Combining Acoustic Trapping With Plane Wave Imaging for Localized Microbubble Accumulation in Large Vessels

Nie, Luzhen; Harput, Sevan; Cowell, David M. J.; Carpenter, Thomas M.; McLaughlan, James R.; Freear, Steven

doi:10.1109/tuffc.2018.2838332

Cited by 13 publications

(11 citation statements)

References 62 publications

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“…Following the study into the PA response of the different sized AuNRs, the largest AuNRs (Au50s) were selected as contrast agents for the PA imaging of a tissue-mimicking phantom (see Section 3.3 for details). The imaging was performed using the Ultrasound Array Research Platform (UARP) II [ 49 ]. Figure 2 shows the plane-wave B-mode image of the tissue-mimicking phantom with the PA signal overlaid.…”

Section: Resultsmentioning

confidence: 99%

Gold Nanorods for Light-Based Lung Cancer Theranostics

Knights

McLaughlan

2018

IJMS

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Gold nanorods (AuNRs) have the potential to be used in photoacoustic (PA) imaging and plasmonic photothermal therapy (PPTT) due to their unique optical properties, biocompatibility, controlled synthesis, and tuneable surface plasmon resonances (SPRs). Conventionally, continuous-wave (CW) lasers are used in PPTT partly due to their small size and low cost. However, if pulsed-wave (PW) lasers could be used to destroy tissue then combined theranostic applications, such as PA-guided PPTT, would be possible using the same laser system and AuNRs. In this study, we present the effects of AuNR size on PA response, PW-PPTT efficacy, and PA imaging in a tissue-mimicking phantom, as a necessary step in the development of AuNRs towards clinical use. At equivalent NP/mL, the PA signal intensity scaled with AuNR size, indicating that overall mass has an effect on PA response, and reinforcing the importance of efficient tumour targeting. Under PW illumination, all AuNRs showed toxicity at a laser fluence below the maximum permissible exposure to skin, with a maximum of 80% cell-death exhibited by the smallest AuNRs, strengthening the feasibility of PW-PPTT. The theranostic potential of PW lasers combined with AuNRs has been demonstrated for application in the lung.

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Section: Resultsmentioning

confidence: 99%

Gold Nanorods for Light-Based Lung Cancer Theranostics

Knights

McLaughlan

2018

IJMS

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“…It takes a number of inputs including frequency, bandwidth (for chirps), and sampling frequency and produces a five-level waveform for any suitable switched circuit or pulser. It has facilitated a number of medical imaging and nondestructive testing applications [56]–[58], but this study is the first time it has been used for HIFU.…”

Section: Switching Schemes and Amplifier Designmentioning

confidence: 99%

HIFU Drive System Miniaturization Using Harmonic Reduced Pulsewidth Modulation

Adams

Carpenter

Cowell

et al. 2018

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Switched excitation has the potential to improve on the cost, efficiency, and size of the linear amplifier circuitry currently used in high-intensity focused ultrasound (HIFU) systems. Existing switching schemes are impaired by high harmonic distortion or lack array apodisation capability, so require adjustable supplies and/or large power filters to be useful. A multilevel pulsewidth modulation (PWM) topology could address both of these issues but the switching-speed limitations of transistors mean that there are a limited number of pulses available in each waveform cycle. In this study, harmonic reduction PWM (HRPWM) is proposed as an algorithmic solution to the design of switched waveforms. Its appropriateness for HIFU was assessed by design of a high power five-level unfiltered amplifier and subsequent thermal-only lesioning of ex vivo chicken breast. Three switched waveforms of different electrical powers (16, 26, 35 W) were generated using the HRPWM algorithm. Lesion sizes were measured and compared with those made at the same electrical power using a linear amplifier and bi-level excitation. HRPWM produced symmetric, thermal-only lesions that were the same size as their linear amplifier equivalents (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$p > 0.05$ \end{document}). At 16 W, bi-level excitation produced smaller lesions but at higher power levels large transients in the acoustic waveform nucleated undesired cavitation. These results demonstrate that HRPWM can minimize HIFU drive circuity size without the need for filters to remove harmonics or adjustable power supplies to achieve array apodisation.

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“…An agar-based tissue-mimicking rotating disk [50] was fabricated for evaluating the effect of the proposed method on image quality in vitro. The average speed of sound and attenuation through this phantom was 1540 m/s and 0.55 dB/MHz/cm, respectively [51].…”

Section: ) Effects Of Motion Compensation On Image Qualitymentioning

confidence: 99%

High-Frame-Rate Contrast-Enhanced Echocardiography Using Diverging Waves: 2-D Motion Estimation and Compensation

Nie

Cowell

Carpenter

et al. 2019

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Combining diverging ultrasound waves and microbubbles could improve contrast-enhanced echocardiography (CEE), by providing enhanced temporal resolution for cardiac function assessment over a large imaging field of view. However, current image formation techniques using coherent summation of echoes from multiple steered diverging waves (DWs) are susceptible to tissue and microbubble motion artifacts, resulting in poor image quality. In this study, we used correlation-based 2-D motion estimation to perform motion compensation for CEE using DWs. The accuracy of this motion estimation method was evaluated with Field II simulations. The root-mean-square velocity errors were 5.9% ± 0.2% and 19.5% ± 0.4% in the axial and lateral directions, when normalized to the maximum value of 62.8 cm/s which is comparable to the highest speed of blood flow in the left ventricle (LV). The effects of this method on image contrast ratio (CR) and contrast-to-noise ratio (CNR) were tested in vitro using a tissue mimicking rotating disk with a diameter of 10 cm. Compared against the control without motion compensation, a mean increase of 12 dB in CR and 7 dB in CNR were demonstrated when using this motion compensation method. The motion correction algorithm was tested in vivo on a CEE data set acquired with the Ultrasound Array Research Platform II performing coherent DW imaging. Improvement of the B-mode and contrast-mode image quality with cardiac motion and blood flow-induced microbubble motion was achieved. The results of motion estimation were further processed to interpret blood flow in the LV. This allowed for a triplex cardiac imaging technique, consisting of B mode, contrast mode, and 2-D vector flow imaging with a high frame rate of 250 Hz.

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Combining Acoustic Trapping With Plane Wave Imaging for Localized Microbubble Accumulation in Large Vessels

Cited by 13 publications

References 62 publications

Gold Nanorods for Light-Based Lung Cancer Theranostics

Gold Nanorods for Light-Based Lung Cancer Theranostics

HIFU Drive System Miniaturization Using Harmonic Reduced Pulsewidth Modulation

High-Frame-Rate Contrast-Enhanced Echocardiography Using Diverging Waves: 2-D Motion Estimation and Compensation

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