Ultrafast radial modulation imaging

Pauline Muleki Seya (1) , Kailiang Xu (1) , Tanter Mickael (1) , Olivier Couture (1)

1 PhysMed Paris - Physique pour la médecine

Radial modulation imaging improves the detection of microbubbles at high frequency by using a dual ultrasonic excitation. However, the synchronization between the imaging pulses is non-trivial because microbubbles need to be interrogated in the compression and the rarefaction phase and the time-delay difference from dispersion has to be corrected. To address these issues, we propose the use of ultrafast radial modulation imaging (uRMI). In this technique, a beat frequency between the modulation pulse (around 1 MHz) and the ultrafast pulse-repetition frequency was exploited to separate microbubbles from tissue phantom in-vitro. This led to a modulated images set in the spectral domain of the slow-time that may then be demodulated through a digital lock-in amplifier to retrieve the contrast image. Ultrafast RMI, applied on a flow phantom with microbubbles, provided a contrast-to-tissue ratio from 7.2 to 14.8 dB at 15 MHz. For flow speed lower than 0.05 mL/min, uRMI (16 dB) provided a better contrast-to-tissue ratio than other techniques: SVD spatiotemporal filter (11 dB), amplitude modulation (9 dB) or microbubbles disruption (6 dB) or. This technique may then be suitable to improve the detection of targeted microbubbles, in ultrasound molecular imaging applications, and the detection of extremely slow microbubbles moving in the finest vessels in ultrasound localization microscopy.

Mots clés: Ultrafast imaging; Microbubbles; Radial modulation; Index Terms-Contrast Imaging

Domaines: Acoustique [physics.class-ph]

Pauline Muleki Seya, Kailiang Xu, Tanter Mickael, Olivier Couture. Ultrafast radial modulation imaging. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2019, ⟨10.1109/TUFFC.2019.2949046⟩. ⟨hal-02345642⟩