Visualization of the intensity field of a high intensity focused ultrasound (HIFU) source in situ

Nguyen, Trong; Minh, N.; Oelze, Michael L.

doi:10.1109/ultsym.2015.0314

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…The Bioeffects Committee of the American Institute of Ultrasound in Medicine has issued important guidelines for the safe use of ultrasound for therapeutic applications (39). Currently, for thermal-based therapeutic applications of HIFU, MRI (MR-guided HIFU) is the standard of care (40) and for nonthermal (i.e., mechanical) therapeutic applications of HIFU, ultrasonic visualization of the HIFU beam can be used to monitor therapy application (41).…”

Section: Hifu Sonication Through the Skull: Potential For Biomedicalmentioning

confidence: 99%

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers

Kim

Lau

Halmes

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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While study in the field of polymer mechanochemistry has yielded mechanophores that perform various chemical reactions in response to mechanical stimuli, there is not yet a triggering method compatible with biological systems. Applications such as using mechanoluminescence to generate localized photon flux in vivo for optogenetics would greatly benefit from such an approach. Here we introduce a method of triggering mechanophores by using high-intensity focused ultrasound (HIFU) as a remote energy source to drive the spatially and temporally resolved mechanicalto-chemical transduction of mechanoresponsive polymers. A HIFU setup capable of controlling the excitation pressure, spatial location, and duration of exposure is employed to activate mechanochemical reactions in a cross-linked elastomeric polymer in a noninvasive fashion. One reaction is the chromogenic isomerization of a naphthopyran mechanophore embedded in a polydimethylsiloxane (PDMS) network. Under HIFU irradiation evidence of the mechanochemical transduction is the observation of a reversible color change as expected for the isomerization. The elastomer exhibits this distinguishable color change at the focal spot, depending on ultrasonic exposure conditions. A second reaction is the demonstration that HIFU irradiation successfully triggers a luminescent dioxetane, resulting in localized generation of visible blue light at the focal spot. In contrast to conventional stimuli such as UV light, heat, and uniaxial compression/tension testing, HIFU irradiation provides spatiotemporal control of the mechanochemical activation through targeted but noninvasive ultrasonic energy deposition. Targeted, remote light generation is potentially useful in biomedical applications such as optogenetics where a light source is used to trigger a cellular response.high-intensity focused ultrasound | mechanochromism | mechanophores | mechanoluminescence | spatiotemporal control M echanical force exerted on a covalent bond acts as an energetic stimulus to drive specific chemical reactivity (mechanochemistry) (1). Particularly, mechanophores, i.e., mechanically sensitive molecules, have attracted attention due to their role in eliciting various chemical transformations in polymers (2). Extensive work in molecular design has revealed a rich library of mechanophores, which when subjected to mechanical stress undergo selective bond cleavage to unveil color change (3, 4), fluorescence (5), new reactive functionality (6), catalytic activity (7), light emission (8), and small-molecule release (9), among other responses. The ability of mechanochromic mechanophores to "visualize" the mechanical response to applied force provides insight for identifying the damage location and the material state in polymeric materials. Of particular importance to extending functionality of these mechanophores is the development of novel force-control tools capable of noninvasively triggering their activation. Mechanochemical responses have been observed when mechanical energy is applied to bulk-phase m...

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Section: Hifu Sonication Through the Skull: Potential For Biomedicalmentioning

confidence: 99%

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers

Kim

Lau

Halmes

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…The values measured with the hydrophone were normalized to the maximum measured pressure at the centre of the focal region. In order to calculate the width and length of the focal region, −3 dB (half magnitude versus the peak) and −6 dB (quarter magnitude versus the peak) values are commonly used (Figure 4; Nguyen et al, 2019). The position and dimensions of the focal zone, as determined using the hydrophone measurements, are summarized in Table 2 (below) together with those from the TLC films.…”

Section: Hydrophone Measurements Of the Acoustic Pressure Fieldmentioning

confidence: 99%

Beam characterization of a custom, handheld focused ultrasound system using thermochromic liquid crystal films

Mohammadabadi

Ahmed

Restaino³

et al. 2020

Med Devices & Sens

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Focused ultrasound (FUS) is a non-invasive therapeutic modality showing promise for treatment of a multitude of disease indications. Its effects on tissue are immediate, precise, and less likely to affect healthy tissues in the body as opposed to other forms of treatment like systemic chemotherapy, surgical techniques and radiation. Many of these now FDA-approved procedures, including ablation of uterine fibroids, prostate metastases, and thalamic tracts for treatment of essential tremor, are provided under image guidance and have dramatically reduced the risk of complications and the need for post-procedural hospital stays (

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“…4N could include harmonic contributions due to scattering from the tubing. The ability to beamform emissions originating from sources other than microbubbles can, however, be useful, such as in mapping the field of a transducer (see for example, [79], [80], or Fig. 7 from [61]).…”

Section: Passive Cavitation Imaging Of Discrete-time Signalsmentioning

confidence: 99%

Quantitative Frequency-Domain Passive Cavitation Imaging

Haworth

Bader

Rich

et al. 2017

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

122

125

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Passive cavitation detection has been an instrumental technique for measuring cavitation dynamics, elucidating concomitant bioeffects, and guiding ultrasound therapies. Recently, techniques have been developed to create images of cavitation activity to provide investigators with a more complete set of information. These techniques use arrays to record and subsequently beamform received cavitation emissions, rather than processing emissions received on a single-element transducer. In this paper, the methods for performing frequency-domain delay, sum, and integrate passive imaging are outlined. The method can be applied to any passively acquired acoustic scattering or emissions, including cavitation emissions. In order to compare data across different systems, techniques for normalizing Fourier transformed data and converting the data to the acoustic energy received by the array are described. A discussion of hardware requirements and alternative imaging approaches are additionally outlined. Examples are provided in MATLAB.

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Visualization of the intensity field of a high intensity focused ultrasound (HIFU) source in situ

Cited by 4 publications

References 4 publications

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers

High-intensity focused ultrasound-induced mechanochemical transduction in synthetic elastomers

Beam characterization of a custom, handheld focused ultrasound system using thermochromic liquid crystal films

Quantitative Frequency-Domain Passive Cavitation Imaging

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