Comparable analysis of bubble translation due to acoustic radiation force based on simultaneous acoustical and optical observation

Abstract

Contrast-enhanced ultrasound imaging using acoustic radiation force, called contrast-enhanced active Doppler ultrasound (CEADUS) imaging, has been proposed for visualizing lymph channels filled with stationary fluid. Based on optical observations and acoustical evaluation, the behaviour of bubbles in a simulated channel during ultrasound exposure was investigated under four conditions for negative peak sound pressure (Pnp), at centre frequency of ultrasound and pulse repetition frequency of 15 MHz and 1 kHz, respectively. There was good correlation between the time changes of mean translational velocity for optical evaluation (VOPT) and acoustical evaluation (VUS). In addition, the maxima of VOPT and VUS were correlated (R = 0.665) and showed a similar trend proportional to the square of Pnp. These results strongly suggest that the acoustically-evaluated bubble translation has information equal to optically-evaluated one, meaning that the simultaneous observation system is useful to understand the bubble behaviours under CEADUS imaging.

Weakly nonlinear theory on ultrasound propagation in liquids containing many microbubbles encapsulated by visco-elastic shell

“…Applications of ultrasound in the medical field have recently received significant attention, and hence, several developments have taken place in this field. [1][2][3][4][5][6][7] The use of microbubbles as ultrasound contrast agents (UCAs) has drastically improved the resolution of images, [8][9][10][11] and ultrasound diagnosis using UCA was first performed in the late 1960s. 12,13) In most UCAs, the gas inside the bubble is stabilized against dissolution by being encapsulated in a lipid shell, membrane, etc.…”

Number density of bubbles under ultrasonic horn measured from stroboscopic images

“…The effects of bubbles are being applied to removing chemical pollutants, [1][2][3][4][5][6] synthesis of chemicals, 7) extraction of mineral oil, 8) and medical diagnosis and treatment. 9,10) The bubbles' effects vary in a complex manner depending on the incident conditions of the ultrasound and the liquids' properties. This is because the number of bubbles and their vibrations change in response to the incident ultrasonic waves and because of the ultrasound field changes due to the bubbles' existence.…”

Size-dependent translational velocity of phospholipid-coated bubbles driven by acoustic radiation force

“…10,11) We recently proposed a technique for visualizing lymph vessels using the Doppler method, where ARF-induced translating bubbles improve detection sensitivity. 12,13) Lymph flow is very slow (10 μm s −1 on average 14) ) and has few acoustic scatterers such as red blood cells, making non-contrast ultrasound Doppler imaging difficult. For highly-sensitive imaging, we aim to increase the translational velocity of bubbles to a level higher than that of tissue motion by optimizing ultrasound transmission parameters.…”

“…pulse repetition time was defined as Doppler signal, and analyzed in the frequency range to evaluate the echo power and the translational velocity of bubbles. 13) The power spectrum (P) of the Doppler signal was analyzed through a Fourier transform where the Doppler shift was represented as Δf. The power at Δf = 0 was defined as the stationary echo power (SEP) and the integrated power excluding Δf = 0 was defined as the dynamic echo power (DEP), where the integrated frequency range was set from -1.25 to 1.25 kHz.…”