Physical mechanisms of the therapeutic effect of ultrasound (a review)

Bailey, Michael R.; Khokhlova, Vera A.; Sapozhnikov, Oleg A.; Kargl, Steven G.; Crum, Lawrence A.

doi:10.1134/1.1591291

Cited by 408 publications

(284 citation statements)

References 97 publications

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“…Some HIFU studies have observed a large increase in subharmonic and broadband emissions simultaneous to, or slightly preceding apparent vaporization (Bailey et al 2003;Rabkin et al 2005Rabkin et al , 2006, while others have also observed significant high-frequency acoustic emissions, indicating cavitation, in the absence of tissue boiling (Khokhlova et al 2006;McLaughlan et al 2006). A possible explanation for this apparent inconsistency is the strong dependence of acoustic emissions on the sonication amplitude, as seen here for the subharmonic emissions depicted in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This behavior may also depend on the sonication frequency. Another reason for strong dependence of acoustic emissions on sonication characteristics are strongly nonlinear effects that can occur in highintensity focused ultrasound beams (Bailey et al 2003;Khokhlova et al 2006). Thus, although high-frequency, cavitational acoustic emissions may show a consistent relationship with tissue temperature for a particular ultrasound ablation scenario, such relationships may not be applicable if the sonication amplitude or other acoustic conditions are significantly modified.…”

Section: Discussionmentioning

confidence: 99%

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Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

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Acoustic emissions associated with cavitation and other bubble activity have previously been observed during ultrasound ablation experiments. Since detectable bubble activity may be related to temperature, tissue state, and sonication characteristics, these acoustic emissions are potentially useful for monitoring and control of ultrasound ablation. To investigate these relationships, ultrasound ablation experiments were performed with simultaneous measurements of acoustic emissions, tissue echogenicity, and tissue temperature, on fresh bovine liver. Ex vivo tissue was exposed to 0.9-3.3 s bursts of unfocused, continuous-wave, 3.10 MHz ultrasound from a miniaturized 32-element array, which performed B-scan imaging with the same piezoelectric elements during brief quiescent periods. Exposures employed pressure amplitudes of 0.8-1.4 MPa for exposure times of 6-20 min, sufficient to achieve significant thermal coagulation in all cases. Acoustic emissions received by a 1 MHz, unfocused passive cavitation detector, beamformed Aline signals acquired by the array, and tissue temperature detected by a needle thermocouple were sampled 0.3-1.1 times per second. Tissue echogenicity was quantified by the backscattered echo energy from a fixed region of interest within the treated zone. Acoustic emission levels were quantified from the spectra of signals measured by the passive cavitation detector, including subharmonic signal components at 1.55 MHz, broadband signal components within the band 0.3-1.1 MHz, and low-frequency components within the band 10-30 kHz. Tissue ablation rates, defined as the thermally ablated volumes per unit time, were assessed by quantitative analysis of digitally imaged, macroscopic tissue sections. Correlation analysis was performed among the averaged and time-dependent acoustic emissions in each band considered, B-mode tissue echogenicity, tissue temperature, and ablation rate. Ablation rate correlated significantly with broadband and low-frequency emissions, but was uncorrelated with subharmonic emissions. Subharmonic emissions were found to depend strongly on temperature in a nonlinear manner, with significant emissions occurring within different temperature ranges for each sonication amplitude. These results suggest potential roles for passive detection of acoustic emissions in guidance and control of bulk ultrasound ablation treatments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

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show abstract

“…When the bubble is exposed to a low-amplitude ultrasound field, the oscillation of its size follows the pressure changes in the sound wave and the bubble remains spherical. Bubbles that have a resonant size with respect to the acoustic wavelength will be driven into oscillation much more efficiently than others; for ultrasound frequencies commonly used in HIFU the resonant bubble diameter range is 1-5 microns (24). Inertial cavitation is a more violent phenomenon, in which the bubble grows during the rarefaction phase and then rapidly collapses which leads to its destruction.…”

Section: Acoustic Cavitationmentioning

confidence: 99%

HIFU for Palliative Treatment of Pancreatic Cancer

Khokhlova

Hwang

2016

Advances in Experimental Medicine and Biology

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KEY WORDSHigh intensity focused ultrasound (HIFU) is a novel non-invasive modality for ablation of various solid tumors including uterine fibroids, prostate cancer, hepatic, renal, breast and pancreatic tumors. HIFU therapy utilizes mechanical energy in the form of a powerful ultrasound wave that is focused inside the body to induce thermal and/or mechanical effects in tissue. Multiple preclinical and non-randomized clinical trials have been performed to evaluate the safety and efficacy of HIFU for palliative treatment of pancreatic tumors. Substantial tumor-related pain reduction was achieved in most cases after HIFU treatment, and no significant side-effects were observed. This review provides a description of different physical mechanisms underlying HIFU therapy, summarizes the clinical experience obtained to date in HIFU treatment of pancreatic tumors, and discusses the challenges, limitations and new approaches in this modality. therapeutic ultrasound; focused ultrasound; HIFU; pancreas cancer; review J Gastrointest Oncol 2011; 2: 175-184.

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“…H igh intensity focused ultrasound (HIFU) therapy is a noninvasive ablation method in which ultrasound energy from an extracorporeal source is focused within the body to locally ablate tissue at the focus without damaging surrounding tissues (1,2). HIFU is most widely used to thermally ablate a variety of both benign and malignant tumors including uterine fibroids, prostate cancer, liver tumors, and other solid tumors that are accessible to ultrasound energy (3)(4)(5)(6).…”

mentioning

confidence: 99%

Ultrasound-guided tissue fractionation by high intensity focused ultrasound in an in vivo porcine liver model

Khokhlova

Wang

Simon

et al. 2014

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

102

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Significance High intensity focused ultrasound (HIFU) therapy is a promising, clinically adopted method of noninvasive tissue ablation used to treat both benign and malignant conditions. This work presents, to our knowledge, the first in vivo validation of a previously developed HIFU-based method that allows for noninvasive fractionation of targeted tissue into subcellular debris—boiling histotripsy—in a large animal model. While fractionating the targeted soft tissue, boiling histotripsy is shown to spare the adjacent connective tissue structures such as blood vessels. The process can be readily targeted and monitored by B-mode ultrasound. The resulting tissue debris are liquid, which provides a potential clinical benefit over thermal ablation in the treatment of tumors that exert uncomfortable pressure on surrounding tissues.

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Physical mechanisms of the therapeutic effect of ultrasound (a review)

Cited by 408 publications

References 97 publications

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

HIFU for Palliative Treatment of Pancreatic Cancer

Ultrasound-guided tissue fractionation by high intensity focused ultrasound in an in vivo porcine liver model

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