phantom with SonoVue® contrast agent.
• Designed a compression filter to extract non-linear microbubble responses.

Main Results:

• Chirp imaging increased image CNR by approximately 10 dB compared to conventional methods.
• Axial resolution degraded by a factor of 1.4 at -3 dB with chirp excitation.
• Chirp reversal (CR) combined with power modulation (PM) yielded the highest CNR and contrast-to-noise ratio (CTR).

Conclusions:

• Chirp sequences offer significant CNR improvement in ultrasound contrast imaging.
• Optimized chirp compression is crucial for recovering non-linear microbubble signals.
• CR combined with PM is superior for achieving maximal contrast enhancement in microbubble imaging.