Bubble dynamics and size distributions during focused ultrasound insonation

Yang, Xinmai; Roy, Ronald A.; Holt, R. Glynn

doi:10.1121/1.1823251

Cited by 57 publications

(44 citation statements)

References 53 publications

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“…Such activity can be exploited to visualize ablation effects (Sanghvi et al 1995;Rabkin et al 2005Rabkin et al , 2006 or to enhance tissue absorption (Melodelima et al 2001;Sokka et al 2003;Umemura et al 2005;Kaneko et al 2005), but can also complicate ultrasound energy deposition and the resulting spatial pattern of tissue coagulation (Watkin et al 1996;Chen et al 2003;Makin et al 2005;. Mechanisms for interactions between cavitation activity and ultrasound-induced heating have been clarified by several detailed numerical modeling studies (Hilgenfeldt et al 2000;Chavrier et al 2000;Yang et al 2004) and phantom experiments (Holt and Roy 2001;Khokhlova et al 2006). Cavitation activity, measured by passive detection of acoustic emissions, has also been found to correlate with cellular-level bioeffects (Edmonds and Ross 1986;Hallow et al 2006) and with ultrasound enhancement of thrombolysis (Datta et al 2006).…”

Section: Introductionmentioning

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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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: Introductionmentioning

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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“…The introduction of cavitation has been investigated as a mechanism to increase the local ultrasound absorption and enhance heating in HIFU. 12,13 Cavitation has been shown to yield elevated heating rates above those produced by classical absorption in tissue 14,15 and can provide a means for improving the efficacy of HIFU treatment. However, preexisting nucleation sites for cavitation are not omnipresent in most tissues in vivo.…”

Section: -mentioning

confidence: 99%

Enhanced-heating effect during photoacoustic imaging-guided high-intensity focused ultrasound

Cui¹,

Yang²

2011

Applied Physics Letters

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Photoacoustic imaging (PAI) technique has been used to monitor thermal lesion formation during high-intensity focused ultrasound (HIFU) treatment. While previous studies focused on photoacoustic detection of changes in temperature during HIFU treatment, we report an enhanced-heating effect when PAI is used to monitor HIFU treatment. We found that the temperature induced by HIFU could be significantly enhanced when the diagnostic laser system for photoacoustic detection was operating during HIFU treatment. This finding demonstrates an advantage of using PAI to guide HIFU therapy.

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“…[6][7][8][9][10][11][12] However, pre-existing nucleation sites for cavitation are not omnipresent in most tissues in vivo. Many research efforts have been made to create nucleation sites for cavitation and reduce cavitation threshold.…”

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confidence: 99%

Laser-enhanced cavitation during high intensity focused ultrasound: An in vivo study

Cui

Zhang²,

Yang³

2013

Applied Physics Letters

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Laser-enhanced cavitation during high intensity focused ultrasound (HIFU) was studied in vivo using a small animal model. Laser light was employed to illuminate the sample concurrently with HIFU radiation. The resulting cavitation was detected with a passive cavitation detector. The in vivo measurements were made under different combinations of HIFU treatment depths, laser wavelengths, and HIFU durations. The results demonstrated that concurrent light illumination during HIFU has the potential to enhance cavitation effect by reducing cavitation threshold in vivo. High intensity focused ultrasound (HIFU) is a truly noninvasive thermal-ablation technique. HIFU works through rapidly depositing high intensity ultrasound energy into a small region to induce cell death primarily by hyperthermia after high intensity ultrasound is absorbed by soft tissue. [1][2][3][4][5] While the application of HIFU therapy is expanding, one concern related to HIFU treatment is the prolonged treatment time for large tumors because HIFU lesion is relatively small for each HIFU shot.Cavitation has been shown to yield elevated heating rate above those produced by classical acoustic absorption in tissue and can provide an effective method to improve the efficiency of HIFU treatment.6-12 However, pre-existing nucleation sites for cavitation are not omnipresent in most tissues in vivo. Many research efforts have been made to create nucleation sites for cavitation and reduce cavitation threshold. Both ultrasound contrast agents (UCAs) [13][14][15][16][17][18] and nanoparticles have been studied as methods to deliver cavitation nuclei into the targeted region.19,20 The use of UCA or nanoparticles, however, requires the systematic injection of foreign particles into the blood stream, and would have major concerns regarding toxicity, efficiency, etc. Cavitation bubbles can also be induced in presonication areas by using low frequency, high intensity ultrasound prior to HIFU treatments. 21,22 This technique can enhance cavitation and create larger size lesions in deep tissue without the injection of any contrast agents. However, this technique requires very high acoustic pressure (generally more than 10 MPa) to be delivered into soft tissues in order to induce cavitation in the beginning. In addition, the inception of cavitation is erratic and difficult to predict when induced by ultrasound alone.Laser light has been widely used as a reliable method to induce cavitation through optical breakdown. This procedure is generally performed with high intensity light, and mostly limited to clear media or sample surfaces. 23,24 Hence the application of this technique is limited in the in vivo applications, where treatments in a certain depth in turbid media are often desired.In a previous study, 25 we reported an enhanced heating effect during photoacoustic imaging-guided HIFU therapy. The results suggested that cavitation was enhanced when a diagnostic laser light beam illuminated the sample concurrently with HIFU radiation. Two features were highlighted...

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Bubble dynamics and size distributions during focused ultrasound insonation

Cited by 57 publications

References 53 publications

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Enhanced-heating effect during photoacoustic imaging-guided high-intensity focused ultrasound

Laser-enhanced cavitation during high intensity focused ultrasound: An in vivo study

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