Ultrasound assessment of translation of microbubbles driven by acoustic radiation force in a channel filled with stationary fluid

Abstract

In this report, a method is proposed to quantify the translation of ultrasound contrast agent (UCA) microbubbles driven by acoustic radiation for the detection of channels filled with stationary fluid. The authors subjected UCA microbubbles in a channel with diameters of 0.1 and 0.5 mm to ultrasound pulses with a center frequency of 14.4 MHz. The translational velocity of the UCA microbubbles increased with the sound pressure and pulse repetition frequency (PRF) of the transmitted ultrasound. The mean translational velocity reached 0.75 mm/s at a negative peak sound pressure of 2.76 MPa and a PRF of 2 kHz. This trend agreed with the theoretical prediction, which indicated that the translational velocity was proportional to the square of the sound pressure and the PRF. Furthermore, an experiment was carried out with a phantom that mimics tissue and found that the proposed method aided in detection of the channel, even in the case of a low contrast-echo to tissue-echo ratio. The authors expect to develop the proposed method into a technique for detecting lymph vessels.

Fluorescence intensity changes depending on viscoelasticity of lipid shell coating microbubbles labeled with an indocyanine green derivative

“…To enhance the CEUS image contrast of LNs and LC buried in surrounding tissues, Yoshida et al proposed a Doppler method to improve their visibility because the image contrast between LN or LC and surrounding tissue is often low due to the presence of fibrous connective tissues in subcutaneous structures. 19,20) NIR fluorescence and ultrasound imaging techniques can provide feature potential applications. For example, Favril et.…”

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

“…25) Thus, we proposed a method using acoustic radiation force to improve the CNR in CEUS imaging. 26) In our proposed method, bubbles were assumed to be dispersed in lymph channels with stationary fluid. The translation of bubbles (contrast agents) was induced by acoustic radiation force by irradiating pulsed ultrasound with a given pulse repetition frequency (PRF), and was quantified by Doppler method.…”

“…Previous studies using a single concave transducer have demonstrated that 15 MHz pulsed ultrasound with PRF of 2 kHz and peak negative sound pressure of 2.76 MPa could move bubbles away from transducer at mean velocity of 0.76 mm s −1 . 26) In addition, it was found that the translational velocity of bubbles was proportional to PRF and the square of peak negative sound pressure. Previous studies suggested that optical observations with a high-speed video camera and streak camera could provide an understanding of bubble dynamics, bubble oscillation, bubble translation, and related phenomena such as microstreaming.…”

Pseudo-Doppler effect at a disappearance of a single microbubble translating owing to acoustic radiation force

“…[11][12][13] We have fabricated lipid MBs with an indocyanine green derivative as a contrast agent for ultrasound and near-infrared fluorescence dual imaging, 14) and proposed the method to detect MBs with high sensitivity by actively moving them using acoustic radiation force. [15][16][17] This technique, which is named the contrast-enhanced active Doppler method (CEADUS), would improve the robustness of visualization of vessels with stationary fluid, e.g. lymph vessels, which conventional contrast-enhanced Doppler ultrasound hardly detects.…”