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Sample records for pulsed ultrasound cavitational

  1. Inertial cavitation initiated by polytetrafluoroethylene nanoparticles under pulsed ultrasound stimulation.

    PubMed

    Jin, Qiaofeng; Kang, Shih-Tsung; Chang, Yuan-Chih; Zheng, Hairong; Yeh, Chih-Kuang

    2016-09-01

    Nanoscale gas bubbles residing on a macroscale hydrophobic surface have a surprising long lifetime (on the order of days) and can serve as cavitation nuclei for initiating inertial cavitation (IC). Whether interfacial nanobubbles (NBs) reside on the infinite surface of a hydrophobic nanoparticle (NP) and could serve as cavitation nuclei is unknown, but this would be very meaningful for the development of sonosensitive NPs. To address this problem, we investigated the IC activity of polytetrafluoroethylene (PTFE) NPs, which are regarded as benchmark superhydrophobic NPs due to their low surface energy caused by the presence of fluorocarbon. Both a passive cavitation detection system and terephthalic dosimetry was applied to quantify the intensity of IC. The IC intensities of the suspension with PTFE NPs were 10.30 and 48.41 times stronger than those of deionized water for peak negative pressures of 2 and 5MPa, respectively. However, the IC activities were nearly completely inhibited when the suspension was degassed or ethanol was used to suspend PTFE NPs, and they were recovered when suspended in saturated water, which may indicates the presence of interfacial NBs on PTFE NPs surfaces. Importantly, these PTFE NPs could sustainably initiate IC for excitation by a sequence of at least 6000 pulses, whereas lipid microbubbles were completely depleted after the application of no more than 50 pulses under the same conditions. The terephthalic dosimetry has shown that much higher hydroxyl yields were achieved when PTFE NPs were present as cavitation nuclei when using ultrasound parameters that otherwise did not produce significant amounts of free radicals. These results show that superhydrophobic NPs may be an outstanding candidate for use in IC-related applications.

  2. Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials.

    PubMed

    Maxwell, Adam D; Cain, Charles A; Hall, Timothy L; Fowlkes, J Brian; Xu, Zhen

    2013-03-01

    In this study, the negative pressure values at which inertial cavitation consistently occurs in response to a single, two-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (P(cav)) for a single pulse as a function of peak negative pressure (p(-)) followed a sigmoid curve, with the probability approaching one when the pressure amplitude was sufficient. The statistical threshold (defined as P(cav) = 0.5) was between p(-) = 26 and 30 MPa in all samples with high water content but varied between p(-) = 13.7 and >36 MPa in other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p(-) = 28.2 megapascals was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at various pressure levels and dimensions of cavitation-induced lesions in tissue.

  3. Why Are Short Pulses More Efficient in Tissue Erosion Using Pulsed Cavitational Ultrasound Therapy (Histotripsy)?

    NASA Astrophysics Data System (ADS)

    Wang, Tzu-Yin; Maxwell, Adam D.; Park, Simone; Xu, Zhen; Fowlkes, J. Brian; Cain, Charles A.

    2010-03-01

    Histotripsy produces mechanical tissue fractionation through controlled cavitation. The histotripsy induced tissue erosion is more efficient with shorter (i.e., 3-6 cycles) rather than longer (i.e. 24 cycles) pulses. In this study, we investigated the reasons behind this observation by studying dynamics of the cavitating bubble clouds and individual bubbles during and after a therapy pulse. Bubble clouds were generated at a gel-water interface using 5 to 30-cycle 1 MHz pulses at P-/P+>19/125-MPa pressure and 1-kHz pulse repetition frequency. The evolution of the overall bubble cloud and individual bubbles were studied using high speed photography. Results show that: 1) within the first 10-15 cycles, the overall cloud grew to its maximum size; the individual bubbles underwent violent expansion and collapse, and grew in size with each cycle of ultrasound; 2) between the 15th cycle and the end of the pulse, the overall cloud size did not change even if further cycles of ultrasound were delivered; the individual bubbles no longer underwent violent collapse; 3) after the pulse, the overall cloud gradually dissolved; the individual bubbles may coalesce into larger bubbles for 0-40 μs, and then gradually dissolved. These observations suggest that violent growth and collapse of individual bubbles occur within the first few cycles of ultrasound pulse most often. This may explain why extremely short pulses are more energy efficient in histotripsy-induced tissue erosion.

  4. Monitoring of transient cavitation induced by ultrasound and intense pulsed light in presence of gold nanoparticles.

    PubMed

    Sazgarnia, Ameneh; Shanei, Ahmad; Shanei, Mohammad Mahdi

    2014-01-01

    One of the most important challenges in medical treatment is invention of a minimally invasive approach in order to induce lethal damages to cancer cells. Application of high intensity focused ultrasound can be beneficial to achieve this goal via the cavitation process. Existence of the particles and vapor in a liquid decreases the ultrasonic intensity threshold required for cavitation onset. In this study, synergism of intense pulsed light (IPL) and gold nanoparticles (GNPs) has been investigated as a means of providing nucleation sites for acoustic cavitation. Several approaches have been reported with the aim of cavitation monitoring. We conducted the experiments on the basis of sonochemiluminescence (SCL) and chemical dosimetric methods. The acoustic cavitation activity was investigated by determining the integrated SCL signal acquired over polyacrylamide gel phantoms containing luminol in the presence and absence of GNPs in the wavelength range of 400-500 nm using a spectrometer equipped with cooled charged coupled devices (CCD) during irradiation by different intensities of 1 MHz ultrasound and IPL pulses. In order to confirm these results, the terephthalic acid chemical dosimeter was utilized as well. The SCL signal recorded in the gel phantoms containing GNPs at different intensities of ultrasound in the presence of intense pulsed light was higher than the gel phantoms without GNPs. These results have been confirmed by the obtained data from the chemical dosimetry method. Acoustic cavitation in the presence of GNPs and intense pulsed light has been suggested as a new approach designed for decreasing threshold intensity of acoustic cavitation and improving targeted therapeutic effects.

  5. Stable cavitation induces increased cytoplasmic calcium in L929 fibroblasts exposed to 1-MHz pulsed ultrasound.

    PubMed

    Tsukamoto, Akira; Higashiyama, Satoru; Yoshida, Kenji; Watanabe, Yoshiaki; Furukawa, Katsuko S; Ushida, Takashi

    2011-12-01

    An increase in cytoplasmic calcium (Ca(2+) increase) is a second messenger that is often observed under ultrasound irradiation. We hypothesize that cavitation is a physical mechanism that underlies the increase in Ca(2+) in these experiments. To control the presence of cavitation, the wave type was controlled in a sonication chamber. One wave type largely contained a traveling wave (wave type A) while the other wave type largely contained a standing wave (wave type B). Fast Fourier transform (FFT) analysis of a sound field produced by the wave types ascertained that stable cavitation was present only under wave type A ultrasound irradiation. Under the two controlled wave types, the increase in Ca(2+) in L929 fibroblasts was observed with fluorescence imaging. Under wave type A ultrasound irradiation, an increase in Ca(2+) was observed; however, no increase in Ca(2+) was observed under wave type B ultrasound irradiation. We conclude that stable cavitation is involved in the increase of Ca(2+) in cells subjected to pulsed ultrasound.

  6. Dependence of pulsed focused ultrasound induced thrombolysis on duty cycle and cavitation bubble size distribution.

    PubMed

    Xu, Shanshan; Zong, Yujin; Feng, Yi; Liu, Runna; Liu, Xiaodong; Hu, Yaxin; Han, Shimin; Wan, Mingxi

    2015-01-01

    In this study, we investigated the relationship between the efficiency of pulsed, focused ultrasound (FUS)-induced thrombolysis, the duty cycle (2.3%, 9%, and 18%) and the size distribution of cavitation bubbles. The efficiency of thrombolysis was evaluated through the degree of mechanical fragmentation, namely the number, mass, and size of clot debris particles. First, we found that the total number and mass of clot debris particles were highest when a duty cycle of 9% was used and that the mean diameter of clot debris particles was smallest. Second, we found that the size distribution of cavitation bubbles was mainly centered around the linear resonance radius (2.5μm) of the emission frequency (1.2MHz) of the FUS transducer when a 9% duty cycle was used, while the majority of cavitation bubbles became smaller or larger than the linear resonance radius when a 2.3% or 18% duty cycle was used. In addition, the inertial cavitation dose from the treatment performed at 9% duty cycle was much higher than the dose obtained with the other two duty cycles. The data presented here suggest that there is an optimal duty cycle at which the thrombolysis efficiency and cavitation activity are strongest. They further indicate that using a pulsed FUS may help control the size distribution of cavitation nuclei within an active size range, which we found to be near the linear resonance radius of the emission frequency of the FUS transducer.

  7. Non-Invasive Thrombolysis Using Pulsed Ultrasound Cavitation Therapy – Histotripsy

    PubMed Central

    Maxwell, Adam D.; Cain, Charles A.; Duryea, Alexander P.; Yuan, Lingqian; Gurm, Hitinder S.; Xu, Zhen

    2009-01-01

    Clinically available thrombolysis techniques are limited by either slow reperfusion (drugs) or invasiveness (catheters), and carry significant risks of bleeding. In this study, the feasibility of using histotripsy as an efficient and non-invasive thrombolysis technique was investigated. Histotripsy fractionates soft tissue through controlled cavitation using focused, short, high-intensity ultrasound pulses. In-vitro blood clots formed from fresh canine blood were treated by histotripsy. The treatment was applied using a focused 1-MHz transducer, with 5-cycle pulses at a pulse repetition rate of 1 kHz. Acoustic pressures varying from 2 – 12 MPa peak negative pressure were tested. Our results show that histotripsy can perform effective thrombolysis with ultrasound energy alone. Histotripsy thrombolysis only occurred at peak negative pressure ≥6 MPa when initiation of a cavitating bubble cloud was detected using acoustic backscatter monitoring. Blood clots weighing 330 mg were completely broken down by histotripsy in 1.5 – 5 minutes. The clot was fractionated to debris with >96% weight smaller than 5 μm diameter. Histotripsy thrombolysis treatment remained effective under a fast, pulsating flow (a circulatory model) as well as in static saline. Additionally, we observed that fluid flow generated by a cavitation cloud can attract, trap, and further break down clot fragments. This phenomenon may provide a non-invasive method to filter and eliminate hazardous emboli during thrombolysis. PMID:19854563

  8. Thresholds for inertial cavitation in albunex suspensions under pulsed ultrasound conditions.

    PubMed

    Chang, P P; Chen, W S; Mourad, P D; Poliachik, S L; Crum, L A

    2001-01-01

    Stabilized microbubbles used as echo-contrast agents can be destroyed by ultrasonic irradiation. We have identified two pressure thresholds at which these microbubbles undergo inertial cavitation (here, defined as the collapse of gas bubbles followed by emission of an acoustic broadband noise). The first threshold (P1) corresponds to the pressure at which all the microbubbles in a cavitation field lose their property as an effective scatterer because of fragmentation or deflation. The second threshold (P2) is associated with the acoustic reactivation of the remnants of the contrast agents and is related to the onset of more violent inertial cavitation. P1 and P2 were measured as a function of the concentration of Albunex (Molecular Biosystems Inc., San Diego, CA) contrast agent, the number of transmitting acoustic cycles, and the pulse repetition frequency (PRF). The ultrasound frequency used was 1.1 MHz, and the peak negative acoustic pressures ranged from 0 to 8 MPa. Our results, measured in Isoton II (Coulter Diagnostics, Miami, FL) and whole blood solutions, showed that P1 increased with increasing Albunex concentration and decreased with increasing PRF, whereas P2 decreased with increasing Albunex concentration and was independent of the PRF. Both P1 and P2 decreased with increasing number of acoustic cycles N for N < 10 and were independent of the number of cycles for N > 10. Ultrasound images of Albunex acquired by a commercial scanner showed echo enhancement not only at pressure levels below P1 but also at levels above P2. The threshold P2 was achieved at ultrasound energies above the diagnostic level. Inertial cavitation produced at P2 was associated with a higher level of hemolysis compared with P1. The results of this investigation have potential significance for both diagnostic and therapeutic ultrasound applications.

  9. Simulation of diagnostic ultrasound image pulse sequences in cavitation bioeffects research.

    PubMed

    Miller, Douglas L; Dou, Chunyan; Wiggins, Roger C

    2007-10-01

    Research on cavitational bioeffects of diagnostic ultrasound (DUS) typically involves a diagnostic scanner as the exposure source. However, this can limit the ranges of exposure parameters for experimentation. Anesthetized hairless rats were mounted in a water bath and their right kidneys were exposed to ultrasound. Amplitude modulation with Gaussian envelopes simulated the image pulse sequences (IPSs) produced by diagnostic scanning. A 10 mulkgmin IV dose of Definity((R)) contrast agent was given during 1-5 min exposures. Glomerular capillary hemorrhage was assessed by histology. A stationary exposure approximated the bioeffects induced by DUS within the beam area. However, the use of five closely spaced exposures more faithfully reproduced the total effect produced within a DUS scan plane. Single pulses delivered at 1 s intervals induced the same effect as the simulated DUS. Use of 100 ms triangle-wave modulations for ramp-up or ramp-down of the IPS gave no effect or a large effect, respectively. Finally, an air-backed transducer simulating DUS without contrast agent showed a zero effect even operating at twice the present DUS guideline upper limit. Relatively simple single-element laboratory exposure systems can simulate diagnostic ultrasound exposure and allow exploration of parameter ranges beyond those available on present clinical systems.

  10. Effect of acoustic parameters on the cavitation behavior of SonoVue microbubbles induced by pulsed ultrasound.

    PubMed

    Lin, Yutong; Lin, Lizhou; Cheng, Mouwen; Jin, Lifang; Du, Lianfang; Han, Tao; Xu, Lin; Yu, Alfred C H; Qin, Peng

    2017-03-01

    SonoVue microbubbles could serve as artificial nuclei for ultrasound-triggered stable and inertial cavitation, resulting in beneficial biological effects for future therapeutic applications. To optimize and control the use of the cavitation of SonoVue bubbles in therapy while ensuring safety, it is important to comprehensively understand the relationship between the acoustic parameters and the cavitation behavior of the SonoVue bubbles. An agarose-gel tissue phantom was fabricated to hold the SonoVue bubble suspension. 1-MHz transmitting transducer calibrated by a hydrophone was used to trigger the cavitation of SonoVue bubbles under different ultrasonic parameters (i.e., peak rarefactional pressure (PRP), pulse repetition frequency (PRF), and pulse duration (PD)). Another 7.5-MHz focused transducer was employed to passively receive acoustic signals from the exposed bubbles. The ultraharmonics and broadband intensities in the acoustic emission spectra were measured to quantify the extent of stable and inertial cavitation of SonoVue bubbles, respectively. We found that the onset of both stable and inertial cavitation exhibited a strong dependence on the PRP and PD and a relatively weak dependence on the PRF. Approximate 0.25MPa PRP with more than 20μs PD was considered to be necessary for ultraharmonics emission of SonoVue bubbles, and obvious broadband signals started to appear when the PRP exceeded 0.40MPa. Moreover, the doses of stable and inertial cavitation varied with the PRP. The stable cavitation dose initially increased with increasing PRP, and then decreased rapidly after 0.5MPa. By contrast, the inertial cavitation dose continuously increased with increasing PRP. Finally, the doses of both stable and inertial cavitation were positively correlated with PRF and PD. These results could provide instructive information for optimizing future therapeutic applications of SonoVue bubbles.

  11. Inertial cavitation in theranostic nanoemulsions with simultaneous pulsed laser and low frequency ultrasound excitation

    NASA Astrophysics Data System (ADS)

    Arnal, Bastien; Wei, Chen-Wei; Xia, Jinjun; Pelivanov, Ivan M.; Lombardo, Michael; Perez, Camilo; Matula, Thomas J.; Pozzo, Danilo; O'Donnell, Matthew

    2014-03-01

    Ultrasound-induced inertial cavitation is a mechanical process used for site-localized therapies such as non-invasive surgery. Initiating cavitation in tissue requires very high intensity focused ultrasound (HIFU) and low-frequencies. Hence, some applications like thrombolysis require targeted contrast agents to reduce peak intensities and the potential for secondary effects. A new type of theranostic nanoemulsion has been developed as a combined ultrasound (US)/photoacoustic(PA) agent for molecular imaging and therapy. It includes a nanoscale emulsion core encapsulated with a layer of gold nanospheres at the water/ oil interface. Its optical absorption exhibits a spectrum broadened up to 1100 nm, opening the possibility that 1064 nm light can excite cavitation nuclei. If optically-excited nuclei are produced at the same time that a low-frequency US wave is at peak negative pressure, then highly localized therapies based on acoustic cavitation may be enabled at very low US pressures. We have demonstrated this concept using a low-cost, low energy, portable 1064 nm fiber laser in conjunction with a 1.24 MHz US transducer for simultaneous laser/US excitation of nanoemulsions. Active cavitation detection from backscattered signals indicated that cavitation can be initiated at very low acoustic pressures (less than 1 MPa) when laser excitation coincides with the rarefaction phase of the acoustic wave, and that no cavitation is produced when light is delivered during the compressive phase. US can sustain cavitation activity during long acoustic bursts and stimulate diffusion of the emulsion, thus increasing treatment speed. An in vitro clot model has been used to demonstrate combined US and laser excitation of the nanoemulsion for efficient thrombolysis.

  12. Effect of hydrodynamic cavitation in the tissue erosion by pulsed high-intensity focused ultrasound (pHIFU)

    NASA Astrophysics Data System (ADS)

    Zhou, Yufeng; Gao, Xiaobin Wilson

    2016-09-01

    High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s-1) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.

  13. Effect of hydrodynamic cavitation in the tissue erosion by pulsed high-intensity focused ultrasound (pHIFU).

    PubMed

    Zhou, Yufeng; Gao, Xiaobin Wilson

    2016-09-21

    High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in clinics. Besides the thermal ablation, tissue disintegration is also possible because of the interaction between the distorted HIFU bursts and either bubble cloud or boiling bubble. Hydrodynamic cavitation is another type of cavitation and has been employed widely in industry, but its role in mechanical erosion to tissue is not clearly known. In this study, the bubble dynamics immediately after the termination of HIFU exposure in the transparent gel phantom was captured by high-speed photography, from which the bubble displacement towards the transducer and the changes of bubble size was quantitatively determined. The characteristics of hydrodynamic cavitation due to the release of the acoustic radiation force and relaxation of compressed surrounding medium were found to associate with the number of pulses delivered and HIFU parameters (i.e. pulse duration and pulse repetition frequency). Because of the initial big bubble (~1 mm), large bubble expansion (up to 1.76 folds), and quick bubble motion (up to ~1 m s(-1)) hydrodynamic cavitation is significant after HIFU exposure and may lead to mechanical erosion. The shielding effect of residual tiny bubbles would reduce the acoustic energy delivered to the pre-existing bubble at the focus and, subsequently, the hydrodynamic cavitation effect. Tadpole shape of mechanical erosion in ex vivo porcine kidney samples was similar to the contour of bubble dynamics in the gel. Liquefied tissue was observed to emit towards the transducer through the punctured tissue after HIFU exposure in the sonography. In summary, the release of HIFU exposure-induced hydrodynamic cavitation produces significant bubble expansion and motion, which may be another important mechanism of tissue erosion. Understanding its mechanism and optimizing the outcome would broaden and enhance HIFU applications.

  14. Laser-nucleated acoustic cavitation in focused ultrasound.

    PubMed

    Gerold, Bjoern; Kotopoulis, Spiros; McDougall, Craig; McGloin, David; Postema, Michiel; Prentice, Paul

    2011-04-01

    Acoustic cavitation can occur in therapeutic applications of high-amplitude focused ultrasound. Studying acoustic cavitation has been challenging, because the onset of nucleation is unpredictable. We hypothesized that acoustic cavitation can be forced to occur at a specific location using a laser to nucleate a microcavity in a pre-established ultrasound field. In this paper we describe a scientific instrument that is dedicated to this outcome, combining a focused ultrasound transducer with a pulsed laser. We present high-speed photographic observations of laser-induced cavitation and laser-nucleated acoustic cavitation, at frame rates of 0.5×10(6) frames per second, from laser pulses of energy above and below the optical breakdown threshold, respectively. Acoustic recordings demonstrated inertial cavitation can be controllably introduced to the ultrasound focus. This technique will contribute to the understanding of cavitation evolution in focused ultrasound including for potential therapeutic applications.

  15. Laser-nucleated acoustic cavitation in focused ultrasound

    NASA Astrophysics Data System (ADS)

    Gerold, Bjoern; Kotopoulis, Spiros; McDougall, Craig; McGloin, David; Postema, Michiel; Prentice, Paul

    2011-04-01

    Acoustic cavitation can occur in therapeutic applications of high-amplitude focused ultrasound. Studying acoustic cavitation has been challenging, because the onset of nucleation is unpredictable. We hypothesized that acoustic cavitation can be forced to occur at a specific location using a laser to nucleate a microcavity in a pre-established ultrasound field. In this paper we describe a scientific instrument that is dedicated to this outcome, combining a focused ultrasound transducer with a pulsed laser. We present high-speed photographic observations of laser-induced cavitation and laser-nucleated acoustic cavitation, at frame rates of 0.5×106 frames per second, from laser pulses of energy above and below the optical breakdown threshold, respectively. Acoustic recordings demonstrated inertial cavitation can be controllably introduced to the ultrasound focus. This technique will contribute to the understanding of cavitation evolution in focused ultrasound including for potential therapeutic applications.

  16. Combined passive detection and ultrafast active imaging of cavitation events induced by short pulses of high-intensity ultrasound.

    PubMed

    Gateau, Jérôme; Aubry, Jean-François; Pernot, Mathieu; Fink, Mathias; Tanter, Mickaël

    2011-03-01

    The activation of natural gas nuclei to induce larger bubbles is possible using short ultrasonic excitations of high amplitude, and is required for ultrasound cavitation therapies. However, little is known about the distribution of nuclei in tissues. Therefore, the acoustic pressure level necessary to generate bubbles in a targeted zone and their exact location are currently difficult to predict. To monitor the initiation of cavitation activity, a novel all-ultrasound technique sensitive to single nucleation events is presented here. It is based on combined passive detection and ultrafast active imaging over a large volume using the same multi-element probe. Bubble nucleation was induced using a focused transducer (660 kHz, f-number = 1) driven by a high-power electric burst (up to 300 W) of one to two cycles. Detection was performed with a linear array (4 to 7 MHz) aligned with the single-element focal point. In vitro experiments in gelatin gel and muscular tissue are presented. The synchronized passive detection enabled radio-frequency data to be recorded, comprising high-frequency coherent wave fronts as signatures of the acoustic emissions linked to the activation of the nuclei. Active change detection images were obtained by subtracting echoes collected in the unnucleated medium. These indicated the appearance of stable cavitating regions. Because of the ultrafast frame rate, active detection occurred as quickly as 330 μs after the high-amplitude excitation and the dynamics of the induced regions were studied individually.

  17. The cavitation threshold of human tissue exposed to 0.2-MHz pulsed ultrasound: preliminary measurements based on a study of clinical lithotripsy.

    PubMed

    Coleman, A J; Kodama, T; Choi, M J; Adams, T; Saunders, J E

    1995-01-01

    Evidence of acoustic cavitation was identified in the form of transient echoes in ultrasound B-scan images of patients receiving extracorporeal shock-wave lithotripsy treatment on a Storz Modulith SL20. This lithotripter generates 10-microseconds duration pulses with a centre frequency of 0.2 MHz at a pulse repetition frequency of 1 Hz. The visual appearance of B-scan images was examined in a total of 30 patients and a quantitative analysis of echogenicity changes was carried out in six cases involving lithotripsy treatment of stones in the renal pelvis. In these patients new echoes were identified in images unaffected by movement artefacts and were found to occur in perinephric fat and adjacent muscle and kidney tissue at positions close to the axis of the shock-wave field between 1 and 2 cm in advance of the indicated beam focus of the lithotripter. The echogenicity within each region increased significantly above the background level when the output of the lithotripter was increased above a threshold value. The acoustic pressures corresponding to this threshold were measured in water using a calibrated PVDF membrane hydrophone. After correction for attenuation in tissue the cavitation thresholds, in terms of the temporal peak negative pressure, are found to lie between 1.5 MPa and 3.5 MPa in all six cases. Interpretation of the measured values in terms of the likely threshold at the higher frequencies used in diagnostic ultrasound is considered using a theoretical model.

  18. Counterbalancing the use of ultrasound contrast agents by a cavitation-regulated system.

    PubMed

    Desjouy, C; Fouqueray, M; Lo, C W; Muleki Seya, P; Lee, J L; Bera, J C; Chen, W S; Inserra, C

    2015-09-01

    The stochastic behavior of cavitation can lead to major problems of initiation and maintenance of cavitation during sonication, responsible of poor reproducibility of US-induced bioeffects in the context of sonoporation for instance. To overcome these disadvantages, the injection of ultrasound contrast agents as cavitation nuclei ensures fast initiation and lower acoustic intensities required for cavitation activity. More recently, regulated-cavitation devices based on the real-time modulation of the applied acoustic intensity have shown their potential to maintain a stable cavitation state during an ultrasonic shot, in continuous or pulsed wave conditions. In this paper is investigated the interest, in terms of cavitation activity, of using such regulated-cavitation device or injecting ultrasound contrast agents in the sonicated medium. When using fixed applied acoustic intensity, results showed that introducing ultrasound contrast agents increases reproducibility of cavitation activity (coefficient of variation 62% and 22% without and with UCA, respectively). Moreover, the use of the regulated-cavitation device ensures a given cavitation activity (coefficient of variation less 0.4% in presence of UCAs or not). This highlights the interest of controlling cavitation over time to free cavitation-based application from the use of UCAs. Interestingly, during a one minute sonication, while ultrasound contrast agents progressively disappear, the regulated-cavitation device counterbalance their destruction to sustain a stable inertial cavitation activity.

  19. Relationship between cavitation and loss of echogenicity from ultrasound contrast agents.

    PubMed

    Radhakrishnan, Kirthi; Bader, Kenneth B; Haworth, Kevin J; Kopechek, Jonathan A; Raymond, Jason L; Huang, Shao-Ling; McPherson, David D; Holland, Christy K

    2013-09-21

    Ultrasound contrast agents (UCAs) have the potential to nucleate cavitation and promote both beneficial and deleterious bioeffects in vivo. Previous studies have elucidated the pulse-duration-dependent pressure amplitude threshold for rapid loss of echogenicity due to UCA fragmentation. Previous studies have demonstrated that UCA fragmentation was concomitant with inertial cavitation. The purpose of this study was to evaluate the relationship between stable and inertial cavitation thresholds and loss of echogenicity of UCAs as a function of pulse duration. Determining the relationship between cavitation thresholds and loss of echogenicity of UCAs would enable monitoring of cavitation based upon the onscreen echogenicity in clinical applications. Two lipid-shelled UCAs, echogenic liposomes (ELIP) and Definity®, were insonified by a clinical ultrasound scanner in duplex spectral Doppler mode at four pulse durations ('sample volumes') in both a static system and a flow system. Cavitation emissions from the UCAs insonified by Doppler pulses were recorded using a passive cavitation detection system and stable and inertial cavitation thresholds ascertained. Loss of echogenicity from ELIP and Definity® was assessed within regions of interest on B-mode images. A numerical model based on UCA rupture predicted the functional form of the loss of echogenicity from ELIP and Definity®. Stable and inertial cavitation thresholds were found to have a weak dependence on pulse duration. Stable cavitation thresholds were lower than inertial cavitation thresholds. The power of cavitation emissions was an exponential function of the loss of echogenicity over the investigated range of acoustic pressures. Both ELIP and Definity® lost more than 80% echogenicity before the onset of stable or inertial cavitation. Once this level of echogenicity loss occurred, both stable and inertial cavitation were detected in the physiologic flow phantom. These results imply that stable and inertial

  20. CAVITATION THRESHOLD OF MICROBUBBLES IN GEL TUNNELS BY FOCUSED ULTRASOUND

    PubMed Central

    Sassaroli, E.; Hynynen, K.

    2007-01-01

    The investigation of inertial cavitation in micro-tunnels has significant implications for the development of therapeutic applications of ultrasound such as ultrasound-mediated drug and gene delivery. The threshold for inertial cavitation was investigated using a passive cavitation detector with a center frequency of 1 MHz. Micro-tunnels of various diameters (90 to 800 μm) embedded in gel were fabricated and injected with a solution of Optison™ contrast agent of concentrations 1.2% and 0.2% diluted in water. An ultrasound pulse of duration 500 ms and center frequency 1.736 MHz was used to insonate the microbubbles. The acoustic pressure was increased at one second intervals until broadband noise emission was detected. The pressure threshold at which broadband noise emission was observed was found to be dependent on the diameter of the micro-tunnels, with an average increase of 1.2 to 1.5 between the smallest and the largest tunnels, depending on the microbubble concentration. The evaluation of inertial cavitation in gel tunnels rather than tubes provides a novel opportunity to investigate microbubble collapse in a situation that simulates in vivo blood vessels better than tubes with solid walls do. PMID:17590501

  1. Spatiotemporal evolution of cavitation dynamics exhibited by flowing microbubbles during ultrasound exposure.

    PubMed

    Choi, James J; Coussios, Constantin-C

    2012-11-01

    Ultrasound and microbubble-based therapies utilize cavitation to generate bioeffects, yet cavitation dynamics during individual pulses and across consecutive pulses remain poorly understood under physiologically relevant flow conditions. SonoVue(®) microbubbles were made to flow (fluid velocity: 10-40 mm/s) through a vessel in a tissue-mimicking material and were exposed to ultrasound [frequency: 0.5 MHz, peak-rarefactional pressure (PRP): 150-1200 kPa, pulse length: 1-100,000 cycles, pulse repetition frequency (PRF): 1-50 Hz, number of pulses: 10-250]. Radiated emissions were captured on a linear array, and passive acoustic mapping was used to spatiotemporally resolve cavitation events. At low PRPs, stable cavitation was maintained throughout several pulses, thus generating a steady rise in energy with low upstream spatial bias within the focal volume. At high PRPs, inertial cavitation was concentrated in the first 6.3 ± 1.3 ms of a pulse, followed by an energy reduction and high upstream bias. Multiple pulses at PRFs below a flow-dependent critical rate (PRF(crit)) produced predictable and consistent cavitation dynamics. Above the PRF(crit), energy generated was unpredictable and spatially biased. In conclusion, key parameters in microbubble-seeded flow conditions were matched with specific types, magnitudes, distributions, and durations of cavitation; this may help in understanding empirically observed in vivo phenomena and guide future pulse sequence designs.

  2. A real-time measure of cavitation induced tissue disruption by ultrasound imaging backscatter reduction.

    PubMed

    Hall, Timothy L; Fowlkes, J Brian; Cain, Charles A

    2007-03-01

    A feedback method for obtaining real-time information on the mechanical disruption of tissue through ultrasound cavitation is presented. This method is based on a substantial reduction in ultrasound imaging backscatter from the target volume as the tissue structure is broken down. Ex-vivo samples of porcine liver were exposed to successive high-intensity ultrasound pulses at a low duty cycle to induce mechanical disruption of tissue parenchyma through cavitation (referred to as histotripsy). At the conclusion of treatment, B-scan imaging backscatter was observed to have decreased by 22.4 +/- 2.3 dB in the target location. Treated samples of tissue were found to contain disrupted tissue corresponding to the imaged hypoechoic volume with no remaining discernable structure and a sharp boundary. The observed, substantial backscatter reduction may be an effective feedback mechanism for assessing treatment efficacy in ultrasound surgery using pulsed ultrasound to create cavitation.

  3. Passive cavitation imaging with ultrasound arrays.

    PubMed

    Salgaonkar, Vasant A; Datta, Saurabh; Holland, Christy K; Mast, T Douglas

    2009-12-01

    A method is presented for passive imaging of cavitational acoustic emissions using an ultrasound array, with potential application in real-time monitoring of ultrasound ablation. To create such images, microbubble emissions were passively sensed by an imaging array and dynamically focused at multiple depths. In this paper, an analytic expression for a passive image is obtained by solving the Rayleigh-Sommerfield integral, under the Fresnel approximation, and passive images were simulated. A 192-element array was used to create passive images, in real time, from 520-kHz ultrasound scattered by a 1-mm steel wire. Azimuthal positions of this target were accurately estimated from the passive images. Next, stable and inertial cavitation was passively imaged in saline solution sonicated at 520 kHz. Bubble clusters formed in the saline samples were consistently located on both passive images and B-scans. Passive images were also created using broadband emissions from bovine liver sonicated at 2.2 MHz. Agreement was found between the images and source beam shape, indicating an ability to map therapeutic ultrasound beams in situ. The relation between these broadband emissions, sonication amplitude, and exposure conditions are discussed.

  4. Transient Cavitation Induced by High Amplitude Diagnostic Ultrasound.

    NASA Astrophysics Data System (ADS)

    Ayme, Eveline J.

    1988-07-01

    Study of the response of gaseous microbubbles to medical ultrasound is essential to apprehend the potentially dangerous effects of transient cavitation on living tissues. However, the prediction of such response is complicated by the finite -amplitude distortion associated with high amplitude acoustic fields. Through a combination of theoretical developments, computer simulations, and experiments, this dissertation investigates the consequences of the interaction between finite-amplitude distortion and transient cavitation, in the context of a diagnostic ultrasonic field. The theoretical approach is to synthesize the asymmetry between compression and rarefaction half-cycles which characterizes a typical nonlinearly distorted pulse obtained at the focus of a diagnostic transducer immersed in water. The synthetic pulse is used to drive a theoretical model for nonlinear bubble dynamics. Comparison with sinusoidal pulses "equivalent" to the distorted pulse as measured by a selection of descriptive parameters shows that: (i) the peak-positive pressure (P_{+} ) in the distorted pulse is a very poor predictor of transient cavitation, (ii) the peak-negative pressure (P_{-}) is a better indicator but underestimates the actual bubble response, (iii) the best predictor is the pressure amplitude of the fundamental (P_{F}) in a Fourier series representation of the distorted pulse. These predictions are tested experimentally on Drosophila larvae. The larvae are exposed to pulsed, symmetric, sinusoidal fields and to pulsed, asymmetric, distorted fields. The killing ratio of the larvae is plotted as a function of the same selection of descriptive parameters, namely P_{+}, P_{ -}, and P_{F}. The resulting curves are compared with the killing ratio plotted against the peak pressure in the sinusoidal, undistorted pulse (P_{A}). If the distorted pulse is described in terms of P_ {-} or P_{+} , the killing ratios are significantly different; if the distorted pulse is described in terms

  5. Ablation of benign prostatic hyperplasia using microbubble-mediated ultrasound cavitation.

    PubMed

    Li, Tao; Liu, Zheng

    2010-04-01

    Benign prostatic hyperplasia (BPH) is a world-wide common disease in elderly male patients. A number of invasive physiotherapies have been used to replace prostatectomy. In this article we report our hypothesis of using microbubbles-mediated ultrasound cavitation effects to ablate prostatic tissues. Microbubble ultrasound contrast agent is widely used contrast media in ultrasonography, yet it is also found to act as cavitation nuclei or enhancer. Once excited by a high peak pressure ultrasound pulse, the mechanical effects, like shock wave and microstream, released from cavitation could produce a series of bioeffects, contributing to sonoporation, microvascular rupture and hematoma. BPH is known to have hyperplastic neovasculature and this make it possible to be disrupted by the physical effects of cavitation under existing microbubbles in circulation. Mechanical ablation of prostatic capillary or small vessels could result in pathological alterations such as thrombosis, micro-circulation blockage, prostatic necrosis and atrophia. Thereupon it could effectively treat BPH by nontraumatic ways.

  6. Loss of echogenicity and onset of cavitation from echogenic liposomes: pulse repetition frequency independence.

    PubMed

    Radhakrishnan, Kirthi; Haworth, Kevin J; Peng, Tao; McPherson, David D; Holland, Christy K

    2015-01-01

    Echogenic liposomes (ELIP) are being developed for the early detection and treatment of atherosclerotic lesions. An 80% loss of echogenicity of ELIP has been found to be concomitant with the onset of stable and inertial cavitation. The ultrasound pressure amplitude at which this occurs is weakly dependent on pulse duration. It has been reported that the rapid fragmentation threshold of ELIP (based on changes in echogenicity) is dependent on the insonation pulse repetition frequency (PRF). The study described here evaluates the relationship between loss of echogenicity and cavitation emissions from ELIP insonified by duplex Doppler pulses at four PRFs (1.25, 2.5, 5 and 8.33 kHz). Loss of echogenicity was evaluated on B-mode images of ELIP. Cavitation emissions from ELIP were recorded passively on a focused single-element transducer and a linear array. Emissions recorded by the linear array were beamformed, and the spatial widths of stable and inertial cavitation emissions were compared with the calibrated azimuthal beamwidth of the Doppler pulse exceeding the stable and inertial cavitation thresholds. The inertial cavitation thresholds had a very weak dependence on PRF, and stable cavitation thresholds were independent of PRF. The spatial widths of the cavitation emissions recorded by the passive cavitation imaging system agreed with the calibrated Doppler beamwidths. The results also indicate that 64%-79% loss of echogenicity can be used to classify the presence or absence of cavitation emissions with greater than 80% accuracy.

  7. Detection of acoustic cavitation in the heart with microbubble contrast agents in vivo: a mechanism for ultrasound-induced arrhythmias.

    PubMed

    Rota, Claudio; Raeman, Carol H; Child, Sally Z; Dalecki, Diane

    2006-11-01

    Ultrasound fields can produce premature cardiac contractions under appropriate exposure conditions. The pressure threshold for ultrasound-induced premature contractions is significantly lowered when microbubble contrast agents are present in the vasculature. The objective of this study was to measure directly ultrasound-induced cavitation in the murine heart in vivo and correlate the occurrence of cavitation with the production of premature cardiac contractions. A passive cavitation detection technique was used to quantify cavitation activity in the heart. Experiments were performed with anesthetized, adult mice given intravenous injections of either a contrast agent (Optison) or saline. Murine hearts were exposed to ultrasound pulses (200 kHz, 1 ms, 0.1-0.25 MPa). Premature beats were produced in mice injected with Optison and the likelihood of producing a premature beat increased with increasing pressure amplitude. Similarly, cavitation was detected in mice injected with Optison and the amplitude of the passive cavitation detector signal increased with increasing exposure amplitude. Furthermore, there was a direct correlation between the extent of cavitation and the likelihood of ultrasound producing a premature beat. Neither premature beats nor cavitation activity were observed in animals injected with saline and exposed to ultrasound. These results are consistent with acoustic cavitation as a mechanism for this bioeffect.

  8. A tissue phantom for visualization and measurement of ultrasound-induced cavitation damage.

    PubMed

    Maxwell, Adam D; Wang, Tzu-Yin; Yuan, Lingqian; Duryea, Alexander P; Xu, Zhen; Cain, Charles A

    2010-12-01

    Many ultrasound studies involve the use of tissue-mimicking materials to research phenomena in vitro and predict in vivo bioeffects. We have developed a tissue phantom to study cavitation-induced damage to tissue. The phantom consists of red blood cells suspended in an agarose hydrogel. The acoustic and mechanical properties of the gel phantom were found to be similar to soft tissue properties. The phantom's response to cavitation was evaluated using histotripsy. Histotripsy causes breakdown of tissue structures by the generation of controlled cavitation using short, focused, high-intensity ultrasound pulses. Histotripsy lesions were generated in the phantom and kidney tissue using a spherically focused 1-MHz transducer generating 15 cycle pulses, at a pulse repetition frequency of 100 Hz with a peak negative pressure of 14 MPa. Damage appeared clearly as increased optical transparency of the phantom due to rupture of individual red blood cells. The morphology of lesions generated in the phantom was very similar to that generated in kidney tissue at both macroscopic and cellular levels. Additionally, lesions in the phantom could be visualized as hypoechoic regions on a B-mode ultrasound image, similar to histotripsy lesions in tissue. High-speed imaging of the optically transparent phantom was used to show that damage coincides with the presence of cavitation. These results indicate that the phantom can accurately mimic the response of soft tissue to cavitation and provide a useful tool for studying damage induced by acoustic cavitation.

  9. Removal of residual nuclei following a cavitation event using low-amplitude ultrasound.

    PubMed

    Duryea, Alexander P; Cain, Charles A; Tamaddoni, Hedieh A; Roberts, William W; Hall, Timothy L

    2014-10-01

    Microscopic residual bubble nuclei can persist on the order of 1 s following a cavitation event. These bubbles can limit the efficacy of ultrasound therapies such as shock wave lithotripsy and histotripsy, because they attenuate pulses that arrive subsequent to their formation and seed repetitive cavitation activity at a discrete set of sites (cavitation memory). Here, we explore a strategy for the removal of these residual bubbles following a cavitation event, using low-amplitude ultrasound pulses to stimulate bubble coalescence. All experiments were conducted in degassed water and monitored using high-speed photography. In each case, a 2-MHz histotripsy transducer was used to initiate cavitation activity (a cavitational bubble cloud), the collapse of which generated a population of residual bubble nuclei. This residual nuclei population was then sonicated using a 1 ms pulse from a separate 500-kHz transducer, which we term the bubble removal pulse. Bubble removal pulse amplitudes ranging from 0 to 1.7 MPa were tested, and the backlit area of shadow from bubbles remaining in the field following bubble removal was calculated to quantify efficacy. It was found that an ideal amplitude range exists (roughly 180 to 570 kPa) in which bubble removal pulses stimulate the aggregation and subsequent coalescence of residual bubble nuclei, effectively removing them from the field. Further optimization of bubble removal pulse sequences stands to provide an adjunct to cavitation-based ultrasound therapies such as shock wave lithotripsy and histotripsy, mitigating the effects of residual bubble nuclei that currently limit their efficacy.

  10. Removal of Residual Nuclei Following a Cavitation Event using Low-Amplitude Ultrasound

    PubMed Central

    Duryea, Alexander P.; Cain, Charles A.; Tamaddoni, Hedieh A.; Roberts, William W.; Hall, Timothy L.

    2014-01-01

    Microscopic residual bubble nuclei can persist on the order of 1 second following a cavitation event. These bubbles can limit the efficacy of ultrasound therapies such as shock wave lithotripsy and histotripsy, as they attenuate pulses that arrive subsequent to their formation and seed repetitive cavitation activity at a discrete set of sites (cavitation memory). Here, we explore a strategy for the removal of these residual bubbles following a cavitation event, using low amplitude ultrasound pulses to stimulate bubble coalescence. All experiments were conducted in degassed water and monitored using high speed photography. In each case, a 2 MHz histotripsy transducer was used to initiate cavitation activity (a cavitational bubble cloud), the collapse of which generated a population of residual bubble nuclei. This residual nuclei population was then sonicated using a 1 ms pulse from a separate 500 kHz transducer, which we term the ‘bubble removal pulse.’ Bubble removal pulse amplitudes ranging from 0 to 1.7 MPa were tested, and the backlit area of shadow from bubbles remaining in the field following bubble removal was calculated to quantify efficacy. It was found that an ideal amplitude range exists (roughly 180 – 570 kPa) in which bubble removal pulses stimulate the aggregation and subsequent coalescence of residual bubble nuclei, effectively removing them from the field. Further optimization of bubble removal pulse sequences stands to provide an adjunct to cavitation-based ultrasound therapies such as shock wave lithotripsy and histotripsy, mitigating the effects of residual bubble nuclei that currently limit their efficacy. PMID:25265172

  11. Ultrasound-enhanced thrombolysis using Definity as a cavitation nucleation agent.

    PubMed

    Datta, Saurabh; Coussios, Constantin-C; Ammi, Azzdine Y; Mast, T Douglas; de Courten-Myers, Gabrielle M; Holland, Christy K

    2008-09-01

    Ultrasound has been shown previously to act synergistically with a thrombolytic agent, such as recombinant tissue plasminogen activator (rt-PA) to accelerate thrombolysis. In this in vitro study, a commercial contrast agent, Definity, was used to promote and sustain the nucleation of cavitation during pulsed ultrasound exposure at 120 kHz. Ultraharmonic signals, broadband emissions and harmonics of the fundamental were measured acoustically by using a focused hydrophone as a passive cavitation detector and used to quantify the level of cavitation activity. Human whole blood clots suspended in human plasma were exposed to a combination of rt-PA, Definity and ultrasound at a range of ultrasound peak-to-peak pressure amplitudes, which were selected to expose clots to various degrees of cavitation activity. Thrombolytic efficacy was determined by measuring clot mass loss before and after the treatment and correlated with the degree of cavitation activity. The penetration depth of rt-PA and plasminogen was also evaluated in the presence of cavitating microbubbles using a dual-antibody fluorescence imaging technique. The largest mass loss (26.2%) was observed for clots treated with 120-kHz ultrasound (0.32-MPa peak-to-peak pressure amplitude), rt-PA and stable cavitation nucleated by Definity. A significant correlation was observed between mass loss and ultraharmonic signals (r = 0.85, p < 0.0001, n = 24). The largest mean penetration depth of rt-PA (222 microm) and plasminogen (241 microm) was observed in the presence of stable cavitation activity. Stable cavitation activity plays an important role in enhancement of thrombolysis and can be monitored to evaluate the efficacy of thrombolytic treatment.

  12. Stabilizing in vitro ultrasound-mediated gene transfection by regulating cavitation.

    PubMed

    Lo, Chia-Wen; Desjouy, Cyril; Chen, Shing-Ru; Lee, Jyun-Lin; Inserra, Claude; Béra, Jean-Christophe; Chen, Wen-Shiang

    2014-03-01

    It is well known that acoustic cavitation can facilitate the inward transport of genetic materials across cell membranes (sonoporation). However, partially due to the unstationary behavior of the initiation and leveling of cavitation, the sonoporation effect is usually unstable, especially in low intensity conditions. A system which is able to regulate the cavitation level during sonication by modulating the applied acoustic intensity with a feedback loop is implemented and its effect on in vitro gene transfection is tested. The regulated system provided better time stability and reproducibility of the cavitation levels than the unregulated conditions. Cultured hepatoma cells (BNL) mixed with 10 μg luciferase plasmids are exposed to 1-MHz pulsed ultrasound with or without cavitation regulation, and the gene transfection efficiency and cell viability are subsequently assessed. Experimental results show that for all exposure intensities (low, medium, and high), stable and intensity dependent, although not higher, gene expression could be achieved in the regulated cavitation system than the unregulated conditions. The cavitation regulation system provides a better control of cavitation and its bioeffect which are crucial important for clinical applications of ultrasound-mediated gene transfection.

  13. Cavitation Generation and Usage Without Ultrasound: Hydrodynamic Cavitation

    NASA Astrophysics Data System (ADS)

    Gogate, Parag R.; Pandit, Aniruddha B.

    Hydrodynamic Cavitation, which was and is still looked upon as an unavoidable nuisance in the flow systems, can be a serious contender as an alternative to acoustic cavitation for harnessing the spectacular effects of cavitation in physical and chemical processing. The present chapter covers the basics of hydrodynamic cavitation including the considerations for the bubble dynamics analysis, reactor designs and recommendations for optimum operating parameters. An overview of applications in different areas of physical, chemical and biological processing on scales ranging from few grams to several hundred kilograms has also been presented. Since hydrodynamic cavitation was initially proposed as an alternative to acoustic cavitation, it is necessary to compare the efficacy of both these modes of cavitations for a variety of applications and hence comparisons have been discussed either on the basis of energy efficiency or based on the scale of operation. Overall it appears that hydrodynamic cavitation results in conditions similar to those generated using acoustic cavitation but at comparatively much larger scale of operation and with better energy efficiencies.

  14. Optimization of ultrasound parameters of myocardial cavitation microlesions for therapeutic application.

    PubMed

    Miller, Douglas L; Dou, Chunyan; Owens, Gabe E; Kripfgans, Oliver D

    2014-06-01

    Intermittent high intensity ultrasound scanning with contrast microbubbles can induce scattered cavitation microlesions in the myocardium, which may be of value for tissue reduction therapy. Anesthetized rats were treated in a heated water bath with 1.5 MHz focused ultrasound pulses, guided by an 8 MHz imaging transducer. The relative efficacy with 2 or 4 MPa pulses, 1:4 or 1:8 trigger intervals and 5 or 10 cycle pulses was explored in six groups. Electrocardiogram premature complexes (PCs) induced by the triggered pulse bursts were counted, and Evans blue stained cardiomyocyte scores (SCSs) were obtained. The increase from 2 to 4 MPa produced significant increases in PCs and SCSs and eliminated an anticipated decline in the rate of PC induction with time, which might hinder therapeutic efficacy. Increased intervals and pulse durations did not yield significant increases in the effects. The results suggest that cavitation microlesion production can be refined and potentially lead to a clinically robust therapeutic method.

  15. CAVITATION DAMAGE STUDY VIA A NOVEL REPETITIVE PRESSURE PULSE APPROACH

    SciTech Connect

    Wang, Jy-An John; Ren, Fei; Wang, Hong

    2010-01-01

    Cavitation damage can significantly affect system performance. Thus, there is great interest in characterizing cavitation damage and improving materials resistance to cavitation damage. In this paper, we present a novel methodology to simulate cavitation environment. A pulsed laser is utilized to induce optical breakdown in the cavitation media, with the emission of shock wave and the generation of bubbles. The pressure waves induced by the optical breakdown fluctuate/propagate within the media, which enables the cavitation to occur and to further develop cavitation damage at the solid boundary. Using the repetitive pulsed-pressure apparatus developed in the current study, cavitation damage in water media was verified on stainless steel and aluminum samples. Characteristic cavitation damages such as pitting and indentation are observed on sample surfaces using scanning electron microscopy.

  16. Study on cavitation behavior during high-intensity focused ultrasound exposure by using optical and ultrasonic imaging

    NASA Astrophysics Data System (ADS)

    Taguchi, Kei; Takagi, Ryo; Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Cavitation bubbles are known to enhance the heating effect of high-intensity focused ultrasound (HIFU). In our previous study, the use of a “triggered HIFU” sequence consisting of a high-intensity pulse and a relatively low-intensity burst was proposed as an effective method to utilize the effect of cavitation bubbles. However, the duration of each component in the sequence has not been optimized. In this study, optical imaging was carried out to observe the behavior of cavitation bubbles in a gel phantom during the triggered HIFU exposure. Ultrasound imaging using the pulse inversion method was also conducted to detect the behavior of the bubbles. The results suggest that the oscillation of cavitation bubbles become inactive as the duration of HIFU burst exposure increases to the order of 10 ms. It was also suggested that ultrasonic imaging has potential use for detecting a change in the oscillation of cavitation bubbles for optimizing a triggered HIFU sequence.

  17. Effect of controlled offset of focal position in cavitation-enhanced high-intensity focused ultrasound treatment

    NASA Astrophysics Data System (ADS)

    Goto, Kota; Takagi, Ryo; Miyashita, Takuya; Jimbo, Hayato; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-07-01

    High-intensity focused ultrasound (HIFU) is a noninvasive treatment for tumors such as cancer. In this method, ultrasound is generated outside the body and focused to the target tissue. Therefore, physical and mental stresses on the patient are minimal. A drawback of the HIFU treatment is a long treatment time for a large tumor due to the small therapeutic volume by a single exposure. Enhancing the heating effect of ultrasound by cavitation bubbles may solve this problem. However, this is rather difficult because cavitation clouds tend to be formed backward from the focal point while ultrasonic intensity for heating is centered at the focal point. In this study, the focal points of the trigger pulses to generate cavitation were offset forward from those of the heating ultrasound to match the cavitation clouds with the heating patterns. Results suggest that the controlled offset of focal points makes the thermal coagulation more predictable.

  18. Ultrasound-microbubble mediated cavitation of plant cells: effects on morphology and viability.

    PubMed

    Qin, Peng; Xu, Lin; Zhong, Wenjing; Yu, Alfred C H

    2012-06-01

    The interaction between ultrasound pulses and microbubbles is known to generate acoustic cavitation that may puncture biological cells. This work presents new experimental findings on the bioeffects of ultrasound-microbubble mediated cavitation in plant cells with emphasis on direct observations of morphological impact and analysis of viability trends in tobacco BY-2 cells that are widely studied in higher plant physiology. The tobacco cell suspensions were exposed to 1 MHz ultrasound pulses in the presence of 1% v/v microbubbles (10% duty cycle; 1 kHz pulse repetition frequency; 70 mm between probe and cells; 1-min exposure time). Few bioeffects were observed at low peak negative pressures (<0.4 MPa) where stable cavitation presumably occurred. In contrast, at 0.9 MPa peak negative pressure (with more inertial cavitation activities according to our passive cavitation detection results), random pores were found on tobacco cell wall (observed via scanning electron microscopy) and enhanced exogenous uptake into the cytoplasm was evident (noted in our fluorescein isothiocyanate dextran uptake analysis). Also, instant lysis was observed in 23.4% of cells (found using trypan blue staining) and programmed cell death was seen in 23.3% of population after 12 h (determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling [TUNEL]). These bioeffects generally correspond in trend with those for mammalian cells. This raises the possibility of developing ultrasound-microbubble mediated cavitation into a targeted gene transfection paradigm for plant cells and, conversely, adopting plant cells as experimental test-beds for sonoporation-based gene therapy in mammalian cells.

  19. Phase-shift nano-emulsions induced cavitation and ablation during high intensity focused ultrasound exposure

    NASA Astrophysics Data System (ADS)

    Qiao, Yangzi; Yin, Hui; Chang, Nan; Wan, Mingxi

    2017-03-01

    Phase-shift Nano-emulsions (PSNEs) with a small initial diameter in nanoscale have the potential to leak out of the blood vessels and to accumulate at target point of tissue. At desired location, PSNEs can undergo acoustic droplet vaporization (ADV) process, change into gas bubbles and enhance focused ultrasound efficiency. The aim of this work was to provide spatial and temporal information on PSNE induced cavitation and ablation effects during pulsed high intensity focused ultrasound (HIFU) exposure. The PSNEs were composed of perfluorohaxane (PFH) and bovine serum albumin (BSA), and then uniformly distributed in a transparent polyacrylamide phantom. The Sonoluminescence (SL) method was employed to visualize the cavitation distribution and formation process of PSNEs induced cavitation. For the phantom which was used for ablation observation, heat sensitive BSA was added. When the temperature generated by ultrasound exposure was high enough to denature BSA, the transparent phantom would turn out white lesions. The shape of the lesion and the formation process were compared with those of cavitation. Each of the pulse contained 12 cycles for a duration of 10 µs. And the duty cycle changed from 1:10 to 1:40. The total "on" time of HIFU was 2s. PSNE can evidently accelerate cavitation emitting bright SL in pre-focal region. The cavitation was generated layer by layer towards the transducer. The formed bubble wall can block acoustic waves transmitting to the distal end. And the lesion appeared to be separated into two parts. One in pre-focal region stemmed from one point and grew quickly toward the transducer. The other in focal region was formed by merging some small white dots, and grew much slower. The influence of duty cycle has also been examined. The lower duty cycle with longer pulse-off time would generate more intense cavitation, however, smaller lesion. Bubble cloud gradually developed within phantom would greatly influence the cavitation and ablation

  20. The Role of Acoustic Cavitation in Ultrasound-triggered Drug Release from Echogenic Liposomes

    NASA Astrophysics Data System (ADS)

    Kopechek, Jonathan A.

    Cardiovascular disease (CVD) is the leading cause of death in the United States and globally. CVD-related mortality, including coronary heart disease, heart failure, or stroke, generally occurs due to atherosclerosis, a condition in which plaques build up within arterial walls, potentially causing blockage or rupture. Targeted therapies are needed to achieve more effective treatments. Echogenic liposomes (ELIP), which consist of a lipid membrane surrounding an aqueous core, have been developed to encapsulate a therapeutic agent and/or gas bubbles for targeted delivery and ultrasound image enhancement. Under certain conditions ultrasound can cause nonlinear bubble growth and collapse, known as "cavitation." Cavitation activity has been associated with enhanced drug delivery across cellular membranes. However, the mechanisms of ultrasound-mediated drug release from ELIP have not been previously investigated. Thus, the objective of this dissertation is to elucidate the role of acoustic cavitation in ultrasound-mediated drug release from ELIP. To determine the acoustic and physical properties of ELIP, the frequency-dependent attenuation and backscatter coefficients were measured between 3 and 30 MHz. The results were compared to a theoretical model by measuring the ELIP size distribution in order to determine properties of the lipid membrane. It was found that ELIP have a broad size distribution and can provide enhanced ultrasound image contrast across a broad range of clinically-relevant frequencies. Calcein, a hydrophilic fluorescent dye, and papaverine, a lipophilic vasodilator, were separately encapsulated in ELIP and exposed to color Doppler ultrasound pulses from a clinical diagnostic ultrasound scanner in a flow system. Spectrophotometric techniques (fluorescence and absorbance measurements) were used to detect calcein or papaverine release. As a positive control, Triton X-100 (a non-ionic detergent) was added to ELIP samples not exposed to ultrasound in order

  1. Strategy of high efficiency and refined high-intensity focused ultrasound and ultrasound monitoring imaging of thermal lesion and cavitation

    NASA Astrophysics Data System (ADS)

    Wan, Mingxi; Zhang, Siyuan; Lu, Mingzhu; Hu, Hong; Jing, Bowen; Liu, Runna; Zhong, Hui

    2017-03-01

    We proposed that high efficiency high-intensity focused ultrasound (HIFU) could be achieved by using a splitting transducer with various frequencies and focusing patterns, and explored the feasibility of using ultrafast active cavitation imaging (UACI), pulse inversion (PI) sub-harmonic cavitation imaging and bubble wavelet transform imaging for monitoring of cavitation during HIFU, as well as the ultrasonic B-mode images, differential integrated backscatter (IBS) images, Nakagami images and elastography for monitoring HIFU-induced lesion. The use of HIFU splitting transducer had the potential to increase the size of the thermal lesion in a shorter duration and may improve the ablation efficiency of HIFU and would shorten the exposure duration significantly. The spatial-temporal evolution of residual cavitation bubbles at the tissue-water interface was obtained by UACI and the results showed that the UACI had a frame rate high enough to capture the transient behavior of the cavitation bubbles. The experiments demonstrated that comparing with normal sub-harmonic and PI harmonic images, PI sub-harmonic images had higher sensitivity and CTR, which was conducive to showing cavitation bubbles. The CTR would be further improved by combining PI ultrafast plane wave transmitting with cavitation bubble wavelet transform.

  2. Cavitation in ultrasound and shockwave therapy

    NASA Astrophysics Data System (ADS)

    Colonius, Tim

    2014-11-01

    Acoustic waves, especially high-intensity ultrasound and shock waves, are used for medical imaging and intra- and extra-corporeal manipulation of cells, tissue, and urinary calculi. Waves are currently used to treat kidney stone disease, plantar fasciitis, and bone nonunion, and they are being investigated as a technique to ablate cancer tumors and mediate drug delivery. In many applications, acoustic waves induce the expansion and collapse of preexisting or newly cavitating bubbles whose presence can either mediate the generation of localized stresses or lead to collateral damage, depending on how effectively they can be controlled. We describe efforts aimed at simulating the collapse of bubbles, both individually and in clusters, with the aim to characterize the induced mechanical stresses and strains. To simulate collapse of one or a few bubbles, compressible Euler and Navier-Stokes simulations of multi-component materials are performed with WENO-based shock and interface capturing schemes. Repetitive insonification generates numerous bubbles that are difficult to resolve numerically. Such clouds are also important in traditional engineering applications such as caveating hydrofoils. Models that incorporate the dynamics of an unresolved dispersed phase consisting of the bubble cloud are also developed. The results of several model problems including bubble collapse near rigid surfaces, bubble collapse near compliant surfaces and in small capillaries are analyzed. The results are processed to determine the potential for micron-sized preexisting gas bubbles to damage capillaries. The translation of the fundamental fluid dynamics into improvements in the design and clinical application of shockwave lithotripters will be discussed. NIH Grant PO1-DK043881.

  3. A New Active Cavitation Mapping Technique for Pulsed HIFU Applications – Bubble Doppler

    PubMed Central

    Li, Tong; Khokhlova, Tatiana; Sapozhnikov, Oleg; Hwang, Joo Ha; Sapozhnikov, Oleg; O’Donnell, Matthew

    2015-01-01

    In this work, a new active cavitation mapping technique for pulsed high-intensity focused ultrasound (pHIFU) applications termed bubble Doppler is proposed and its feasibility tested in tissue-mimicking gel phantoms. pHIFU therapy uses short pulses, delivered at low pulse repetition frequency, to cause transient bubble activity that has been shown to enhance drug and gene delivery to tissues. The current gold standard for detecting and monitoring cavitation activity during pHIFU treatments is passive cavitation detection (PCD), which provides minimal information on the spatial distribution of the bubbles. B-mode imaging can detect hyperecho formation, but has very limited sensitivity, especially to small, transient microbubbles. The bubble Doppler method proposed here is based on a fusion of the adaptations of three Doppler techniques that had been previously developed for imaging of ultrasound contrast agents – color Doppler, pulse inversion Doppler, and decorrelation Doppler. Doppler ensemble pulses were interleaved with therapeutic pHIFU pulses using three different pulse sequences and standard Doppler processing was applied to the received echoes. The information yielded by each of the techniques on the distribution and characteristics of pHIFU-induced cavitation bubbles was evaluated separately, and found to be complementary. The unified approach - bubble Doppler – was then proposed to both spatially map the presence of transient bubbles and to estimate their sizes and the degree of nonlinearity. PMID:25265178

  4. Effects of ultrasound frequency and tissue stiffness on the histotripsy intrinsic threshold for cavitation.

    PubMed

    Vlaisavljevich, Eli; Lin, Kuang-Wei; Maxwell, Adam; Warnez, Matthew T; Mancia, Lauren; Singh, Rahul; Putnam, Andrew J; Fowlkes, Brian; Johnsen, Eric; Cain, Charles; Xu, Zhen

    2015-06-01

    Histotripsy is an ultrasound ablation method that depends on the initiation of a cavitation bubble cloud to fractionate soft tissue. Previous work has indicated that a cavitation cloud can be formed by a single pulse with one high-amplitude negative cycle, when the negative pressure amplitude directly exceeds a pressure threshold intrinsic to the medium. We hypothesize that the intrinsic threshold in water-based tissues is determined by the properties of the water inside the tissue, and changes in tissue stiffness or ultrasound frequency will have a minimal impact on the histotripsy intrinsic threshold. To test this hypothesis, the histotripsy intrinsic threshold was investigated both experimentally and theoretically. The probability of cavitation was measured by subjecting tissue phantoms with adjustable mechanical properties and ex vivo tissues to a histotripsy pulse of 1-2 cycles produced by 345-kHz, 500-kHz, 1.5-MHz and 3-MHz histotripsy transducers. Cavitation was detected and characterized by passive cavitation detection and high-speed photography, from which the probability of cavitation was measured versus pressure amplitude. The results revealed that the intrinsic threshold (the negative pressure at which probability = 0.5) is independent of stiffness for Young's moduli (E) <1 MPa, with only a small increase (∼2-3 MPa) in the intrinsic threshold for tendon (E = 380 MPa). Additionally, results for all samples revealed only a small increase of ∼2-3 MPa when the frequency was increased from 345 kHz to 3 MHz. The intrinsic threshold was measured to be between 24.7 and 30.6 MPa for all samples and frequencies tested in this study. Overall, the results of this study indicate that the intrinsic threshold to initiate a histotripsy bubble cloud is not significantly affected by tissue stiffness or ultrasound frequency in the hundreds of kilohertz to megahertz range.

  5. Variations of bubble cavitation and temperature elevation during lesion formation by high-intensity focused ultrasound.

    PubMed

    Zhou, Yufeng; Gao, Xiaobin Wilson

    2013-08-01

    High-intensity focused ultrasound (HIFU) is emerging as an effective therapeutic modality in both thermal ablations for solid tumor/cancer and soft-tissue fragmentation. Mechanical and thermal effects, which play an important role in the HIFU treatment simultaneously, are dependent on the operating parameters and may vary with the progress of therapy. Mechanical erosion in the shape of a "squid," a "dumbbell" lesion with both mechanical and thermal lesions, or a "tadpole" lesion with mechanical erosion at the center and thermal necrosis on the boundary in the transparent gel phantom could be produced correspondingly with the pulse duration of 5-30 ms, which is much longer than histotripsy burst but shorter than the time for tissue boiling, and pulse repetition frequency (PRF) of 0.2-5 Hz. Meanwhile, variations of bubble cavitation (both inertial and stable cavitation) and temperature elevation in the focal region (i.e., z = -2.5, 0, and 2.5 mm) were measured by passive cavitation detection (PCD) and thermocouples during the therapeutic procedure, respectively. Stable cavitation increased with the pulse duration, PRF, and the number of pulses delivered. However, inertial cavitation was found to increase initially and then decrease with long pulse duration and high PRF. Temperature in the pre-focal region is always higher than those at the focal and post-focal position in all tests. Great variations of PCD signals and temperature elevation are due to the generation and persistence of large bubble, which is resistant to collapse and occurs with the increase of pulse duration and PRF. Similar lesion pattern and variations were also observed in ex vivo porcine kidneys. Hyperechoes in the B-mode ultrasound image were comparable to the shape and size of lesions in the dissected tissue. Thermal lesion volume increased with the increase of pulse duration and PRF, but mechanical erosion reached its maximum volume with the pulse duration of 20 ms and PRF of 1

  6. Size distribution estimation of cavitation bubble cloud via bubbles dissolution using an ultrasound wide-beam method

    NASA Astrophysics Data System (ADS)

    Xu, Shanshan; Zong, Yujin; Liu, Xiaodong; Wan, Mingxi

    2017-03-01

    This paper proposed an acoustic technique to estimate size distribution of a cavitation bubble cloud induced by focused ultrasound (FUS) based on the dissolution of bubble cloud trapped by a wide beam of low acoustic pressure, after the acoustic exposure of FUS is turned off. Dissolution of cavitation bubbles in saline and in phase-shift nanodroplet emulsion diluted with degassed saline or saturated saline has been respectively studied to quantify the effects of pulse duration (PD) and acoustic power (AP) or peak negative pressure (PNP) of FUS on size distribution of cavitation bubbles.

  7. Ultrasound line-by-line scanning method of spatial-temporal active cavitation mapping for high-intensity focused ultrasound.

    PubMed

    Ding, Ting; Zhang, Siyuan; Fu, Quanyou; Xu, Zhian; Wan, Mingxi

    2014-01-01

    This paper presented an ultrasound line-by-line scanning method of spatial-temporal active cavitation mapping applicable in a liquid or liquid filled tissue cavities exposed by high-intensity focused ultrasound (HIFU). Scattered signals from cavitation bubbles were obtained in a scan line immediately after one HIFU exposure, and then there was a waiting time of 2 s long enough to make the liquid back to the original state. As this pattern extended, an image was built up by sequentially measuring a series of such lines. The acquisition of the beamformed radiofrequency (RF) signals for a scan line was synchronized with HIFU exposure. The duration of HIFU exposure, as well as the delay of the interrogating pulse relative to the moment while HIFU was turned off, could vary from microseconds to seconds. The feasibility of this method was demonstrated in tap-water and a tap-water filled cavity in the tissue-mimicking gelatin-agar phantom as capable of observing temporal evolutions of cavitation bubble cloud with temporal resolution of several microseconds, lateral and axial resolution of 0.50 mm and 0.29 mm respectively. The dissolution process of cavitation bubble cloud and spatial distribution affected by cavitation previously generated were also investigated. Although the application is limited by the requirement for a gassy fluid (e.g. tap water, etc.) that allows replenishment of nuclei between HIFU exposures, the technique may be a useful tool in spatial-temporal cavitation mapping for HIFU with high precision and resolution, providing a reference for clinical therapy.

  8. Passive cavitation detection during pulsed HIFU exposures of ex vivo tissues and in vivo mouse pancreatic tumors.

    PubMed

    Li, Tong; Chen, Hong; Khokhlova, Tatiana; Wang, Yak-Nam; Kreider, Wayne; He, Xuemei; Hwang, Joo Ha

    2014-07-01

    Pulsed high-intensity focused ultrasound (pHIFU) has been shown to enhance vascular permeability, disrupt tumor barriers and enhance drug penetration into tumor tissue through acoustic cavitation. Monitoring of cavitation activity during pHIFU treatments and knowing the ultrasound pressure levels sufficient to reliably induce cavitation in a given tissue are therefore very important. Here, three metrics of cavitation activity induced by pHIFU and evaluated by confocal passive cavitation detection were introduced: cavitation probability, cavitation persistence and the level of the broadband acoustic emissions. These metrics were used to characterize cavitation activity in several ex vivo tissue types (bovine tongue and liver and porcine adipose tissue and kidney) and gel phantoms (polyacrylamide and agarose) at varying peak-rare factional focal pressures (1-12 MPa) during the following pHIFU protocol: frequency 1.1 MHz, pulse duration 1 ms and pulse repetition frequency 1 Hz. To evaluate the relevance of the measurements in ex vivo tissue, cavitation metrics were also investigated and compared in the ex vivo and in vivo murine pancreatic tumors that develop spontaneously in transgenic KrasLSL.G12 D/+; p53 R172 H/+; PdxCretg/+ (KPC) mice and closely re-capitulate human disease in their morphology. The cavitation threshold, defined at 50% cavitation probability, was found to vary broadly among the investigated tissues (within 2.5-10 MPa), depending mostly on the water-lipid ratio that characterizes the tissue composition. Cavitation persistence and the intensity of broadband emissions depended both on tissue structure and lipid concentration. Both the cavitation threshold and broadband noise emission level were similar between ex vivo and in vivo pancreatic tumor tissue. The largest difference between in vivo and ex vivo settings was found in the pattern of cavitation occurrence throughout pHIFU exposure: it was sporadic in vivo, but it decreased rapidly and stopped

  9. Sonoporation of adherent cells under regulated ultrasound cavitation conditions.

    PubMed

    Muleki Seya, Pauline; Fouqueray, Manuela; Ngo, Jacqueline; Poizat, Adrien; Inserra, Claude; Béra, Jean-Christophe

    2015-04-01

    A sonoporation device dedicated to the adherent cell monolayer has been implemented with a regulation process allowing the real-time monitoring and control of inertial cavitation activity. Use of the cavitation-regulated device revealed first that adherent cell sonoporation efficiency is related to inertial cavitation activity, without inducing additional cell mortality. Reproducibility is enhanced for the highest sonoporation rates (up to 17%); sonoporation efficiency can reach 26% when advantage is taken of the standing wave acoustic configuration by applying a frequency sweep with ultrasound frequency tuned to the modal acoustic modes of the cavity. This device allows sonoporation of adherent and suspended cells, and the use of regulation allows some environmental parameters such as the temperature of the medium to be overcome, resulting in the possibility of cell sonoporation even at ambient temperature.

  10. The dynamic behavior of microbubbles during long ultrasound tone-burst excitation: mechanistic insights into ultrasound-microbubble mediated therapeutics using high-speed imaging and cavitation detection

    PubMed Central

    Pacella, John J.; Villanueva, Flordeliza S.

    2015-01-01

    Ultrasound (US)-microbubble (MB) mediated therapies have been shown to restore perfusion and enhance drug/gene delivery. Due to the presumption that MBs do not persist during long US exposure under high acoustic pressures, most schemes utilize short US pulses when a high US pressure is employed. However, we recently observed an enhanced thrombolytic effect using long US pulses at high acoustic pressures. Therefore we explored the fate of MBs during long tone-burst exposures (5 ms) at various acoustic pressures and MB concentrations via direct high-speed optical observation and passive cavitation detection. MBs first underwent stable or inertial cavitation depending on the acoustic pressure, and then formed gas-filled clusters that continued to oscillate, break up, and form new clusters. Cavitation detection confirmed continued, albeit diminishing acoustic activity throughout the 5-ms US excitation. These data suggest that persisting cavitation activity during long tone-bursts may confer additional therapeutic effects. PMID:26603628

  11. Gauging the likelihood of stable cavitation from ultrasound contrast agents.

    PubMed

    Bader, Kenneth B; Holland, Christy K

    2013-01-07

    The mechanical index (MI) was formulated to gauge the likelihood of adverse bioeffects from inertial cavitation. However, the MI formulation did not consider bubble activity from stable cavitation. This type of bubble activity can be readily nucleated from ultrasound contrast agents (UCAs) and has the potential to promote beneficial bioeffects. Here, the presence of stable cavitation is determined numerically by tracking the onset of subharmonic oscillations within a population of bubbles for frequencies up to 7 MHz and peak rarefactional pressures up to 3 MPa. In addition, the acoustic pressure rupture threshold of an UCA population was determined using the Marmottant model. The threshold for subharmonic emissions of optimally sized bubbles was found to be lower than the inertial cavitation threshold for all frequencies studied. The rupture thresholds of optimally sized UCAs were found to be lower than the threshold for subharmonic emissions for either single cycle or steady state acoustic excitations. Because the thresholds of both subharmonic emissions and UCA rupture are linearly dependent on frequency, an index of the form I(CAV) = P(r)/f (where P(r) is the peak rarefactional pressure in MPa and f is the frequency in MHz) was derived to gauge the likelihood of subharmonic emissions due to stable cavitation activity nucleated from UCAs.

  12. Sonoluminescence characterization of inertial cavitation inside a BSA phantom treated by pulsed HIFU.

    PubMed

    Yin, Hui; Chang, Nan; Xu, Shanshan; Wan, Mingxi

    2016-09-01

    The aim of this study was to investigate the inertial cavitation inside a phantom treated by pulsed HIFU (pHIFU). Basic bovine serum albumin (BSA) phantoms without any inherent ultrasound contrast agents (UCAs) or phase-shift nano-emulsions (PSNEs) were used. During the treatment, sonoluminescence (SL) recordings were performed to characterize the spatial distribution of inertial cavitation adjacent to the focal region. High-speed photographs and thermal coagulations, comparing with the SL results, were also recorded and presented. A series of pulse parameters (pulse duration (PD) was between 1 and 23 cycles and pulse repetition frequency (PRF) was between 0.5kHz and 100kHz) were performed to make a systematic investigation under certain acoustic power (APW). Continuous HIFU (cHIFU) investigation was also performed to serve as control group. It was found that, when APW was 19.5W, pHIFU with short PD was much easier to form SL adjacent to the focal region inside the phantom, while it was difficult for cHIFU to generate cavitation bubbles. With appropriate PD and PRF, the residual bubbles of the previous pulses could be stimulated by the incident pulses to oscillate in a higher level and even violently collapse, resulting to enhanced physical thermogenesis. The experimental results showed that the most violent inertial cavitation occurs when PD was set to 6 cycles (5μs) and PRF to 10kHz, while the highest level of thermal coagulation was observed when PD was set to 10 cycles. The cavitational and thermal characteristics were in good correspondence, exhibiting significant potentiality regarding to inject-free cavitation bubble enhanced thermal ablation under lower APW, compared to the conventional thermotherapy.

  13. Understanding Cavitation Intensity through Pitting and Pressure Pulse Analysis

    NASA Astrophysics Data System (ADS)

    Jayaprakash, A.; Singh, S.; Choi, J.-K.; Chahine, G.

    2011-11-01

    Cavitation erosion is of interest to the designers of ship propulsion devices because of its detrimental effects. One of the difficulties of predicting cavitation erosion is that the intensity of cavitation is not well predicted or defined. In this work we attempt to define the intensity of a cavitation erosion field through analysis of cavitation induced erosion pits and pressure pulses. In the pitting tests, material samples were subjected to cavitation field for a short duration of time selected within the test sample's incubation period, so that the test sample undergoes plastic deformation only. The sample material reacts to these cavitation events by undergoing localized permanent deformation, called pits. The resulting pitted sample surfaces were then optically scanned and analyzed. The pressure signals under cavitating jets and ultrasonic horns, for different conditions, were experimentally recorded using high frequency response pressure transducers. From the analysis of the pitting data and recorded pressure signals, we propose a model that describes the statistics, which in the future can be used to define the cavitation field intensity. Support for this work was provided by Office of Naval Research (ONR) under contract number N00014-08-C-0450, monitored by Dr. Ki-Han Kim.

  14. Alternative approach for cavitation damage study utilizing repetitive laser pulses

    SciTech Connect

    Ren, Fei; Wang, Jy-An John; Wang, Hong

    2010-01-01

    Cavitation is a common phenomenon in fluid systems that can lead to dramatic degradation of solid materials surface in contact with the cavitating media. Study of cavitation damage has great significance in many engineering fields. Current techniques for cavitation damage study either require large scale equipments or tend to introduce damages from other mechanisms. In this project, we utilized the cavitation phenomenon induced by laser optical breakdown and developed a prototype apparatus for cavitation damage study. In our approach, cavitation was generated by the repetitive pressure waves induced by high-power laser pulses. As proof of principal study, stainless steel and aluminum samples were tested using the novel apparatus. Surface characterization via scanning electron microscopy revealed damages such as indentation and surface pitting, which were similar to those reported in literature using other state-of-the-art techniques. These preliminary results demonstrated the new device was capable of generating cavitation damages and could be used as an alternative method for cavitation damage study.

  15. Spatial-temporal ultrasound imaging of residual cavitation bubbles around a fluid-tissue interface in histotripsy.

    PubMed

    Hu, Hong; Xu, Shanshan; Yuan, Yuan; Liu, Runna; Wang, Supin; Wan, Mingxi

    2015-05-01

    Cavitation is considered as the primary mechanism of soft tissue fragmentation (histotripsy) by pulsed high-intensity focused ultrasound. The residual cavitation bubbles have a dual influence on the histotripsy pulses: these serve as nuclei for easy generation of new cavitation, and act as strong scatterers causing energy "shadowing." To monitor the residual cavitation bubbles in histotripsy, an ultrafast active cavitation imaging method with relatively high signal-to-noise ratio and good spatial-temporal resolution was proposed in this paper, which combined plane wave transmission, minimum variance beamforming, and coherence factor weighting. The spatial-temporal evolutions of residual cavitation bubbles around a fluid-tissue interface in histotripsy under pulse duration (PD) of 10-40 μs and pulse repetition frequency (PRF) of 0.67-2 kHz were monitored by this method. The integrated bubble area curves inside the tissue interface were acquired from the bubble image sequence, and the formation process of histotripsy damage was estimated. It was observed that the histotripsy efficiency decreased with both longer PDs and higher PRFs. A direct relationship with a coefficient of 1.0365 between histotripsy lesion area and inner residual bubble area was found. These results can assist in monitoring and optimization of the histotripsy treatment further.

  16. Optimization of Ultrasound Parameters of Myocardial Cavitation Microlesions for Therapeutic Application

    PubMed Central

    Miller, Douglas L.; Dou, Chunyan; Owens, Gabe E.; Kripfgans, Oliver D.

    2014-01-01

    Intermittent high intensity ultrasound scanning with contrast microbubbles can induce scattered cavitation microlesions in the myocardium, which may be of value for tissue reduction therapy. Anesthetized rats were treated in a heated water bath with 1.5 MHz focused ultrasound pulses, guided by an 8 MHz imaging transducer. The relative efficacy with 2 or 4 MPa pulses, 1:4 or 1:8 trigger intervals and 5 or 10 cycle pulses was explored in 6 groups. ECG premature complexes (PCs) induced by the triggered pulse bursts were counted, and Evans blue stained cardiomyocyte scores (SCSs) were obtained. The increase from 2 to 4 MPa produced significant increases in PCs and SCSs, and eliminated an anticipated decline in the rate of PC induction with time, which might hinder therapeutic efficacy. Increased intervals and pulse durations did not yield significant increases in the effects. The results suggest that cavitation microlesion production can be refined and potentially lead to a clinically robust therapeutic method. PMID:24613640

  17. Complete Inhibition Of Ultrasound Induced Cytolysis In The Presence Of Inertial Cavitation

    NASA Astrophysics Data System (ADS)

    Sostaric, Joe Z.; Miyoshi, Norio; Riesz, Peter; De Graff, William G.; Mitchell, James B.

    2006-05-01

    The investigation of ultrasound for biotechnological applications including non-invasive surgery (HIFU), drug/gene delivery to cells (sonoporation) or through the skin (sonophoresis) and ultrasound assisted bioreactors has focused mainly on the physical effects of ultrasound. The beneficial effects of ultrasound rely on a number of application-dependent mechanisms, and may include tissue heating, acoustic streaming or cavitation. Although acoustic cavitation is necessary in some systems, cavitation bubbles simultaneously result in uncontrollable cell damage and cytolysis. Thus, the development of a number of biotechnological uses of ultrasound has been hampered by the necessity to constrain exposure parameters in order to prevent the occurrence of acoustic cavitation or to at least limit the detrimental effects of cavitation. The current study shows that non-toxic concentrations of specific n-alkyl solutes completely inhibit ultrasound induced cytolysis of in vitro suspensions of human leukemia cells (HL-60). Protection of the whole cell population from cytolysis is achieved even under extreme ultrasound exposure conditions that result in cytolysis of 100 % of the cell population in the absence of the n-alkyl solutes. Furthermore, the n-alkyl solutes did not hinder the process of inertial cavitation. This method may allow utilization of beneficial effects of ultrasound and cavitation while protecting cells from cavitation induced cytolysis and thereby presents new possibilities for ultrasound in medicine and biology.

  18. Plasma and Cavitation Dynamics during Pulsed Laser Microsurgery in vivo

    SciTech Connect

    Hutson, M. Shane; Ma Xiaoyan

    2007-10-12

    We compare the plasma and cavitation dynamics underlying pulsed laser microsurgery in water and in fruit fly embryos (in vivo)--specifically for nanosecond pulses at 355 and 532 nm. We find two key differences. First, the plasma-formation thresholds are lower in vivo --especially at 355 nm--due to the presence of endogenous chromophores that serve as additional sources for plasma seed electrons. Second, the biological matrix constrains the growth of laser-induced cavitation bubbles. Both effects reduce the disrupted region in vivo when compared to extrapolations from measurements in water.

  19. Observation of a cavitation cloud in tissue using correlation between ultrafast ultrasound images.

    PubMed

    Prieur, Fabrice; Zorgani, Ali; Catheline, Stefan; Souchon, Rémi; Mestas, Jean-Louis; Lafond, Maxime; Lafon, Cyril

    2015-07-01

    The local application of ultrasound is known to improve drug intake by tumors. Cavitating bubbles are one of the contributing effects. A setup in which two ultrasound transducers are placed confocally is used to generate cavitation in ex vivo tissue. As the transducers emit a series of short excitation bursts, the evolution of the cavitation activity is monitored using an ultrafast ultrasound imaging system. The frame rate of the system is several thousands of images per second, which provides several tens of images between consecutive excitation bursts. Using the correlation between consecutive images for speckle tracking, a decorrelation of the imaging signal appears due to the creation, fast movement, and dissolution of the bubbles in the cavitation cloud. By analyzing this area of decorrelation, the cavitation cloud can be localized and the spatial extent of the cavitation activity characterized.

  20. Spatial-temporal dynamics of cavitation bubble clouds in 1.2 MHz focused ultrasound field.

    PubMed

    Chen, Hong; Li, Xiaojing; Wan, Mingxi

    2006-09-01

    Cavitation bubbles have been recognized as being essential to many applications of ultrasound. Temporal evolution and spatial distribution of cavitation bubble clouds induced by a focused ultrasound transducer of 1.2 MHz center frequency are investigated by high-speed photography. It is revealed that at a total acoustic power of 72 W the cavitation bubble cloud first emerges in the focal region where cavitation bubbles are observed to generate, grow, merge and collapse during the initial 600 micros. The bubble cloud then grows upward to the post-focal region, and finally becomes visible in the pre-focal region. The structure of the final bubble cloud is characterized by regional distribution of cavitation bubbles in the ultrasound field. The cavitation bubble cloud structure remains stable when the acoustic power is increased from 25 W to 107 W, but it changes to a more violent form when the acoustic power is further increased to 175 W.

  1. Investigations on the destruction of ultrasound contrast agents: Fragmentation thresholds, inertial cavitation, and bioeffects

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Shiang

    Ultrasound contrast agents (UCA) have shown great potential in both diagnostic and therapeutic applications recently. To fully explore the possible applications and the safety concerns of using UCA, a complete understanding of the UCA responses to various acoustic fields is necessary. Therefore, we performed a series of experiments and simulations to investigate the various acoustic properties of UCA with different gases and shells. We also investigated the mechanisms of some UCA-enhanced bioeffects including thrombolysis, hemolysis and high-intensity focused ultrasound (HIFU) tumor ablation. Two pressure thresholds were found: the fragmentation threshold and continuous inertial cavitation (IC) threshold. At the fragmentation threshold, bubbles were destroyed and the released gas dissolved in the surrounding solution at a rate which depended on the bubble's initial size and type of gas. The continuous IC threshold occurred at a higher pressure, where fragments of destroyed UCA (derivative bubbles) underwent violent inertial collapse; the period of activity depending on acoustic parameters such as frequency, pressure, pulse length, and pulse repetition frequency (PRF). Different UCA had different threshold pressures and demonstrated different magnitudes of IC activity after destruction. The amount of derivative bubbles generated by IC was determined by several acoustic parameters including pressure, pulse length and PRE For the same acoustic energy delivered, longer pulses generated more bubbles. More IC could be induced if the derivative bubbles could survive through the 'off' period of the pulsed ultrasound waves, and served as nuclei for the subsequent IC. In therapeutic applications, evidences of IC activity were recorded during the hemolysis, thrombolysis, and the lesion-formation processes with UCA. Hemolysis and thrombolysis were highly correlated to the presence of ultrasound and UCA, and correlated well with the amount of the IC activity. Finally, the

  2. Observation of the inception and evolution of a cavitation cloud in tissue with ultrafast ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Prieur, Fabrice; Zorgani, Ali; Catheline, Stefan

    2017-03-01

    The local application of ultrasound is known to improve drug intake by tumors. Cavitating bubbles are one of the contributing effects. A setup where two ultrasound transducers are placed confocally is used to generate cavitation in ex vivo tissue. As the transducers emit a series of short bursts, the creation and evolution of the cavitation activity is monitored using an ultrafast ultrasound imaging system. This system capable of frame rates up to 10000 frames per second provides several tens of images between consecutive bursts. A cross-correlation between consecutive images used for speckle tracking shows a decorrelation of the imaging signal due to changes induced by the cavitation cloud. This post-processed sequence of images reveals that once bubbles have been created in the tissue, they remain for a short time even when no ultrasound is applied. The evolution of the size and place of the cavitation cloud between bursts show a repeatable pattern through a burst sequence.

  3. Identifying the Inertial Cavitation Pressure Threshold and Skull Effects in a Vessel Phantom Using Focused Ultrasound and Microbubbles

    NASA Astrophysics Data System (ADS)

    Tung, Yao-Sheng; Choi, James J.; Konofagou, Elisa E.

    2010-03-01

    Using Focused Ultrasound (FUS) and microbubbles to open the blood-brain barrier (BBB) has been shown promising for brain drug delivery. However, the exact mechanism behind the opening remains unknown. Here, the effects of the murine skull on the threshold of inertial cavitation were investigated. In order to investigate the pressure threshold for inertial cavitation of preformed microbubbles during sonication, passive cavitation detection in conjunction with B-mode imaging was used. A cylindrical vessel with a 610-μm diameter inside a polyacrylamide gel was generated within a polyacrylamide gel to simulate large blood vessels. Definity® (Lantheus Medical Imaging, MA, USA) microbubbles with a 1.1-3.3 μm in diameter at 2.5×107 bubbles/mL were injected into the channel before sonication (frequency: 1.525 MHz; pulse length: 100 cycles; PRF: 10 Hz; sonication duration: 2 s) through an excised mouse skull. A cylindrically focused hydrophone, confocal with the FUS transducer, acted as a passive cavitation detector (PCD) to identify the threshold. A 7.5 MHz linear array with the field-of-view perpendicular to the axial length of the FUS beam was also used to image the occurrence of bubble fragmentation. The broadband spectral response acquired at the passive cavitation detector (PCD) and the B-mode images identified the occurrence and location of the inertial cavitation, respectively. Findings indicated that the peak-rarefactional pressure threshold was approximately equal to 0.45 MPa at the presence or the absence of the skull. However, the skull induced 10-50% lower inertial cavitation dose. Mouse skulls did not affect the pressure threshold of inertial cavitation but resulted in a lower inertial cavitation dose. The broadband response could be captured through the murine skull, so the same PCD setup can be used in future in vivo applications.

  4. Exploiting flow to control the in vitro spatiotemporal distribution of microbubble-seeded acoustic cavitation activity in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Bonaccorsi, Simone; Choi, James J

    2014-11-21

    Focused ultrasound and microbubbles have been extensively used to generate therapeutic bioeffects. Despite encouraging in vivo results, there remains poor control of the magnitude and spatial distribution of these bioeffects due to the limited ability of conventional pulse shapes and sequences to control cavitation dynamics. Thus current techniques are restricted by an efficacy-safety trade-off. The primary aim of the present study was to incorporate the presence of flow in the design of new short pulse sequences, which can more uniformly distribute the cavitation activity. Microbubbles flowing (fluid velocity: 10 mm s(-1)) through a 300 μm tube were sonicated with a focused 0.5 MHz transducer while acoustic emissions were captured with an inserted focused 7.5 MHz passive cavitation detector. The two foci were co-axially aligned and their focal points were overlapped. Whereas conventional sequences are composed of a long burst (>10,000 cycles) emitted at a low burst repetition frequency (<10 Hz), we decomposed this burst into short pulses by adding intervals to facilitate inter-pulse microbubble movement. To evaluate how this sequence influenced cavitation distribution, we emitted short pulses (peak-rarefactional pressure (PRP): 40-366 kPa, pulse length (PL): 5-25 cycles) at high pulse repetition frequencies (PRF: 0.625-10 kHz) for a burst length of 100 ms. Increased cavitation persistence, implied by the duration of the microbubble acoustic emissions, was a measure of improved distribution due to the presence of flow. Sonication at lower acoustic pressures, longer pulse intervals and lower PLs improved the spatial distribution of cavitation. Furthermore, spectral analysis of the microbubble emissions revealed that the improvement at low pressures is due to persisting stable cavitation. In conclusion, new short-pulse sequences were shown to improve spatiotemporal control of acoustic cavitation dynamics during physiologically relevant flow. This

  5. Promoting inertial cavitation by nonlinear frequency mixing in a bifrequency focused ultrasound beam.

    PubMed

    Saletes, Izella; Gilles, Bruno; Bera, Jean-Christophe

    2011-01-01

    Enhancing cavitation activity with minimal acoustic intensities could be interesting in a variety of therapeutic applications where mechanical effects of cavitation are needed with minimal heating of surrounding tissues. The present work focuses on the relative efficiency of a signal combining two neighbouring frequencies and a one-frequency signal for initiating ultrasound inertial cavitation. Experiments were carried out in a water tank, using a 550kHz piezoelectric composite spherical transducer focused on targets with 46μm roughness. The acoustic signal scattered, either by the target or by the cavitation bubbles, is filtered using a spectral and cepstral-like method to obtain an inertial cavitation activity measurement. The ultrasound excitations consist of 1.8ms single bursts of single frequency f(0)=550kHz excitation, in the monofrequency case, and of dual frequency f(1)=535kHz and f(2)=565kHz excitation, in the bifrequency case. It is shown that depending on the value of the monofrequency cavitation threshold intensity the bifrequency excitation can increase or reduce the cavitation threshold. The analysis of the thresholds indicates that the mechanisms involved are nonlinear. The progress of the cavitation activity beyond the cavitation threshold is also studied. The slope of the cavitation activity considered as a function of the acoustic intensity is always steeper in the case of the bifrequency excitation. This means that the delimitation of the region where cavitation occurs should be cleaner than with a classical monofrequency excitation.

  6. Microbubble cavitation imaging.

    PubMed

    Vignon, Francois; Shi, William T; Powers, Jeffry E; Everbach, E Carr; Liu, Jinjin; Gao, Shunji; Xie, Feng; Porter, Thomas R

    2013-04-01

    Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications such as sonothrombolysis (STL) in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (moderate oscillations, stable cavitation, and inertial cavitation) and activity level in and around a treatment area. Acoustic passive cavitation detectors (PCDs) have been used to this end but do not provide spatial information. This paper presents a prototype of a 2-D cavitation imager capable of producing images of the dominant cavitation state and activity level in a region of interest. Similar to PCDs, the cavitation imaging described here is based on the spectral analysis of the acoustic signal radiated by the cavitating microbubbles: ultraharmonics of the excitation frequency indicate stable cavitation, whereas elevated noise bands indicate inertial cavitation; the absence of both indicates moderate oscillations. The prototype system is a modified commercially available ultrasound scanner with a sector imaging probe. The lateral resolution of the system is 1.5 mm at a focal depth of 3 cm, and the axial resolution is 3 cm for a therapy pulse length of 20 μs. The maximum frame rate of the prototype is 2 Hz. The system has been used for assessing and mapping the relative importance of the different cavitation states of a microbubble contrast agent. In vitro (tissue-mimicking flow phantom) and in vivo (heart, liver, and brain of two swine) results for cavitation states and their changes as a function of acoustic amplitude are presented.

  7. Trans-Stent B-Mode Ultrasound and Passive Cavitation Imaging.

    PubMed

    Haworth, Kevin J; Raymond, Jason L; Radhakrishnan, Kirthi; Moody, Melanie R; Huang, Shao-Ling; Peng, Tao; Shekhar, Himanshu; Klegerman, Melvin E; Kim, Hyunggun; McPherson, David D; Holland, Christy K

    2016-02-01

    Angioplasty and stenting of a stenosed artery enable acute restoration of blood flow. However, restenosis or a lack of re-endothelization can subsequently occur depending on the stent type. Cavitation-mediated drug delivery is a potential therapy for these conditions, but requires that particular types of cavitation be induced by ultrasound insonation. Because of the heterogeneity of tissue and stochastic nature of cavitation, feedback mechanisms are needed to determine whether the sustained bubble activity is induced. The objective of this study was to determine the feasibility of passive cavitation imaging through a metal stent in a flow phantom and an animal model. In this study, an endovascular stent was deployed in a flow phantom and in porcine femoral arteries. Fluorophore-labeled echogenic liposomes, a theragnostic ultrasound contrast agent, were injected proximal to the stent. Cavitation images were obtained by passively recording and beamforming the acoustic emissions from echogenic liposomes insonified with a low-frequency (500 kHz) transducer. In vitro experiments revealed that the signal-to-noise ratio for detecting stable cavitation activity through the stent was greater than 8 dB. The stent did not significantly reduce the signal-to-noise ratio. Trans-stent cavitation activity was also detected in vivo via passive cavitation imaging when echogenic liposomes were insonified by the 500-kHz transducer. When stable cavitation was detected, delivery of the fluorophore into the arterial wall was observed. Increased echogenicity within the stent was also observed when echogenic liposomes were administered. Thus, both B-mode ultrasound imaging and cavitation imaging are feasible in the presence of an endovascular stent in vivo. Demonstration of this capability supports future studies to monitor restenosis with contrast-enhanced ultrasound and pursue image-guided ultrasound-mediated drug delivery to inhibit restenosis.

  8. Investigation on the inertial cavitation threshold and shell properties of commercialized ultrasound contrast agent microbubbles.

    PubMed

    Guo, Xiasheng; Li, Qian; Zhang, Zhe; Zhang, Dong; Tu, Juan

    2013-08-01

    The inertial cavitation (IC) activity of ultrasound contrast agents (UCAs) plays an important role in the development and improvement of ultrasound diagnostic and therapeutic applications. However, various diagnostic and therapeutic applications have different requirements for IC characteristics. Here through IC dose quantifications based on passive cavitation detection, IC thresholds were measured for two commercialized UCAs, albumin-shelled KangRun(®) and lipid-shelled SonoVue(®) microbubbles, at varied UCA volume concentrations (viz., 0.125 and 0.25 vol. %) and acoustic pulse lengths (viz., 5, 10, 20, 50, and 100 cycles). Shell elastic and viscous coefficients of UCAs were estimated by fitting measured acoustic attenuation spectra with Sarkar's model. The influences of sonication condition (viz., acoustic pulse length) and UCA shell properties on IC threshold were discussed based on numerical simulations. Both experimental measurements and numerical simulations indicate that IC thresholds of UCAs decrease with increasing UCA volume concentration and acoustic pulse length. The shell interfacial tension and dilatational viscosity estimated for SonoVue (0.7 ± 0.11 N/m, 6.5 ± 1.01 × 10(-8) kg/s) are smaller than those of KangRun (1.05 ± 0.18 N/m, 1.66 ± 0.38 × 10(-7) kg/s); this might result in lower IC threshold for SonoVue. The current results will be helpful for selecting and utilizing commercialized UCAs for specific clinical applications, while minimizing undesired IC-induced bioeffects.

  9. Cavitation-induced damage in soft tissue phantoms by focused ultrasound bursts

    NASA Astrophysics Data System (ADS)

    Movahed, Pooya; Kreider, Wayne; Maxwell, Adam D.; Bailey, Michael R.; Hutchens, Shelby B.; Freund, Jonathan B.

    2015-11-01

    Cavitation in soft tissues, similar to that in purely hydrodynamic configurations, is thought to cause tissue injury in therapeutic ultrasound treatments. Our goal is to generalize bubble dynamics models to represent this phenomenon, which we pursue experimentally with observations in tissue-mimicking polyacrylamide and agarose phantoms and semi-analytic generalization of Rayleigh-Plesset-type bubble dynamics models. The phantoms were imaged with high-speed cameras while subjected to a series of multiple pressure wave bursts, of the kind being considered specifically for burst-wave lithotripsy (BWL). The experimental observations show bubble activation at multiple sites during the initial pulses. After multiple pulses, a further onset of cavitation is observed at some new locations suggesting material failure due to fatigue under cyclic loading. A nonlinear strain-energy with strain hardening is used to represent the elasticity of the surrounding medium. Griffith's fracture criterion is then applied in order to determine the onset of material damage. The damaged material is then represented as a Newtonian fluid. By assuming that such a decrease in the fracture toughness occurs under cyclic loading, the fatigue behavior observed in the experiments can be reproduced by our model. This work was supported by NIH grant NIDDK PO1-DK043881.

  10. Wavelet-transform-based active imaging of cavitation bubbles in tissues induced by high intensity focused ultrasound.

    PubMed

    Liu, Runna; Xu, Shanshan; Hu, Hong; Huo, Rui; Wang, Supin; Wan, Mingxi

    2016-08-01

    Cavitation detection and imaging are essential for monitoring high-intensity focused ultrasound (HIFU) therapies. In this paper, an active cavitation imaging method based on wavelet transform is proposed to enhance the contrast between the cavitation bubbles and surrounding tissues. The Yang-Church model, which is a combination of the Keller-Miksis equation with the Kelvin-Voigt equation for the pulsations of gas bubbles in simple linear viscoelastic solids, is utilized to construct the bubble wavelet. Experiments with porcine muscles demonstrate that image quality is associated with the initial radius of the bubble wavelet and the scale. Moreover, the Yang-Church model achieves a somewhat better performance compared with the Rayleigh-Plesset-Noltingk-Neppiras-Poritsky model. Furthermore, the pulse inversion (PI) technique is combined with bubble wavelet transform to achieve further improvement. The cavitation-to-tissue ratio (CTR) of the best tissue bubble wavelet transform (TBWT) mode image is improved by 5.1 dB compared with that of the B-mode image, while the CTR of the best PI-based TBWT mode image is improved by 7.9 dB compared with that of the PI-based B-mode image. This work will be useful for better monitoring of cavitation in HIFU-induced therapies.

  11. Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C.; Konofagou, Elisa E.

    2015-12-01

    Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r2  =  0.77) (2) the permeability of the opened BBB (r2  =  0.82) (3) the likelihood of safe opening (P  <  0.05, safe opening compared to cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r2  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore

  12. Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening.

    PubMed

    Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

    2015-12-07

    Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r(2)  =  0.77); (2) the permeability of the opened BBB (r(2)  =  0.82); (3) the likelihood of safe opening (P  <  0.05, safe opening compared to cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r(2)  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response

  13. Dynamic Behavior of Microbubbles during Long Ultrasound Tone-Burst Excitation: Mechanistic Insights into Ultrasound-Microbubble Mediated Therapeutics Using High-Speed Imaging and Cavitation Detection.

    PubMed

    Chen, Xucai; Wang, Jianjun; Pacella, John J; Villanueva, Flordeliza S

    2016-02-01

    Ultrasound (US)-microbubble (MB)-mediated therapies have been found to restore perfusion and enhance drug/gene delivery. On the presumption that MBs do not persist during long US exposure under high acoustic pressures, most schemes use short US pulses when a high US pressure is employed. However, we recently observed an enhanced thrombolytic effect using long US pulses at high acoustic pressures. Therefore, we explored the fate of MBs during long tone-burst exposures (5 ms) at various acoustic pressures and MB concentrations via direct high-speed optical observation and passive cavitation detection. MBs first underwent stable or inertial cavitation depending on the acoustic pressure and then formed gas-filled clusters that continued to oscillate, break up and form new clusters. Cavitation detection confirmed continued, albeit diminishing, acoustic activity throughout the 5-ms US excitation. These data suggest that persisting cavitation activity during long tone bursts may confer additional therapeutic effects.

  14. Visualization of ultrasound induced cavitation bubbles using the synchrotron x-ray Analyzer Based Imaging technique.

    PubMed

    Izadifar, Zahra; Belev, George; Izadifar, Mohammad; Izadifar, Zohreh; Chapman, Dean

    2014-12-07

    Observing cavitation bubbles deep within tissue is very difficult. The development of a method for probing cavitation, irrespective of its location in tissues, would improve the efficiency and application of ultrasound in the clinic. A synchrotron x-ray imaging technique, which is capable of detecting cavitation bubbles induced in water by a sonochemistry system, is reported here; this could possibly be extended to the study of therapeutic ultrasound in tissues. The two different x-ray imaging techniques of Analyzer Based Imaging (ABI) and phase contrast imaging (PCI) were examined in order to detect ultrasound induced cavitation bubbles. Cavitation was not observed by PCI, however it was detectable with ABI. Acoustic cavitation was imaged at six different acoustic power levels and six different locations through the acoustic beam in water at a fixed power level. The results indicate the potential utility of this technique for cavitation studies in tissues, but it is time consuming. This may be improved by optimizing the imaging method.

  15. Mercury Cavitation Phenomenon in Pulsed Spallation Neutron Sources

    SciTech Connect

    Futakawa, Masatoshi; Naoe, Takashi; Kawai, Masayoshi

    2008-06-24

    Innovative researches will be performed at Materials and Life Science Experimental Facility in J-PARC, in which a mercury target system will be installed as MW-class pulse spallation neutron sources. Proton beams will be injected into mercury target to induce the spallation reaction. At the moment the intense proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by micro-jets and/or shock waves which are caused by cavitation bubble collapse impose pitting damage on the vessel wall. The pitting damage which degrades the structural integrity of target vessels is a crucial issue for high power mercury targets. Micro-gas-bubbles injection into mercury may be useful to mitigate the pressure wave and the pitting damage. The visualization of cavitation-bubble and gas-bubble collapse behaviors was carried out by using a high-speed video camera. The differences between them are recognized.

  16. Transfection effect of microbubbles on cells in superposed ultrasound waves and behavior of cavitation bubble.

    PubMed

    Kodama, Tetsuya; Tomita, Yukio; Koshiyama, Ken-Ichiro; Blomley, Martin J K

    2006-06-01

    The combination of ultrasound and ultrasound contrast agents (UCAs) is able to induce transient membrane permeability leading to direct delivery of exogenous molecules into cells. Cavitation bubbles are believed to be involved in the membrane permeability; however, the detailed mechanism is still unknown. In the present study, the effects of ultrasound and the UCAs, Optison on transfection in vitro for different medium heights and the related dynamic behaviors of cavitation bubbles were investigated. Cultured CHO-E cells mixed with reporter genes (luciferase or beta-gal plasmid DNA) and UCAs were exposed to 1 MHz ultrasound in 24-well plates. Ultrasound was applied from the bottom of the well and reflected at the free surface of the medium, resulting in the superposition of ultrasound waves within the well. Cells cultured on the bottom of 24-well plates were located near the first node (displacement node) of the incident ultrasound downstream. Transfection activity was a function determined with the height of the medium (wave traveling distance), as well as the concentration of UCAs and the exposure time was also determined with the concentration of UCAs and the exposure duration. Survival fraction was determined by MTT assay, also changes with these values in the reverse pattern compared with luciferase activity. With shallow medium height, high transfection efficacy and high survival fraction were obtained at a low concentration of UCAs. In addition, capillary waves and subsequent atomized particles became significant as the medium height decreased. These phenomena suggested cavitation bubbles were being generated in the medium. To determine the effect of UCAs on bubble generation, we repeated the experiments using crushed heat-treated Optison solution instead of the standard microbubble preparation. The transfection ratio and survival fraction showed no additional benefit when ultrasound was used. These results suggested that cavitation bubbles created by the

  17. Effects of tissue stiffness, ultrasound frequency, and pressure on histotripsy-induced cavitation bubble behavior

    NASA Astrophysics Data System (ADS)

    Vlaisavljevich, Eli; Lin, Kuang-Wei; Warnez, Matthew T.; Singh, Rahul; Mancia, Lauren; Putnam, Andrew J.; Johnsen, Eric; Cain, Charles; Xu, Zhen

    2015-03-01

    Histotripsy is an ultrasound ablation method that controls cavitation to fractionate soft tissue. In order to effectively fractionate tissue, histotripsy requires cavitation bubbles to rapidly expand from nanometer-sized initial nuclei into bubbles often larger than 50 µm. Using a negative pressure high enough to initiate a bubble cloud and expand bubbles to a sufficient size, histotripsy has been shown capable of completely fractionating soft tissue into acelluar debris resulting in effective tissue removal. Previous work has shown that the histotripsy process is affected by tissue mechanical properties with stiffer tissues showing increased resistance to histotripsy fractionation, which we hypothesize to be caused by impeded bubble expansion in stiffer tissues. In this study, the hypothesis that increases in tissue stiffness cause a reduction in bubble expansion was investigated both theoretically and experimentally. High speed optical imaging was used to capture a series of time delayed images of bubbles produced inside mechanically tunable agarose tissue phantoms using histotripsy pulses produced by 345 kHz, 500 kHz, 1.5 MHz, and 3 MHz histotripsy transducers. The results demonstrated a significant decrease in maximum bubble radius (Rmax) and collapse time (tc) with both increasing Young’s modulus and increasing frequency. Furthermore, results showed that Rmax was not increased by raising the pressure above the intrinsic threshold. Finally, this work demonstrated the potential of using a dual-frequency strategy to modulate the expansion of histotripsy bubbles. Overall, the results of this study improve our understanding of how tissue stiffness and ultrasound parameters affect histotripsy-induced bubble behavior and provide a rational basis to tailor acoustic parameters for treatment of the specific tissues of interest.

  18. Characteristics of the pulsed ultrasound field.

    PubMed Central

    Wien, K. D.; Harder, D.

    1982-01-01

    Pulsed ultrasound fields show some quantitative differences from continuous fields. In order to support the analysis of bioeffects of pulsed ultrasound fields these differences are characterized. For each observation point, the sound pulse is calculated by wavelet addition. The total pulse length has a maximum near the transducer surface, corresponding to large differences in acoustical pathlength from the surface elements. Accordingly, the spectrum varies strongly in the near field. In the far field, pulse-length and spectrum are almost constant as long as frequency-dependent absorption is negligible. The radiation field at each point is described by the time integral of sound intensity over one pulse (energy transport per unit area) and by the corresponding "dose" (absorbed energy per unit volume in one pulse). Differences between the spatial distributions of these two quantities are mainly detectable in the near field, which is also the region where differences between continuous and pulsed ultrasound (at the same centre frequency) are considerable. PMID:6950776

  19. Compare ultrasound-mediated heating and cavitation between flowing polymer- and lipid-shelled microbubbles during focused ultrasound exposures.

    PubMed

    Zhang, Siyuan; Zong, Yujin; Wan, Mingxi; Yu, Xiaojun; Fu, Quanyou; Ding, Ting; Zhou, Fanyu; Wang, Supin

    2012-06-01

    This paper compares the efficiency of flowing polymer- and lipid-shelled microbubbles (MBs) in the heating and cavitation during focused ultrasound exposures. Temperature and cavitation activity were simultaneously measured as the two types of shelled MBs and saline flowing through a 3 mm diameter vessel in the phantom with varying flow velocities (0-20 cm/s) at different acoustic power levels (0.6-20 W) with each exposure for 5 s. Temperature and cavitation for the lipid-shelled MBs were higher than those for the polymer-shelled MBs. Temperature rise decreased with increasing flow velocities for the two types of shelled MBs and saline at acoustic power 1.5 W. At acoustic power 11.1 W, temperature rise increased with increasing flow velocities for the lipid-shelled MBs. For the polymer-shelled MBs, the temperature rise increased with increasing flow velocities from 3-15 cm/s and decreased at 20 cm/s. Cavitation increased with increasing flow velocity for the two shelled MBs and there were no significant changes of cavitation with increasing flow velocities for saline. These results suggested that lipid-shelled MBs may have a greater efficiency than polymer-shelled MBs in heating and cavitation during focused ultrasound exposures.

  20. Single-transducer dual-frequency ultrasound generation to enhance acoustic cavitation.

    PubMed

    Liu, Hao-Li; Hsieh, Chao-Ming

    2009-03-01

    Dual- or multiple-frequency ultrasound stimulation is capable of effectively enhancing the acoustic cavitation effect over single-frequency ultrasound. Potential application of this sonoreactor design has been widely proposed such as on sonoluminescence, sonochemistry enhancement, and transdermal drug release enhancement. All currently available sonoreactor designs employed multiple piezoelectric transducers for generating single-frequency ultrasonic waves separately and then these waves were mixed and interfered in solutions. The purpose of this research is to propose a novel design of generating dual-frequency ultrasonic waves with single piezoelectric elements, thereby enhancing acoustic cavitation. Macroscopic bubbles were detected optically, and they were quantified at either a single-frequency or for different frequency combinations for determining their efficiency for enhancing acoustic cavitation. Visible bubbles were optically detected and hydrogen peroxide was measured to quantify acoustic cavitation. Test water samples with different gas concentrations and different power levels were used to determine the efficacy of enhancing acoustic cavitation of this design. The spectrum obtained from the backscattered signals was also recorded and examined to confirm the occurrence of stable cavitation. The results confirmed that single-element dual-frequency ultrasound stimulation can enhance acoustic cavitation. Under certain testing conditions, the generation of bubbles can be enhanced up to a level of five times higher than the generation of bubbles in single-frequency stimulation, and can increase the hydrogen peroxide production up to an increase of one fold. This design may serve as a useful alternative for future sonoreactor design owing to its simplicity to produce dual- or multiple-frequency ultrasound.

  1. Ultrasound-induced inertial cavitation from gas-stabilizing nanoparticles.

    PubMed

    Kwan, J J; Graham, S; Myers, R; Carlisle, R; Stride, E; Coussios, C C

    2015-08-01

    The understanding of cavitation from nanoparticles has been hindered by the inability to control nanobubble size. We present a method to manufacture nanoparticles with a tunable single hemispherical depression (nanocups) of mean diameter 90, 260, or 650 nm entrapping a nanobubble. A modified Rayleigh-Plesset crevice model predicts the inertial cavitation threshold as a function of cavity size and frequency, and is verified experimentally. The ability to tune cavitation nanonuclei and predict their behavior will be useful for applications ranging from cancer therapy to ultrasonic cleaning.

  2. Treatment of Breast Tumors using Pulsed HIFU for Delivery and Activation of Sonosensitizers

    DTIC Science & Technology

    2010-02-14

    treated and control tumors. 15. SUBJECT TERMS high intensity focused ultrasound , sonodynamic, cavitation , free radicals, chemotherapy, targeted...vivo in combination with cavitation driven by high intensity focused ultrasound (HIFU). Applying HIFU in pulsed mode (to avoid overheating) has...synergistic effect, with the combination of compound and ultrasound cavitation killing over 95% of cells, while neither the drug nor the ultrasound alone

  3. Enhanced cavitation by using two consecutive ultrasound waves at different frequencies

    PubMed Central

    Yang, Xinmai; Jo, Janggun

    2014-01-01

    Efficient and noninvasive generation of cavitation bubbles in soft tissue is a challenging task due to the lack of cavitation nuclei (i.e., pre-existing gas bubbles). In this study, we present a method to generate and enhance cavitation activity based on the utilization of two consecutive ultrasound waves at different frequencies. First, a high frequency (5 MHz) high intensity focused ultrasound (HIFU) wave was applied to a tissue-mimicking phantom to induce a rapid temperature rise in the ultrasound focal region. Immediately following the high frequency HIFU wave, a low frequency (1 MHz) HIFU wave was applied to the same focal region to induce acoustic cavitation. We found that cavitation activity was enhanced when the temperature in the tissue-mimicking phantom was first elevated by the high frequency HIFU wave. The enhancement was greater when a higher intensity of high frequency HIFU wave was applied. This result may be due to the temporary super-saturation of air in the initially air-saturated test samples and the reduction of surface tension at an elevated temperature. PMID:25425746

  4. Development of a Pulsed Pressure-Based Technique for Cavitation Damage Study

    SciTech Connect

    Ren, Fei; Wang, Jy-An John; Liu, Yun; Wang, Hong

    2012-01-01

    Cavitation occurs in many fluid systems and can lead to severe material damage. To assist the study of cavitation damage, a novel testing method utilizing pulsed pressure was developed. In this talk, the scientific background and the technical approach of this development are present and preliminary testing results are discussed. It is expected that this technique can be used to evaluate cavitation damage under various testing conditions including harsh environments such as those relevant to geothermal power generation.

  5. AUGMENTATION OF LIMB PERFUSION AND REVERSAL OF TISSUE ISCHEMIA PRODUCED BY ULTRASOUND-MEDIATED MICROBUBBLE CAVITATION

    PubMed Central

    Belcik, J. Todd; Mott, Brian H.; Xie, Aris; Zhao, Yan; Kim, Sajeevani; Lindner, Nathan J.; Ammi, Azzdine; Linden, Joel M.; Lindner, Jonathan R.

    2015-01-01

    Background Ultrasound can increase tissue blood flow in part through the intravascular shear produced by oscillatory pressure fluctuations. We hypothesized that ultrasound-mediated increases in perfusion can be augmented by microbubble contrast agents that undergo ultrasound-mediated cavitation, and sought to characterize the biologic mediators. Methods and Results Contrast ultrasound perfusion imaging of hindlimb skeletal muscle and femoral artery diameter measurement were performed in non-ischemic mice after unilateral 10 min exposure to intermittent ultrasound alone (mechanical index [MI] 0.6 or 1.3) or ultrasound with lipid microbubbles (2×108 I.V.). Studies were also performed after inhibiting shear- or pressure-dependent vasodilator pathways, and in mice with hindlimb ischemia. Ultrasound alone produced a 2-fold increase (p<0.05) in muscle perfusion regardless of ultrasound power. Ultrasound-mediated augmentation in flow was greater with microbubbles (3-fold and 10-fold higher than control for MI 0.6 and 1.3, respectively; p<0.05), as was femoral artery dilation. Inhibition of endothelial nitric oxide synthase (eNOS) attenuated flow augmentation produced by ultrasound and microbubbles by 70% (p<0.01), whereas inhibition of adenosine-A2a receptors and epoxyeicosatrienoic acids had minimal effect. Limb nitric oxide (NO) production and muscle phospho-eNOS increased in a stepwise fashion by ultrasound and ultrasound with microbubbles. In mice with unilateral hindlimb ischemia (40–50% reduction in flow), ultrasound (MI 1.3) with microbubbles increased perfusion by 2-fold to a degree that was greater than the control non-ischemic limb. Conclusions Increases in muscle blood flow during high-power ultrasound are markedly amplified by the intravascular presence of microbubbles and can reverse tissue ischemia. These effects are most likely mediated by cavitation-related increases in shear and activation of eNOS. PMID:25834183

  6. Ultrafast active cavitation imaging with enhanced cavitation to tissue ratio based on wavelet transform and pulse inversion.

    PubMed

    Liu, Runna; Hu, Hong; Xu, Shanshan; Huo, Rui; Wang, Supin; Wan, Mingxi

    2015-06-01

    The quality of ultrafast active cavitation imaging (UACI) using plane wave transmission is hindered by low transmission pressure, which is necessary to prevent bubble destruction. In this study, a UACI method that combined wavelet transform with pulse inversion (PI) was proposed to enhance the contrast between the cavitation bubbles and surrounding tissues. The main challenge in using wavelet transform is the selection of the optimum mother wavelet. A mother wavelet named "cavitation bubble wavelet" and constructed according to Rayleigh-Plesset-Noltingk-Neppiras-Poritsky model was expected to obtain a high correlation between the bubbles and beamformed echoes. The method was validated by in vitro experiments. Results showed that the image quality was associated with the initial radius of bubble and the scale. The signal-to-noise ratio (SNR) of the best optimum cavitation bubble wavelet transform (CBWT) mode image was improved by 3.2 dB compared with that of the B-mode image in free-field experiments. The cavitation-to-tissue ratio of the best optimum PI-based CBWT mode image was improved by 2.3 dB compared with that of the PI-based B-mode image in tissue experiments. Furthermore, the SNR versus initial radius curve had the potential to estimate the size distribution of cavitation bubbles.

  7. Cancer treatment using an optically inert Rose Bengal derivative combined with pulsed focused ultrasound

    NASA Astrophysics Data System (ADS)

    Kim, Yoo-Shin; Rubio, Valentina; Qi, Jianjun; Xia, Rongmin; Shi, Zheng-Zheng; Peterson, Leif; Tung, Ching-Hsuan; O'Neill, Brian E.

    2012-10-01

    Pulsed high intensity focused ultrasound (HIFU) produced has been combined with a photo-insensitive Rose Bengal derivative (RB2) to provide a synergistic cytotoxicity requiring the presence of both ultrasonic cavitation and drug. In vitro tests have shown that a short treatment (less than 30 s) of pulsed HIFU with peak negative pressure >7 MPa (˜27 W acoustic power at 1.4 MHz) destroys >95 % of breast cancer cells MDA-MB-231 in suspension with >10 μM of the compound. Neither the pulsed HIFU nor the RB2 compound was found to have any significant impact on the viability of the cells when used alone. Introducing an antioxidant (Nacetylcysteine) reduced the effectiveness of the treatment. In vivo tests using these same cells growing as a xenograft in nu/nu mice were also done. An ultrasound contrast agent (Optison) and lower frequency (1.0 MHz) was used to help initiate cavitation at the tumor site. We were able to demonstrate tumor regression with cavitation alone, however, addition of RB2 compound injected i.v. yielded a substantial synergistic improvement over either cavitation or RB2 injection alone.

  8. Cavitation-enhanced delivery of a replicating oncolytic adenovirus to tumors using focused ultrasound.

    PubMed

    Bazan-Peregrino, Miriam; Rifai, Bassel; Carlisle, Robert C; Choi, James; Arvanitis, Costas D; Seymour, Leonard W; Coussios, Constantin C

    2013-07-10

    Oncolytic viruses (OV) and ultrasound-enhanced drug delivery are powerful novel technologies. OV selectively self-amplify and kill cancer cells but their clinical use has been restricted by limited delivery from the bloodstream into the tumor. Ultrasound has been previously exploited for targeted release of OV in vivo, but its use to induce cavitation, microbubble oscillations, for enhanced OV tumor extravasation and delivery has not been previously reported. By identifying and optimizing the underlying physical mechanism, this work demonstrates that focused ultrasound significantly enhances the delivery and biodistribution of systemically administered OV co-injected with microbubbles. Up to a fiftyfold increase in tumor transgene expression was achieved, without any observable tissue damage. Ultrasound exposure parameters were optimized as a function of tumor reperfusion time to sustain inertial cavitation, a type of microbubble activity, throughout the exposure. Passive detection of acoustic emissions during treatment confirmed inertial cavitation as the mechanism responsible for enhanced delivery and enabled real-time monitoring of successful viral delivery.

  9. Time-resolved measurement of bubble cavitation by using power Doppler ultrasound image

    NASA Astrophysics Data System (ADS)

    Koda, Ren; Izumi, Yosuke; Nagai, Hayato; Yamakoshi, Yoshiki

    2017-04-01

    In this study, a novel measurement method for a secondary ultrasound wave irradiated by microbubble cavitation is proposed. High-intensity ultrasound (h-US, 1.0–1.5 MPa), which produces bubble cavitation, is irradiated with a fixed time delay after introducing imaging US, whose frequency is different from that of the h-US. The bubble cavitation signal (BCS) is detected by the signal-processing unit of an ultrasound power Doppler imaging instrument. By this method, both a spatially resolved bubble image (S-image) and the temporal transition of the BCS (T-image) are monitored simultaneously. A feature of the method is that the BCS is observed in situ with sub-µs time resolution. The accuracy of the method is evaluated and it is found that the maximum deviation of the amplitude of the simulated BCS is 4.80%. This method is applied to measure the BCS of ultrasound contrast agent microbubbles. As a result, the dependence of the inherent temporal transition of the BCS on the sound pressure of the h-US (0.6–1.2 MPa) is observed.

  10. Detecting cavitation in mercury exposed to a high-energy pulsed proton beam.

    PubMed

    Manzi, Nicholas J; Chitnis, Parag V; Holt, R Glynn; Roy, Ronald A; Cleveland, Robin O; Riemer, Bernie; Wendel, Mark

    2010-04-01

    The Oak Ridge National Laboratory Spallation Neutron Source employs a high-energy pulsed proton beam incident on a mercury target to generate short bursts of neutrons. Absorption of the proton beam produces rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these cavitation bubbles promote erosion of the steel target walls. Preliminary measurements using two passive cavitation detectors (megahertz-frequency focused and unfocused piezoelectric transducers) installed in a mercury test target to monitor cavitation generated by proton beams with charges ranging from 0.041 to 4.1 muC will be reported on. Cavitation was initially detected for a beam charge of 0.082 muC by the presence of an acoustic emission approximately 250 mus after arrival of the incident proton beam. This emission was consistent with an inertial cavitation collapse of a bubble with an estimated maximum bubble radius of 0.19 mm, based on collapse time. The peak pressure in the mercury for the initiation of cavitation was predicted to be 0.6 MPa. For a beam charge of 0.41 muC and higher, the lifetimes of the bubbles exceeded the reverberation time of the chamber ( approximately 300 mus), and distinct windows of cavitation activity were detected, a phenomenon that likely resulted from the interaction of the reverberation in the chamber and the cavitation bubbles.

  11. Detecting cavitation in mercury exposed to a high-energy pulsed proton beam

    SciTech Connect

    Manzi, Nicholas J; Chitnis, Parag V; Holt, Ray G; Roy, Ronald A; Cleveland, Robin O; Riemer, Bernie; Wendel, Mark W

    2010-01-01

    The Oak Ridge National Laboratory Spallation Neutron Source employs a high-energy pulsed proton beam incident on a mercury target to generate short bursts of neutrons. Absorption of the proton beam produces rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these cavitation bubbles promote erosion of the steel target walls. Preliminary measurements using two passive cavitation detectors (megahertz-frequency focused and unfocused piezoelectric transducers) installed in a mercury test target to monitor cavitation generated by proton beams with charges ranging from 0.041 to 4.1 C will be reported on. Cavitation was initially detected for a beam charge of 0.082 C by the presence of an acoustic emission approximately 250 s after arrival of the incident proton beam. This emission was consistent with an inertial cavitation collapse of a bubble with an estimated maximum bubble radius of 0.19 mm, based on collapse time. The peak pressure in the mercury for the initiation of cavitation was predicted to be 0.6 MPa. For a beam charge of 0.41 C and higher, the lifetimes of the bubbles exceeded the reverberation time of the chamber (~300 s), and distinct windows of cavitation activity were detected, a phenomenon that likely resulted from the interaction of the reverberation in the chamber and the cavitation bubbles.

  12. Loss of gas from echogenic liposomes exposed to pulsed ultrasound

    NASA Astrophysics Data System (ADS)

    Raymond, Jason L.; Luan, Ying; Peng, Tao; Huang, Shao-Ling; McPherson, David D.; Versluis, Michel; de Jong, Nico; Holland, Christy K.

    2016-12-01

    The destruction of echogenic liposomes (ELIP) in response to pulsed ultrasound excitations has been studied acoustically previously. However, the mechanism underlying the loss of echogenicity due to cavitation nucleated by ELIP has not been fully clarified. In this study, an ultra-high speed imaging approach was employed to observe the destruction phenomena of single ELIP exposed to ultrasound bursts at a center frequency of 6 MHz. We observed a rapid size reduction during the ultrasound excitation in 139 out of 397 (35%) ultra- high-speed recordings. The shell dilation rate, which is defined as the microbubble wall velocity divided by the instantaneous radius, \\dot{{R}}  /R, was extracted from the radius versus time response of each ELIP, and was found to be correlated with the deflation. Fragmentation and surface mode vibrations were also observed and are shown to depend on the applied acoustic pressure and initial radius. Results from this study can be utilized to optimize the theranostic application of ELIP, e.g. by tuning the size distribution or the excitation frequency.

  13. Pulse Compression Techniques for Laser Generated Ultrasound

    NASA Technical Reports Server (NTRS)

    Anastasi, R. F.; Madaras, E. I.

    1999-01-01

    Laser generated ultrasound for nondestructive evaluation has an optical power density limit due to rapid high heating that causes material damage. This damage threshold limits the generated ultrasound amplitude, which impacts nondestructive evaluation inspection capability. To increase ultrasound signal levels and improve the ultrasound signal-to-noise ratio without exceeding laser power limitations, it is possible to use pulse compression techniques. The approach illustrated here uses a 150mW laser-diode modulated with a pseudo-random sequence and signal correlation. Results demonstrate the successful generation of ultrasonic bulk waves in aluminum and graphite-epoxy composite materials using a modulated low-power laser diode and illustrate ultrasound bandwidth control.

  14. Damage mechanisms for ultrasound-induced cavitation in tissue

    NASA Astrophysics Data System (ADS)

    Warnez, M.; Vlaisavljevich, E.; Xu, Z.; Johnsen, E.

    2017-03-01

    In a variety of biomedical applications, cavitation occurs in soft tissue. Although significant amounts of research have been performed on cavitation in water, bubble dynamics, and related bioeffects remain poorly understood. We use numerical simulations of spherical bubble dynamics in soft tissue to assess the extent to which viscoelasticity affects "known" and introduces "new" damage mechanisms. We find that deviatoric stresses - although not an important damage mechanism in water - are significantly enhanced and could be an important bioeffect mechanism in tissue. Both the viscoelastic properties and the nonlinear, large-collapse radius contribute to stress amplification in the surroundings. In addition, temperatures in the surrounding medium increase more in the Zener tissue than in water, due to viscous heating.

  15. Dual pulses for cavitation control in lithotripsy: Shock wave-bubble interactions and bioeffects

    NASA Astrophysics Data System (ADS)

    Sokolov, Dahlia L.

    2002-08-01

    Cavitation, the growth and collapse of gas/vapor bubbles, appears to play an important role in both stone comminution and tissue injury during shock wave lithotripsy, the clinical treatment in which focused, high amplitude shock pulses are used to comminute kidney stones. The goal of this research was to characterize in vitro cavitation activity and stone and cell damage in a novel system that uses converging dual pulses, produced by two identical, confocal lithotripters, to modify the cavitation field. The cavitation bubble dynamics were numerically calculated, and experiments were performed in a research electrohydraulic shock wave lithotripter to determine bubble size, lifetime, and pit depth created in aluminum foils by cavitation collapse. Furthermore, damage to model stones and to red blood cells was measured for both single and dual-pulses. A single shock pulse creates a ˜15 x 100 mm cloud of bubbles in water. The greatest cavitation activity and stone damage from single-pulses was found to occur 2 cm proximal to the geometric focus, F2, where the stone is normally aligned. Therefore, a 2 cm shift in stone alignment may potentially improve stone comminution and reduce tissue injury in clinical treatment. The dual-pulse lithotripter, on the other hand, generates a localized and intensified cavitation field that increased stone comminution efficiency at F2 by at least three times the maximum values achieved by single-pulses. At F2, acoustic pressure approximately doubled, as did bubble size, collapse time, and pit depth on foils. A significant reduction in comminution of stones suspended in glycerol indicates that cavitation activity, not the doubling of acoustic pressure, explains the increased comminution. On either side of F2, the second delayed pulse mitigated bubble collapse, resulting in little or no pitting on foils and reduced hemolysis, even when compared with single pulses. Numerical calculations of radial dynamics agreed with experimental findings

  16. Using passive cavitation images to classify high-intensity focused ultrasound lesions.

    PubMed

    Haworth, Kevin J; Salgaonkar, Vasant A; Corregan, Nicholas M; Holland, Christy K; Mast, T Douglas

    2015-09-01

    Passive cavitation imaging provides spatially resolved monitoring of cavitation emissions. However, the diffraction limit of a linear imaging array results in relatively poor range resolution. Poor range resolution has limited prior analyses of the spatial specificity and sensitivity of passive cavitation imaging in predicting thermal lesion formation. In this study, this limitation is overcome by orienting a linear array orthogonal to the high-intensity focused ultrasound propagation direction and performing passive imaging. Fourteen lesions were formed in ex vivo bovine liver samples as a result of 1.1-MHz continuous-wave ultrasound exposure. The lesions were classified as focal, "tadpole" or pre-focal based on their shape and location. Passive cavitation images were beamformed from emissions at the fundamental, harmonic, ultraharmonic and inharmonic frequencies with an established algorithm. Using the area under a receiver operating characteristic curve (AUROC), fundamental, harmonic and ultraharmonic emissions were found to be significant predictors of lesion formation for all lesion types. For both harmonic and ultraharmonic emissions, pre-focal lesions were classified most successfully (AUROC values of 0.87 and 0.88, respectively), followed by tadpole lesions (AUROC values of 0.77 and 0.64, respectively) and focal lesions (AUROC values of 0.65 and 0.60, respectively).

  17. Development of a confocal ultrasound device using an inertial cavitation control for transfection in-vitro

    NASA Astrophysics Data System (ADS)

    Mestas, J. L.; Chettab, K.; Roux, S.; Prieur, F.; Lafond, M.; Dumontet, C.; Lafon, C.

    2015-12-01

    Sonoporation using low-frequency high-pressure ultrasound (US) is a non-viral approach for in vitro and in vivo gene delivery. We developed a new sonoporation device designed for spatial and temporal control of ultrasound cavitation. This device was evaluated for the in vitro transfection efficiency of a plasmid coding for Green Fluorescent Protein (peGFP- C1) in adherent and non-adherent cell lines. The frequency spectrum of the signal receive by a hydrophone is used to compute a cavitation index (CI) representative of the inertial cavitation activity. The influence of the CI on transfection efficiency, as well as reproducibility were determined. A real-time feedback loop control on CI was integrated in the process to regulate the cavitation level during sonoporation. In both adherent and non-adherent cell lines, the sonoporation device produced a highly efficient transfection of peGFP-C1 (40-80%), as determined by flow cytometry analysis of GFP expression, along with a low rate of mortality assessed by propidium iodide staining. Moreover, the sonoporation of non-adherent cell lines Jurkat and K562 was found to be equivalent to nucleofection in terms of efficiency and toxicity while these two cell lines were resistant to transfection with lipofection.

  18. Visualization and optimization of cavitation activity at a solid surface in high frequency ultrasound fields.

    PubMed

    Kauer, Markus; Belova-Magri, Valentina; Cairós, Carlos; Schreier, Hans-Jürgen; Mettin, Robert

    2017-01-01

    Despite the increasing use of high frequency ultrasound in heterogeneous reactions, knowledge about the spatial distribution of cavitation bubbles at the irradiated solid surface is still lacking. This gap hinders controllable surface sonoreactions. Here we present an optimization study of the cavitation bubble distribution at a solid sample using sonoluminescence and sonochemiluminescence imaging. The experiments were performed at three ultrasound frequencies, namely 580, 860 and 1142kHz. We found that position and orientation of the sample to the transducer, as well as its material properties influence the distribution of active cavitation bubbles at the sample surface in the reactor. The reason is a significant modification of the acoustic field due to reflections and absorption of the ultrasonic wave by the solid. This is retraced by numerical simulations employing the Finite Element Method, yielding reasonable agreement of luminescent zones and high acoustic pressure amplitudes in 2D simulations. A homogeneous coverage of the test sample surface with cavitation is finally reached at nearly vertical inclination with respect to the incident wave.

  19. A reduced-order, single-bubble cavitation model with applications to therapeutic ultrasound

    PubMed Central

    Kreider, Wayne; Crum, Lawrence A.; Bailey, Michael R.; Sapozhnikov, Oleg A.

    2011-01-01

    Cavitation often occurs in therapeutic applications of medical ultrasound such as shock-wave lithotripsy (SWL) and high-intensity focused ultrasound (HIFU). Because cavitation bubbles can affect an intended treatment, it is important to understand the dynamics of bubbles in this context. The relevant context includes very high acoustic pressures and frequencies as well as elevated temperatures. Relative to much of the prior research on cavitation and bubble dynamics, such conditions are unique. To address the relevant physics, a reduced-order model of a single, spherical bubble is proposed that incorporates phase change at the liquid-gas interface as well as heat and mass transport in both phases. Based on the energy lost during the inertial collapse and rebound of a millimeter-sized bubble, experimental observations were used to tune and test model predictions. In addition, benchmarks from the published literature were used to assess various aspects of model performance. Benchmark comparisons demonstrate that the model captures the basic physics of phase change and diffusive transport, while it is quantitatively sensitive to specific model assumptions and implementation details. Given its performance and numerical stability, the model can be used to explore bubble behaviors across a broad parameter space relevant to therapeutic ultrasound. PMID:22088026

  20. Temperature and stress fields produced by ultrasound-induced cavitation in a viscoelastic medium

    NASA Astrophysics Data System (ADS)

    Mancia, Lauren; Johnsen, Eric

    2016-11-01

    Ultrasound contrast agents can act as cavitation nuclei that mechanically damage surrounding tissue when they oscillate in diagnostic ultrasound. Encapsulated microbubbles have also been proposed as a means to improve the efficiency and efficacy of therapeutic ultrasound by increasing the rate of tissue heating. However, the thermal and mechanical effects of cavitation are difficult to distinguish from each other and to quantify experimentally as they often occur simultaneously. To address this challenge, we study the cavitation-induced temperature and stress fields produced by a spherical bubble oscillating in a Kelvin-Voigt viscoelastic medium with nonlinear elasticity using a model that also accounts for energy transport inside and outside the bubble. We find that the primary contribution to heating is viscous dissipation, which itself depends on both the material (viscosity) and the bubble dynamics. We examine the rate of viscous heating and the magnitude of stresses over a relevant range of tissue properties and waveform parameters to determine regimes where heating is expected to be dominant. A means of estimating the expected significance of viscous dissipation from given tissue properties and waveform parameters is proposed.

  1. A reduced-order, single-bubble cavitation model with applications to therapeutic ultrasound.

    PubMed

    Kreider, Wayne; Crum, Lawrence A; Bailey, Michael R; Sapozhnikov, Oleg A

    2011-11-01

    Cavitation often occurs in therapeutic applications of medical ultrasound such as shock-wave lithotripsy (SWL) and high-intensity focused ultrasound (HIFU). Because cavitation bubbles can affect an intended treatment, it is important to understand the dynamics of bubbles in this context. The relevant context includes very high acoustic pressures and frequencies as well as elevated temperatures. Relative to much of the prior research on cavitation and bubble dynamics, such conditions are unique. To address the relevant physics, a reduced-order model of a single, spherical bubble is proposed that incorporates phase change at the liquid-gas interface as well as heat and mass transport in both phases. Based on the energy lost during the inertial collapse and rebound of a millimeter-sized bubble, experimental observations were used to tune and test model predictions. In addition, benchmarks from the published literature were used to assess various aspects of model performance. Benchmark comparisons demonstrate that the model captures the basic physics of phase change and diffusive transport, while it is quantitatively sensitive to specific model assumptions and implementation details. Given its performance and numerical stability, the model can be used to explore bubble behaviors across a broad parameter space relevant to therapeutic ultrasound.

  2. Efficient generation of cavitation bubbles and reactive oxygen species using triggered high-intensity focused ultrasound sequence for sonodynamic treatment

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Sonodynamic treatment is a method of treating cancer using reactive oxygen species (ROS) generated by cavitation bubbles in collaboration with a sonosensitizer at a target tissue. In this treatment method, both localized ROS generation and ROS generation with high efficiency are important. In this study, a triggered high-intensity focused ultrasound (HIFU) sequence, which consists of a short, extremely high intensity pulse immediately followed by a long, moderate-intensity burst, was employed for the efficient generation of ROS. In experiments, a solution sealed in a chamber was exposed to a triggered HIFU sequence. Then, the distribution of generated ROS was observed by the luminol reaction, and the amount of generated ROS was quantified using KI method. As a result, the localized ROS generation was demonstrated by light emission from the luminol reaction. Moreover, it was demonstrated that the triggered HIFU sequence has higher efficiency of ROS generation by both the KI method and the luminol reaction emission.

  3. Cavitation and contrast: the use of bubbles in ultrasound imaging and therapy.

    PubMed

    Stride, E P; Coussios, C C

    2010-01-01

    Microbubbles and cavitation are playing an increasingly significant role in both diagnostic and therapeutic applications of ultrasound. Microbubble ultrasound contrast agents have been in clinical use now for more than two decades, stimulating the development of a range of new contrast-specific imaging techniques which offer substantial benefits in echocardiography, microcirculatory imaging, and more recently, quantitative and molecular imaging. In drug delivery and gene therapy, microbubbles are being investigated/developed as vehicles which can be loaded with the required therapeutic agent, traced to the target site using diagnostic ultrasound, and then destroyed with ultrasound of higher intensity energy burst to release the material locally, thus avoiding side effects associated with systemic administration, e.g. of toxic chemotherapy. It has moreover been shown that the motion of the microbubbles increases the permeability of both individual cell membranes and the endothelium, thus enhancing therapeutic uptake, and can locally increase the activity of drugs by enhancing their transport across biologically inaccessible interfaces such as blood clots or solid tumours. In high-intensity focused ultrasound (HIFU) surgery and lithotripsy, controlled cavitation is being investigated as a means of increasing the speed and efficacy of the treatment. The aim of this paper is both to describe the key features of the physical behaviour of acoustically driven bubbles which underlie their effectiveness in biomedical applications and to review the current state of the art.

  4. Controlling the acoustic streaming by pulsed ultrasounds.

    PubMed

    Hoyos, Mauricio; Castro, Angélica

    2013-01-01

    We propose a technique based on pulsed ultrasounds for controlling, reducing to a minimum observable value the acoustic streaming in closed ultrasonic standing wave fluidic resonators. By modifying the number of pulses and the repetition time it is possible to reduce the velocity of the acoustic streaming with respect to the velocity generated by the continuous ultrasound mode of operation. The acoustic streaming is observed at the nodal plane where a suspension of 800nm latex particles was focused by primary radiation force. A mixture of 800nm and 15μm latex particles has been also used for showing that the acoustic streaming is hardly reduced while primary and secondary forces continue to operate. The parameter we call "pulse mode factor" i.e. the time of applied ultrasound divided by the duty cycle, is found to be the adequate parameter that controls the acoustic streaming. We demonstrate that pulsed ultrasound is more efficient for controlling the acoustic streaming than the variation of the amplitude of the standing waves.

  5. Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

    PubMed Central

    Gruber, Matthew J.; Bader, Kenneth B.; Holland, Christy K.

    2014-01-01

    Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity®) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540–900 kHz) and a broad frequency bandwidth (0.54–1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle. PMID:25234874

  6. Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound.

    PubMed

    Gruber, Matthew J; Bader, Kenneth B; Holland, Christy K

    2014-02-01

    Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity(®)) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540-900 kHz) and a broad frequency bandwidth (0.54-1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.

  7. Characterization of the shock pulse-induced cavitation bubble activities recorded by an optical fiber hydrophone.

    PubMed

    Kang, Gwansuk; Cho, Sung Chan; Coleman, Andrew John; Choi, Min Joo

    2014-03-01

    A shock pressure pulse used in an extracorporeal shock wave treatment has a large negative pressure (<-5 MPa) which can produce cavitation. Cavitation cannot be measured easily, but may have known therapeutic effects. This study considers the signal recorded for several hundred microseconds using an optical hydrophone submerged in water at the focus of shock pressure field. The signal is characterized by shock pulse followed by a long tail after several microseconds; this signal is regarded as a cavitation-related signal (CRS). An experimental investigation of the CRS was conducted in the shock pressure field produced in water using an optical hydrophone (FOPH2000, RP Acoustics, Germany). The CRS was found to contain characteristic information about the shock pulse-induced cavitation. The first and second collapse times (t1 and t2) were identified in the CRS. The collapse time delay (tc = t2 - t1) increased with the driving shock pressures. The signal amplitude integrated for time from t1 to t2 was highly correlated with tc (adjusted R(2) = 0.990). This finding suggests that a single optical hydrophone can be used to measure shock pulse and to characterize shock pulse-induced cavitation.

  8. In vivo transcranial cavitation threshold detection during ultrasound-induced blood-brain barrier opening in mice.

    PubMed

    Tung, Yao-Sheng; Vlachos, Fotios; Choi, James J; Deffieux, Thomas; Selert, Kirsten; Konofagou, Elisa E

    2010-10-21

    The in vivo cavitation response associated with blood-brain barrier (BBB) opening as induced by transcranial focused ultrasound (FUS) in conjunction with microbubbles was studied in order to better identify the underlying mechanism in its noninvasive application. A cylindrically focused hydrophone, confocal with the FUS transducer, was used as a passive cavitation detector (PCD) to identify the threshold of inertial cavitation (IC) in the presence of Definity® microbubbles (mean diameter range: 1.1-3.3 µm, Lantheus Medical Imaging, MA, USA). A vessel phantom was first used to determine the reliability of the PCD prior to in vivo use. A cerebral blood vessel was simulated by generating a cylindrical channel of 610 µm in diameter inside a polyacrylamide gel and by saturating its volume with microbubbles. The microbubbles were sonicated through an excised mouse skull. Second, the same PCD setup was employed for in vivo noninvasive (i.e. transdermal and transcranial) cavitation detection during BBB opening. After the intravenous administration of Definity® microbubbles, pulsed FUS was applied (frequency: 1.525 or 1.5 MHz, peak-rarefactional pressure: 0.15-0.60 MPa, duty cycle: 20%, PRF: 10 Hz, duration: 1 min with a 30 s interval) to the right hippocampus of twenty-six (n = 26) mice in vivo through intact scalp and skull. T1 and T2-weighted MR images were used to verify the BBB opening. A spectrogram was generated at each pressure in order to detect the IC onset and duration. The threshold of BBB opening was found to be at a 0.30 MPa peak-rarefactional pressure in vivo. Both the phantom and in vivo studies indicated that the IC pressure threshold had a peak-rarefactional amplitude of 0.45 MPa. This indicated that BBB opening may not require IC at or near the threshold. Histological analysis showed that BBB opening could be induced without any cellular damage at 0.30 and 0.45 MPa. In conclusion, the cavitation response could be detected without craniotomy in mice

  9. In vivo transcranial cavitation threshold detection during ultrasound-induced blood-brain barrier opening in mice

    NASA Astrophysics Data System (ADS)

    Tung, Yao-Sheng; Vlachos, Fotios; Choi, James J.; Deffieux, Thomas; Selert, Kirsten; Konofagou, Elisa E.

    2010-10-01

    The in vivo cavitation response associated with blood-brain barrier (BBB) opening as induced by transcranial focused ultrasound (FUS) in conjunction with microbubbles was studied in order to better identify the underlying mechanism in its noninvasive application. A cylindrically focused hydrophone, confocal with the FUS transducer, was used as a passive cavitation detector (PCD) to identify the threshold of inertial cavitation (IC) in the presence of Definity® microbubbles (mean diameter range: 1.1-3.3 µm, Lantheus Medical Imaging, MA, USA). A vessel phantom was first used to determine the reliability of the PCD prior to in vivo use. A cerebral blood vessel was simulated by generating a cylindrical channel of 610 µm in diameter inside a polyacrylamide gel and by saturating its volume with microbubbles. The microbubbles were sonicated through an excised mouse skull. Second, the same PCD setup was employed for in vivo noninvasive (i.e. transdermal and transcranial) cavitation detection during BBB opening. After the intravenous administration of Definity® microbubbles, pulsed FUS was applied (frequency: 1.525 or 1.5 MHz, peak-rarefactional pressure: 0.15-0.60 MPa, duty cycle: 20%, PRF: 10 Hz, duration: 1 min with a 30 s interval) to the right hippocampus of twenty-six (n = 26) mice in vivo through intact scalp and skull. T1 and T2-weighted MR images were used to verify the BBB opening. A spectrogram was generated at each pressure in order to detect the IC onset and duration. The threshold of BBB opening was found to be at a 0.30 MPa peak-rarefactional pressure in vivo. Both the phantom and in vivo studies indicated that the IC pressure threshold had a peak-rarefactional amplitude of 0.45 MPa. This indicated that BBB opening may not require IC at or near the threshold. Histological analysis showed that BBB opening could be induced without any cellular damage at 0.30 and 0.45 MPa. In conclusion, the cavitation response could be detected without craniotomy in mice

  10. Detection of cystic structures using pulsed ultrasonically induced resonant cavitation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph (Inventor); Kovach, John S. (Inventor)

    2002-01-01

    Apparatus and method for early detection of cystic structures indicative of ovarian and breast cancers uses ultrasonic wave energy at a unique resonance frequency for inducing cavitation in cystic fluid characteristic of cystic structures in the ovaries associated with ovarian cancer, and in cystic structures in the breast associated with breast cancer. Induced cavitation bubbles in the cystic fluid implode, creating implosion waves which are detected by ultrasonic receiving transducers attached to the abdomen of the patient. Triangulation of the ultrasonic receiving transducers enables the received signals to be processed and analyzed to identify the location and structure of the cyst.

  11. Ultrasound-induced cavitation enhances the delivery and therapeutic efficacy of an oncolytic virus in an in vitro model.

    PubMed

    Bazan-Peregrino, Miriam; Arvanitis, Costas D; Rifai, Bassel; Seymour, Leonard W; Coussios, Constantin-C

    2012-01-30

    We investigated whether ultrasound-induced cavitation at 0.5 MHz could improve the extravasation and distribution of a potent breast cancer-selective oncolytic adenovirus, AdEHE2F-Luc, to tumour regions that are remote from blood vessels. We developed a novel tumour-mimicking model consisting of a gel matrix containing human breast cancer cells traversed by a fluid channel simulating a tumour blood vessel, through which the virus and microbubbles could be made to flow. Ultrasonic pressures were chosen to maximize either broadband emissions, associated with inertial cavitation, or ultraharmonic emissions, associated with stable cavitation, while varying duty cycle to keep the total acoustic energy delivered constant for comparison across exposures. None of the exposure conditions tested affected cell viability in the absence of the adenovirus. When AdEHE2F-Luc was delivered via the vessel, inertial cavitation increased transgene expression in tumour cells by up to 200 times. This increase was not observed in the absence of Coxsackie and Adenovirus Receptor cell expression, discounting sonoporation as the mechanism of action. In the presence of inertial cavitation, AdEHE2F-Luc distribution was greatly improved in the matrix surrounding the vessel, particularly in the direction of the ultrasound beam; this enabled AdEHE2F-Luc to kill up to 80% of cancer cells within the ultrasound focal volume in the gel 24 hours after delivery, compared to 0% in the absence of cavitation.

  12. Cavitating ultrasound hydrogenation of water-soluble olefins employing inert dopants: Studies of activity, selectivity and reaction mechanisms

    SciTech Connect

    Disselkamp, Robert S.; Chajkowski, Sarah M.; Boyles, Kelly R.; Hart, Todd R.; Peden, Charles HF

    2006-12-07

    Here we discuss results obtained as part of a three-year investigation at Pacific Northwest National Laboratory of ultrasound processing to effect selectivity and activity in the hydrogenation of water-soluble olefins on transition metal catalysts. We have shown previously that of the two regimes for ultrasound processing, high-power cavitating and high-power non-cavitating, only the former can effect product selectivity dramatically (> 1000%) whereas the selectivity of the latter was comparable with those obtained in stirred/silent control experiments [R.S. Disselkamp, Y.-H. Chin, C.H.F. Peden, J. Catal., 227, 552 (2005)]. As a means of ensuring the benefits of cavitating ultrasound processing, we introduced the concept of employing inert dopants into the reacting solution. These inert dopants do not partake in solution chemistry but enable a more facile transition from high-power non-cavitating to cavitating conditions during sonication treatment. With cavitation processing conditions ensured, we discuss here results of isotopic H/D substitution for a variety of substrates and illustrate how such isotope dependent chemistries during substrate hydrogenation elucidate detailed mechanistic information about these reaction systems.

  13. In Vitro Investigation of the Individual Contributions of Ultrasound-Induced Stable and Inertial Cavitation in Targeted Drug Delivery.

    PubMed

    Gourevich, Dana; Volovick, Alexander; Dogadkin, Osnat; Wang, Lijun; Mulvana, Helen; Medan, Yoav; Melzer, Andreas; Cochran, Sandy

    2015-07-01

    Ultrasound-mediated targeted drug delivery is a therapeutic modality under development with the potential to treat cancer. Its ability to produce local hyperthermia and cell poration through cavitation non-invasively makes it a candidate to trigger drug delivery. Hyperthermia offers greater potential for control, particularly with magnetic resonance imaging temperature measurement. However, cavitation may offer reduced treatment times, with real-time measurement of ultrasonic spectra indicating drug dose and treatment success. Here, a clinical magnetic resonance imaging-guided focused ultrasound surgery system was used to study ultrasound-mediated targeted drug delivery in vitro. Drug uptake into breast cancer cells in the vicinity of ultrasound contrast agent was correlated with occurrence and quantity of stable and inertial cavitation, classified according to subharmonic spectra. During stable cavitation, intracellular drug uptake increased by a factor up to 3.2 compared with the control. Reported here are the value of cavitation monitoring with a clinical system and its subsequent employment for dose optimization.

  14. Intramembrane cavitation as a unifying mechanism for ultrasound-induced bioeffects.

    PubMed

    Krasovitski, Boris; Frenkel, Victor; Shoham, Shy; Kimmel, Eitan

    2011-02-22

    The purpose of this study was to develop a unified model capable of explaining the mechanisms of interaction of ultrasound and biological tissue at both the diagnostic nonthermal, noncavitational (<100 mW · cm(-2)) and therapeutic, potentially cavitational (>100 mW · cm(-2)) spatial peak temporal average intensity levels. The cellular-level model (termed "bilayer sonophore") combines the physics of bubble dynamics with cell biomechanics to determine the dynamic behavior of the two lipid bilayer membrane leaflets. The existence of such a unified model could potentially pave the way to a number of controlled ultrasound-assisted applications, including CNS modulation and blood-brain barrier permeabilization. The model predicts that the cellular membrane is intrinsically capable of absorbing mechanical energy from the ultrasound field and transforming it into expansions and contractions of the intramembrane space. It further predicts that the maximum area strain is proportional to the acoustic pressure amplitude and inversely proportional to the square root of the frequency (ε A,max ∝ P(A)(0.8f - 0.5) and is intensified by proximity to free surfaces, the presence of nearby microbubbles in free medium, and the flexibility of the surrounding tissue. Model predictions were experimentally supported using transmission electron microscopy (TEM) of multilayered live-cell goldfish epidermis exposed in vivo to continuous wave (CW) ultrasound at cavitational (1 MHz) and noncavitational (3 MHz) conditions. Our results support the hypothesis that ultrasonically induced bilayer membrane motion, which does not require preexistence of air voids in the tissue, may account for a variety of bioeffects and could elucidate mechanisms of ultrasound interaction with biological tissue that are currently not fully understood.

  15. Effective cancer cell killing by hydrophobic nanovoid-enhanced cavitation under safe low-energy ultrasound.

    PubMed

    Zhao, Yang; Zhu, Yingchun; Fu, Jingke; Wang, Lianzhou

    2014-03-01

    β-Cyclodextrin (β-CD)-capped mesoporous silica nanoparticles with hydrophobic internal nanovoids were prepared and used for effective cancer cell killing in synergistic combination with low-energy ultrasound (≤1.0 W cm(-2) , 1 MHz). The water-dispersible nanoparticles with hydrophobic internal nanovoids can be taken up by cancer cells and subsequently evoke a remarkable cavitation effect under irradiation with mild low-energy ultrasound (≤1.0 W cm(-2) , 1 MHz). A significant cancer cell killing effect was observed in cancer cells and in a mouse xenograft tumor model treated with the nanoagents together with the low-energy ultrasound, showing a distinct dependence on the concentration of nanoagents and ultrasound intensity. By contrast, an antitumor effect was not observed when either low-energy ultrasound or nanoagents were applied alone. These findings are significant as the technique promises a safe, low-cost, and effective treatment for cancer therapy.

  16. Cavitation-based third ventriculostomy using MRI-guided focused ultrasound

    PubMed Central

    Alkins, Ryan; Huang, Yuexi; Pajek, Dan; Hynynen, Kullervo

    2014-01-01

    Object Transcranial focused ultrasound is increasingly being investigated as a minimally invasive treatment for a range of intracranial pathologies. At higher peak rarefaction pressures than those used for thermal ablation, focused ultrasound can initiate inertial cavitation and create holes in the brain by fractionation of the tissue elements. The authors investigated the technical feasibility of using MRI-guided focused ultrasound to perform a third ventriculostomy as a possible noninvasive alternative to endoscopic third ventriculostomy for hydrocephalus. Methods A craniectomy was performed in male pigs weighing 13–19 kg to expose the supratentorial brain, leaving the dura mater intact. Seven pigs were treated through the craniectomy, while 2 pigs were treated through ex vivo human skulls placed in the beam path. Registration and targeting was done using T2-weighted MRI sequences. For transcranial treatments a CT scan was used to correct the beam from aberrations due to the skull and maintain a small, high-intensity focus. Sonications were performed at both 650 kHz and 230 kHz at a range of intensities, and the in situ pressures were estimated both from simulations and experimental data to establish a threshold for tissue fractionation in the brain. Results In craniectomized animals at 650 kHz, a peak pressure ≥ 22.7 MPa for 1 second was needed to reliably create a ventriculostomy. Transcranially at this frequency the ExAblate 4000 was unable to generate the required intensity to fractionate tissue, although cavitation was initiated. At 230 kHz, ventriculostomy was successful through the skull with a peak pressure of 8.8 MPa. Conclusions This is the first study to suggest that it is possible to perform a completely noninvasive third ventriculostomy using ultrasound. This may pave the way for future studies and eventually provide an alternative means for the creation of CSF communications in the brain, including perforation of the septum pellucidum or

  17. Precise spatial control of cavitation erosion in a vessel phantom by using an ultrasonic standing wave.

    PubMed

    Shi, Aiwei; Huang, Peixuan; Guo, Shifang; Zhao, Lu; Jia, Yingjie; Zong, Yujin; Wan, Mingxi

    2016-07-01

    In atherosclerotic inducement in animal models, the conventionally used balloon injury is invasive, produces excessive vessel injuries at unpredictable locations and is inconvenient in arterioles. Fortunately, cavitation erosion, which plays an important role in therapeutic ultrasound in blood vessels, has the potential to induce atherosclerosis noninvasively at predictable sites. In this study, precise spatial control of cavitation erosion for superficial lesions in a vessel phantom was realised by using an ultrasonic standing wave (USW) with the participation of cavitation nuclei and medium-intensity ultrasound pulses. The superficial vessel erosions were restricted between adjacent pressure nodes, which were 0.87 mm apart in the USW field of 1 MHz. The erosion positions could be shifted along the vessel by nodal modulation under a submillimetre-scale accuracy without moving the ultrasound transducers. Moreover, the cavitation erosion of the proximal or distal wall could be determined by the types of cavitation nuclei and their corresponding cavitation pulses, i.e., phase-change microbubbles with cavitation pulses of 5 MHz and SonoVue microbubbles with cavitation pulses of 1 MHz. Effects of acoustic parameters of the cavitation pulses on the cavitation erosions were investigated. The flow conditions in the experiments were considered and discussed. Compared to only using travelling waves, the proposed method in this paper improves the controllability of the cavitation erosion and reduces the erosion depth, providing a more suitable approach for vessel endothelial injury while avoiding haemorrhage.

  18. Effect of pulse repetition frequency of high-intensity focused ultrasound on in vitro thrombolysis.

    PubMed

    Yang, Wenjing; Zhou, Yufeng

    2017-03-01

    Vascular occlusion by the thrombi is the main reason for ischemic stroke and deep vein thrombosis. High-intensity focused ultrasound (HIFU) and histotripsy or microtripsy pulses can effectively dissolve the blood clot with no use of thrombolytic agent and ultrasound contrast agent (microbubbles). In this study, HIFU bursts at the same duty cycle (2%) but varied pulse repetition frequency (PRF) from 1Hz to 1000Hz were delivered to in vitro porcine blood clot for 30s. Thrombolysis efficiency initially increases slightly with the PRF, 86.4±10.3%, 89.9±11.9, and 92.9±12.8% at the PRF of 1Hz, 10Hz, and 100Hz, respectively, without significant difference (p>0.05), but then drops dramatically to 37.9±6.9% at the PRF of 1000Hz (p<0.05). The particle size in the supernatant of dissolution is 547.1±129.5nm, which suggests the disruption of thrombi into the subcellular level. Thrombi motion during HIFU exposure shows violent motion and significant curling at the low PRF, rotation about its axis with occasional curling at the moderate PRF, and localized vibration at the high PRF due to the generation of acoustic radiation force and streaming. Quantitative analysis of recorded motion shows the axial displacement decreases with the PRF of delivered HIFU bursts, from 3.9±1.5mm at 1Hz to 0.7±0.4mm at 1000Hz. Bubble cavitation during HIFU exposure to the blood clot was also monitored. The increase of PRF led to the increase of inertial cavitation but the decrease of stable cavitation. In summary, the PRF of delivered HIFU bursts at the same output energy has a significant effect on the thrombi motion, bubble cavitation activities, and subsequently thrombolysis efficiencies.

  19. Ultrasound-Mediated Vascular Gene Transfection by Cavitation of Endothelial-Targeted Cationic Microbubbles

    PubMed Central

    Xie, Aris; Belcik, Todd; Qi, Yue; Morgan, Terry K.; Champaneri, Shivam A.; Taylor, Sarah; Davidson, Brian P.; Zhao, Yan; Klibanov, Alexander L.; Kuliszewski, Michael A.; Leong-Poi, Howard; Ammi, Azzdine; Lindner, Jonathan R.

    2013-01-01

    OBJECTIVES Ultrasound-mediated gene delivery can be amplified by acoustic disruption of microbubble carriers that undergo cavitation. We hypothesized that endothelial targeting of microbubbles bearing cDNA is feasible and, through optimizing proximity to the vessel wall, increases the efficacy of gene transfection. BACKGROUND Contrast ultrasound-mediated gene delivery is a promising approach for site-specific gene therapy, although there are concerns with the reproducibility of this technique and the safety when using high-power ultrasound. METHODS Cationic lipid-shelled decafluorobutane microbubbles bearing a targeting moiety were prepared and compared with nontargeted microbubbles. Microbubble targeting efficiency to endothelial adhesion molecules (P-selectin or intercellular adhesion molecule [ICAM]-1) was tested using in vitro flow chamber studies, intravital microscopy of tumor necrosis factor-alpha (TNF-α)–stimulated murine cremaster muscle, and targeted contrast ultrasound imaging of P-selectin in a model of murine limb ischemia. Ultrasound-mediated transfection of luciferase reporter plasmid charge coupled to microbubbles in the post-ischemic hindlimb muscle was assessed by in vivo optical imaging. RESULTS Charge coupling of cDNA to the microbubble surface was not influenced by the presence of targeting ligand, and did not alter the cavitation properties of cationic microbubbles. In flow chamber studies, surface conjugation of cDNA did not affect attachment of targeted microbubbles at microvascular shear stresses (0.6 and 1.5 dyne/cm2). Attachment in vivo was also not affected by cDNA according to intravital microscopy observations of venular adhesion of ICAM-1–targeted microbubbles and by ultrasound molecular imaging of P-selectin–targeted microbubbles in the post-ischemic hindlimb in mice. Transfection at the site of high acoustic pressures (1.0 and 1.8 MPa) was similar for control and P-selectin–targeted microbubbles but was associated with

  20. Spatial-temporal three-dimensional ultrasound plane-by-plane active cavitation mapping for high-intensity focused ultrasound in free field and pulsatile flow.

    PubMed

    Ding, Ting; Hu, Hong; Bai, Chen; Guo, Shifang; Yang, Miao; Wang, Supin; Wan, Mingxi

    2016-07-01

    Cavitation plays important roles in almost all high-intensity focused ultrasound (HIFU) applications. However, current two-dimensional (2D) cavitation mapping could only provide cavitation activity in one plane. This study proposed a three-dimensional (3D) ultrasound plane-by-plane active cavitation mapping (3D-UPACM) for HIFU in free field and pulsatile flow. The acquisition of channel-domain raw radio-frequency (RF) data in 3D space was performed by sequential plane-by-plane 2D ultrafast active cavitation mapping. Between two adjacent unit locations, there was a waiting time to make cavitation nuclei distribution of the liquid back to the original state. The 3D cavitation map equivalent to the one detected at one time and over the entire volume could be reconstructed by Marching Cube algorithm. Minimum variance (MV) adaptive beamforming was combined with coherence factor (CF) weighting (MVCF) or compressive sensing (CS) method (MVCS) to process the raw RF data for improved beamforming or more rapid data processing. The feasibility of 3D-UPACM was demonstrated in tap-water and a phantom vessel with pulsatile flow. The time interval between temporal evolutions of cavitation bubble cloud could be several microseconds. MVCF beamformer had a signal-to-noise ratio (SNR) at 14.17dB higher, lateral and axial resolution at 2.88times and 1.88times, respectively, which were compared with those of B-mode active cavitation mapping. MVCS beamformer had only 14.94% time penalty of that of MVCF beamformer. This 3D-UPACM technique employs the linear array of a current ultrasound diagnosis system rather than a 2D array transducer to decrease the cost of the instrument. Moreover, although the application is limited by the requirement for a gassy fluid medium or a constant supply of new cavitation nuclei that allows replenishment of nuclei between HIFU exposures, this technique may exhibit a useful tool in 3D cavitation mapping for HIFU with high speed, precision and resolution

  1. Safety of Pulsed High Intensity Focused Ultrasound for Enhanced Drug and Gene Delivery

    NASA Astrophysics Data System (ADS)

    Kam, Anthony W.; Wang, Honghui; Farahani, Keyvan; Thomasson, David; O'Neill, Brian; Angstadt, Mary; Jesson, Johnny; Li, King C. P.

    2007-05-01

    For a limited range of exposure parameters, pulsed high intensity focused ultrasound (HIFU) has been shown to increase the delivery of certain systemically administered macromolecular diagnostic and therapeutic agents in mice. The mechanism for the enhanced delivery has not been demonstrated definitively and, in principle, can include thermal, cavitational, and non-cavitation mechanical effects. The sonicated tissue has no damage on histology. As a step towards clinical translation, the safety of this technique needs to be assessed in a clinically relevant manner. In this study, the safety of pulsed HIFU is evaluated with near real-time phase shift magnetic resonance (MR) thermometry and anatomic MR imaging using rabbits as subjects. MR guidance enables pulsed HIFU enhanced delivery to be implemented safely from a thermal standpoint. Although the effects of pulsed HIFU are not seen on anatomic MR images, they may be detected on MR sequences sensitive to permeability, diffusion, and elasticity. Such work that may optimize pulsed HIFU enhanced delivery is in progress.

  2. Shock wave and cavitation bubble measurements of ultrashort-pulse laser-induced breakdown in water

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Thomas, Robert J.; Frenz, Martin; Jansen, E. Duco; Noojin, Gary D.; Diggs, Sarah J.; Noack, Joachim; Vogel, Alfred; Rockwell, Benjamin A.

    1996-05-01

    Laser-induced breakdown (LIB) has long been used in ophthalmic microsurgery as a mechanism for disruption of tissue. The goal of this surgery has been precise tissue cutting by plasma formation and a minimization of collateral damage due to shock wave and cavitation bubble formation. We investigate the strength of the shock wave emission, the size of the cavitation bubble, and the amount of plasma shielding to determine the efficacy of using femtosecond pulses in surgery to reduce collateral photoacoustic damage. A pump-probe technique is used to image the time-resolved evolution of the cavitation bubble produced by focused laser pulses with pulsewidths of 130 fs, 300 fs, 3 ps, and 60 ps. Simultaneously, a hydrophone is used to measure the pressure response generated by the initial plasma shock wave and subsequent shock waves generated by the collapse and rebound of the cavitation bubbles. In addition, transmission measurements are made which indicate the amount of energy shielded beyond the focus by the plasma. These measurements give a good indication of the degree to which collateral damage may be reduced as the pulsewidths is decreased from the picosecond to the femtosecond time regime.

  3. Advantage of annular focus generation by sector-vortex array in cavitation-enhanced high-intensity focused ultrasound treatment

    NASA Astrophysics Data System (ADS)

    Jimbo, Hayato; Takagi, Ryo; Taguchi, Kei; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    High-intensity focused ultrasound (HIFU) is a noninvasive method for cancer treatment. One of the disadvantages of this method is that it has a long total treatment time because of the smallness of the treatment volume by a single exposure. To solve this problem, we have proposed a method of cavitation-enhanced heating, which utilized the heat generated by oscillating the cavitation bubbles, in combination with the method of lateral enlargement of a HIFU focal zone to minimize the surface volume ratio. In a previous study, focal spot scanning at multiple points was employed for the enlargement. This method involves nonlinear propagation and absorption due to the high spatial-peak temporal-peak (SPTP) intensity in addition to the cavitation-enhanced heating. However, it is difficult to predict the size and position of the coagulation volume because they are significantly affected by the nonlinear parameters of the tissue. In this study, a sector vortex method was employed to directly synthesize an annular focal pattern. Since this method can keep the SPTP intensity at a manageably low level, nonlinear propagation and absorption can be minimized. Experimental results demonstrate that the coagulation was generated only in the region where both the cavitation cloud and the heating ultrasound were matched. The proposed method will make the cavitation-enhanced HIFU treatment more accurate and predictable.

  4. An Investigation of Acoustic Cavitation Produced by Pulsed Ultrasound

    DTIC Science & Technology

    1987-12-01

    minor contribution of the vapor pressure has been neglected). Assuming that the liquid undergoes an incremental change in hydrostatic pressure to a new...shear viscosity of the liquid, and Pv is its vapor pressure . Differentiating (2.18) and substituting (2.19) for PL and P. = Po + P(t). we find that 3...viscosity is ignored; 6. The liquid is incompressible; 7. Gas content of the bubble is constant- no diffusion occurs; 8. Vapor pressure . Pv, is constant

  5. Cavitation effect of holmium laser pulse applied to ablation of hard tissue underwater.

    PubMed

    Lü, Tao; Xiao, Qing; Xia, Danqing; Ruan, Kai; Li, Zhengjia

    2010-01-01

    To overcome the inconsecutive drawback of shadow and schlieren photography, the complete dynamics of cavitation bubble oscillation or ablation products induced by a single holmium laser pulse [2.12 microm, 300 micros (FWHM)] transmitted in different core diameter (200, 400, and 600 microm) fibers is recorded by means of high-speed photography. Consecutive images from high-speed cameras can stand for the true and complete process of laser-water or laser-tissue interaction. Both laser pulse energy and fiber diameter determine cavitation bubble size, which further determines acoustic transient amplitudes. Based on the pictures taken by high-speed camera and scanned by an optical coherent microscopy (OCM) system, it is easily seen that the liquid layer at the distal end of the fiber plays an important role during the process of laser-tissue interaction, which can increase ablation efficiency, decrease heat side effects, and reduce cost.

  6. Jet atomization and cavitation induced by interactions between focused ultrasound and a water surfacea)

    NASA Astrophysics Data System (ADS)

    Tomita, Y.

    2014-09-01

    Atomization of a jet produced by the interaction of 1 MHz focused ultrasound with a water surface was investigated using high-speed photography. Viewing various aspects of jet behavior, threshold conditions were obtained necessary for water surface elevation and jet breakup, including drop separation and spray formation. In addition, the position of drop atomization, where a single drop separates from the tip of a jet without spraying, showed good correlation with the jet Weber number. For a set of specified conditions, multiple beaded water masses were formed, moving upwards to produce a vigorous jet. Cavitation phenomena occurred near the center of the primary drop-shaped water mass produced at the leading part of the jet; this was accompanied by fine droplets at the neck between the primary and secondary drop-shaped water masses, due to the collapse of capillary waves.

  7. Inverse effects of flowing phase-shift nanodroplets and lipid-shelled microbubbles on subsequent cavitation during focused ultrasound exposures.

    PubMed

    Zhang, Siyuan; Cui, Zhiwei; Xu, Tianqi; Liu, Pan; Li, Dapeng; Shang, Shaoqiang; Xu, Ranxiang; Zong, Yujin; Niu, Gang; Wang, Supin; He, Xijing; Wan, Mingxi

    2017-01-01

    This paper compared the effects of flowing phase-shift nanodroplets (NDs) and lipid-shelled microbubbles (MBs) on subsequent cavitation during focused ultrasound (FUS) exposures. The cavitation activity was monitored using a passive cavitation detection method as solutions of either phase-shift NDs or lipid-shelled MBs flowed at varying velocities through a 5-mm diameter wall-less vessel in a transparent tissue-mimicking phantom when exposed to FUS. The intensity of cavitation for the phase-shift NDs showed an upward trend with time and cavitation for the lipid-shelled MBs grew to a maximum at the outset of the FUS exposure followed by a trend of decreases when they were static in the vessel. Meanwhile, the increase of cavitation for the phase-shift NDs and decrease of cavitation for the lipid-shelled MBs had slowed down when they flowed through the vessel. During two discrete identical FUS exposures, while the normalized inertial cavitation dose (ICD) value for the lipid-shelled MB solution was higher than that for the saline in the first exposure (p-value <0.05), it decreased to almost the same level in the second exposure. For the phase-shift NDs, the normalized ICD was 0.71 in the first exposure and increased to 0.97 in the second exposure. At a low acoustic power, the normalized ICD values for the lipid-shelled MBs tended to increase with increasing velocities from 5 to 30cm/s (r>0.95). Meanwhile, the normalized ICD value for the phase-shift NDs was 0.182 at a flow velocity of 5cm/s and increased to 0.188 at a flow velocity of 15cm/s. As the flow velocity increased to 20cm/s, the normalized ICD was 0.185 and decreased to 0.178 at a flow velocity of 30cm/s. At high acoustic power, the normalized ICD values for both the lipid-shelled MBs and the phase-shift NDs increased with increasing flow velocities from 5 to 30cm/s (r>0.95). The effects of the flowing phase-shift NDs vaporized into gas bubbles as cavitation nuclei on the subsequent cavitation were inverse to

  8. Use of Dual-Pulse Lithotripter to Generate a Localized Intensified Cavitation Field

    SciTech Connect

    Sokolov, Dihlia L.; Bailey, Michael R.; Crum, Lawrence A.

    2001-09-01

    Localizing cavitation to the kidney stone in extracorporeal shock wave lithotripsy may be desirable since cavitation appears to play a major role in both stone comminution and renal tissue damage. A method has been developed to localize and intensify cavitation damage in vitro. Cavitation fields in water were filmed with a high-speed digital video camera. In a conventional lithotripter (CL), the shock wave produced by a single source creates a 2 x 10 cm cylindrical cloud of bubbles in water. Bubbles in the CL field collapse simultaneously along the focal axis to produce a nearly uniform 1-mm x 8-cm line of pits in 25- mm-thick aluminum foil. Our dual-pulse lithotripter (DPL) uses two shock wave sources, facing each other, confocal, and triggered simultaneously to create a 4 x 5 cm cylindrical cloud of bubbles that collapse over a range of times and strengths such that the greatest pit damage on foils is contained within a few square millimeters of the focus. The time for bubbles to grow and collapse was measured with a focused hydrophone and compared with calculations based on the Gilmore equation. Pressure doubling due to synchronous arrival of the two pulses at the focus created increased bubble growth and increased foil pit depth. Asynchronous timing between the two pulses elsewhere in the DPL field resulted in disruption of radial dynamics and negligible pitting to foils. Translation of bubbles was also investigated, both numerically and experimentally. While net translation was calculated to be ,0.3 mm in all cases, the rapid

  9. Noninvasive Ureterocele Puncture Using Pulsed Focused Ultrasound: An In Vitro Study

    PubMed Central

    Hsi, Ryan S.; Bailey, Michael R.; Casale, Pasquale; Lendvay, Thomas S.

    2014-01-01

    Abstract Purpose: To evaluate the feasibility of performing noninvasive puncture of pediatric ureteroceles with cavitation-based focused ultrasound (US) (histotripsy). Materials and Methods: A model for the ureterocele wall was developed from an excised bovine bladder wall. The model was exposed to focused US pulses in a water bath under three different US parameter sets for up to 300 seconds to create localized perforations in the wall. B-mode US imaging was used to monitor the treatment and assess potential imaging guidance and feedback. Results: Punctures were formed between 46–300 seconds, depending on the focused US exposure parameters and model wall thickness. Puncture diameter was controllable through choice of exposure parameters and could be varied between 0.8–2.8 mm mean diameter. US-induced cavitation was visible on B-mode imaging, which provided targeting and treatment feedback. Conclusions: Cavitation-based focused US can create punctures in a model that mimics the tissue properties of a ureterocele wall, under guidance from US imaging. PMID:24171441

  10. AN EFFICIENT TREATMENT STRATEGY FOR HISTOTRIPSY BY REMOVING CAVITATION MEMORY

    PubMed Central

    Wang, Tzu-Yin; Xu, Zhen; Hall, Timothy L.; Fowlkes, J. Brian; Cain, Charles A.

    2012-01-01

    Cavitation memory effects occur when remnants of cavitation bubbles (nuclei) persist in the host medium and act as seeds for subsequent events. In pulsed cavitational ultrasound therapy, or histotripsy, this effect may cause cavitation to repeatedly occur at these seeded locations within a target volume, producing inhomogeneous tissue fractionation or requiring an excess number of pulses to completely homogenize the target volume. We hypothesized that by removing the cavitation memory, i.e., the persistent nuclei, the cavitation bubbles could be induced at random locations in response to each pulse; therefore, complete disruption of a tissue volume may be achieved with fewer pulses. To test the hypothesis, the cavitation memory was passively removed by increasing the intervals between successive pulses, Δt, from 2, 10, 20, 50 and 100, to 200 ms. Histotripsy treatments were performed in red blood cell tissue phantoms and ex vivo livers using 1-MHz ultrasound pulses of 10 cycles at P−/P+ pressure of 21/59 MPa. The phantom study allowed for direct visualization of the cavitation patterns and the lesion development process in real time using high-speed photography; the ex vivo tissue study provided validation of the memory effect in real tissues. Results of the phantom study showed an exponential decrease in the correlation coefficient between cavitation patterns in successive pulses from 0.5 ± 0.1 to 0.1 ± 0.1 as Δt increased from 2–200 ms; correspondingly, the lesion was completely fractionated with significantly fewer pulses for longer Δts. In the tissue study, given the same number of therapy pulses, complete and homogeneous tissue fractionation with well-defined lesion boundaries was achieved only for Δt ≥ 100 ms. These results indicated that the removal of the cavitation memory resulted in more efficient treatments and homogeneous lesions. PMID:22402025

  11. Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.

    PubMed

    Yasui, Kyuichi; Towata, Atsuya; Tuziuti, Toru; Kozuka, Teruyuki; Kato, Kazumi

    2011-11-01

    The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles.

  12. MR-Guided Pulsed High-Intensity Focused Ultrasound Enhancement of Gene Therapy Combined With Androgen Deprivation and Radiotherapy for Prostate Cancer Treatment

    DTIC Science & Technology

    2009-09-01

    ultrasound . J. Acoust. Soc.Am. 72 1926-1932, (1982) (7) Neppiras E A. Acoustic cavitation . Physics reports 61(3): 159-251, (1980) (8) ter Haar G R, Daniels...Guided Pulsed High-Intensity Focused Ultrasound Enhancement of 5b. GRANT NUMBER W81XWH-08-1-0469 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...failing to This work is aimed to study MR guided high intensity focused ultrasound (MRgHIFU) enhancement of gene therapy for Prostate Cancer. The

  13. Pulmonary Capillary Hemorrhage Induced by Fixed-Beam Pulsed Ultrasound.

    PubMed

    Miller, Douglas L; Dou, Chunyan; Raghavendran, Krishnan

    2015-08-01

    The induction of pulmonary capillary hemorrhage (PCH) by pulsed ultrasound was discovered 25 y ago, but early research used fixed-beam systems rather than actual diagnostic ultrasound machines. In this study, results of exposure of rats to fixed-beam focused ultrasound for 5 min at 1.5 and 7.5 MHz were compared with recent research on diagnostic ultrasound. One exposure condition at each frequency used 10-μs pulses delivered at 25-ms intervals. Three conditions involved Gaussian modulation of the pulse amplitudes at 25-ms intervals to simulate diagnostic scanning: 7.5 MHz with 0.3- and 1.5-μs pulses at 100- and 500-μs pulse repetition periods, respectively, and 1.5 MHz with 1.7-μs pulses at 500-μs repetition periods. Four groups were tested for each condition to assess PCH areas at different exposure levels and to determine occurrence thresholds. The conditions with identical pulse timing resulted in smaller PCH areas for the smaller 7.5-MHz beam, but both had thresholds of 0.69-0.75 MPa in situ peak rarefactional pressure amplitude. The Gaussian modulation conditions for both 7.5 MHz with 0.3-μs pulses and 1.5 MHz with 1.7-μs pulses had thresholds of 1.12-1.20 MPa peak rarefactional pressure amplitude, although the relatively long 1.5-μs pulses at 7.5 MHz yielded a threshold of 0.75 MPa. The fixed-beam pulsed ultrasound exposures produced lower thresholds than diagnostic ultrasound. There was no clear tendency for thresholds to increase with increasing ultrasonic frequency when pulse timing conditions were similar.

  14. Ultrasound vibrometry using orthogonal- frequency-based vibration pulses.

    PubMed

    Zheng, Yi; Yao, Aiping; Chen, Shigao; Urban, Matthew W; Lin, Haoming; Chen, Xin; Guo, Yanrong; Chen, Ke; Wang, Tianfu; Chen, Siping

    2013-11-01

    New vibration pulses are developed for shear wave generation in a tissue region with preferred spectral distributions for ultrasound vibrometry applications. The primary objective of this work is to increase the frequency range of detectable harmonics of the shear wave. The secondary objective is to reduce the required peak intensity of transmitted pulses that induce the vibrations and shear waves. Unlike the periodic binary vibration pulses, the new vibration pulses have multiple pulses in one fundamental period of the vibration. The pulses are generated from an orthogonal-frequency wave composed of several sinusoidal signals, the amplitudes of which increase with frequency to compensate for higher loss at higher frequency in tissues. The new method has been evaluated by studying the shear wave propagation in in vitro chicken and swine liver. The experimental results show that the new vibration pulses significantly increase tissue vibration with a reduced peak ultrasound intensity, compared with the binary vibration pulses.

  15. Interaction mechanisms of cavitation bubbles induced by spatially and temporally separated fs-laser pulses.

    PubMed

    Tinne, Nadine; Kaune, Brigitte; Krüger, Alexander; Ripken, Tammo

    2014-01-01

    The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots. In order to get more insight into the dynamics a time-resolved photographic analysis of the interaction of cavitation bubbles is presented. Particularly, we investigated the influence of fs-laser pulses and their resulting bubble dynamics with various spatial as well as temporal separations. Different time courses of characteristic interaction effects between the cavitation bubbles were observed depending on pulse energy and spatio-temporal pulse separation. These ranged from merely no interaction to the phenomena of strong water jet formation. Afterwards, the mechanisms are discussed regarding their impact on the medical application of effective tissue cutting lateral to the laser beam direction with best possible axial precision: the mechanical forces of photodisruption as well as the occurring water jet should have low axial extend and a preferably lateral priority. Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components. In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

  16. Interaction Mechanisms of Cavitation Bubbles Induced by Spatially and Temporally Separated fs-Laser Pulses

    PubMed Central

    Tinne, Nadine; Kaune, Brigitte; Krüger, Alexander; Ripken, Tammo

    2014-01-01

    The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots. In order to get more insight into the dynamics a time-resolved photographic analysis of the interaction of cavitation bubbles is presented. Particularly, we investigated the influence of fs-laser pulses and their resulting bubble dynamics with various spatial as well as temporal separations. Different time courses of characteristic interaction effects between the cavitation bubbles were observed depending on pulse energy and spatio-temporal pulse separation. These ranged from merely no interaction to the phenomena of strong water jet formation. Afterwards, the mechanisms are discussed regarding their impact on the medical application of effective tissue cutting lateral to the laser beam direction with best possible axial precision: the mechanical forces of photodisruption as well as the occurring water jet should have low axial extend and a preferably lateral priority. Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components. In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers. PMID:25502697

  17. Spatial distribution of sonoluminescence and sonochemiluminescence generated by cavitation bubbles in 1.2 MHz focused ultrasound field.

    PubMed

    Cao, Hua; Wan, Mingxi; Qiao, Yangzi; Zhang, Shusheng; Li, Ruixue

    2012-03-01

    An intensified charge coupled device (ICCD) camera was used to observe the spatial distribution of sonoluminescence (SL) and sonochemiluminescence (SCL) generated by cavitation bubbles in a 1.2 MHz focused ultrasound (FU) field in order to investigate the mechanisms of acoustic cavitation under different sonication conditions for FU therapeutic applications. It was found that SL emissions were located in the post-focal region. When the intensity of SL and SCL increased as the power rose, the growth of SCL was much higher than that of SL. In the post-focal region, the SCL emissions moved along specific paths and formed branch-like streamers. At the beginning of the ultrasound irradiation, cavitation bubbles generated SCL in both the pre-focal and the post-focal region. When the electrical power or the sonication time increased, the SCL in the post-focal region increased and became higher than that in the pre-focal region. The intensity of SCL in the focal region is usually the weakest because of "oversaturation". The spatial distribution of SCL near a tissue boundary differed from that obtained in free fields. It organized into special structures under different acoustic amplitudes. When the electrical power was relatively low, the SCL emission was conical shape which suggested a standing wave formation at the tissue-fluid boundary. When the electrical power exceeded a certain threshold, only a bright spot could be captured in the focus. The cavitation bubbles which centralized in the focus concentrated energy and hindered the formation of standing waves. With rising electrical power at high levels, besides a bright spot in the focus, there were some irregular light spots in pre-focal region, which indicated some cavitation bubbles or small bubble clusters achieved the threshold of SCL and induced the reaction with the luminol solution.

  18. Enhancement of Sonochemical Reaction by Dual-Pulse Ultrasound

    NASA Astrophysics Data System (ADS)

    Xu, Zheng; Yasuda, Keiji

    2011-07-01

    In order to apply sonochemistry in wastewater treatment, enhancement of sonochemical reaction is necessary. Oxidation of potassium iodide and the degradation of acid orange 7 in aqueous solution using ultrasound irradiation were performed at 490 kHz. Power-modulated pulsed waves were employed and the enhancement of reaction amount was observed compared with using continuous wave. The enhancement ratio for irradiation to rigid wall was larger than that for irradiation to free surface. Moreover, the best modulated pulsed on time was experimentally determined and the effect of the superposition of pulsed waves (dual-pulse) was studied. Enhancement was also observed and calculated separately when using dual-pulse ultrasound. The enhancement upon the use of the dual-transducer was ascribed to the enlargement of sonochemical reaction field. The enhancement upon the incorporating pulsed waves was ascribed to both the reduction of reaction threshold effect and the residual acoustical pressure at the pulsed off time.

  19. Cavitation and spallation in liquid metal droplets produced by subpicosecond pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Krivokorytov, M. S.; Vinokhodov, A. Yu.; Sidelnikov, Yu. V.; Krivtsun, V. M.; Kompanets, V. O.; Lash, A. A.; Koshelev, K. N.; Medvedev, V. V.

    2017-03-01

    The deformation and fragmentation of liquid metal microdroplets by intense subpicosecond Ti:sapphire laser pulses is experimentally studied with stroboscopic shadow photography. The experiments are performed at a peak intensity of 1014W /c m2 at the target's surface, which produces shock waves with pressures in the Mbar range. As a result of such a strong impact, the droplet is transformed into a complex-shaped hollow structure that undergoes asymmetrical expansion and eventually fragments. The hollow structure of the expanding target is explained by the effects of cavitation and spallation that follow the propagation of the laser-induced shock wave.

  20. A Low Cost Compact 512 Channel Therapeutic Ultrasound System For Transcutaneous Ultrasound Surgery

    NASA Astrophysics Data System (ADS)

    Hall, Tim; Cain, Charles

    2006-05-01

    A low cost 512 channel therapeutic ultrasound system was designed and tested with a 2D array transducer. The system was optimized for high energy, low duty cycle pulsing applications (cavitation mediated therapy), but is also folly compatible with continuous wave applications. The effective steering range was measured to be 40 mm FWHM over a 3D volume. Well defined volumes of liver tissue were disrupted with high energy cavitation generating ultrasound pulses in ex-vivo liver experiments.

  1. Exploitation of sub-micron cavitation nuclei to enhance ultrasound-mediated transdermal transport and penetration of vaccines.

    PubMed

    Bhatnagar, Sunali; Kwan, James J; Shah, Apurva R; Coussios, Constantin-C; Carlisle, Robert C

    2016-09-28

    Inertial cavitation mediated by ultrasound has been previously shown to enable skin permeabilisation for transdermal drug and vaccine delivery, by sequentially applying the ultrasound then the therapeutic in liquid form on the skin surface. Using a novel hydrogel dosage form, we demonstrate that the use of sub-micron gas-stabilising polymeric nanoparticles (nanocups) to sustain and promote cavitation activity during simultaneous application of both drug and vaccine results in a significant enhancement of both the dose and penetration of a model vaccine, Ovalbumin (OVA), to depths of 500μm into porcine skin. The nanocups themselves exceeded the penetration depth of the vaccine (up to 700μm) due to their small size and capacity to 'self-propel'. In vivo murine studies indicated that nanocup-assisted ultrasound transdermal vaccination achieved significantly (p<0.05) higher delivery doses without visible skin damage compared to the use of a chemical penetration enhancer. Transdermal OVA doses of up to 1μg were achieved in a single 90-second treatment, which was sufficient to trigger an antigen-specific immune response. Furthermore, ultrasound-assisted vaccine delivery in the presence of nanocups demonstrated substantially higher specific anti-OVA IgG antibody levels compared to other transdermal methods. Further optimisation can lead to a viable, safe and non-invasive delivery platform for vaccines with potential use in a primary care setting or personalized self-vaccination at home.

  2. Sonoluminescence and sonochemiluminescence study of cavitation field in a 1.2MHz focused ultrasound

    NASA Astrophysics Data System (ADS)

    Yin, Hui; Qiao, Yangzi; Cao, Hua; Wan, Mingxi

    2017-03-01

    An intensified CCD (ICCD) and an electron-multiplying CCD (EMCCD) were employed to observe the spatial distribution of sonoluminescence (SL) and sonochemiluminescence (SCL) generated by cavitation bubbles in a 1.2MHz HIFU field. Various sonication conditions, which are free field and focal region near a water-parenchyma interface, were studied. In addition, the differences of two shells coated UCAs were also investigated. In this study, an acoustic radiation force (ARF) counterbalance appliance was added to reduce bubble displacement. Cavitation mapping in this situation was also operated through SCL recording. SCL was also employed to measure cavitation does and map the spatial distribution of cavitation near a boundary of parenchyma.

  3. Enhanced cavitation and heating of flowing polymer- and lipid-shelled microbubbles and phase-shift nanodroplets during focused ultrasound exposures

    NASA Astrophysics Data System (ADS)

    Zhang, Siyuan; Cui, Zhiwei; Li, Chong; Zhou, Fanyu; Zong, Yujin; Wang, Supin; Wan, Mingxi

    2017-03-01

    Cavitation and heating are the primary mechanisms of numerous therapeutic applications of ultrasound. Various encapsulated microbubbles (MBs) and phase-shift nanodroplets (NDs) have been used to enhance local cavitation and heating, creating interests in developing ultrasound therapy using these encapsulated MBs and NDs. This work compared the efficiency of flowing polymer- and lipid-shelled MBs and phase-shift NDs in cavitation and heating during focused ultrasound (FUS) exposures. Cavitation activity and temperature were investigated when the solution of polymer- and lipid-shelled MBs and NDs flowed through the vessel in a tissue-mimicking phantom with varying flow velocities when exposed to FUS at various acoustic power levels. The inertial cavitation dose (ICD) for the encapsulated MBs and NDs were higher than those for the saline. Temperature initially increased with increasing flow velocities of the encapsulated MBs, followed by a decrease of the temperature with increasing flow velocities when the velocity was much higher. Meanwhile, ICD showed a trend of increases with increasing flow velocity. For the phase-shift NDs, ICD after the first FUS exposure was lower than those after the second FUS exposure. For the encapsulated MBs, ICD after the first FUS exposure was higher than those after the second FUS exposure. Further studies are necessary to investigate the treatment efficiency of different encapsulated MBs and phase-shift NDs in cavitation and heating.

  4. [Enhancement of reversing drug resistance of K562/A02 cells to adriamycin by ultrasound-induced cavitation].

    PubMed

    Chen, Bao-An; Meng, Qing-Qi; Wu, Wei; Gao, Feng; Shao, Ze-Ye; Ding, Jia-Hua; Gao, Chong; Sun, Xin-Chen; Cheng, Hong-Yan; Sun, Yun-Yu; Wang, Jun; Cheng, Jian; Zhao, Gang; Song, Hui-Hui; Bao, Wen; Ma, Yan; Wang, Xue-Mei

    2008-12-01

    This study was aimed to investigate the effects of low frequency and power ultrasound combined with adriamycin on apoptosis of drug-resistant leukemia cell line K562/A02 in vitro, to find out the parameters of optimal exposure, and to explore the possible mechanism reversing drug-resistance of K562/A02 cells. The K562/A02 cells in logarithmic growth phase were used in experiments. The experiments were divided into 4 groups: group control, group adriamycin (A02) alone, group ultrasound (US) alone and group A02+US. The trypan blue dye exclusion test and MTT assay were used to determine the cell viability; Wright's staining was used to detect the apoptosis; the flow cytometry was used to analyze the drug concentration, and the scanning electron microscopy was used to observe the changes of cell surface. The results showed that the significant differences in cell viability, intracellular adriamycin concentration and changes of cell membrane were found between ultrasound-treated and untreated cells in the presence of various concentration of adriamycin. The exposure to ultrasound at 20 kHZ, 0.25 W/cm2 for 60 seconds could obviously decrease LC50 of adriamycin to K562/A02 cells, while the exposure to ultrasound at 20 kHZ, 0.05 W/cm2 for 60 seconds could kill K562/A02 cells at once. After being treated by low frequency ultrasound, the small holes with diameter about 1-2 microm in the cell surface appeared. The ultrasound increased the adriamycin concentration in the cells, accelerated the formation of apoptotic bodies, and promoted apoptosis of adriamycin-resistant cells. It is concluded that the ultrasound at optimal parameters enhances inhibitory effect of adriamycin on drug-resistant cell line, thereby reverses drug-resistance of drug-resistant cell line through sound-hole effect in tumor cells resulting from ultrasound induced cavitation.

  5. Imaging monitored loosening of dense fibrous tissues using high-intensity pulsed ultrasound

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Lun; Li, Pai-Chi; Shih, Wen-Pin; Huang, Pei-Shin; Kuo, Po-Ling

    2013-10-01

    Pulsed high-intensity focused ultrasound (HIFU) is proposed as a new alternative treatment for contracture of dense fibrous tissue. It is hypothesized that the pulsed-HIFU can release the contracted tissues by attenuating tensile stiffness along the fiber axis, and that the stiffness reduction can be quantitatively monitored by change of B-mode images. Fresh porcine tendons and ligaments were adapted to an ex vivo model and insonated with pulsed-HIFU for durations ranging from 5 to 30 min. The pulse length was 91 µs with a repetition frequency of 500 Hz, and the peak rarefactional pressure was 6.36 MPa. The corresponding average intensities were kept around 1606 W cm-2 for ISPPA and 72.3 W cm-2 for ISPTA. B-mode images of the tissues were acquired before and after pulsed-HIFU exposure, and the changes in speckle intensity and organization were analyzed. The tensile stiffness of the HIFU-exposed tissues along the longitudinal axis was examined using a stretching machine. Histology examinations were performed by optical and transmission electron microscopy. Pulsed-HIFU exposure significantly decreased the tensile stiffness of the ligaments and tendons. The intensity and organization of tissue speckles in the exposed region were also decreased. The speckle changes correlated well with the degree of stiffness alteration. Histology examinations revealed that pulsed-HIFU exposure probably damages tissues via a cavitation-mediated mechanism. Our results suggest that pulsed-HIFU with a low duty factor is a promising tool for developing new treatment strategies for orthopedic disorders.

  6. Evaluation of pulsed high intensity focused ultrasound exposures on metastasis in a murine model

    PubMed Central

    Hancock, Hilary; Dreher, Matthew R.; Crawford, Nigel; Pollock, Claire B.; Shih, Jennifer; Wood, Bradford J.; Hunter, Kent; Frenkel, Victor

    2014-01-01

    High intensity focused ultrasound (HIFU) may be employed in two ways: continuous exposures for thermal ablation of tissue (>60°C), and pulsed-exposures for non-ablative effects, including low temperature hyperthermia (37–45°C), and non thermal effects (e.g. acoustic cavitation and radiation forces). Pulsed-HIFU effects may enhance the tissue's permeability for improved delivery of drugs and genes, for example, by opening up gaps between cells in the vasculature and parenchyma. Inducing these effects may improve local targeting of therapeutic agents, however; concerns exist that pulsed exposures could theoretically also facilitate dissemination of tumor cells and exacerbate metastases. In the present study, the influence of pulsed-HIFU exposures on increasing metastatic burden was evaluated in a murine model with metastatic breast cancer. A preliminary study was carried out to validate the model and determine optimal timing for treatment and growth of lung metastases. Next, the effect of pulsed-HIFU on the metastatic burden was evaluated using quantitative image processing of whole-lung histological sections. Compared to untreated controls (2/15), a greater number of mice treated with pulsed-HIFU were found to have lungs “overgrown” with metastases (7/15), where individual metastases grew together such that they could not accurately be counted. Furthermore, area fraction of lung metastases (area of metastases/area of lungs) was ~30% greater in mice treated with pulsed-HIFU; however, these differences were not statistically significant. The present study details the development of an animal model for investigating the influence of interventional techniques or exposures (such as pulsed HIFU) on metastatic burden. PMID:19517258

  7. Comments on the possibility of cavitation in liquid metal targets for pulsed spallation neutron sources

    SciTech Connect

    Carpenter J.M.

    1996-06-01

    When short pulses of protons strike the volume of a liquid target, the rapid heating produces a pressurized region which relaxes as the pressure wave propagates outward. Skala and Bauer have modeled the effects of the pressure wave impinging on the container walls of a liquid mercury target under ESS conditions. They find that high pressures and high wall stresses result if the medium is uniform, nearly incompressible liquid. The pressure and the stresses are much reduced if the liquid contains bubbles of helium, due to their high compressibility. However, according to the calculation, the pressure still reaches an atmosphere or so at the surface, which reflects the compressive wave as a rarefaction wave of the same magnitude. Even such modest underpressures can lead to the growth of bubbles (cavitation) at or near the surface, which can collapse violently and erode the container surface. It is necessary to avoid this. Leighton provides a wide ranging discussion of pressure waves in bubbly media, which may provide insights into the nature and control of cavitation phenomena. The paper surveys some of the relevant information from that source.

  8. Pulse sequences for uniform perfluorocarbon droplet vaporization and ultrasound imaging.

    PubMed

    Puett, C; Sheeran, P S; Rojas, J D; Dayton, P A

    2014-09-01

    Phase-change contrast agents (PCCAs) consist of liquid perfluorocarbon droplets that can be vaporized into gas-filled microbubbles by pulsed ultrasound waves at diagnostic pressures and frequencies. These activatable contrast agents provide benefits of longer circulating times and smaller sizes relative to conventional microbubble contrast agents. However, optimizing ultrasound-induced activation of these agents requires coordinated pulse sequences not found on current clinical systems, in order to both initiate droplet vaporization and image the resulting microbubble population. Specifically, the activation process must provide a spatially uniform distribution of microbubbles and needs to occur quickly enough to image the vaporized agents before they migrate out of the imaging field of view. The development and evaluation of protocols for PCCA-enhanced ultrasound imaging using a commercial array transducer are described. The developed pulse sequences consist of three states: (1) initial imaging at sub-activation pressures, (2) activating droplets within a selected region of interest, and (3) imaging the resulting microbubbles. Bubble clouds produced by the vaporization of decafluorobutane and octafluoropropane droplets were characterized as a function of focused pulse parameters and acoustic field location. Pulse sequences were designed to manipulate the geometries of discrete microbubble clouds using electronic steering, and cloud spacing was tailored to build a uniform vaporization field. The complete pulse sequence was demonstrated in the water bath and then in vivo in a rodent kidney. The resulting contrast provided a significant increase (>15 dB) in signal intensity.

  9. Correlation between microbubble-induced acoustic cavitation and hemolysis in vitro

    NASA Astrophysics Data System (ADS)

    Zhang, Chun-Bing; Liu, Zheng; Guo, Xia-Sheng; Zhang, Dong

    2011-02-01

    Microbubbles promise to enhance the efficiency of ultrasound-mediated drug delivery and gene therapy by taking advantage of artificial cavitation nuclei. The purpose of this study is to examine the ultrasound-induced hemolysis in the application of drug delivery in the presence of microbubbles. To achieve this goal, human red blood cells mixed with microbubbles were exposed to 1-MHz pulsed ultrasound. The hemolysis level was measured by a flow cytometry, and the cavitation dose was detected by a passive cavitation detecting system. The results demonstrate that larger cavitation dose would be generated with the increase of acoustic pressure, which might give rise to the enhancement of hemolysis. Besides the experimental observations, the acoustic pressure dependence of the radial oscillation of microbubble was theoretically estimated. The comparison between the experimental and calculation results indicates that the hemolysis should be highly correlated to the acoustic cavitation.

  10. Investigation of spatial distribution of sound field parameters in ultrasound cleaning baths under the influence of cavitation.

    PubMed

    Jenderka, Klaus-Vitold; Koch, Christian

    2006-12-22

    Ultrasound cleaning baths fitting the full range from micromechanical components up to large machine parts, are regularly used in industry and in the lab. Despite the large number of applications, generally approved principles and objective criteria for parameter settings which allow an efficient operation are non-existent. The empirical selections of the running parameters often impede an optimization in terms of produce and reproducibility. One proposal for an objective description of the processes is the characterization of the sound field in the cleaning bath, which causes cavities, and subsequently, the cleaning process. Sound field measurements in the appropriate frequency range from 20kHz up to more then 1MHz incorporate a number of problems, such as large sensors disturbing the sound field, a lack of accuracy and the risk of being destroyed by cavitation bubbles. Measurement systems based on optical fiber tips and piezo-electrical hydrophones will be presented, which fulfil the accuracy requirements and withstand ultrasound fields with high power and cavitation. The spatial distribution of sound field parameters such as positive and negative peak pressure, amplitudes of fundamentals, harmonics and sub-harmonics as well as the energy density and spectral density in several frequency ranges are determined in experiments. Finally, the determined field parameters are related to the cavitation effects by means of photometric analysis of perforated aluminium foil. Perforations as well as intentions are analyzed and quantified from scanner images of the exposed foil samples using special image processing software. The experiments indicate clear differences in the structure of the sound fields and the spectral properties between the several types of cleaning baths, transducer arrangements and excitations.

  11. Biological Effects of Acoustic Cavitation

    DTIC Science & Technology

    2007-11-02

    rectified diffusion. 56 III. STABLE CAVITATION A. Introduction There are manv areas associated with the biological effects of ultrasound in which the...used said as cavitation indicators. Further, if clinical ultrasound systems are found to be inducing cavitation , either stable or transient, it will...O BIOLOGICAL EFFECTS OF ACOUSTIC CAVITATION by Lawrence A. Crum -- Physical Acoustics Research Laboratory Department of Physics and Astronomy ’ CTE

  12. Detecting cavitation in vivo from shock-wave therapy devices

    NASA Astrophysics Data System (ADS)

    Matula, Thomas J.; Yu, Jinfei; Bailey, Michael R.

    2005-04-01

    Extracorporeal shock-wave therapy (ESWT) has been used as a treatment for plantar faciitis, lateral epicondylitis, shoulder tendonitis, non-unions, and other indications where conservative treatments have been unsuccessful. However, in many areas, the efficacy of SW treatment has not been well established, and the mechanism of action, particularly the role of cavitation, is not well understood. Research indicates cavitation plays an important role in other ultrasound therapies, such as lithotripsy and focused ultrasound surgery, and in some instances, cavitation has been used as a means to monitor or detect a biological effect. Although ESWT can generate cavitation easily in vitro, it is unknown whether or not cavitation is a significant factor in vivo. The purpose of this investigation is to use diagnostic ultrasound to detect and monitor cavitation generated by ESWT devices in vivo. Diagnostic images are collected at various times during and after treatment. The images are then post-processed with image-processing algorithms to enhance the contrast between bubbles and surrounding tissue. The ultimate goal of this research is to utilize cavitation as a means for optimizing shock wave parameters such as amplitude and pulse repetition frequency. [Work supported by APL internal funds and NIH DK43881 and DK55674.

  13. Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal function

    NASA Astrophysics Data System (ADS)

    Kudo, Ken-ichi; Ito, Hironori; Ihara, Satoshi; Terato, Hiroaki

    2015-09-01

    Plasma-based techniques are expected to have practical use for wastewater purification with a potential for killing contaminated microorganisms and degrading recalcitrant materials. In the present study, we analysed oxidative DNA damage in bacterial cells treated by the plasma to unveil its mechanisms in the bactericidal process. Escherichia coli cell suspension was exposed to the plasma induced by applying an alternating-current voltage of about 1 kV with bubbling formed by water-cavitation, termed pulsed discharge with cavitation. Chromosomal DNA damage, such as double strand break (DSB) and oxidative base lesions, increased proportionally with the applied energy, as determined by electrophoretic and mass spectrometric analyses. Among the base lesions identified, the yields of 8-hydroxyguanine (8-OH-G) and 5-hydroxycytosine (5-OH-C) in chromosomal DNA increased by up to 4- and 15-fold, respectively, compared to untreated samples. The progeny DNA sequences, derived from plasmid DNA exposed to the plasma, indicated that the production rate of 5-OH-C exceeded that of 8-OH-G, as G:C to A:T transitions accounted for 65% of all base changes, but only a few G:C to T:A transversions were observed. The cell viabilities of E. coli cells decreased in direct proportion to increases in the applied energy. Therefore, the plasma-induced bactericidal mechanism appears to relate to oxidative damage caused to bacterial DNA. These results were confirmed by observing the generation of hydroxyl radicals and hydrogen peroxide molecules following the plasma exposure. We also compared our results with the plasma to those obtained with 137Cs γ-rays, as a well-known ROS generator to confirm the DNA-damaging mechanism involved.

  14. New coding concept for fast ultrasound imaging using pulse trains

    NASA Astrophysics Data System (ADS)

    Misaridis, Thanasis; Jensen, Joergen A.

    2002-04-01

    Frame rate in ultrasound imaging can be increased by simultaneous transmission of multiple beams using coded waveforms. However, the achievable degree of orthogonality among coded waveforms is limited in ultrasound, and the image quality degrades unacceptably due to interbeam interference. In this paper, an alternative combined time-space coding approach is undertaken. In the new method all transducer elements are excited with short pulses and the high time-bandwidth (TB) product waveforms are generated acoustically. Each element transmits a short pulse spherical wave with a constant transmit delay from element to element, long enough to assure no pulse overlapping for all depths in the image. Frequency shift keying is used for per element coding. The received signals from a point scatterer are staggered pulse trains which are beamformed for all beam directions and further processed with a bank of matched filters (one for each beam direction). Filtering compresses the pulse train to a single pulse at the scatterer position with a number of spike axial sidelobes. Cancellation of the ambiguity spikes is done by applying additional phase modulation from one emission to the next and summing every two successive images. Simulation results presented for QLFM and Costas spatial encoding schemes show that the proposed method can yield images with range sidelobes down to -45 dB using only two emissions.

  15. The role of positive and negative pressure on cavitation nucleation in nanodroplet-mediated histotripsy.

    PubMed

    Vlaisavljevich, Eli; Aydin, Omer; Lin, Kuang-Wei; Durmaz, Yasemin Yuksel; Fowlkes, Brian; ElSayed, Mohamed; Xu, Zhen

    2016-01-21

    Nanodroplet-mediated histotripsy (NMH) is an ultrasound ablation technique combining histotripsy with acoustically sensitive perfluorocarbon (PFC) nanodroplets that can be selectively delivered to tumor cells for targeted tumor ablation. NMH takes advantage of the significantly reduced cavitation threshold of the nanodroplets, allowing for cavitation to be selectively generated only in regions containing nanodroplets. Understanding the physical mechanisms underlying the nanodroplet cavitation process is essential to the development of NMH. In this study, we hypothesize that cavitation nucleation is caused by the negative pressure (p-) exposed to the PFC, and the NMH cavitation threshold is therefore determined by the incident p-  of the single-cycle pulses commonly used in NMH. This paper reports the first study that separately investigates the effects of negative and positive pressure on the NMH cavitation threshold using near half-cycle ultrasound pulses with dominant negative (negative-polarity pulses) or positive (positive-polarity pulses) pressure phases. Tissue phantoms containing perfluorohexane (PFH) nanodroplets were exposed to negative-polarity and positive-polarity pulses generated by a frequency compounding transducer recently developed in our lab, and the probability of generating cavitation was measured as a function of peak negative (p-) and peak positive (p+) pressure. The results showed close agreement in the p- cavitation threshold for PFH phantoms exposed to negative-polarity (11.4 ± 0.1 MPa) and positive-polarity (11.7 ± 0.2 MPa) pulses. The p+ at the cavitation threshold, in contrast, was measured to be sign ficantly different for the negative-polarity (4.0 ± 0.1 MPa) and positive-polarity (42.6 ± 0.2 MPa) pulses. In the final part of this study, the experimental results were compared to the cavitation threshold predicted by classical nucleation theory (CNT), with results showing close agreement between simulations and experiments

  16. In Situ Synchrotron X-ray Study of Ultrasound Cavitation and Its Effect on Solidification Microstructures

    NASA Astrophysics Data System (ADS)

    Mi, Jiawei; Tan, Dongyue; Lee, Tung Lik

    2015-08-01

    Considerable progress has been made in studying the mechanism and effectiveness of using ultrasound waves to manipulate the solidification microstructures of metallic alloys. However, uncertainties remain in both the underlying physics of how microstructures evolve under ultrasonic waves, and the best technological approach to control the final microstructures and properties. We used the ultrafast synchrotron X-ray phase contrast imaging facility housed at the Advanced Photon Source, Argonne National Laboratory, US to study in situ the highly transient and dynamic interactions between the liquid metal and ultrasonic waves/bubbles. The dynamics of ultrasonic bubbles in liquid metal and their interactions with the solidifying phases in a transparent alloy were captured in situ. The experiments were complemented by the simulations of the acoustic pressure field, the pulsing of the bubbles, and the associated forces acting onto the solidifying dendrites. The study provides more quantitative understanding on how ultrasonic waves/bubbles influence the growth of dendritic grains and promote the grain multiplication effect for grain refinement.

  17. Improving the cardio protective effect of aFGF in ischemic myocardium with ultrasound-mediated cavitation of heparin modified microbubbles: preliminary experiment.

    PubMed

    Zhao, Ying-Zheng; Lu, Cui-Tao; Li, Xiao-Kun; Tang, Qin-Qin; Tian, Xin-Qiao; Zhao, Ya-Ping; Zhang, Yan; Tian, Ji-Lai; Yang, Wei; Ge, Shuping; Nair, Chandra K; Shen, Xuedong

    2012-08-01

    Ultrasound (US)-mediated cavitation of microbubbles has evolved into a new tool for organ-specific gene and drug delivery. This paper was to investigate the feasibility of acidic fibroblast growth factor (aFGF) intravenous delivery to the ischemic myocardium of rats by ultrasonic microbubbles modified with heparin. Heparin modified microbubbles (HMB) were prepared by the freeze-dried method. Acute myocardial infarction (AMI) model was established and the cardio protective effect of the aFGF combing with HMB (aFGF-HMB) under US-mediated cavitation technique was investigated. aFGF-HMB combined with US-mediated cavitation technique was examined by ECG. Ejection fraction (EF), fractional shortening (FS) and left ventricular diastolic diameter (LVDd) were measured to monitor the improvement of global myocardial contractile function. Myocardial tissue was stained with hematoxylin and eosine (HE) to evaluate the elaborate general morphology of the ischemic myocardium. From morphologic observation and echocardiography in rat heart, aFGF-HMB had suitable size distribution, physical stability and good acoustic resonance function. From AMI rat experiments, aFGF-HMB under US-mediated cavitation technique exerted aFGF cardio protective effect in ischemic myocardium. From histological evaluation, US-mediated cavitation of aFGF-HMB showed improvement of myocardial ischemia. With the visual imaging and US-triggered drug release advantages, US-mediated cavitation of aFGF-HMB might be developed as a novel technique for targeting delivery of aFGF into ischemic myocardium.

  18. Focused Ultrasound-Induced Blood-Brain Barrier Opening: Association with Mechanical Index and Cavitation Index Analyzed by Dynamic Contrast-Enhanced Magnetic-Resonance Imaging

    PubMed Central

    Chu, Po-Chun; Chai, Wen-Yen; Tsai, Chih-Hung; Kang, Shih-Tsung; Yeh, Chih-Kuang; Liu, Hao-Li

    2016-01-01

    Focused ultrasound (FUS) with microbubbles can temporally open the blood-brain barrier (BBB), and the cavitation activities of microbubbles play a key role in the BBB-opening process. Previous attempts used contrast-enhanced magnetic resonance imaging (CE-MRI) to correlate the mechanical index (MI) with the scale of BBB-opening, but MI only partially gauged acoustic activities, and CE-MRI did not fully explore correlations of pharmacodynamic/pharmacokinetic behaviors. Recently, the cavitation index (CI) has been derived to serve as an indicator of microbubble-ultrasound stable cavitation, and may also serve as a valid indicator to gauge the level of FUS-induced BBB opening. This study investigates the feasibility of gauging FUS-induced BBB opened level via the two indexes, MI and CI, through dynamic contrast-enhanced (DCE)-MRI analysis as well as passive cavitation detection (PCD) analysis. Pharmacodynamic/pharmacokinetic parameters derived from DCE-MRI were characterized to identify the scale of FUS-induced BBB opening. Our results demonstrated that DCE-MRI can successfully access pharmacodynamic/pharmacokinetic BBB-opened behavior, and was highly correlated both with MI and CI, implying the feasibility in using these two indices to gauge the scale of FUS-induced BBB opening. The proposed finding may facilitate the design toward using focused ultrasound as a safe and reliable noninvasive CNS drug delivery. PMID:27630037

  19. Focused Ultrasound-Induced Blood-Brain Barrier Opening: Association with Mechanical Index and Cavitation Index Analyzed by Dynamic Contrast-Enhanced Magnetic-Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Chu, Po-Chun; Chai, Wen-Yen; Tsai, Chih-Hung; Kang, Shih-Tsung; Yeh, Chih-Kuang; Liu, Hao-Li

    2016-09-01

    Focused ultrasound (FUS) with microbubbles can temporally open the blood-brain barrier (BBB), and the cavitation activities of microbubbles play a key role in the BBB-opening process. Previous attempts used contrast-enhanced magnetic resonance imaging (CE-MRI) to correlate the mechanical index (MI) with the scale of BBB-opening, but MI only partially gauged acoustic activities, and CE-MRI did not fully explore correlations of pharmacodynamic/pharmacokinetic behaviors. Recently, the cavitation index (CI) has been derived to serve as an indicator of microbubble-ultrasound stable cavitation, and may also serve as a valid indicator to gauge the level of FUS-induced BBB opening. This study investigates the feasibility of gauging FUS-induced BBB opened level via the two indexes, MI and CI, through dynamic contrast-enhanced (DCE)-MRI analysis as well as passive cavitation detection (PCD) analysis. Pharmacodynamic/pharmacokinetic parameters derived from DCE-MRI were characterized to identify the scale of FUS-induced BBB opening. Our results demonstrated that DCE-MRI can successfully access pharmacodynamic/pharmacokinetic BBB-opened behavior, and was highly correlated both with MI and CI, implying the feasibility in using these two indices to gauge the scale of FUS-induced BBB opening. The proposed finding may facilitate the design toward using focused ultrasound as a safe and reliable noninvasive CNS drug delivery.

  20. Focused Ultrasound-Induced Blood-Brain Barrier Opening: Association with Mechanical Index and Cavitation Index Analyzed by Dynamic Contrast-Enhanced Magnetic-Resonance Imaging.

    PubMed

    Chu, Po-Chun; Chai, Wen-Yen; Tsai, Chih-Hung; Kang, Shih-Tsung; Yeh, Chih-Kuang; Liu, Hao-Li

    2016-09-15

    Focused ultrasound (FUS) with microbubbles can temporally open the blood-brain barrier (BBB), and the cavitation activities of microbubbles play a key role in the BBB-opening process. Previous attempts used contrast-enhanced magnetic resonance imaging (CE-MRI) to correlate the mechanical index (MI) with the scale of BBB-opening, but MI only partially gauged acoustic activities, and CE-MRI did not fully explore correlations of pharmacodynamic/pharmacokinetic behaviors. Recently, the cavitation index (CI) has been derived to serve as an indicator of microbubble-ultrasound stable cavitation, and may also serve as a valid indicator to gauge the level of FUS-induced BBB opening. This study investigates the feasibility of gauging FUS-induced BBB opened level via the two indexes, MI and CI, through dynamic contrast-enhanced (DCE)-MRI analysis as well as passive cavitation detection (PCD) analysis. Pharmacodynamic/pharmacokinetic parameters derived from DCE-MRI were characterized to identify the scale of FUS-induced BBB opening. Our results demonstrated that DCE-MRI can successfully access pharmacodynamic/pharmacokinetic BBB-opened behavior, and was highly correlated both with MI and CI, implying the feasibility in using these two indices to gauge the scale of FUS-induced BBB opening. The proposed finding may facilitate the design toward using focused ultrasound as a safe and reliable noninvasive CNS drug delivery.

  1. Surface vibration and nearby cavitation of an ex vivo bovine femur exposed to high intensity focused ultrasound.

    PubMed

    Zhang, Siyuan; Li, Chong; Yin, Hui; Wang, Supin; Wan, Mingxi

    2013-08-01

    The acoustic pressure distribution, thermal ablation, and sonochemiluminescence (SCL) generated by cavitation near the surface of an ex vivo bovine femur were investigated at normal and oblique incidences of high intensity focused ultrasound (HIFU), as were the characteristics of bone surface vibrations. The acoustic pressure at the HIFU focus, the width of thermal ablation, and the SCL intensity in the pre-focal region were 1.3 MPa, 7 mm, and 454 electrons, respectively, in the control group at normal incidence, and they respectively increased to 1.5 MPa, 12 mm and 968 electrons in the presence of the bone. At oblique incidence from the left, the acoustic pressure at 3 mm to the right of the HIFU focus was 0.6 MPa and decreased to 0.4 MPa at 3 mm to the left of the focus. The thermal ablation was 20 mm in width and extended along the front surface of the bone to the right of the HIFU focus. The SCL intensity on the right of the HIFU focus was 394 electrons and was 362 electrons on the left. The presence of bone would directionally change the spatial distribution of acoustic pressure, thermal and cavitation effects for oblique incidence of HIFU.

  2. Acoustic methods for cavitation mapping in biomedical applications

    NASA Astrophysics Data System (ADS)

    Wan, M.; Xu, S.; Ding, T.; Hu, H.; Liu, R.; Bai, C.; Lu, S.

    2015-12-01

    In recent years, cavitation is increasingly utilized in a wide range of applications in biomedical field. Monitoring the spatial-temporal evolution of cavitation bubbles is of great significance for efficiency and safety in biomedical applications. In this paper, several acoustic methods for cavitation mapping proposed or modified on the basis of existing work will be presented. The proposed novel ultrasound line-by-line/plane-by-plane method can depict cavitation bubbles distribution with high spatial and temporal resolution and may be developed as a potential standard 2D/3D cavitation field mapping method. The modified ultrafast active cavitation mapping based upon plane wave transmission and reception as well as bubble wavelet and pulse inversion technique can apparently enhance the cavitation to tissue ratio in tissue and further assist in monitoring the cavitation mediated therapy with good spatial and temporal resolution. The methods presented in this paper will be a foundation to promote the research and development of cavitation imaging in non-transparent medium.

  3. A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping.

    PubMed

    Deng, Lulu; O'Reilly, Meaghan A; Jones, Ryan M; An, Ran; Hynynen, Kullervo

    2016-12-21

    Focused ultrasound (FUS) phased arrays show promise for non-invasive brain therapy. However, the majority of them are limited to a single transmit/receive frequency and therefore lack the versatility to expose and monitor the treatment volume. Multi-frequency arrays could offer variable transmit focal sizes under a fixed aperture, and detect different spectral content on receive for imaging purposes. Here, a three-frequency (306, 612, and 1224 kHz) sparse hemispherical ultrasound phased array (31.8 cm aperture; 128 transducer modules) was constructed and evaluated for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. The array is able to perform effective electronic beam steering over a volume spanning (-40, 40) and (-30, 50) mm in the lateral and axial directions, respectively. The focal size at the geometric center is approximately 0.9 (2.1) mm, 1.7 (3.9) mm, and 3.1 (6.5) mm in lateral (axial) pressure full width at half maximum (FWHM) at 1224, 612, and 306 kHz, respectively. The array was also found capable of dual-frequency excitation and simultaneous multi-foci sonication, which enables the future exploration of more complex exposure strategies. Passive acoustic mapping of dilute microbubble clouds demonstrated that the point spread function of the receive array has a lateral (axial) intensity FWHM between 0.8-3.5 mm (1.7-11.7 mm) over a volume spanning (-25, 25) mm in both the lateral and axial directions, depending on the transmit/receive frequency combination and the imaging location. The device enabled both half and second harmonic imaging through the intact skull, which may be useful for improving the contrast-to-tissue ratio or imaging resolution, respectively. Preliminary in vivo experiments demonstrated the system's ability to induce blood-brain barrier opening and simultaneously spatially map microbubble cavitation activity in a rat model. This work presents a tool to investigate optimal strategies for non

  4. A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping

    NASA Astrophysics Data System (ADS)

    Deng, Lulu; O'Reilly, Meaghan A.; Jones, Ryan M.; An, Ran; Hynynen, Kullervo

    2016-12-01

    Focused ultrasound (FUS) phased arrays show promise for non-invasive brain therapy. However, the majority of them are limited to a single transmit/receive frequency and therefore lack the versatility to expose and monitor the treatment volume. Multi-frequency arrays could offer variable transmit focal sizes under a fixed aperture, and detect different spectral content on receive for imaging purposes. Here, a three-frequency (306, 612, and 1224 kHz) sparse hemispherical ultrasound phased array (31.8 cm aperture; 128 transducer modules) was constructed and evaluated for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. The array is able to perform effective electronic beam steering over a volume spanning (-40, 40) and (-30, 50) mm in the lateral and axial directions, respectively. The focal size at the geometric center is approximately 0.9 (2.1) mm, 1.7 (3.9) mm, and 3.1 (6.5) mm in lateral (axial) pressure full width at half maximum (FWHM) at 1224, 612, and 306 kHz, respectively. The array was also found capable of dual-frequency excitation and simultaneous multi-foci sonication, which enables the future exploration of more complex exposure strategies. Passive acoustic mapping of dilute microbubble clouds demonstrated that the point spread function of the receive array has a lateral (axial) intensity FWHM between 0.8-3.5 mm (1.7-11.7 mm) over a volume spanning (-25, 25) mm in both the lateral and axial directions, depending on the transmit/receive frequency combination and the imaging location. The device enabled both half and second harmonic imaging through the intact skull, which may be useful for improving the contrast-to-tissue ratio or imaging resolution, respectively. Preliminary in vivo experiments demonstrated the system’s ability to induce blood-brain barrier opening and simultaneously spatially map microbubble cavitation activity in a rat model. This work presents a tool to investigate optimal strategies for non

  5. Pulsed Ultrasound Enhances Nanoparticle Penetration into Breast Cancer Spheroids

    PubMed Central

    Grainger, Stephanie J.; Serna, Juliana Valencia; Sunny, Steffi; Zhou, Yun; Deng, Cheri X.; El-Sayed, Mohamed E.H.

    2010-01-01

    Effective treatment of solid tumors requires homogenous distribution of anticancer drugs within the entire tumor volume to deliver lethal concentrations to resistant cancer cells and tumor-initiating cancer stem cells. However, penetration of small molecular weight chemotherapeutic agents and drug-loaded polymeric and lipid particles into the hypoxic and necrotic regions of solid tumors remains a significant challenge. This article reports the results of pulsed ultrasound enhanced penetration of nano-sized fluorescent particles into MCF-7 breast cancer spheroids (300-350 μm diameter) as a function of particle size and charge. With pulsed ultrasound application in the presence of microbubbles, small (20 nm) particles achieve 6-20 folds higher penetration and concentration in the spheroid's core compared to those not exposed to ultrasound. Increase in particle size to 40 nm and 100 nm results in their effective penetration into the spheroid's core to 9 and 3 folds, respectively. In addition, anionic carboxylate particles achieved higher penetration (2.3, 3.7, and 4.7 folds) into the core (0.25r) of MCF-7 breast cancer spheroids compared to neutral (2.2, 1.9, and 2.4 folds) and cationic particles (1.5, 1.4 and 1.9 folds) upon US exposure for 30, 60, and 90 seconds under the same experimental conditions. These results demonstrate the feasibility of utilizing pulsed ultrasound to increase the penetration of nano-sized particles into MCF-7 spheroids mimicking tumor tissue. The effects of particle properties on the penetration enhancement were also illustrated. PMID:20957996

  6. Cavitation dynamics and directional microbubble ejection induced by intense femtosecond laser pulses in liquids.

    PubMed

    Faccio, D; Tamošauskas, G; Rubino, E; Darginavičius, J; Papazoglou, D G; Tzortzakis, S; Couairon, A; Dubietis, A

    2012-09-01

    We study cavitation dynamics when focusing ring-shaped femtosecond laser beams in water. This focusing geometry reduces detrimental nonlinear beam distortions and enhances energy deposition within the medium, localized at the focal spot. We observe remarkable postcollapse dynamics of elongated cavitation bubbles with high-speed ejection of microbubbles out of the laser focal region. Bubbles are ejected along the laser axis in both directions (away and towards the laser). The initial shape of the cavitation bubble is also seen to either enhance or completely suppress jet formation during collapse. In the absence of jetting, microbubble ejection occurs orthogonal to the laser propagation axis.

  7. Optimization of parameters for photodisruptively nucleated ultrasonic cavitation in water and tissue models

    NASA Astrophysics Data System (ADS)

    Spooner, Greg J. R.; Marre, Gabrielle; Miller, Doug L.; Williams, A. R.

    2000-06-01

    Laser induced optical breakdown (LIOB) in fluids produces a localized plasma, an expanding radial shock wave front, heat transfer from the plasma to the fluid, and the formation of cavitation bubbles. Collectively these phenomena are referred to as photodisruption. Subjecting photodisruptively produced cavitation bubble nuclei to an ultrasonic field can result in strong cavitation and local cellular destruction. The ability of ultrafast lasers to produce spatially localized photodisruptions with microJoule pulse energies in combination with the possibility of larger scale tissue destruction using ultrasound presents an attractive and novel technique for selective and non-invasive tissue modification, referred to as photodisruptively nucleated ultrasonic cavitation (PNUC). Optimization of PNUC parameters in a confocal laser and ultrasound geometry is presented. The cavitation signal as measured with an ultrasound receiver was maximized to determine optimal laser and ultrasound spatial overlap in water. A flow chamber was used to evaluate the effect of the laser and ultrasound parameters on the lysis of whole canine red blood cells in saline. Parameters evaluated included laser pulse energy and ultrasound pressure amplitude.

  8. Inertial cavitation threshold of nested microbubbles.

    PubMed

    Wallace, N; Dicker, S; Lewin, Peter; Wrenn, S P

    2015-04-01

    Cavitation of ultrasound contrast agents (UCAs) promotes both beneficial and detrimental bioeffects in vivo (Radhakrishnan et al., 2013) [1]. The ability to determine the inertial cavitation threshold of UCA microbubbles has potential application in contrast imaging, development of therapeutic agents, and evaluation of localized effects on the body (Ammi et al., 2006) [2]. This study evaluates a novel UCA and its inertial cavitation behavior as determined by a home built cavitation detection system. Two 2.25 MHz transducers are placed at a 90° angle to one another where one transducer is driven by a high voltage pulser and the other transducer receives the signal from the oscillating microbubble. The sample chamber is placed in the overlap of the focal region of the two transducers where the microbubbles are exposed to a pulser signal consisting of 600 pulse trains per experiment at a pulse repetition frequency of 5 Hz where each train has four pulses of four cycles. The formulation being analyzed is comprised of an SF6 microbubble coated by a DSPC PEG-3000 monolayer nested within a poly-lactic acid (PLA) spherical shell. The effect of varying shell diameters and microbubble concentration on cavitation threshold profile for peak negative pressures ranging from 50 kPa to 2 MPa are presented and discussed in this paper. The nesting shell decreases inertial cavitation events from 97.96% for an un-nested microbubble to 19.09% for the same microbubbles nested within a 2.53 μm shell. As shell diameter decreases, the percentage of inertially cavitating microbubbles also decreases. For nesting formulations with average outer capsule diameters of 20.52, 14.95, 9.95, 5.55, 2.53, and 1.95 μm, the percentage of sample destroyed at 1 MPa was 51.02, 38.94, 33.25, 25.27, 19.09, and 5.37% respectively.

  9. Investigation of Cellular and Molecular Responses to Pulsed Focused Ultrasound in a Mouse Model

    PubMed Central

    Burks, Scott R.; Ziadloo, Ali; Hancock, Hilary A.; Chaudhry, Aneeka; Dean, Dana D.; Lewis, Bobbi K.; Frenkel, Victor; Frank, Joseph A.

    2011-01-01

    Continuous focused ultrasound (cFUS) has been widely used for thermal ablation of tissues, relying on continuous exposures to generate temperatures necessary to induce coagulative necrosis. Pulsed FUS (pFUS) employs non-continuous exposures that lower the rate of energy deposition and allow cooling to occur between pulses, thereby minimizing thermal effects and emphasizing effects created by non-thermal mechanisms of FUS (i.e., acoustic radiation forces and acoustic cavitation). pFUS has shown promise for a variety of applications including drug and nanoparticle delivery; however, little is understood about the effects these exposures have on tissue, especially with regard to cellular pro-homing factors (growth factors, cytokines, and cell adhesion molecules). We examined changes in murine hamstring muscle following pFUS or cFUS and demonstrate that pFUS, unlike cFUS, has little effect on the histological integrity of muscle and does not induce cell death. Infiltration of macrophages was observed 3 and 8 days following pFUS or cFUS exposures. pFUS increased expression of several cytokines (e.g., IL-1α, IL-1β, TNFα, INFγ, MIP-1α, MCP-1, and GMCSF) creating a local cytokine gradient on days 0 and 1 post-pFUS that returns to baseline levels by day 3 post-pFUS. pFUS exposures induced upregulation of other signaling molecules (e.g., VEGF, FGF, PlGF, HGF, and SDF-1α) and cell adhesion molecules (e.g., ICAM-1 and VCAM-1) on muscle vasculature. The observed molecular changes in muscle following pFUS may be utilized to target cellular therapies by increasing homing to areas of pathology. PMID:21931834

  10. Localized removal of layers of metal, polymer, or biomaterial by ultrasound cavitation bubbles

    PubMed Central

    Fernandez Rivas, David; Verhaagen, Bram; Seddon, James R. T.; Zijlstra, Aaldert G.; Jiang, Lei-Meng; van der Sluis, Luc W. M.; Versluis, Michel; Lohse, Detlef; Gardeniers, Han J. G. E.

    2012-01-01

    We present an ultrasonic device with the ability to locally remove deposited layers from a glass slide in a controlled and rapid manner. The cleaning takes place as the result of cavitating bubbles near the deposited layers and not due to acoustic streaming. The bubbles are ejected from air-filled cavities micromachined in a silicon surface, which, when vibrated ultrasonically at a frequency of 200 kHz, generate a stream of bubbles that travel to the layer deposited on an opposing glass slide. Depending on the pressure amplitude, the bubble clouds ejected from the micropits attain different shapes as a result of complex bubble interaction forces, leading to distinct shapes of the cleaned areas. We have determined the removal rates for several inorganic and organic materials and obtained an improved efficiency in cleaning when compared to conventional cleaning equipment. We also provide values of the force the bubbles are able to exert on an atomic force microscope tip. PMID:23964308

  11. Small Gas Bubble Experiment for Mitigation of Cavitation Damage and Pressure Waves in Short-pulse Mercury Spallation Targets

    SciTech Connect

    Wendel, Mark W; Felde, David K; Sangrey, Robert L; Abdou, Ashraf A; West, David L; Shea, Thomas J; Hasegawa, Shoichi; Kogawa, Hiroyuki; Naoe, Dr. Takashi; Farny, Dr. Caleb H.; Kaminsky, Andrew L

    2014-01-01

    Populations of small helium gas bubbles were introduced into a flowing mercury experiment test loop to evaluate mitigation of beam-pulse induced cavitation damage and pressure waves. The test loop was developed and thoroughly tested at the Spallation Neutron Source (SNS) prior to irradiations at the Los Alamos Neutron Science Center - Weapons Neutron Research Center (LANSCE-WNR) facility. Twelve candidate bubblers were evaluated over a range of mercury flow and gas injection rates by use of a novel optical measurement technique that accurately assessed the generated bubble size distributions. Final selection for irradiation testing included two variations of a swirl bubbler provided by Japan Proton Accelerator Research Complex (J-PARC) collaborators and one orifice bubbler developed at SNS. Bubble populations of interest consisted of sizes up to 150 m in radius with achieved gas void fractions in the 10^-5 to 10^-4 range. The nominal WNR beam pulse used for the experiment created energy deposition in the mercury comparable to SNS pulses operating at 2.5 MW. Nineteen test conditions were completed each with 100 pulses, including variations on mercury flow, gas injection and protons per pulse. The principal measure of cavitation damage mitigation was surface damage assessment on test specimens that were manually replaced for each test condition. Damage assessment was done after radiation decay and decontamination by optical and laser profiling microscopy with damaged area fraction and maximum pit depth being the more valued results. Damage was reduced by flow alone; the best mitigation from bubble injection was between half and a quarter that of flow alone. Other data collected included surface motion tracking by three laser Doppler vibrometers (LDV), loop wall dynamic strain, beam diagnostics for charge and beam profile assessment, embedded hydrophones and pressure sensors, and sound measurement by a suite of conventional and contact microphones.

  12. The effect of cavitating ultrasound on the aqueous phase hydrogenation of cis-2-buten-1-ol and cis-2-penten-1-ol on Pd-black

    SciTech Connect

    Disselkamp, Robert S.; Denslow, Kayte M.; Hart, Todd R.; White, James F.; Peden, Charles HF.

    2005-07-15

    We have studied the effect of cavitating ultrasound on the heterogeneous aqueous hydrogenation of cis-2-buten-1-ol (C4 olefin) and cis-2-penten-1-ol (C5 olefin) on Pd-black to form the trans-olefins (trans-2-buten-1-ol and trans-2-penten-1-ol) and saturated alcohols (1-butanol and 1-pentanol, respectively). Silent (and magnetically stirred) experiments served as control experiments. As described in an earlier publication by our group, we have added an inert dopant, 1-propanol, in the reaction mixture to ensure the rapid onset of cavitation in the ultrasound-assisted reactions that can lead to altered selectivity compared to silent reaction systems [R.S. Disselkamp, Ya-Huei Chin, C.H.F. Peden, J. Catal. 227 (2004) 552]. The motivation for this study is to examine whether cavitating ultrasound can reduce the [trans-olefin/saturated alcohol] molar ratio during the course of the reaction. This could have practical application in that it may offer an alternative processing methodology of synthesizing healthier edible seed oils by reducing trans-fat content.We have observed that cavitating ultrasound results in a [(trans-olefin/saturated alcohol)ultrasound/(trans-olefin/saturated alcohol)silent] ratio quantity less than 0.5 at the reaction mid-point for both the C4 and C5 olefin systems. This indicates that ultrasound reduces trans-olefin production compared to the silent control experiment. Furthermore, there is an added 30% reduction for the C5 versus C4 olefin compounds again at reaction mid-point. We attribute differences in the ratio quantity as a moment of inertia effect. In principle, the C4 versus C5 olefins has a {approx}52% increase in moment of inertia about C2 C3 double bond slowing isomerization. Since seed oils are C18 multiple cis-olefins and have a moment of inertia even greater than our C5 olefin here, our study suggests that even a greater reduction in trans-olefin content may occur for partial hydrogenation of C18 seed oils.

  13. The Effect of Cavitating Ultrasound on the Aqueous Phase Hydrogenation of Cis-2-buten-1-ol and Cis-2-penten-1-ol on Pd-black

    SciTech Connect

    Disselkamp, Robert S.; Denslow, Kayte M.; Hart, Todd R.; White, James F.; Peden, Charles HF.

    2005-07-15

    We have studied the effect of cavitating ultrasound on the heterogeneous aqueous hydrogenation of cis-2-buten-1-ol (C4 olefin) and cis-2-penten-1-ol (C5 olefin) on Pd-black to form the trans-olefins (trans-2-buten-1-ol and trans-2-penten-1-ol) and saturated alcohols (1-butanol and 1-pentanol, respectively). Silent (and magnetically stirred) experiments served as control experiments. As described in an earlier publication by our group, we have added an inert dopant, 1-propanol, in the reaction mixture to ensure the rapid onset of cavitation in the ultrasound-assisted reactions that can lead to altered selectivity compared to silent reaction systems [Disselkamp et al., J. Catal., 227 (2004) 552]. The motivation for this study is to examine whether cavitating ultrasound can reduce the [trans-olefin/saturated alcohol] molar ratio during the course of the reaction. This could have practical application in that it may offer an alternative processing methodology of synthesizing healthier edible seed oils by reducing trans-fat content. We have observed that cavitating ultrasound results in a [(trans-olefin/saturated alcohol)ultrasound/(trans-olefin/saturated alcohol)silent] ratio quantity less than 0.5 at the reaction mid-point for both the C4 and C5 olefin systems. This indicates that ultrasound reduces trans-olefin production compared to the silent control experiment. Furthermore, there is an added 30% reduction for the C5 versus C4 olefin compounds again at reaction mid-point. We attribute differences in the ratio quantity as a moment of inertia effect. In principle, the C4 versus C5 olefins has a {approx}52% increase in moment of inertia about C2=C3 double bond slowing isomerization. Since seed oils are C18 multiple cis olefins and have an moment of inertia even greater than our C5 olefin here, our study suggests that even a greater reduction in trans-olefin content may occur for partial hydrogenation of C18 seed oils.

  14. Therapeutic efficacy of the combination of doxorubicin-loaded liposomes with inertial cavitation generated by confocal ultrasound in AT2 Dunning rat tumour model.

    PubMed

    Mestas, Jean-Louis; Fowler, R Andrew; Evjen, Tove J; Somaglino, Lucie; Moussatov, Alexei; Ngo, Jacqueline; Chesnais, Sabrina; Røgnvaldsson, Sibylla; Fossheim, Sigrid L; Nilssen, Esben A; Lafon, Cyril

    2014-09-01

    The combination of liposomal doxorubicin (DXR) and confocal ultrasound (US) was investigated for the enhancement of drug delivery in a rat tumour model. The liposomes, based on the unsaturated phospholipid dierucoylphosphocholine, were designed to be stable during blood circulation in order to maximize accumulation in tumour tissue and to release drug content upon US stimulation. A confocal US setup was developed for delivering inertial cavitation to tumours in a well-controlled and reproducible manner. In vitro studies confirm drug release from liposomes as a function of inertial cavitation dose, while in vivo pharmacokinetic studies show long blood circulation times and peak tumour accumulation at 24-48 h post intravenous administration. Animals injected 6 mg kg(-1) liposomal DXR exposed to US treatment 48 h after administration show significant tumour growth delay compared to control groups. A liposomal DXR dose of 3 mg kg(-1), however, did not induce any significant therapeutic response. This study demonstrates that inertial cavitation can be generated in such a fashion as to disrupt drug carrying liposomes which have accumulated in the tumour, and thereby increase therapeutic effect with a minimum direct effect on the tissue. Such an approach is an important step towards a therapeutic application of cavitation-induced drug delivery and reduced chemotherapy toxicity.

  15. Temporal effect of inertial cavitation with and without microbubbles on surface deformation of agarose S gel in the presence of 1-MHz focused ultrasound.

    PubMed

    Tomita, Y; Matsuura, T; Kodama, T

    2015-01-01

    Sonoporation has the potential to deliver extraneous molecules into a target tissue non-invasively. There have been numerous investigations of cell membrane permeabilization induced by microbubbles, but very few studies have been carried out to investigate sonoporation by inertial cavitation, especially from a temporal perspective. In the present paper, we show the temporal variations in nano/micro-pit formations following the collapse of inertial cavitation bubbles, with and without Sonazoid® microbubbles. Using agarose S gel as a target material, erosion experiments were conducted in the presence of 1-MHz focused ultrasound applied for various exposure times, Tex (0.002-60 s). Conventional microscopy was used to measure temporal variations in micrometer-scale pit numbers, and atomic force microscopy utilized to detect surface roughness on a nanometer scale. The results demonstrated that nanometer-scale erosion was predominantly caused by Sonazoid® microbubbles and C4F10 gas bubbles for 0.002 scavitation bubbles such as C4F10 gas bubbles and vapor bubbles, increased exponentially with increasing Tex in the range 0.1 scavitation-induced sonoporation can produce various pore sizes in membranes, enabling the delivery of external molecules of differing sizes into cells or tissues.

  16. Development of Targeted Nanobubbles for Ultrasound Imaging and Ablation of Metastatic Prostate Cancer Lesions

    DTIC Science & Technology

    2014-08-01

    the ultrasound pulses to vaporize the nanodroplets delivered to the surface of the tumor nodules and form gas bubbles. Using the resulting gas...of 1 Hz. The camera was externally triggered from the FPGA board with each ultrasound pulse . The camera recorded 20 images after each pulse . In...different samples at a pulse repetition frequency (PRF) of 0.5 Hz. The PRF was kept very low to minimize the possibility that cavitation from 1

  17. Controlled permeation of cell membrane by single bubble acoustic cavitation.

    PubMed

    Zhou, Y; Yang, K; Cui, J; Ye, J Y; Deng, C X

    2012-01-10

    Sonoporation is the membrane disruption generated by ultrasound and has been exploited as a non-viral strategy for drug and gene delivery. Acoustic cavitation of microbubbles has been recognized to play an important role in sonoporation. However, due to the lack of adequate techniques for precise control of cavitation activities and real-time assessment of the resulting sub-micron process of sonoporation, limited knowledge has been available regarding the detail processes and correlation of cavitation with membrane disruption at the single cell level. In the current study, we developed a combined approach including optical, acoustical, and electrophysiological techniques to enable synchronized manipulation, imaging, and measurement of cavitation of single bubbles and the resulting cell membrane disruption in real-time. Using a self-focused femtosecond laser and high frequency ultrasound (7.44MHz) pulses, a single microbubble was generated and positioned at a desired distance from the membrane of a Xenopus oocyte. Cavitation of the bubble was achieved by applying a low frequency (1.5MHz) ultrasound pulse (duration 13.3 or 40μs) to induce bubble collapse. Disruption of the cell membrane was assessed by the increase in the transmembrane current (TMC) of the cell under voltage clamp. Simultaneous high-speed bright field imaging of cavitation and measurements of the TMC were obtained to correlate the ultrasound-generated bubble activities with the cell membrane poration. The change in membrane permeability was directly associated with the formation of a sub-micrometer pore from a local membrane rupture generated by bubble collapse or bubble compression depending on ultrasound amplitude and duration. The impact of the bubble collapse on membrane permeation decreased rapidly with increasing distance (D) between the bubble (diameter d) and the cell membrane. The effective range of cavitation impact on membrane poration was determined to be D/d=0.75. The maximum mean

  18. Pre-breakdown cavitation nanopores in the dielectric fluid in the inhomogeneous, pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Pekker, Mikhail; Shneider, Mikhail N.

    2015-10-01

    This paper discusses the nanopores emerging and developing in a liquid dielectric under the action of the ponderomotive electrostrictive forces in a nonuniform electric field. It is shown that the gradient of the electric field in the vicinity of the rupture (cavitation nanopore) substantially increases and determines whether the rupture grows or collapses. The cavitation rupture in the liquid (nanopore) tends to stretch along the lines of the original field. The mechanism of the breakdown associated with the generation of secondary ruptures in the vicinity of the poles of the nanopore is proposed. The estimations of the extension time for nanopore in water and oil (polar and nonpolar liquids, respectively) are presented. A new mechanism of nano- and subnanosecond breakdown in the insulating (transformer) oil that can be realized in the vicinity of water microdroplets in nanosecond high-voltage devices is considered.

  19. Antitumor effect of microbubbles enhanced by low frequency ultrasound cavitation on prostate carcinoma xenografts in nude mice

    PubMed Central

    WANG, YU; HU, BING; DIAO, XUEHONG; ZHANG, JIZHEN

    2012-01-01

    The aim of this study was to investigate the antitumor effect induced by low frequency (20 kHz) ultrasound (US) radiation combined with intravenous injection of microbubbles (Mbs) on prostate carcinoma Du145 xenografts in nude mice. Du145 prostate tumors were percutaneously implanted in 40 nude mice, which were randomly divided into 4 groups (n=10 each): US+Mbs, US, Mbs and control groups. The mice in the US+Mbs group were treated with 20 kHz, 200 mW/cm2 US radiation and with 0.2 ml Mbs injected intravenously. Mice in the US and Mbs groups were only treated with US radiation and injection of Mbs, respectively. Tumors were measured with sonography, and the ratio of antitumor growth was calculated. The mice were sacrificed 14 days after treatment. Specimens of the tumor tissues were observed pathologically using light microscopy and transmission electron microscopy. Microvessel density and the average optical density of vascular endothelial growth factor were compared among groups by immunohistochemistry. The average gross tumor volume of the US+Mbs group was significantly reduced compared with the other groups following treatment (P<0.05). The ratio of the antitumor growth in the US+Mbs group was significantly greater than that of the US and Mbs group (P<0.05). Histological examination showed signs of tumor cell injury in the US+Mbs group. Examination by electron microscopy revealed vessel injury in the endothelium in the tumors treated with US+Mbs. Microvessel density and the average optical density of vascular endothelial growth factor in the US+Mbs group were significantly less than that of other groups (P<0.05). In conclusion, low frequency US of 20 kHz radiation combined with Mbs may be used to inhibit the growth of human prostate carcinoma xenografts in nude mice, and the effect is likely realized through microvessel destruction caused by cavitation. PMID:22969866

  20. Antitumor effect of microbubbles enhanced by low frequency ultrasound cavitation on prostate carcinoma xenografts in nude mice.

    PubMed

    Wang, Yu; Hu, Bing; Diao, Xuehong; Zhang, Jizhen

    2012-02-01

    The aim of this study was to investigate the antitumor effect induced by low frequency (20 kHz) ultrasound (US) radiation combined with intravenous injection of microbubbles (Mbs) on prostate carcinoma Du145 xenografts in nude mice. Du145 prostate tumors were percutaneously implanted in 40 nude mice, which were randomly divided into 4 groups (n=10 each): US+Mbs, US, Mbs and control groups. The mice in the US+Mbs group were treated with 20 kHz, 200 mW/cm(2) US radiation and with 0.2 ml Mbs injected intravenously. Mice in the US and Mbs groups were only treated with US radiation and injection of Mbs, respectively. Tumors were measured with sonography, and the ratio of antitumor growth was calculated. The mice were sacrificed 14 days after treatment. Specimens of the tumor tissues were observed pathologically using light microscopy and transmission electron microscopy. Microvessel density and the average optical density of vascular endothelial growth factor were compared among groups by immunohistochemistry. The average gross tumor volume of the US+Mbs group was significantly reduced compared with the other groups following treatment (P<0.05). The ratio of the antitumor growth in the US+Mbs group was significantly greater than that of the US and Mbs group (P<0.05). Histological examination showed signs of tumor cell injury in the US+Mbs group. Examination by electron microscopy revealed vessel injury in the endothelium in the tumors treated with US+Mbs. Microvessel density and the average optical density of vascular endothelial growth factor in the US+Mbs group were significantly less than that of other groups (P<0.05). In conclusion, low frequency US of 20 kHz radiation combined with Mbs may be used to inhibit the growth of human prostate carcinoma xenografts in nude mice, and the effect is likely realized through microvessel destruction caused by cavitation.

  1. Pulsed Ultrasound Enhances the Killing of Escherichia coli Biofilms by Aminoglycoside Antibiotics In Vivo

    PubMed Central

    Rediske, Andrea M.; Roeder, Beverly L.; Nelson, Jared L.; Robison, Rachel L.; Schaalje, G. Bruce; Robison, Richard A.; Pitt, William G.

    2000-01-01

    Escherichia coli biofilms on two polyethylene disks were implanted subcutaneously into rabbits receiving systemic gentamicin. Ultrasound was applied for 24 h to one disk. Both disks were removed, and viable bacteria were counted. Pulsed ultrasound significantly reduced bacterial viability below that of nontreated biofilms without damage to the skin. PMID:10681355

  2. Study of the onset of the acoustic streaming in parallel plate resonators with pulse ultrasound.

    PubMed

    Castro, Angelica; Hoyos, Mauricio

    2016-03-01

    In a previous study, we introduced pulse mode ultrasound as a new method for reducing and controlling the acoustic streaming in parallel plate resonators (Hoyos and Castro, 2013). Here, by modifying other parameters such as the resonator geometry and the particle size, we have found a threshold for particle manipulation with ultrasonic standing waves in confined resonators without the influence of the acoustic streaming. We demonstrate that pulse mode ultrasound open the possibility of manipulating particles smaller than 1 μm size.

  3. Pulsed ultrasound expands the extracellular and perivascular spaces of the brain.

    PubMed

    Hersh, David S; Nguyen, Ben A; Dancy, Jimena G; Adapa, Arjun R; Winkles, Jeffrey A; Woodworth, Graeme F; Kim, Anthony J; Frenkel, Victor

    2016-09-01

    Diffusion within the extracellular and perivascular spaces of the brain plays an important role in biological processes, therapeutic delivery, and clearance mechanisms within the central nervous system. Recently, ultrasound has been used to enhance the dispersion of locally administered molecules and particles within the brain, but ultrasound-mediated effects on the brain parenchyma remain poorly understood. We combined an electron microscopy-based ultrastructural analysis with high-resolution tracking of non-adhesive nanoparticles in order to probe changes in the extracellular and perivascular spaces of the brain following a non-destructive pulsed ultrasound regimen known to alter diffusivity in other tissues. Freshly obtained rat brain neocortical slices underwent sham treatment or pulsed, low intensity ultrasound for 5min at 1MHz. Transmission electron microscopy revealed intact cells and blood vessels and evidence of enlarged spaces, particularly adjacent to blood vessels, in ultrasound-treated brain slices. Additionally, ultrasound significantly increased the diffusion rate of 100nm, 200nm, and 500nm nanoparticles that were injected into the brain slices, while 2000nm particles were unaffected. In ultrasound-treated slices, 91.6% of the 100nm particles, 20.7% of the 200nm particles, 13.8% of the 500nm particles, and 0% of the 2000nm particles exhibited diffusive motion. Thus, pulsed ultrasound can have meaningful structural effects on the brain extracellular and perivascular spaces without evidence of tissue disruption.

  4. Application of ultrasound in periodontics: Part I

    PubMed Central

    Bains, Vive K.; Mohan, Ranjana; Bains, Rhythm

    2008-01-01

    Ultrasonic is a branch of acoustics concerned with sound vibrations in frequency ranges above audible level. Ultrasound uses the transmission and reflection of acoustic energy. A pulse is propagated and its reflection is received, both by the transducer. For clinical purposes ultrasound is generated by transducers, which converts electrical energy into ultrasonic waves. This is usually achieved by magnetostriction or piezoelectricity. Primary effects of ultrasound are thermal, mechanical (cavitation and microstreaming), and chemical (sonochemicals). Knowledge of the basic and other secondary effects of ultrasound is essential for the development of techniques of application. PMID:20142941

  5. Relations between acoustic cavitation and skin resistance during intermediate- and high-frequency sonophoresis.

    PubMed

    Rich, Kyle T; Hoerig, Cameron L; Rao, Marepalli B; Mast, T Douglas

    2014-11-28

    Enhanced skin permeability is known to be achieved during sonophoresis due to ultrasound-induced cavitation. However, the mechanistic role of cavitation during sonophoresis has been extensively investigated only for low-frequency (LFS, <100 kHz) applications. Here, mechanisms of permeability-enhancing stable and inertial cavitation were investigated by passively monitoring subharmonic and broadband emissions arising from cavitation isolated within or external to porcine skin in vitro during intermediate- (IFS, 100-700 kHz) and high-frequency sonophoresis (HFS, >1 MHz). The electrical resistance of skin, a surrogate measure of the permeability of skin to a variety of compounds, was measured to quantify the reduction and subsequent recovery of the skin barrier during and after exposure to pulsed (1 second pulse, 20% duty cycle) 0.41 and 2.0 MHz ultrasound over a range of acoustic powers (0-21.7 W) for 30 min. During IFS, significant skin resistance reductions and acoustic emissions from cavitation were measured exclusively when cavitation was isolated outside of the skin. Time-dependent skin resistance reductions measured during IFS correlated significantly with subharmonic and broadband emission levels. During HFS, significant skin resistance reductions were accompanied by significant acoustic emissions from cavitation measured during trials that isolated cavitation activity either outside of skin or within skin. Time-dependent skin resistance reductions measured during HFS correlated significantly greater with subharmonic than with broadband emission levels. The reduction of the skin barrier due to sonophoresis was reversible in all trials; however, effects incurred during IFS recovered more slowly and persisted over a longer period of time than HFS. These results quantitatively demonstrate the significance of cavitation during sonophoresis and suggest that the mechanisms and post-treatment longevity of permeability enhancement due to IFS and HFS treatments are

  6. All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2016-02-01

    High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

  7. Low-intensity pulsed ultrasound in dentofacial tissue engineering.

    PubMed

    Tanaka, Eiji; Kuroda, Shingo; Horiuchi, Shinya; Tabata, Akira; El-Bialy, Tarek

    2015-04-01

    Oral and maxillofacial diseases affect millions of people worldwide and hence tissue engineering can be considered an interesting and clinically relevant approach to regenerate orofacial tissues after being affected by different diseases. Among several innovations for tissue regeneration, low-intensity pulsed ultrasound (LIPUS) has been used extensively in medicine as a therapeutic, operative, and diagnostic tool. LIPUS is accepted to promote bone fracture repair and regeneration. Furthermore, the effect of LIPUS on soft tissues regeneration has been paid much attention, and many studies have performed to evaluate the potential use of LIPUS to tissue engineering soft tissues. The present article provides an overview about the status of LIPUS stimulation as a tool to be used to enhance regeneration/tissue engineering. This review consists of five parts. Part 1 is a brief introduction of the acoustic description of LIPUS and mechanical action. In Part 2, biological problems in dentofacial tissue engineering are proposed. Part 3 explores biologic mechanisms of LIPUS to cells and tissues in living body. In Part 4, the effectiveness of LIPUS on cell metabolism and tissue regeneration in dentistry are summarized. Finally, Part 5 relates the possibility of clinical application of LIPUS in orthodontics. The present review brings out better understanding of the bioeffect of LIPUS therapy on orofacial tissues which is essential to the successful integration of management remedies for tissue regeneration/engineering. To develop an evidence-based approach to clinical management and treatment of orofacial degenerative diseases using LIPUS, we would like to be in full pursuit of LIPUS biotherapy. Still, there are many challenges for this relatively new strategy, but the up to date achievements using it promises to go far beyond the present possibilities.

  8. GPU simulation of nonlinear propagation of dual band ultrasound pulse complexes

    SciTech Connect

    Kvam, Johannes Angelsen, Bjørn A. J.; Elster, Anne C.

    2015-10-28

    In a new method of ultrasound imaging, called SURF imaging, dual band pulse complexes composed of overlapping low frequency (LF) and high frequency (HF) pulses are transmitted, where the frequency ratio LF:HF ∼ 1 : 20, and the relative bandwidth of both pulses are ∼ 50 − 70%. The LF pulse length is hence ∼ 20 times the HF pulse length. The LF pulse is used to nonlinearly manipulate the material elasticity observed by the co-propagating HF pulse. This produces nonlinear interaction effects that give more information on the propagation of the pulse complex. Due to the large difference in frequency and pulse length between the LF and the HF pulses, we have developed a dual level simulation where the LF pulse propagation is first simulated independent of the HF pulse, using a temporal sampling frequency matched to the LF pulse. A separate equation for the HF pulse is developed, where the the presimulated LF pulse modifies the propagation velocity. The equations are adapted to parallel processing in a GPU, where nonlinear simulations of a typical HF beam of 10 MHz down to 40 mm is done in ∼ 2 secs in a standard GPU. This simulation is hence very useful for studying the manipulation effect of the LF pulse on the HF pulse.

  9. Arterial pulse wave propagation velocity in healthy dogs by pulse wave Doppler ultrasound.

    PubMed

    Nogueira, Rodrigo B; Pereira, Lucas A; Basso, Alice F; da Fonseca, Ingrid S; Alves, Lorena A

    2017-03-01

    The aim of this study was to prospectively evaluate the carotid-femoral pulse wave velocity (PWV) values in healthy dogs using pulse wave Doppler ultrasound. A secondary aim was to determine the feasibility of this method and to report the intra- and interobserver reproducibilities of the PWV in conscious dogs. The data were studied in 30 healthy, adult, male (n = 15) and female (n = 15) dogs. The time interval marked between the R wave peak of the electrocardiogram and the intersection of the blood flow wave upstroke of the Doppler spectrum with the baseline of zero frequency was determined for the carotid (T1) and for the femoral (T2) arteries. The distance covered by the pulse wave (L) was determined. The PWV was then calculated using the following formula: L/T2 - T1. The mean values of PWV calculated from the total sample (n = 30) evaluated were 13.41 ± 2.20 m/s. No significant statistical difference was observed for the PWV measurements between males (14.82 ± 3.18 m/s) and females (12.64 ± 2.45 m/s). The analysis revealed no intra nor interobserver differences. A reasonable reproducibility of the PWV measurements was showed by intraclass correlation coefficients (ICC), and the coefficients of variation (CV). These data demonstrate that noninvasive vascular Doppler analysis is a feasible and reproducible method to determine the carotid-femoral PWV in dogs.

  10. CO2 bubbling-based 'Nanobomb' System for Targetedly Suppressing Panc-1 Pancreatic Tumor via Low Intensity Ultrasound-activated Inertial Cavitation.

    PubMed

    Zhang, Kun; Xu, Huixiong; Chen, Hangrong; Jia, Xiaoqing; Zheng, Shuguang; Cai, Xiaojun; Wang, Ronghui; Mou, Juan; Zheng, Yuanyi; Shi, Jianlin

    2015-01-01

    Noninvasive and targeted physical treatment is still desirable especially for those cancerous patients. Herein, we develop a new physical treatment protocol by employing CO2 bubbling-based 'nanobomb' system consisting of low-intensity ultrasound (1.0 W/cm(2)) and a well-constructed pH/temperature dual-responsive CO2 release system. Depending on the temperature elevation caused by exogenous low-intensity therapeutic ultrasound irradiation and the low pH caused by the endogenous acidic-environment around/within tumor, dual-responsive CO2 release system can quickly release CO2 bubbles, and afterwards, the generated CO2 bubbles waves will timely explode before dissolution due to triggering by therapeutic ultrasound waves. Related bio-effects (e.g., cavitation, mechanical, shock waves, etc) caused by CO2 bubbles' explosion effectively induce instant necrosis of panc-1 cells and blood vessel destruction within panc-1 tumor, and consequently inhibit the growth of panc-1 solid tumor, simultaneously minimizing the side effects to normal organs. This new physiotherapy employing CO2 bubbling-based 'nanobomb' system promises significant potentials in targetedly suppressing tumors, especially for those highly deadly cancers.

  11. CO2 bubbling-based 'Nanobomb' System for Targetedly Suppressing Panc-1 Pancreatic Tumor via Low Intensity Ultrasound-activated Inertial Cavitation

    PubMed Central

    Zhang, Kun; Xu, Huixiong; Chen, Hangrong; Jia, Xiaoqing; Zheng, Shuguang; Cai, Xiaojun; Wang, Ronghui; Mou, Juan; Zheng, Yuanyi; Shi, Jianlin

    2015-01-01

    Noninvasive and targeted physical treatment is still desirable especially for those cancerous patients. Herein, we develop a new physical treatment protocol by employing CO2 bubbling-based 'nanobomb' system consisting of low-intensity ultrasound (1.0 W/cm2) and a well-constructed pH/temperature dual-responsive CO2 release system. Depending on the temperature elevation caused by exogenous low-intensity therapeutic ultrasound irradiation and the low pH caused by the endogenous acidic-environment around/within tumor, dual-responsive CO2 release system can quickly release CO2 bubbles, and afterwards, the generated CO2 bubbles waves will timely explode before dissolution due to triggering by therapeutic ultrasound waves. Related bio-effects (e.g., cavitation, mechanical, shock waves, etc) caused by CO2 bubbles' explosion effectively induce instant necrosis of panc-1 cells and blood vessel destruction within panc-1 tumor, and consequently inhibit the growth of panc-1 solid tumor, simultaneously minimizing the side effects to normal organs. This new physiotherapy employing CO2 bubbling-based 'nanobomb' system promises significant potentials in targetedly suppressing tumors, especially for those highly deadly cancers. PMID:26379793

  12. Remote Control of Intact Mammalian Brain Circuits Using Pulsed Ultrasound

    DTIC Science & Technology

    2012-12-31

    neuromodulation by brain stimulation with transcranial ultrasound, Nature Protocols, (09 2011): 1453. doi: 10.1038/nprot.2011.371 04/26/2012 2.00...is outlined. We initiated a series of investigations aimed at developing noninvasive brain stimulation methods employing ultrasound. We indeed...circuits with a spatial resolution approximately five times better than other noninvasive state-of-the-art brain stimulation methods such as TMS and

  13. Effect of low-intensity pulsed ultrasound on l929 fibroblasts

    PubMed Central

    Franco de Oliveira, Rodrigo; Pires Oliveira, Deise A. A.; Soares, Cristina Pacheco

    2011-01-01

    Introduction Ultrasound has proven to be an important therapeutic resource regarding musculoskeletal disease and is routinely used in physical therapy and medicine both therapeutically and diagnostically. The aim of the present study was to analyse the effects with different ultrasound intensities in order to establish the ideal radiation level in cell cultures. Material and methods Fibroblast cell cultures were divided into five groups: group I – control (did not receive irradiation); group II – 0.2 W/cm2 in pulsed mode at 10% (1 : 9 duty cycle); group III – 0.6 W/cm2 in pulsed mode at 10% (1 : 9 duty cycle); group IV – 0.2 W/cm2 in pulsed mode at 20% (2 : 8 duty cycle); and group V – 0.6 W/cm2 in pulsed mode at 20% (2 : 8 duty cycle). Each group was irradiated with 24-h intervals, observing the following post-irradiation incubation times: 24, 48, 72 and 96 h; after 24 h of each irradiation, cultures were analysed using the MTT method. Results Analysis of the results following ultrasound irradiation demonstrated that the effect of ultrasound with 0.6 W/cm2 in pulsed mode at 10% (1 : 9 duty cycle) was statistically significant in relation to ultrasonic irradiation in pulsed mode at 20% (2 : 8 duty cycle) (p < 0.05). Conclusions According to parameters used in the irradiation of cultivated fibroblasts, the pulse mode regime and the control of intensity are of fundamental importance for the optimal use of therapeutic ultrasound. Furthermore, low and medium intensities decreased cell damage, which establishes that acoustic pulsed energy induces the proliferation of fibroblast cells. PMID:22291760

  14. Cardiac arrhythmias produced by ultrasound and contrast agents

    NASA Astrophysics Data System (ADS)

    Rota, Claudio

    Ultrasound is used widely in medicine for both diagnostic and therapeutic applications. Ultrasound contrast agents are suspensions of gas-filled microbubbles used to enhance diagnostic imaging. Microbubble contrast agents can increase the likelihood of bioeffects of ultrasound associated with acoustic cavitation. Under certain exposure conditions, the interaction of ultrasound with cardiac tissues can produce cardiac arrhythmias. The general objective of this thesis was to develop a greater understanding of ultrasound-induced premature cardiac beats. The hypothesis guiding this work was that acoustic cavitation is the physical mechanism for the production of arrhythmias with ultrasound. This hypothesis was tested through a series of experiments with mice in vivo and theoretical investigations. Results of this research supported the acoustic cavitation hypothesis. The acoustic pressure threshold for premature beats was significantly lower with microbubble contrast agents present in the blood than without. With microbubbles, the threshold for premature beats was below the current output limits of diagnostic devices. The threshold was not significantly dependent upon contrast agent type and was not influenced by contrast agent dose over three orders of magnitude. Furthermore, the dependence of the threshold on acoustic frequency was consistent with the frequency dependence of acoustic cavitation. Experimentally determined thresholds for premature beats in vivo were in excellent agreement with theoretically estimated thresholds for inertial cavitation. A passive cavitation detector (PCD) was used to measure the acoustic emissions produced by cavitating microbubbles in vivo. A direct correlation between the amplitude of the PCD and the percentage of ultrasound pulses producing a premature beat was consistent with cavitation as a mechanism for this bioeffect. Although this thesis focused on the mechanistic understanding of ultrasound-induced arrhythmias, more persistent

  15. Role of H2O2 in the fluctuating patterns of COD (chemical oxygen demand) during the treatment of palm oil mill effluent (POME) using pilot scale triple frequency ultrasound cavitation reactor.

    PubMed

    Manickam, Sivakumar; Abidin, Norhaida binti Zainal; Parthasarathy, Shridharan; Alzorqi, Ibrahim; Ng, Ern Huay; Tiong, Timm Joyce; Gomes, Rachel L; Ali, Asgar

    2014-07-01

    Palm oil mill effluent (POME) is a highly contaminating wastewater due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Conventional treatment methods require longer residence time (10-15 days) and higher operating cost. Owing to this, finding a suitable and efficient method for the treatment of POME is crucial. In this investigation, ultrasound cavitation technology has been used as an alternative technique to treat POME. Cavitation is the phenomenon of formation, growth and collapse of bubbles in a liquid. The end process of collapse leads to intense conditions of temperature and pressure and shock waves which assist various physical and chemical transformations. Two different ultrasound systems i.e. ultrasonic bath (37 kHz) and a hexagonal triple frequency ultrasonic reactor (28, 40 and 70 kHz) of 15 L have been used. The results showed a fluctuating COD pattern (in between 45,000 and 60,000 mg/L) while using ultrasound bath alone, whereas a non-fluctuating COD pattern with a final COD of 27,000 mg/L was achieved when hydrogen peroxide was introduced. Similarly for the triple frequency ultrasound reactor, coupling all the three frequencies resulted into a final COD of 41,300 mg/L compared to any other individual or combination of two frequencies. With the possibility of larger and continuous ultrasonic cavitational reactors, it is believed that this could be a promising and a fruitful green process engineering technique for the treatment of POME.

  16. Cavitation inception by the backscattering of pressure waves from a bubble interface

    SciTech Connect

    Takahira, Hiroyuki Ogasawara, Toshiyuki Mori, Naoto Tanaka, Moe

    2015-10-28

    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  17. Variations of bubble cavitation and temperature elevation during acculysis

    NASA Astrophysics Data System (ADS)

    Zhou, Yufeng; Gao, Xiaobin Wilson

    2017-03-01

    High-intensity focused ultrasound (HIFU) is effective in both thermal ablations and soft-tissue fragmentation. Mechanical and thermal effects depend on the operating parameters and vary with the progress of therapy. Different types of lesions could be produced with the pulse duration of 5-30 ms, much longer than histotripsy burst but shorter than the time for tissue boiling, and pulse repetition frequency (PRF) of 0.2-5 Hz. Meanwhile, bubble cavitation and temperature elevation in the focal region were measured by passive cavitation detection (PCD) and thermocouples, respectively. Temperature in the pre-focal region is always higher than those at the focal and post-focal position in all tests. Overall, it is suggested that appropriate synergy and monitoring of mechanical and thermal effects would broaden the HIFU application and enhance its efficiency as well as safety.

  18. Pulsed Ultrasound Fails To Diminish Delayed-Onset Muscle Soreness Symptoms

    PubMed Central

    Stay, Jeffrey C.; Richard, Mark D.; Draper, David O.; Schulthies, Shane S.; Durrant, Earlene

    1998-01-01

    Objective: We investigated the effects of pulsed ultrasound on swelling, muscle soreness perception, relaxed-elbow extension angle, and muscular strength. Design and Setting: Eight sets of concentric and eccentric actions induced delayed-onset muscle soreness of the elbow flexors. Group 1 received 20% pulsed ultrasound treatments (1-MHz, 7 minutes, 1.5 W/ cm2 temporal peak intensity) twice a day immediately after postexercise assessments and at 3, 24, 27, 48, 51, 72, and 75 hours postexercise. Group 2 received sham treatments immediately after postexercise assessments and at 3,27, 51, and 75 hours postexercise and true treatments of pulsed ultrasound at 24, 48, and 72 hours postexercise. Group 3 received sham treatments of no ultrasonic output immediately after postexercise assessments and at 3, 24, 27, 48, 51, 72, and 75 hours postexercise. Subjects: Thirty-six college-age females. Measurements: We recorded upper-arm circumference, perceived soreness, relaxed-elbow extension angle, and elbow-flexion strength before (pretest), immediately postexercise, and at 24, 48, 72, and 96 hours postexercise. Results: We noted differences over time but no treatment effect between groups or interactions between time and group for upper-arm circumference, perceived soreness, relaxed-elbow extension angle, or elbow-flexion strength. Conclusions: Pulsed ultrasound as used in this study did not significantly diminish the effects of delayed-onset muscle soreness on soreness perception, swelling, relaxed-elbow extension angle, and strength. PMID:16558532

  19. Direct Measurement of Basilar Membrane Motion Using Pulsed-Wave Doppler High-Frequency Ultrasound

    NASA Astrophysics Data System (ADS)

    Torbatian, Z.; Garland, P.; Adamson, R. B. A.; Bance, M.; Brown, J. A.

    2011-11-01

    We present a preliminary report on the use of a new technique for measuring the motion of the basilar membrane, high-frequency ultrasound Doppler vibrometry. Using a custom-built, 1 mm diameter probe, we collected ultrasonic reflections from intracochlear structures and applied pulsed-wave Doppler vibrometry to measure the basilar membrane response to pressure applied in the ear canal.

  20. Predicting the growth of nanoscale nuclei by histotripsy pulses

    PubMed Central

    Bader, Kenneth B; Holland, Christy K

    2016-01-01

    Histotripsy is a focused ultrasound therapy that ablates tissue through the mechanical action of cavitation. Histotripsy-initiated cavitation activity is generated from shocked ultrasound pulses that scatter from incidental nuclei (shock scattering histotripsy), or purely tensile ultrasound pulses (microtripsy). The Yang/Church model was numerically integrated to predict the behavior of the cavitation nuclei exposed to measured shock scattering histotripsy pulses. The bubble motion exhibited expansion only behavior, suggesting that the ablative action of a histotripsy pulse is related to the maximum size of the bubble. The analytic model of Holland and Apfel was extended to predict the maximum size of cavitation nuclei for both shock scattering histotripsy and microtripsy excitations. The predictions of the analytic model and the numerical model agree within 2% for fully developed shock scattering histotripsy pulses (>72 MPa peak positive pressure). For shock scattering histotripsy pulses that are not fully developed (<72 MPa), the analytic model underestimated the maximum size by less than 5%. The analytic model was also used to predict bubble growth nucleated from microtripsy insonations, and was found to be consistent with experimental observations. Based on the extended analytic model, metrics were developed to predict the extent of the treatment zone from histotripsy pulses. PMID:26988374

  1. Effects of Temperature on the Histotripsy Intrinsic Threshold for Cavitation.

    PubMed

    Vlaisavljevich, Eli; Xu, Zhen; Maxwell, Adam; Mancia, Lauren; Zhang, Xi; Lin, Kuang-Wei; Duryea, Alexander; Sukovich, Jonathan; Hall, Tim; Johnsen, Eric; Cain, Charles

    2016-05-10

    Histotripsy is an ultrasound ablation method that depends on the initiation of a dense cavitation bubble cloud to fractionate soft tissue. Previous work has demonstrated that a cavitation cloud can be formed by a single acoustic pulse with one high amplitude negative cycle, when the negative pressure amplitude exceeds a threshold intrinsic to the medium. The intrinsic thresholds in soft tissues and tissue phantoms that are water-based are similar to the intrinsic threshold of water over an experimentally verified frequency range of 0.3-3 MHz. Previous work studying the histotripsy intrinsic threshold has been limited to experiments performed at room temperature (~20°C). In this study, we investigate the effects of temperature on the histotripsy intrinsic threshold in water, which is essential to accurately predict the intrinsic thresholds expected over the full range of in vivo therapeutic temperatures. Based on previous work studying the histotripsy intrinsic threshold and classical nucleation theory, we hypothesize that the intrinsic threshold will decrease with increasing temperature. To test this hypothesis, the intrinsic threshold in water was investigated both experimentally and theoretically. The probability of generating cavitation bubbles was measured by applying a single pulse with one high amplitude negative cycle at 1 MHz to distilled, degassed water at temperatures ranging from 10°C-90°C. Cavitation was detected and characterized by passive cavitation detection and high-speed photography, from which the probability of cavitation was measured vs. pressure amplitude. The results indicate that the intrinsic threshold (the negative pressure at which the cavitation probability=0.5) significantly decreases with increasing temperature, showing a nearly linear decreasing trend from 29.8±0.4 MPa at 10˚C to 14.9±1.4 MPa at 90˚C. Overall, the results of this study support our hypothesis that the intrinsic threshold is highly dependent upon the temperature

  2. Influence of shock wave pressure amplitude and pulse repetition frequency on the lifespan, size and number of transient cavities in the field of an electromagnetic lithotripter

    NASA Astrophysics Data System (ADS)

    Huber, Peter; Jöchle, Knut; Debus, Jürgen

    1998-10-01

    Monitoring the generation of cavitation is of great interest for diagnostic and therapeutic use of ultrasound in medicine, since cavitation is considered to play a major role in nonthermal ultrasound interactions with tissue. Important parameters are the number of cavitation events and the energy released during the bubble collapse. This energy is correlated to the maximum bubble radius which is related to the cavitation lifespan. The aim of this study was therefore to investigate the influence of the acoustic pressure amplitude and the pulse repetition frequency (PRF) in the field of a lithotripter (Lithostar, Siemens) on the number, size and lifespan of transient cavitation bubbles in water. We used scattered laser light recorded by a photodiode and stroboscopic photographs to monitor the cavitation activity. We found that PRF (range 0.5-5 Hz) had no influence on the cavitation bubble lifespan and size, whereas lifespan and size increased with the acoustic pressure amplitude. In contrast, the number of cavitation events strongly increased with PRF, whereas the pressure amplitude had no significant influence on the number of cavitation events. Thus, by varying the pressure amplitude and PRF, it might be possible to deliver a defined relative number of cavitations at a defined relative energy level in a defined volume. This seems to be relevant to further studies that address the biological effects of transient cavitation occurring in the fields of lithotripters.

  3. Dynamics of shock waves and cavitation bubbles in bilinear elastic-plastic media, and the implications to short-pulsed laser surgery

    NASA Astrophysics Data System (ADS)

    Brujan, E.-A.

    2005-01-01

    The dynamics of shock waves and cavitation bubbles generated by short laser pulses in water and elastic-plastic media were investigated theoretically in order to get a better understanding of their role in short-pulsed laser surgery. Numerical simulations were performed using a spherical model of bubble dynamics which include the elastic-plastic behaviour of the medium surrounding the bubble, compressibility, viscosity, density and surface tension. Breakdown in water produces a monopolar acoustic signal characterized by a compressive wave. Breakdown in an elastic-plastic medium produces a bipolar acoustic signal, with a leading positive compression wave and a trailing negative tensile wave. The calculations revealed that consideration of the tissue elasticity is essential to describe the bipolar shape of the shock wave emitted during optical breakdown. The elastic-plastic response of the medium surrounding the bubble leads to a significant decrease of the maximum size of the cavitation bubble and pressure amplitude of the shock wave emitted during bubble collapse, and shortening of the oscillation period of the bubble. The results are discussed with respect to collateral damage in short-pulsed laser surgery.

  4. Cavitation clouds created by shock scattering from bubbles during histotripsy.

    PubMed

    Maxwell, Adam D; Wang, Tzu-Yin; Cain, Charles A; Fowlkes, J Brian; Sapozhnikov, Oleg A; Bailey, Michael R; Xu, Zhen

    2011-10-01

    Histotripsy is a therapy that focuses short-duration, high-amplitude pulses of ultrasound to incite a localized cavitation cloud that mechanically breaks down tissue. To investigate the mechanism of cloud formation, high-speed photography was used to observe clouds generated during single histotripsy pulses. Pulses of 5-20 cycles duration were applied to a transparent tissue phantom by a 1-MHz spherically focused transducer. Clouds initiated from single cavitation bubbles that formed during the initial cycles of the pulse, and grew along the acoustic axis opposite the propagation direction. Based on these observations, we hypothesized that clouds form as a result of large negative pressure generated by the backscattering of shockwaves from a single bubble. The positive-pressure phase of the wave inverts upon scattering and superimposes on the incident negative-pressure phase to create this negative pressure and cavitation. The process repeats with each cycle of the incident wave, and the bubble cloud elongates toward the transducer. Finite-amplitude propagation distorts the incident wave such that the peak-positive pressure is much greater than the peak-negative pressure, which exaggerates the effect. The hypothesis was tested with two modified incident waves that maintained negative pressure but reduced the positive pressure amplitude. These waves suppressed cloud formation which supported the hypothesis.

  5. Characterization and Ultrasound-Pulse Mediated Destruction of Ultrasound Contrast Microbubbles

    NASA Astrophysics Data System (ADS)

    Sarkar, Kausik; Jain, Pankaj; Chatterjee, Dhiman

    2006-05-01

    Intravenously injected encapsulated microbubbles improve the contrast of an ultrasound image. Their destruction is used in measuring blood flow, stimulating arteriogenesis, and drug delivery. We measure attenuation and scattering of ultrasound through solution of commercial contrast agents such as Sonazoid and Definity. We have developed a number of different interfacial rheology models for the encapsulation of such microbubbles. By matching with experimentally measured attenuation, we obtain the characteristic rheological parameters. We compare model predictions with measured subharmonic responses. We also investigate microbubble destruction under acoustic excitation by measuring time-varying attenuation data.

  6. Clinical applications of low-intensity pulsed ultrasound and its potential role in urology

    PubMed Central

    Lin, Guiting; Lei, Hongen; Lue, Tom F.; Guo, Yinglu

    2016-01-01

    Low-intensity pulsed ultrasound (LIPUS) is a form of ultrasound that delivered at a much lower intensity (<3 W/cm2) than traditional ultrasound energy and output in the mode of pulse wave, and it is typically used for therapeutic purpose in rehabilitation medicine. LIPUS has minimal thermal effects due to its low intensity and pulsed output mode, and its non-thermal effects which is normally claimed to induce therapeutic changes in tissues attract most researchers’ attentions. LIPUS have been demonstrated to have a rage of biological effects on tissues, including promoting bone-fracture healing, accelerating soft-tissue regeneration, inhibiting inflammatory responses and so on. Recent studies showed that biological effects of LIPUS in healing morbid body tissues may be mainly associated with the upregulation of cell proliferation through activation of integrin receptors and Rho/ROCK/Src/ERK signaling pathway, and with promoting multilineage differentiation of mesenchyme stem/progenitor cell lines through ROCK-Cot/Tpl2-MEK-ERK signaling pathway. Hopefully, LIPUS may become an effective clinical procedure for the treatment of urological diseases, such as chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), erectile dysfunction (ED), and stress urinary incontinence (SUI) in the field of urology. It still needs an intense effort for basic-science and clinical investigators to explore the biomedical applications of ultrasound. PMID:27141455

  7. Low-Intensity Pulsed Ultrasound Treatment for Scaphoid Fracture Nonunions in Adolescents

    PubMed Central

    Carlson, Erik J.; Save, Ameya V.; Slade, Joseph F.; Dodds, Seth D.

    2015-01-01

    Background Treatment of scaphoid nonunion is challenging, leading clinicians to pursue innovation in surgical technique and adjunctive therapies to improve union rates. Purpose The purpose of this study was to investigate the use of low-intensity pulsed ultrasound as an adjunctive treatment modality following surgical treatment of scaphoid nonunion in adolescent patients, for whom this therapy has not yet been FDA-approved. Patients and Methods We performed a retrospective review of adolescent patients with scaphoid nonunion treated surgically followed by adjunctive low-intensity pulsed ultrasound therapy. All patients underwent 20 minutes of daily ultrasound therapy postoperatively until there was evidence of bony healing, based on both clinical and radiographic criteria. Final healing was confirmed by > 50% bone bridging on CT scan. Results Thirteen of fourteen (93%) patients healed at a mean interval of 113 days (range 61–217 days). There were no surgical or postoperative complications. One patient developed heterotopic bone formation about the scaphoid. Conclusions Our study suggests that low-intensity pulsed ultrasound therapy can safely be utilized as an adjunctive modality in adolescents to augment scaphoid healing following surgical intervention. Level of Evidence Level IV, Case series PMID:25945296

  8. Removal of Residual Cavitation Nuclei to Enhance Histotripsy Fractionation of Soft Tissue

    PubMed Central

    Duryea, Alexander P.; Cain, Charles A.; Roberts, William W.; Hall, Timothy L.

    2015-01-01

    Remnant bubble nuclei generated by primary cavitation collapse can limit the efficiency of histotripsy soft tissue fractionation. When these residual bubbles persist from one histotripsy pulse to the next, they can seed the repetitive nucleation of cavitation bubbles at a discrete set of sites within the focal volume. This effect—referred to as cavitation memory—manifests in inefficient lesion formation, as certain sites within the focal volume are overtreated while others remain undertreated. While the cavitation memory effect can be passively mitigated by using a low pulse repetition frequency (PRF) that affords remnant nuclei sufficient time for dissolution between successive pulses, this low PRF also results in slow lesion production. As such, it would be highly desirable to maintain the high per-pulse efficiency associated with low pulse rates when much higher PRFs are utilized. In this vein we have developed a strategy for the active removal of the remnant bubble nuclei following primary cavitation collapse, using low amplitude ultrasound sequences (termed bubble removal sequences) to stimulate the aggregation and subsequent coalescence of these bubbles. In this study, bubble removal sequences were incorporated in high-PRF histotripsy treatment (100 Hz) of a red blood cell tissue-mimicking phantom that allows for the visualization of lesion development in real-time. A series of reference treatments were also conducted at the low PRF of 1 Hz in order to provide a point of comparison when cavitation memory effects are minimal. It was found that bubble removal sequences as short as 1 ms are capable of maintaining the efficacious lesion development characteristics associated with the low PRF of 1 Hz when the much higher pulse rate of 100 Hz is used. These results were then extended to the treatment of a large volume within the tissue phantom, and optimal bubble removal sequences identified for the single-focal-spot case were utilized to homogenize a 10 × 10

  9. Pulsed-ultrasound tagging of light in living tissues

    NASA Astrophysics Data System (ADS)

    Lev, Aner; Rubanov, E.; Pomerantz, Ami; Sfez, Bruno G.

    2004-07-01

    Ultrasound can be used in order to locally modulate, or tag, light in a turbid medium. This tagging process is made possible due to the extreme sensitivity of laser speckle distribution to minute changes within the medium. This hybrid technique presents several advantages compared to all-optical tomographic techniques, in that the image resolution is fixed by the ultrasound focus diameter. To our best knowledge, only in vitro experiments have been performed, either on tissue-like phantoms or meat. However a strong difference exists between these sample and living tissues. In living tissues, different kind of liquids flow through the capillaries, strongly reducing the sspeckle autocorrelation time. We have performed experiments on both mice and humans, showing that the autocorrelation time is much shorter than what was previously thought. We show however that it is possible to obtain signal with acceptable signal to noise ratio down to a few cm depth. We will also discuss the origin and characteristics of the speckle noise.

  10. Surfactant shedding and gas diffusion during pulsed ultrasound through a microbubble contrast agent suspension.

    PubMed

    O'Brien, Jean-Pierre; Stride, Eleanor; Ovenden, Nicholas

    2013-08-01

    Interest in coated microbubbles as agents for therapeutic and quantitative imaging applications in biomedical ultrasound has increased the need for their accurate theoretical characterization. Effects such as gas diffusion, variation in the properties of the coating and the resulting changes in bubble behavior under repeated exposure to ultrasound pulses are, however, still not well understood. In this study, a revised equation for microbubble motion is proposed that includes the effects of gas diffusion, as well as adsorption, desorption and shedding of a surfactant from the bubble surface. This is incorporated into a nonlinear wave propagation model to account for these additional time dependent effects in the response of microbubble populations. The results from the model indicate there can be significant changes in both bubble behavior and the propagated pulse over time. This is in agreement with existing experimental data but is not predicted by existing propagation models. The analysis indicates that changes in bubble dynamics are dominated by surfactant shedding on the timescale of a diagnostic ultrasound pulse and gas diffusion over the timescale of the pulse repetition frequency. The implications of these results for the development of more accurate algorithms for quantitative imaging and for therapeutic applications are discussed.

  11. Understanding ultrasound induced sonoporation: definitions and underlying mechanisms.

    PubMed

    Lentacker, I; De Cock, I; Deckers, R; De Smedt, S C; Moonen, C T W

    2014-06-01

    In the past two decades, research has underlined the potential of ultrasound and microbubbles to enhance drug delivery. However, there is less consensus on the biophysical and biological mechanisms leading to this enhanced delivery. Sonoporation, i.e. the formation of temporary pores in the cell membrane, as well as enhanced endocytosis is reported. Because of the variety of ultrasound settings used and corresponding microbubble behavior, a clear overview is missing. Therefore, in this review, the mechanisms contributing to sonoporation are categorized according to three ultrasound settings: i) low intensity ultrasound leading to stable cavitation of microbubbles, ii) high intensity ultrasound leading to inertial cavitation with microbubble collapse, and iii) ultrasound application in the absence of microbubbles. Using low intensity ultrasound, the endocytotic uptake of several drugs could be stimulated, while short but intense ultrasound pulses can be applied to induce pore formation and the direct cytoplasmic uptake of drugs. Ultrasound intensities may be adapted to create pore sizes correlating with drug size. Small molecules are able to diffuse passively through small pores created by low intensity ultrasound treatment. However, delivery of larger drugs such as nanoparticles and gene complexes, will require higher ultrasound intensities in order to allow direct cytoplasmic entry.

  12. In-situ structural integrity evaluation for high-power pulsed spallation neutron source - Effects of cavitation damage on structural vibration

    NASA Astrophysics Data System (ADS)

    Wan, Tao; Naoe, Takashi; Futakawa, Masatoshi

    2016-01-01

    A double-wall structure mercury target will be installed at the high-power pulsed spallation neutron source in the Japan Proton Accelerator Research Complex (J-PARC). Cavitation damage on the inner wall is an important factor governing the lifetime of the target-vessel. To monitor the structural integrity of the target vessel, displacement velocity at a point on the outer surface of the target vessel is measured using a laser Doppler vibrometer (LDV). The measured signals can be used for evaluating the damage inside the target vessel because of cyclic loading and cavitation bubble collapse caused by pulsed-beam induced pressure waves. The wavelet differential analysis (WDA) was applied to reveal the effects of the damage on vibrational cycling. To reduce the effects of noise superimposed on the vibration signals on the WDA results, analysis of variance (ANOVA) and analysis of covariance (ANCOVA), statistical methods were applied. Results from laboratory experiments, numerical simulation results with random noise added, and target vessel field data were analyzed by the WDA and the statistical methods. The analyses demonstrated that the established in-situ diagnostic technique can be used to effectively evaluate the structural response of the target vessel.

  13. Non-invasive and real-time passive acoustic mapping of ultrasound-mediated drug delivery

    NASA Astrophysics Data System (ADS)

    Choi, James J.; Carlisle, Robert C.; Coviello, Christian; Seymour, Len; Coussios, Constantin-C.

    2014-09-01

    New classes of biologically active materials, such as viruses, siRNA, antibodies and a wide range of engineered nanoparticles have emerged as potent agents for diagnosing and treating diseases, yet many of these agents fail because there is no effective route of delivery to their intended targets. Focused ultrasound and its ability to drive microbubble-seeded cavitation have been shown to facilitate drug delivery. However, cavitation is difficult to control temporally and spatially, making prediction of therapeutic outcomes deep in the body difficult. Here, we utilized passive acoustic mapping in vivo to understand how ultrasound parameters influence cavitation dynamics and to correlate spatial maps of cavitation to drug delivery. Focused ultrasound (center frequency: 0.5 MHz, peak-rarefactional pressure: 1.2 MPa, pulse length: 25 cycles or 50,000 cycles, pulse repetition interval: 0.02, 0.2, 1 or 3 s, number of pulses: 80 pulses) was applied to murine xenograft-model tumors in vivo during systemic injection of microbubbles with and without cavitation-sensitive liposomes or type 5 adenoviruses. Analysis of in vivo cavitation dynamics through several pulses revealed that cavitation was more efficiently produced at a lower pulse repetition frequency of 1 Hz than at 50 Hz. Within a pulse, inertial cavitation activity was shown to persist but reduced to 50% and 25% of its initial magnitude in 4.3 and 29.3 ms, respectively. Both through several pulses and within a pulse, the spatial distribution of cavitation was shown to change in time due to variations in microbubble distribution present in tumors. Finally, we demonstrated that the centroid of the mapped cavitation activity was within 1.33  ±  0.6 mm and 0.36 mm from the centroid location of drug release from liposomes and expression of the reporter gene encoded by the adenovirus, respectively. Thus passive acoustic mapping not only unraveled key mechanisms whereby a successful outcome is achieved

  14. Effect of pulsed and continuous therapeutic ultrasound on healthy skeletal muscle in rats

    PubMed Central

    Vásquez, Bélgica; Navarrete, Javiera; Farfán, Emilio; Cantín, Mario

    2014-01-01

    Ultrasound therapy is used to treat injuries in joints, nerves and tendons. Part of the radiation generated is absorbed by nearby undamaged tissues, such as muscles. The aim was to evaluate histomorphological changes in the healthy gastrocnemius muscle in rats irradiated with continuous ultrasound (CUS) and pulsed ultrasound (PUS). Healthy adult rats were used, separated into two groups: CUS and PUS. Both were irradiated in the gastrocnemius muscle for 10 days: the CUS group in continuous mode (3 MHz, 1.0 W/cm2, 1 min/session) and the PUS group in pulsed mode (3 MHz, 1.0 W/cm2, 100 Hz, 50% duty cycle, 1 min/session). The contralateral muscles were used as a control. Their histological characteristics were analyzed, and the area and perimeter of the muscle fibers were measured. The connective tissue showed no histological changes. The area of muscle fibers of the irradiated groups was significantly greater (CUS 1325.2±182.1 μm2, p=0.0278 and PUS 1019.4±125.3 μm2, p=0.0398) than the control, and the CUS area was greater than the PUS (p=0.0383). The perimeter of muscle fibers showed significant differences between the irradiated groups (CUS 148±11.12 μm, p=0.0178 and PUS 129.3±8.83 μm, p=0.0236) compared to the control, as well as differences between CUS and PUS (p=0.0319). The application of ultrasound on healthy muscle produces hypertrophy of the muscle fibers, greater when continuous mode is used. It is advisable to apply pulsed, focused ultrasound therapies with sound heads sufficient for the tissue or zone to be treated, thereby reducing the risk of altering the adjacent healthy tissue. PMID:24551303

  15. Design and Implementation of High Frequency Ultrasound Pulsed-Wave Doppler Using FPGA

    PubMed Central

    Hu, Chang-hong; Zhou, Qifa; Shung, K. Kirk

    2009-01-01

    The development of a field-programmable gate array (FPGA)-based pulsed-wave Doppler processing approach in pure digital domain is reported in this paper. After the ultrasound signals are digitized, directional Doppler frequency shifts are obtained with a digital-down converter followed by a low-pass filter. A Doppler spectrum is then calculated using the complex fast Fourier transform core inside the FPGA. In this approach, a pulsed-wave Doppler implementation core with reconfigurable and real-time processing capability is achieved. PMID:18986909

  16. Ultrasound

    MedlinePlus

    ... your test will be done. Alternative Names Sonogram Images Abdominal ultrasound Ultrasound in pregnancy 17 week ultrasound ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  17. Ultrasound

    MedlinePlus

    Ultrasound is a type of imaging. It uses high-frequency sound waves to look at organs and ... liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound ...

  18. Cavitational Hydrothermal Oxidation: A New Remediation Process - Final Report

    SciTech Connect

    Suslick, K. S.

    2001-07-05

    During the past year, we have continued to make substantial scientific progress on our understanding of cavitation phenomena in aqueous media and applications of cavitation to remediation processes. Our efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions.

  19. Comparing microbubble cavitation at 500 kHz and 70 kHz related to micellar drug delivery using ultrasound.

    PubMed

    Diaz de la Rosa, Mario A; Husseini, Ghaleb A; Pitt, William G

    2013-02-01

    We have previously reported that ultrasonic drug release at 70kHz was found to correlate with the presence of subharmonic emissions. No evidence of drug release or of the subharmonic emissions were detected in experiments at 500kHz. In an attempt to understand the difference in drug release behavior between low- and mid-frequency ultrasound, a mathematical model of a bubble oscillator was developed to explore the difference in the behavior of a single 10-μm bubble under 500- and 70-kHz ultrasound. The dynamics were found to be fundamentally different; the 500-kHz bubble follows a period-doubling route to chaos while a 70-kHz bubble follows an intermittent route to chaos. We propose that this type of "intermittent subharmonic" oscillation behavior is associated with the drug release observed experimentally.

  20. Review on Lithotripsy and Cavitation in Urinary Stone Therapy.

    PubMed

    Ghorbani, Morteza; Oral, Ozlem; Ekici, Sinan; Gozuacik, Devrim; Kosar, Ali

    2016-01-01

    Cavitation is the sudden formation of vapor bubbles or voids in liquid media and occurs after rapid changes in pressure as a consequence of mechanical forces. It is mostly an undesirable phenomenon. Although the elimination of cavitation is a major topic in the study of fluid dynamics, its destructive nature could be exploited for therapeutic applications. Ultrasonic and hydrodynamic sources are two main origins for generating cavitation. The purpose of this review is to give the reader a general idea about the formation of cavitation phenomenon and existing biomedical applications of ultrasonic and hydrodynamic cavitation. Because of the high number of the studies on ultrasound cavitation in the literature, the main focus of this review is placed on the lithotripsy techniques, which have been widely used for the treatment of urinary stones. Accordingly, cavitation phenomenon and its basic concepts are presented in Section II. The significance of the ultrasound cavitation in the urinary stone treatment is discussed in Section III in detail and hydrodynamic cavitation as an important alternative for the ultrasound cavitation is included in Section IV. Finally, side effects of using both ultrasound and hydrodynamic cavitation in biomedical applications are presented in Section V.

  1. Ultrasound-modulated optical imaging using a photorefractive interferometer and a powerful long pulse laser

    NASA Astrophysics Data System (ADS)

    Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

    2009-02-01

    Ultrasound-modulated optical imaging is an emerging biodiagnostic technique which provides the optical spectroscopic signature and the spatial localization of an optically absorbing object embedded in a strongly scattering medium. The transverse resolution of the technique is determined by the lateral extent of ultrasound beam focal zone while the axial resolution is obtained by using short ultrasound pulses. The practical application of this technique is presently limited by its poor sensitivity. Moreover, any method to enhance the signal-to-noise ratio must satisfy the biomedical safety limits. In this paper, we propose to use a pulsed single-frequency laser source to raise the optical peak power applied to the scattering medium and to collect more ultrasonically tagged photons. Such a laser source allows illuminating the tissues mainly during the transit time of the ultrasonic wave. A single-frequency Nd:YAG laser emitting 500-μs pulses with a peak power superior to 100 W was used. Tagged photons were detected with a GaAs photorefractive interferometer characterized by a large optical etendue. When pumped by high intensity laser pulses, such an interferometer provides the fast response time essential to obtain an apparatus insensitive to the speckle decorrelation encountered in biomedical applications. Consequently, the combination of a large-etendue photorefractive interferometer with a high-power pulsed laser could allow obtaining both the sensitivity and the fast response time necessary for biomedical applications. Measurements performed in 30- and 60-mm thick optical phantoms made of titanium dioxide particles dispersed in sunflower oil are presented. Results obtained in 30- and 60-mm thick chicken breast samples are also reported.

  2. The Role of Cavitation in Liposome Formation

    PubMed Central

    Richardson, Eric S.; Pitt, William G.; Woodbury, Dixon J.

    2007-01-01

    Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of ultrasound on cells. In this study, we correlate the presence and type of cavitation with a decrease in liposome size. Aqueous lipid suspensions surrounding a hydrophone were exposed to various intensities of ultrasound and hydrostatic pressures before measuring their size distribution with dynamic light scattering. As expected, increasing ultrasound intensity at atmospheric pressure decreased the average liposome diameter. The presence of collapse cavitation was manifested in the acoustic spectrum at high ultrasonic intensities. Increasing hydrostatic pressure was shown to inhibit the presence of collapse cavitation. Collapse cavitation, however, did not correlate with decreases in liposome size, as changes in size still occurred when collapse cavitation was inhibited either by lowering ultrasound intensity or by increasing static pressure. We propose a mechanism whereby stable cavitation, another type of cavitation present in sound fields, causes fluid shearing of liposomes and reduction of liposome size. A mathematical model was developed based on the Rayleigh-Plesset equation of bubble dynamics and principles of acoustic microstreaming to estimate the shear field magnitude around an oscillating bubble. This model predicts the ultrasound intensities and pressures needed to create shear fields sufficient to cause liposome size change, and correlates well with our experimental data. PMID:17766335

  3. Cavitation-controlled ultrasonic agitator

    SciTech Connect

    Sheen, S.H.; Lawrence, W.P.; Raptis, A.C.

    1989-10-01

    High-intensity ultrasound generally produces nonlinear acoustic cavitation and streaming in liquids. The ultrasonic energy required to cause cavitation and streaming in a liquid depends on the physical properties of the liquid, e.g., surface tension, viscosity, and entrained gases. Both cavitation and streaming generate acoustic noise whose signatures may be used to distinguish the stage of agitation and thus allow the process to be controlled. An ultrasonic agitator has been designed for application in a confined area with a high-temperature, high-pressure, and corrosive environment. Control of this agitator is based on the detection of noise levels and subharmonics produced during cavitation and streaming. Noise signatures of agitation in different liquids and in liquids with particles have been determined, and discussed. 6 refs., 6 figs.

  4. A simulation model for predicting the temperature during the application of MR-guided focused ultrasound for stroke treatment using pulsed ultrasound

    NASA Astrophysics Data System (ADS)

    Hadjisavvas, V.; Damianou, C.

    2011-09-01

    In this paper a simulation model for predicting the temperature during the application of MR-guided focused ultrasound for stroke treatment using pulsed ultrasound is presented. A single element spherically focused transducer of 5 cm diameter, focusing at 10 cm and operating at either 0.5 MHz or 1 MHz was considered. The power field was estimated using the KZK model. The temperature was estimated using the bioheat equation. The goal was to extract the acoustic parameters (power, pulse duration, duty factor and pulse repetition frequency) that maintain a temperature increase of less than 1 °C during the application of a pulse ultrasound protocol. It was found that the temperature change increases linearly with duty factor. The higher the power, the lower the duty factor needed to keep the temperature change to the safe limit of 1 °C. The higher the frequency the lower the duty factor needed to keep the temperature change to the safe limit of 1 °C. Finally, the deeper the target, the higher the duty factor needed to keep the temperature change to the safe limit of 1 °C. The simulation model was tested in brain tissue during the application of pulse ultrasound and the measured temperature was in close agreement with the simulated temperature. This simulation model is considered to be very useful tool for providing acoustic parameters (frequency, power, duty factor, pulse repetition frequency) during the application of pulsed ultrasound at various depths in tissue so that a safe temperature is maintained during the treatment. This model could be tested soon during stroke clinical trials.

  5. Removal of Residual Cavitation Nuclei to Enhance Histotripsy Erosion of Model Urinary Stones

    PubMed Central

    Duryea, Alexander P.; Roberts, William W.; Cain, Charles A.; Hall, Timothy L.

    2015-01-01

    Histotripsy has been shown to be an effective treatment for model kidney stones, eroding their surface to tiny particulate debris via a cavitational bubble cloud. However, similar to shock wave lithotripsy, histotripsy stone treatments display a rate-dependent efficacy with pulses applied at low rate generating more efficient stone erosion in comparison to those applied at high rate. This is hypothesized to be the result of residual cavitation bubble nuclei generated by bubble cloud collapse. While the histotripsy bubble cloud only lasts on the order of 100 µs, these microscopic remnant bubbles can persist on the order of 1 second—inducing direct attenuation of subsequent histotripsy pulses and influencing bubble cloud dynamics. In an effort to mitigate these effects, we have developed a novel strategy to actively remove residual cavitation nuclei from the field using low-amplitude ultrasound pulses. Previous work has demonstrated that with selection of the appropriate acoustic parameters these bubble removal pulses can stimulate the aggregation and subsequent coalescence of microscopic bubble nuclei—effectively deleting them from the target volume. Here, we incorporate bubble removal pulses in histotripsy treatment of model kidney stones. It was found that when histotripsy is applied at low rate (1 Hz), bubble removal does not produce a statistically significant change in erosion. At higher pulse rates of 10, 100, and 500 Hz, incorporating bubble removal results in 3.7-, 7.5-, and 2.7-fold increases in stone erosion, respectively. High speed imaging indicates that the introduction of bubble removal pulses allows bubble cloud dynamics resulting from high pulse rates to more closely approximate those generated at the low rate of 1 Hz. These results corroborate previous work in the field of shock wave lithotripsy regarding the ill-effects of residual bubble nuclei, and suggest that high treatment efficiency can be recovered at high pulse rates through

  6. Removal of residual cavitation nuclei to enhance histotripsy erosion of model urinary stones.

    PubMed

    Duryea, Alexander P; Roberts, William W; Cain, Charles A; Hall, Timothy L

    2015-05-01

    Histotripsy has been shown to be an effective treatment for model kidney stones, eroding their surface to tiny particulate debris via a cavitational bubble cloud. However, similar to shock wave lithotripsy, histotripsy stone treatments display a rate-dependent efficacy, with pulses applied at a low rate generating more efficient stone erosion in comparison with those applied at a high rate. This is hypothesized to be the result of residual cavitation bubble nuclei generated by bubble cloud collapse. Although the histotripsy bubble cloud only lasts on the order of 100 μs, these microscopic remnant bubbles can persist on the order of 1 s, inducing direct attenuation of subsequent histotripsy pulses and influencing bubble cloud dynamics. In an effort to mitigate these effects, we have developed a novel strategy to actively remove residual cavitation nuclei from the field using low-amplitude ultrasound pulses. Previous work has demonstrated that with selection of the appropriate acoustic parameters these bubble removal pulses can stimulate the aggregation and subsequent coalescence of microscopic bubble nuclei, effectively deleting them from the target volume. Here, we incorporate bubble removal pulses in histotripsy treatment of model kidney stones. It was found that when histotripsy is applied at low rate (1 Hz), bubble removal does not produce a statistically significant change in erosion. At higher pulse rates of 10, 100, and 500 Hz, incorporating bubble removal results in 3.7-, 7.5-, and 2.7-fold increases in stone erosion, respectively. High-speed imaging indicates that the introduction of bubble removal pulses allows bubble cloud dynamics resulting from high pulse rates to more closely approximate those generated at the low rate of 1 Hz. These results corroborate previous work in the field of shock wave lithotripsy regarding the ill effects of residual bubble nuclei, and suggest that high treatment efficiency can be recovered at high pulse rates through

  7. Doppler ultrasound in the measurement of pulse wave velocity: agreement with the Complior method

    PubMed Central

    2011-01-01

    Aortic stiffness is an independent predictor factor for cardiovascular risk. Different methods for determining pulse wave velocity (PWV) are used, among which the most common are mechanical methods such as SphygmoCor or Complior, which require specific devices and are limited by technical difficulty in obtaining measurements. Doppler guided by 2D ultrasound is a good alternative to these methods. We studied 40 patients (29 male, aged 21 to 82 years) comparing the Complior method with Doppler. Agreement of both devices was high (R = 0.91, 0.84-0.95, 95% CI). The reproducibility analysis revealed no intra-nor interobserver differences. Based on these results, we conclude that Doppler ultrasound is a reliable and reproducible alternative to other established methods for the measurement of aortic PWV. PMID:21496271

  8. Photoacoustic and ultrasound imaging using dual contrast perfluorocarbon nanodroplets triggered by laser pulses at 1064 nm.

    PubMed

    Hannah, Alexander S; VanderLaan, Donald; Chen, Yun-Sheng; Emelianov, Stanislav Y

    2014-09-01

    Recently, a dual photoacoustic and ultrasound contrast agent-named photoacoustic nanodroplet-has been introduced. Photoacoustic nanodroplets consist of a perfluorocarbon core, surfactant shell, and encapsulated photoabsorber. Upon pulsed laser irradiation the perfluorocarbon converts to gas, inducing a photoacoustic signal from vaporization and subsequent ultrasound contrast from the resulting gas microbubbles. In this work we synthesize nanodroplets which encapsulate gold nanorods with a peak absorption near 1064 nm. Such nanodroplets are optimal for extended photoacoustic imaging depth and contrast, safety and system cost. We characterized the nanodroplets for optical absorption, image contrast and vaporization threshold. We then imaged the particles in an ex vivo porcine tissue sample, reporting contrast enhancement in a biological environment. These 1064 nm triggerable photoacoustic nanodroplets are a robust biomedical tool to enhance image contrast at clinically relevant depths.

  9. Ultrasound-guided Pulsed Radiofrequency Lesioning of the Phrenic Nerve in a Patient with Intractable Hiccup

    PubMed Central

    Kang, Keum Nae; Park, In Kyung; Suh, Jeong Hun; Leem, Jeong Gill

    2010-01-01

    Persistent and intractable hiccups (with respective durations of more than 48 hours and 1 month) can result in depression, fatigue, impaired sleep, dehydration, weight loss, malnutrition, and aspiration syndromes. The conventional treatments for hiccups are either non-pharmacological, pharmacological or a nerve block treatment. Pulsed radiofrequency lesioning (PRFL) has been proposed for the modulation of the excited nervous system pathway of pain as a safe and nondestructive treatment method. As placement of the electrode in close proximity to the targeted nerve is very important for the success of PRFL, ultrasound appears to be well suited for this technique. A 74-year-old man suffering from intractable hiccups that had developed after a coronary artery bypass graft and had continued for 7 years was referred to our pain clinic. He had not been treated with conventional methods or medications. We performed PRFL of the phrenic nerve guided by ultrasound and the hiccups disappeared. PMID:20830266

  10. Pulsed laser generation of ultrasound in a metal plate between the melting and ablation thresholds

    SciTech Connect

    Every, A. G.; Utegulov, Z. N.; Veres, I. A.

    2015-03-31

    The generation of ultrasound in a metal plate exposed to nanosecond pulsed laser heating, sufficient to cause melting but not ablation, is treated. Consideration is given to the spatial and temporal profiles of the laser pulse, penetration of the laser beam into the sample, the evolution of the melt pool, and thermal conduction in the melt and surrounding solid. The excitation of the ultrasound takes place over a few nanoseconds, and occurs predominantly within the thermal diffusion length of a micron or so beneath the surface. Because of this, the output of the thermal simulations can be represented as axially symmetric transient radial and normal surface force distributions. The epicentral displacement response at the opposite surface to these forces is obtained by two methods, the one based on the elastodynamic Green’s functions for plate geometry determined by the Cagniard generalized ray method, and the other using a finite element numerical method. The two approaches are in very close agreement. Numerical simulations are reported of the epicentral displacement response of a 3.12mm thick tungsten plate irradiated with a 4 ns pulsed laser beam with Gaussian spatial profile, at intensities below and above the melt threshold. Comparison is made between results obtained using available temperature dependent thermophysical data, and room temperature materials constants except near the melting point.

  11. A new method for evaluating the degeneration of articular cartilage using pulse-echo ultrasound

    NASA Astrophysics Data System (ADS)

    Sun, Anyu; Bai, Xiaolong; Ju, Bing-Feng

    2015-03-01

    This paper presents a novel nondestructive ultrasonic technique for measuring the sound speed and acoustic impedance of articular cartilage using the pulsed V(z,t) technique. V(z,t) data include a series of pulsed ultrasonic echoes collected using different distances between the ultrasonic transducer and the specimen. The 2D Fourier transform is applied to the V(z,t) data to reconstruct the 2D reflection spectrum R(θ,ω). To obtain the reflection coefficient of articular cartilage, the V(z,t) data from a reference specimen with a well-known reflection coefficient are obtained to eliminate the dependence on the general system transfer function. The ultrasound-derived aggregate modulus (Ha) is computed based on the measured reflection coefficient and the sound speed. In the experiment, 32 cartilage-bone samples were prepared from bovine articular cartilage, and 16 samples were digested using 0.25% trypsin solution. The sound speed and Ha of these cartilage samples were evaluated before and after degeneration. The magnitude of the sound speed decreased with trypsin digestion (from 1663 ± 5.6 m/s to 1613 ± 5.3 m/s). Moreover, the Young's modulus in the corresponding degenerative state was measured and was correlated with the ultrasound-derived aggregate modulus. The ultrasound-derived aggregate modulus was determined to be highly correlated with the Young's modulus (n = 16, r>0.895, p<0.003, Pearson correlation test for each measurement). The results demonstrate the effectiveness of using the proposed method to assess the changes in sound speed and the ultrasound-derived aggregate modulus of cartilage after degeneration.

  12. Pulse-echo ultrasound transit time spectroscopy: A comparison of experimental measurement and simulation prediction.

    PubMed

    Wille, Marie-Luise; Almualimi, Majdi A; Langton, Christian M

    2016-01-01

    Considering ultrasound propagation through complex composite media as an array of parallel sonic rays, a comparison of computer-simulated prediction with experimental data has previously been reported for transmission mode (where one transducer serves as transmitter, the other as receiver) in a series of 10 acrylic step-wedge samples, immersed in water, exhibiting varying degrees of transit time inhomogeneity. In this study, the same samples were used but in pulse-echo mode, where the same ultrasound transducer served as both transmitter and receiver, detecting both 'primary' (internal sample interface) and 'secondary' (external sample interface) echoes. A transit time spectrum was derived, describing the proportion of sonic rays with a particular transit time. A computer simulation was performed to predict the transit time and amplitude of various echoes created, and compared with experimental data. Applying an amplitude-tolerance analysis, 91.7% ± 3.7% of the simulated data were within ±1 standard deviation of the experimentally measured amplitude-time data. Correlation of predicted and experimental transit time spectra provided coefficients of determination (R(2)%) ranging from 100.0% to 96.8% for the various samples tested. The results acquired from this study provide good evidence for the concept of parallel sonic rays. Furthermore, deconvolution of experimental input and output signals has been shown to provide an effective method to identify echoes otherwise lost due to phase cancellation. Potential applications of pulse-echo ultrasound transit time spectroscopy include improvement of ultrasound image fidelity by improving spatial resolution and reducing phase interference artefacts.

  13. Pulsed Focused Ultrasound Induced Displacements in Confined In Vitro Blood Clots

    PubMed Central

    Wright, Cameron C.; Hynynen, Kullervo; Goertz, David E.

    2015-01-01

    Ultrasound has been shown to potentiate the effects of tissue plasminogen activator (tPA) to improve clot lysis in a range of in vitro and in vivo studies as well as in clinical trials. One possible mechanism of action is acoustic radiation force induced clot displacements. In this study we investigate the temporal and spatial dynamics of clot displacements and strain initiated by focused ultrasound pulses. Displacements were produced by a 1.51 MHz f-number 1 transducer over a range of acoustic powers (1–85 W) in clots constrained within an agar vessel phantom channel. Displacements were tracked during and after a 5.45 ms therapy pulse using a 20 MHz high frequency ultrasound imaging probe. Peak thrombus displacements were found to be linear as a function of acoustic power up to 60 W before leveling off near 128 μm for the highest transmit powers. The time to peak displacement and recovery time of blood clots were largely independent of acoustic powers with measured values near 2 ms. A linear relationship between peak axial strain and transmit power was observed, reaching a peak value of 11% at 35 W. The peak strain occurred ~0.75 mm from the focal zone for all powers investigated in both lateral and axial directions. These results indicate that substantial displacements can be induced by focused ultrasound in confined blood clots, and that the spatial and temporal displacement patterns are complex and highly dependant on exposure conditions, which has implications for future work investigating their link to clot lysis and for developing approaches to exploit these effects. PMID:22194235

  14. A new method for evaluating the degeneration of articular cartilage using pulse-echo ultrasound.

    PubMed

    Sun, Anyu; Bai, Xiaolong; Ju, Bing-Feng

    2015-03-01

    This paper presents a novel nondestructive ultrasonic technique for measuring the sound speed and acoustic impedance of articular cartilage using the pulsed Vz,t technique. Vz,t data include a series of pulsed ultrasonic echoes collected using different distances between the ultrasonic transducer and the specimen. The 2D Fourier transform is applied to the Vz,t data to reconstruct the 2D reflection spectrum Rθ,ω. To obtain the reflection coefficient of articular cartilage, the Vz,t data from a reference specimen with a well-known reflection coefficient are obtained to eliminate the dependence on the general system transfer function. The ultrasound-derived aggregate modulus (Ha) is computed based on the measured reflection coefficient and the sound speed. In the experiment, 32 cartilage-bone samples were prepared from bovine articular cartilage, and 16 samples were digested using 0.25% trypsin solution. The sound speed and Ha of these cartilage samples were evaluated before and after degeneration. The magnitude of the sound speed decreased with trypsin digestion (from 1663 ± 5.6 m/s to 1613 ± 5.3 m/s). Moreover, the Young's modulus in the corresponding degenerative state was measured and was correlated with the ultrasound-derived aggregate modulus. The ultrasound-derived aggregate modulus was determined to be highly correlated with the Young's modulus (n = 16, r>0.895, p<0.003, Pearson correlation test for each measurement). The results demonstrate the effectiveness of using the proposed method to assess the changes in sound speed and the ultrasound-derived aggregate modulus of cartilage after degeneration.

  15. Removal of residual nuclei following a cavitation event: a parametric study.

    PubMed

    Duryea, Alexander P; Tamaddoni, Hedieh A; Cain, Charles A; Roberts, William W; Hall, Timothy L

    2015-09-01

    The efficacy of ultrasound therapies such as hock-wave lithotripsy and histotripsy can be compromised by residual cavitation bubble nuclei that persist following the collapse of primary cavitation. In our previous work, we have developed a unique strategy for mitigating the effects of these residual bubbles using low-amplitude ultrasound pulses to stimulate their aggregation and subsequent coalescence—effectively removing them from the field. Here, we further develop this bubble removal strategy through an investigation of the effect of frequency on the consolidation process. Bubble removal pulses ranging from 0.5 to 2 MHz were used to sonicate the population of residual nuclei produced upon collapse of a histotripsy bubble cloud. For each frequency, mechanical index(MI) values ranging from 0 to approximately 1.5 were tested.Results indicated that, when evaluated as a function of bubble removal pulse MI, the efficacy of bubble removal shows markedly similar trends for all frequencies tested. This behavior divides into three distinct regimes (with provided cutoffs being approximate): 1) MI < 0.2: Minimal effect on the population of remanent cavitation nuclei; 2) 0.2 < MI < 1: Aggregation and subsequent coalescence of residual bubbles, the extent of which trends toward a maximum; and 3) MI > 1: Bubble coalescence is compromised as bubble removal pulses induce high-magnitude inertial cavitation of residual bubbles. The major distinction in these trends came for bubble removal pulses applied at 2 MHz, which were observed to generate the most effective bubble coalescence of all frequencies tested. We hypothesize that this is a consequence of the secondary Bjerknes force being the major facilitator of the consolidation process, the magnitude of which increases when the bubble size distribution is far from resonance such that the phase difference of oscillation of individual bubbles is minimal.

  16. Heat Distribution in the Lower Leg from Pulsed Short-Wave Diathermy and Ultrasound Treatments

    PubMed Central

    Garrett, Candi L.; Draper, David O.; Knight, Kenneth L.

    2000-01-01

    Objective: To compare tissue temperature rise and decay after 20-minute diathermy and ultrasound treatments. Design and Setting: We inserted 3 26-gauge thermistor microprobes into the medial aspect of the anesthetized triceps surae muscle at a depth of 3 cm and spaced 5 cm apart. Eight subjects received the diathermy treatment first, followed by the ultrasound treatment. This sequence was reversed for the remaining 8 subjects. The diathermy was applied at a frequency of 27.12 MHz at the following settings: 800 bursts per second, 400-microsecond burst duration, 850-microsecond interburst interval, peak root mean square amplitude of 150 W per burst, and an average root mean square output of 48 W per burst. The ultrasound was delivered at a frequency of 1 MHz and an intensity of 1.5 W/cm2 in the continuous mode for 20 minutes over an area of 40 times the effective radiating area. The study was performed in a ventilated research laboratory. Subjects: Sixteen (11 men, 5 women) healthy subjects (mean age = 23.56 ± 4.73 years) volunteered to participate in this study. Measurements: We recorded baseline, final, and decay temperatures for each of the 3 sites. Results: The average temperature increases over baseline temperature after pulsed short-wave diathermy were 3.02°C ± 1.02°C in site 1, 4.58°C ± 0.87°C in site 2, and 3.28°C ± 1.64°C in site 3. The average temperature increases over baseline temperature after ultrasound were only 0.17°C ± 0.40°C, 0.09°C ± 0.56°C, and -0.43°C ± 0.41°C in sites 1, 2, and 3, respectively. The temperature dropped only 1°C in 7.65 ± 4.96 minutes after pulsed short-wave diathermy. Conclusions: We conclude that pulsed short-wave diathermy was more effective than 1-MHz ultrasound in heating a large muscle mass and resulted in the muscles' retaining heat longer. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5. PMID:16558608

  17. Cost-effective design of a concurrent photoacoustic-ultrasound microscope using single laser pulses

    NASA Astrophysics Data System (ADS)

    Wu, Wen-Shao; Liu, Wei-Wen; Li, Pai-Chi

    2016-03-01

    A method for concurrent photoacoustic (PA) and ultrasound (US) imaging with single laser pulses was previously demonstrated. An optical-absorbing multilayer film that can generate a US pulse based on the thermoelastic effect is used. With such a film, the generated US can be adjusted so that it does not overlap with the spectrum of the PA signal generated by the light transmitting through the layer. Thus, the US signal and the PA signal can be generated and separated by using a single laser pulse with spectral filtering. In this study, we continue with the same concurrent imaging approach and propose a cost-effective and portable design. The design consists of a pulsed laser diode with the repetition rate up to 25 kHz and energy of 2 μJ/pulse. A multilayer film is employed to generate narrow band US signals under laser excitation for US imaging. With simple spectral filtering, the PA signals and the US signals can be separated. With optical resolution, the system has a theoretical lateral resolution of 2 μm in PA imaging and 200 μm in US imaging. One of the applications of the proposed microscope is for tumor biology, where angiogenesis is an essential topic for understanding tumor growth and tumor metastasis. We will demonstrate performance of the proposed system by imaging vasculature networks.

  18. Ultrasound contrast imaging: influence of scatterer motion in multi-pulse techniques.

    PubMed

    Lin, Fanglue; Cachard, Christian; Mori, Riccardo; Varray, Francois; Guidi, Francesco; Basset, Olivier

    2013-10-01

    In ultrasound contrast imaging, many techniques based on multiple transmissions have been proposed to increase the contrast-to-tissue ratio (CTR). They are generally based on the response of static scatterers inside the imaged region. However, scatterer motion, for example in blood vessels, has an inevitable influence on multi-pulse techniques, which can either enhance or degrade the technique involved. This paper investigates the response of static nonlinear media insonated by multi-pulses with various phase shifts, and the influence of scatterer motion on multi-pulse techniques. Simulations and experimental results from a single bubble and clouds of bubbles show that the phase shift of the echoes backscattered from bubbles is dependent on the transmissions' phase shift, and that the bubble motion influences the efficiency of multi-pulse techniques: fundamental and second-harmonic amplitudes of the processed signal change periodically, exhibiting maximum or minimum values, according to scatterer motion. Furthermore, experimental results based on the second-harmonic inversion (SHI) technique reveal that bubble motion can be taken into account to regulate the pulse repetition frequency (PRF). With the optimal PRF, the CTR of SHI images can be improved by about 12 dB compared with second-harmonic images.

  19. Observation of cavitation during shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael R.; Crum, Lawrence A.; Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.

    2005-04-01

    A system was built to detect cavitation in pig kidney during shock wave lithotripsy (SWL) with a Dornier HM3 lithotripter. Active detection, using echo on B-mode ultrasound, and passive cavitation detection (PCD), using coincident signals on confocal, orthogonal receivers, were equally sensitive and were used to interrogate the renal collecting system (urine) and the kidney parenchyma (tissue). Cavitation was detected in urine immediately upon SW administration in urine or urine plus X-ray contrast agent, but in tissue, cavitation required hundreds of SWs to initiate. Localization of cavitation was confirmed by fluoroscopy, sonography, and by thermally marking the kidney using the PCD receivers as high intensity focused ultrasound sources. Cavitation collapse times in tissue and native urine were about the same but less than in urine after injection of X-ray contrast agent. Cavitation, especially in the urine space, was observed to evolve from a sparse field to a dense field with strong acoustic collapse emissions to a very dense field that no longer produced detectable collapse. The finding that cavitation occurs in kidney tissue is a critical step toward determining the mechanisms of tissue injury in SWL. [Work sup ported by NIH (DK43881, DK55674, FIRCA), ONRIFO, CRDF and NSBRI SMS00203.

  20. An ultrasound-based method for determining pulse wave velocity in superficial arteries.

    PubMed

    Rabben, Stein Inge; Stergiopulos, Nikos; Hellevik, Leif Rune; Smiseth, Otto A; Slørdahl, Stig; Urheim, Stig; Angelsen, Bjørn

    2004-10-01

    In this paper, we present a method for estimating local pulse wave velocity (PWV) solely from ultrasound measurements: the area-flow (QA) method. With the QA method, PWV is estimated as the ratio between change in flow and change in cross-sectional area (PWV = dQ/dA) during the reflection-free period of the cardiac cycle. In four anaesthetized dogs and 21 human subjects (age 23-74) we measured the carotid flow and cross-sectional area non-invasively by ultrasound. As a reference method we used the Bramwell-Hill (BH) equation which estimates PWV from pulse pressure and cross-sectional area. Additionally, we therefore measured brachial pulse pressure by oscillometry in the human subjects, and central aortic pulse pressure by micro-manometry in the dogs. As predicted by the pressure dependency of arterial stiffness, the estimated PWV decreased when the aortic pressure was lowered in two of the dogs. For the human subjects, the QA and BH estimates were correlated (R=0.43, p<0.05) and agreed on average (mean difference of -0.14 m/s). The PWV by the BH method increased with age (p<0.01) whereas the PWV by the QA method tended to increase with age (p<0.1). This corresponded to a larger residual variance (residual = deviation of the estimated PWV from the regression line) for the QA method than for the BH method, indicating different precisions for the two methods. This study illustrates that the simple equation PWV = dQ/dA gives estimates correlated to the PWV of the reference method. However, improvements in the basic measurements seem necessary to increase the precision of the method.

  1. High speed observation of HIFU-induced cavitation cloud near curved rigid boundaries

    NASA Astrophysics Data System (ADS)

    Zuo, Z. G.; Wang, F. B.; Liu, S. H.; Wu, S. J.

    2015-01-01

    This paper focuses on the experimental study of the influence of surface curvature to the behaviour of HIFU-induced cavitation cloud. A Q-switched ruby pulse laser is used to induce cavitation nuclei in deionized water. A piezoelectric ultrasonic transducer (1.7 MHz) provides a focused ultrasound field to inspire the nucleus to cavitation cloud. A PZT probe type hydrophone is applied for measuring the HIFU sound field. It was observed that the motion of cavitation cloud located near the boundary is significantly influenced by the distance between cloud and boundary, as well as the curvature of the boundary. The curvature was defined by parameters λ and ξ. Convex boundary, concave boundary, and flat boundary correspond to ξ <1, ξ >1 and ξ = 1, respectively. Different behaviours of the cloud, including the migration of the cloud, the characteristics of oscillation, etc., were observed under different boundary curvatures by high-speed photography. Sonoluminescence of the acoustic cavitation bubble clouds were also studied to illustrate the characteristics of acoustic streaming.

  2. Pulsed radiofrequency under ultrasound guidance for the tarsal tunnel syndrome: two case reports.

    PubMed

    Chon, Jin Young; Hahn, Yun Jin; Sung, Choon Ho; Jung, Sung Hoon; Moon, Ho Sik

    2014-12-01

    Tarsal tunnel syndrome (TTS) is a compression neuropathy that results from entrapment of the posterior tibial nerve or its branches. TTS may be treated either by conservative measures, including physical therapy, medications, and steroid injections, or by surgical decompression. Despite a variety of treatments, a few cases of TTS will relapse, and many cases of recurrent TTS will require re-operation. Pulsed radiofrequency (PRF) is known to have a number of advantages for pain management, particularly as this technique does not cause neural compromise such as motor weakness. Here, we report a new application of ultrasound-guided PRF in two cases of intractable TTS. Both patients had a long duration of severe foot pain and had been treated with various therapeutic modalities without lasting relief. We applied ultrasound-guided PRF to the affected posterior tibial nerve in each patient, and both had significantly reduced pain intensity scores and analgesic requirements without any complications. Ultrasound-guided PRF for intractable TTS relieved severe foot pain. It may supersede surgery as a reliable treatment for intractable TTS.

  3. Ultrasound-guided pulsed radiofrequency treatment of the cervical sympathetic chain for complex regional pain syndrome

    PubMed Central

    Kim, Eung Don; Yoo, Woo Joo; Kim, Yoo Na; Park, Hue Jung

    2017-01-01

    Abstract The stellate ganglion is a common target to manage neuropathic pain in the upper extremities. However, the effect duration of a single stellate ganglion block is often temporary. To overcome the short-term effects of a single sympathetic block, pulsed radiofrequency (PRF) can be applied. The aim of the present study was to investigate the efficacy of PRF on the cervical sympathetic chain under ultrasound guidance for complex regional pain syndrome (CRPS). Twelve CRPS patients who underwent PRF on the cervical sympathetic chain were enrolled in this retrospective analysis. Under ultrasound guidance, PRF was performed for 420 seconds at 42°C on the C6- and C7-level sympathetic chain. The pain intensity decreased significantly at 1 week after the procedure. Overall, 91.7% of patients experienced at least moderate improvement. A positive correlation was observed between the extent of pain reduction at 1 week after PRF and the degree of overall benefit (r = 0.605, P = 0.037). This reduction in symptoms was maintained for a mean of 31.41 ± 26.07 days after PRF. There were no complications associated with this procedure. PRF on the cervical sympathetic chain, which can be performed easily and safely under ultrasound guidance, should be considered an option for managing CRPS of the upper extremities. PMID:28072749

  4. Identification of genes responsive to low intensity pulsed ultrasound in a human leukemia cell line Molt-4.

    PubMed

    Tabuchi, Yoshiaki; Ando, Hidetaka; Takasaki, Ichiro; Feril, Loreto B; Zhao, Qing-Li; Ogawa, Ryohei; Kudo, Nobuki; Tachibana, Katsuro; Kondo, Takashi

    2007-02-08

    We examined the gene expression of human leukemia Molt-4 cells treated with non-thermal low intensity pulsed ultrasound. Six hours after 0.3W/cm(2) pulsed ultrasound treatment, apoptosis (24+/-3.3%, mean+/-SD) with minimal cell lysis was observed. Of approximately 16,600 genes analyzed, BCL2-associated athanogene 3 (BAG3), DnaJ (Hsp40) homolog, subfamily B, member 1 (DNAJB1), heat shock 70 kDa protein 1B (HSPA1B), and heat shock 70 kDa protein 6 (HSPA6) showed increased levels of expression while isopentenyl-diphosphate delta isomerase (IDI1) and 3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) showed decreased levels in the cells 3h after the ultrasound treatment. The expression levels of these six genes were confirmed by a real-time quantitative polymerase chain reaction. To our knowledge, this is the first report of DNA microarray analysis of genes that are differentially expressed in response to apoptosis induced by non-thermal low intensity pulsed ultrasound in human leukemia cells. The present results will provide a basis for further understanding of the molecular mechanisms of effects of not only low intensity pulsed ultrasound but also that of mechanical shear stress in the cells.

  5. MATLAB/Simulink Pulse-Echo Ultrasound System Simulator Based on Experimentally Validated Models.

    PubMed

    Kim, Taehoon; Shin, Sangmin; Lee, Hyongmin; Lee, Hyunsook; Kim, Heewon; Shin, Eunhee; Kim, Suhwan

    2016-02-01

    A flexible clinical ultrasound system must operate with different transducers, which have characteristic impulse responses and widely varying impedances. The impulse response determines the shape of the high-voltage pulse that is transmitted and the specifications of the front-end electronics that receive the echo; the impedance determines the specification of the matching network through which the transducer is connected. System-level optimization of these subsystems requires accurate modeling of pulse-echo (two-way) response, which in turn demands a unified simulation of the ultrasonics and electronics. In this paper, this is realized by combining MATLAB/Simulink models of the high-voltage transmitter, the transmission interface, the acoustic subsystem which includes wave propagation and reflection, the receiving interface, and the front-end receiver. To demonstrate the effectiveness of our simulator, the models are experimentally validated by comparing the simulation results with the measured data from a commercial ultrasound system. This simulator could be used to quickly provide system-level feedback for an optimized tuning of electronic design parameters.

  6. Formation of Single Bubbles from a Submerged Orifice Using Pulsed Ultrasound Waves

    NASA Astrophysics Data System (ADS)

    Shirota, Minori; Imamura, Tomohiro; Kameda, Masaharu

    A new experimental method is presented in which single small gas bubbles are generated in a liquid from a submerged orifice using pulsed ultrasound waves. Pulsed ultrasound waves having a frequency of 15 kHz and a maximum pressure amplitude of approximately 10 kPa are irradiated to a bubble growing from an orifice. Single air bubbles ranging from approximately 0.05 to 0.2 mm in radius are obtained in silicone oil (kinematic viscosity: 1 mm2/s) by using two orifices (0.02 and 0.04 mm in diameter) and by shifting the onset of the detachment-assistance pressure wave. The bubble deformation and detaching processes were visualized and analyzed using high-speed video imaging and direct numerical simulation. Consequently, it is revealed that the bubbles are forced to elongate upward due to the fast oscillatory flow of gas through the orifice, and the elongation causes the bubbles to detach from the orifice. The size of the bubbles at detachment is well estimated by employing a common spherical bubble formation model.

  7. ULTRASOUND PULSE-ECHO IMAGING USING THE SPLIT-STEP FOURIER PROPAGATOR

    SciTech Connect

    HUANG, LIANJIE; QUAN, YOULI

    2007-01-31

    Ultrasonic reflection imaging has the potential to produce higher image resolution than transmission tomography, but imaging resolution and quality still need to be further improved for early cancer detection and diagnosis. We present an ultrasound reflection image reconstruction method using the split-step Fourier propagator. It is based on recursive inward continuation of ultrasonic wavefields in the frequency-space and frequency-wavenumber domains. The inward continuation within each extrapolation interval consists of two steps. In the first step, a phase-shift term is applied to the data in the frequency-wavenumber domain for propagation in a reference medium. The second step consists of applying another phase-shift term to data in the frequency-space domain to approximately compensate for ultrasonic scattering effects of heterogeneities within the breast. We use synthetic ultrasound pulse-echo data recorded around a ring for heterogeneous, computer-generated numerical breast phantoms to study the imaging capability of the method. The phantoms are derived from an experimental breast phantom and a sound-speed tomography image of an in-vivo ultrasound breast data collected usi ng a ring array. The heterogeneous sound-speed models used for pulse-echo imaging are obtained using a computationally efficient, first-arrival-time (time-of-flight) transmission tomography method. Our studies demonstrate that reflection image reconstruction using the split-step Fourier propagator with heterogeneous sound-speed models significantly improves image quality and resolution. We also numerically verify the spatial sampling criterion of wavefields for a ring transducer array.

  8. Harmonic responses and cavitation activity of encapsulated microbubbles coupled with magnetic nanoparticles.

    PubMed

    Gu, Yuyang; Chen, Chuyi; Tu, Juan; Guo, Xiasheng; Wu, Hongyi; Zhang, Dong

    2016-03-01

    Encapsulated microbubbles coupled with magnetic nanoparticles, one kind of hybrid agents that can integrate both ultrasound and magnetic resonance imaging/therapy functions, have attracted increasing interests in both research and clinic communities. However, there is a lack of comprehensive understanding of their dynamic behaviors generated in diagnostic and therapeutic applications. In the present work, a hybrid agent was synthesized by integrating superparamagnetic iron oxide nanoparticles (SPIOs) into albumin-shelled microbubbles (named as SPIO-albumin microbubbles). Then, both the stable and inertial cavitation thresholds of this hybrid agent were measured at varied SPIO concentrations and ultrasound parameters (e.g., frequency, pressure amplitude, and pulse length). The results show that, at a fixed acoustic driving frequency, both the stable and inertial cavitation thresholds of SPIO-albumin microbubble should decrease with the increasing SPIO concentration and acoustic driving pulse length. The inertial cavitation threshold of SPIO-albumin microbubbles also decreases with the raised driving frequency, while the minimum sub- and ultra-harmonic thresholds appear at twice and two thirds resonance frequency, respectively. It is also noticed that both the stable and inertial cavitation thresholds of SonoVue microbubbles are similar to those measured for hybrid microbubbles with a SPIO concentration of 114.7 μg/ml. The current work could provide better understanding on the impact of the integrated SPIOs on the dynamic responses (especially the cavitation activities) of hybrid microbubbles, and suggest the shell composition of hybrid agents should be appropriately designed to improve their clinical diagnostic and therapeutic performances of hybrid microbubble agents.

  9. Effect of pulsed ultrasound on the physicochemical characteristics and emulsifying properties of squid (Dosidicus gigas) mantle proteins.

    PubMed

    Higuera-Barraza, O A; Torres-Arreola, W; Ezquerra-Brauer, J M; Cinco-Moroyoqui, F J; Rodríguez Figueroa, J C; Marquez-Ríos, E

    2017-01-12

    Food technologists are always looking to improve the functional properties of proteins. In this sense, in last years ultrasound has been used to improve some functional properties. For this reason, and considering that jumbo squid is an important fishery in northwest Mexico, the purpose of this research was to determine the effect of pulsed ultrasound on the physicochemical characteristics and emulsifying properties of squid (Dosidicus gigas) mantle proteins. Pulsed ultrasound (20kHz, 20, and 40% amplitude) was applied for 30, 60, and 90s to a protein extract prepared from giant squid mantle causing an increase (p<0.05) in surface hydrophobicity (So) from 108.4±1.4 to 239.1±2.4 after application of pulsed ultrasound at 40% of amplitude for 90s. The electrophoretic profile and the total and reactive sulfhydryl contents were not affected (p⩾0.05) by the ultrasound treatment. The emulsifying ability of the protein solution was improved (p<0.05), whereas the Emulsifier Activity Index (EAI) varied from123.67±5.52m(2)/g for the control and increased up to 217.7±3.8m(2)/g after application of the ultrasound. The Stability Emulsifier Index (EEI) was improved at 40% of amplitude by 60 and 90s. The results suggested that pulsed ultrasound used as pretreatment induced conformational changes in giant squid proteins, which improved the interfacial association between protein-oil phases, thus contributing to the improvement of their emulsifient properties.

  10. Histotripsy-Induced Cavitation Cloud Initiation Thresholds in Tissues of Different Mechanical Properties

    PubMed Central

    Vlaisavljevich, Eli; Maxwell, Adam; Warnez, Matthew; Johnsen, Eric; Cain, Charles A.; Xu, Zhen

    2014-01-01

    Histotripsy is an ultrasound ablation method that depends on the initiation and maintenance of a cavitation bubble cloud to fractionate soft tissue. This paper studies how tissue properties impact the pressure threshold to initiate the cavitation bubble cloud. Our previous study showed that shock scattering off one or more initial bubbles, expanded to sufficient size in the focus, plays an important role in initiating a dense cavitation cloud. In this process, the shock scattering causes the positive pressure phase to be inverted, resulting in a scattered wave that has the opposite polarity of the incident shock. The inverted shock is superimposed on the incident negative pressure phase to form extremely high negative pressures, resulting in a dense cavitation cloud growing toward the transducer. We hypothesize that increased tissue stiffness impedes the expansion of initial bubbles, reducing the scattered tensile pressure, and thus requiring higher initial intensities for cloud initiation. To test this hypothesis, 5-cycle histotripsy pulses at pulse repetition frequencies (PRFs) of 10, 100, or 1000 Hz were applied by a 1-MHz transducer focused inside mechanically tunable tissue-mimicking agarose phantoms and various ex vivo porcine tissues covering a range of Young’s moduli. The threshold to initiate a cavitation cloud and resulting bubble expansion were recorded using acoustic backscatter detection and optical imaging. In both phantoms and ex vivo tissue, results demonstrated a higher cavitation cloud initiation threshold for tissues of higher Young’s modulus. Results also demonstrated a decrease in bubble expansion in phantoms of higher Young’s modulus. These results support our hypothesis, improve our understanding of the effect of histotripsy in tissues with different mechanical properties, and provide a rational basis to tailor acoustic parameters for fractionation of specific tissues. PMID:24474139

  11. Biological response in vitro of skeletal muscle cells treated with different intensity continuous and pulsed ultrasound fields

    NASA Astrophysics Data System (ADS)

    Abrunhosa, Viviane M.; Mermelstein, Claudia S.; Costa, Manoel L.; Costa-Felix, Rodrigo P. B.

    2011-02-01

    Therapeutic ultrasound has been used in physiotherapy to accelerate tissue healing. Although the ultrasonic wave is widely used in clinical practice, not much is known about the biological effects of ultrasound on cells and tissues. This study aims to evaluate the biological response of ultrasound in primary cultures of chick myogenic cells. To ensure the metrological reliability of whole measurement process, the ultrasound equipment was calibrated in accordance with IEC 61689:2007. The skeletal muscle cells were divided in four samples. One sample was used as a control group and the others were submitted to different time and intensity and operation mode of ultrasound: 1) 0.5 W/cm2 continuous for 5 minutes, 2) 0.5 W/cm2 pulsed for 5 minutes, 3) 1.0 W/cm2 pulsed for 10 minutes. The samples were analyzed with phase contrast optical microscopy before and after the treatment. The results showed alignment of myogenic cells in the sample treated with 0.5 W/cm2 continuous during 5 minutes when compared with the control group and the other samples. This study is a first step towards a metrological and scientific based protocol to cells and tissues treatment under different ultrasound field exposures.

  12. Cavitation in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael R.; Crum, Lawrence A.; Sapozhnikov, Oleg A.; Evan, Andrew P.; McAteer, James A.; Colonius, Tim; Cleveland, Robin O.

    2003-10-01

    A case is presented for the important role of cavitation in stone comminution and tissue injury in shock wave lithotripsy (SWL). Confocal hydrophones and a coincidence algorithm were used to detect cavitation in kidney parenchyma. Elevated hydrostatic pressure dissolved cavitation nuclei and suppressed cell injury and stone comminution in vitro. A low-insertion-loss, thin, mylar film nearly eliminated stone erosion and crack formation only when in direct contact with the stone. This result indicates not only that cavitation is important in both cracking and erosion but also that bubbles act at the surface. Time inversion of the shock wave by use of a pressure-release reflector reduced the calculated pressure at bubble collapse and the measured depth of bubble-induced pits in aluminum. Correspondingly tissue injury in vivo was nearly eliminated. Cavitation was localized and intensified by the use of synchronously triggered, facing lithotripters. This dual pulse lithotripter enhanced comminution at its focus and reduced lysis in surrounding blood samples. The enhancement of comminution was lost when stones were placed in glycerol, which retarded bubble implosion. Thus, cavitation is important in comminution and injury and can be controlled to optimize efficacy and safety. [Work supported by NIH DK43381, DK55674, and FIRCA.

  13. Measurement of the contrast agent intrinsic and native harmonic response with single transducer pulse waved ultrasound systems.

    PubMed

    Verbeek, X A; Willigers, J M; Brands, P J; Ledoux, L A; Hoeks, A P

    1999-01-01

    Ultrasound contrast agents, i.e., small gas filled microbubbles, enhance the echogenicity of blood and have the potential to be used for tissue perfusion assessment. The contrast agents scatter ultrasound in a nonlinear manner and thereby introduce harmonics in the ultrasound signal. This property is exploited in new ultrasound techniques like harmonic imaging, which aims to display only the contrast agent presence. Much attention has already been given to the physical properties of the contrast agent. The present study focuses on practical aspects of the measurement of the intrinsic harmonic response of ultrasound contrast agents with single transducer pulse waved ultrasound systems. Furthermore, the consequences of two other sources of harmonics are discussed. These sources are the nonlinear distortion of ultrasound in a medium generating native harmonics, and the emitted signal itself which might contain contaminating harmonics. It is demonstrated conceptually and by experiments that optimization of the contrast agent harmonic response measured with a single transducer is governed by the transducer spectral sensitivity distribution rather than the resonance properties of the contrast agent. Both native and contaminating harmonics may be of considerable strength and can be misinterpreted as intrinsic harmonics of the contrast agent. Practical difficulties to filter out the harmonic component selectively, without deteriorating the image, may cause misinterpretation of the fundamental as a harmonic.

  14. Ultrasound-Guided Pulsed Radiofrequency for Carpal Tunnel Syndrome: A Single-Blinded Randomized Controlled Study

    PubMed Central

    2015-01-01

    Objective We assessed the therapeutic efficiency of ultrasound-guided pulsed radiofrequency (PRF) treatment of the median nerve in patients with carpal tunnel syndrome (CTS). Methods We conducted a prospective, randomized, controlled, single-blinded study. Forty-four patients with CTS were randomized into intervention or control groups. Patients in the intervention group were treated with PRF and night splint, and the control group was prescribed night splint alone. Primary outcome was the onset time of significant pain relief assessed using the visual analog scale (VAS), and secondary outcomes included evaluation of the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) results, cross-sectional area (CSA) of the median nerve, sensory nerve conduction velocity (SNCV) of the median nerve, and finger pinch strength. All outcome measurements were performed at 1, 4, 8, and 12 weeks after treatment. Results Thirty-six patients completed the study. The onset time of pain relief in the intervention group was significantly shorter (median onset time of 2 days vs. 14 days; hazard ratio = 7.37; 95% CI, 3.04–17.87) compared to the control group (p < 0.001). Significant improvement in VAS and BCTQ scores (p < 0.05) was detected in the intervention group at all follow-up periods compared to the controls (except for the severity subscale of BCTQ at week 1). Ultrasound-guided PRF treatment resulted in a lower VAS score and stronger finger pinch compared to the control group over the entire study. Conclusions Our study shows that ultrasound-guided PRF serves as a better approach for pain relief in patients with CTS. Trial Registration ClinicalTrials.gov NCT02217293 PMID:26067628

  15. Ultrasound-modulated optical imaging using a powerful long pulse laser.

    PubMed

    Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

    2008-08-18

    Ultrasound-modulated optical imaging (or tomography) is an emerging biodiagnostic technique which provides the optical spectroscopic signature and the localization of an absorbing object embedded in a strongly scattering medium. We propose to improve the sensitivity of the technique by using a pulsed single-frequency laser to raise the optical peak power applied to the scattering medium and thereby collect more ultrasonically tagged photons. Moreover, when the detection of tagged photons is done with a photorefractive interferometer, the high optical peak power reduces the response time of the photorefractive crystal below the speckle field decorrelation time. Results obtained with a GaAs photorefractive interferometer are presented for 30- and 60-mm thick scattering media.

  16. Preliminary Study on the Efficacy of Low Intensity Pulsed ultrasound for Osteoporosis

    NASA Astrophysics Data System (ADS)

    Yamanaka, Makoto; Koji, Akiyama; Tokita, Akihumi; Ishijima, Muneaki; Nozawa, Masahiko; Kurosawa, Hisashi

    2005-03-01

    Low-intensity pulsed ultrasound (LIPUS) has recently been shown to accelerate long bone fracture healing, but its effect on osteoporosis is not clear. The aim of this study is to investigate whether bone mineral density (BMD) of distal one-third radius of older woman is influenced with LIPUS. Six Japanese women who were outpatients at our hospital were recruited in this study and ranged from seventy to seventy-four years of age. In this study LIPUS exposed unilateral distal one-third of the radius for 20 min/once, 3 times and over every week for six months. The contralateral side was not exposed. The intensity of ultrasound was 30 mW/cm2 spatial-average temporal-average. Bone status was assessed by dual energy X-ray absorptiometry at baseline and 3 and 6 months later. Medication for osteoporosis were not changed. A significant increases in BMD at the treatment site were found in 3 women without alendronate and menatetrenone medication (averaged 4.5%). No significant differences were found in women on these medications. No remarkable changes were found away from the treatment site. These results suggest the possibility of effectiveness of LIPUS applied to a local area of osteoporosis and that pharmacological intervention is capable of influencing the effect of LIPUS for osteoporosis.

  17. Robert Apfel's contribution to clinical diagnostic ultrasound: The mechanical index

    NASA Astrophysics Data System (ADS)

    Holland, Christy K.

    2004-05-01

    The mechanical index, MI, resulted from theoretical considerations of the short-pulse acoustic threshold for inertial cavitation in water populated with microbubbles of all sizes [R. E. Apfel and C. K. Holland, Ultrasound Med Biol. 17, 179-185 (1991)]. In this review, the onset of cavitation will be discussed with reference to Robert Apfel's legacy of theoretical and experimental data. The questions arise: Can the utility of the MI be extended to situations in which the threshold MI is exceeded, thereby allowing for some estimate of the quantification of a potential bioeffect due to microcavitation? Also, can the MI be extended to situations in which pulses are, unlike the original formulation, not short? Is there a theoretical or semi-empirical basis for the MI threshold below which cavitation is unlikely? Can the MI be used to predict gas contrast agent destruction? The possible consequences of gas body activation associated with aerated lung tissue, intestinal gas pockets or encapsulated gas contrast agents represent specific instances of cavitation considerations relevant to clinical practice. Monitoring the real-time display of the MI (mandated by the FDA) helps clinicians evaluate and minimize the potential risks in the use of diagnostic ultrasound instrumentation. [Research supported by National Institutes of Health Grant R29 HL58761.

  18. Superharmonic microbubble Doppler effect in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Choi, James J

    2016-08-21

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  10(4)-5  ×  10(7) microbubbles ml(-1)) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s(-1), prior to the onset

  19. Superharmonic microbubble Doppler effect in ultrasound therapy

    NASA Astrophysics Data System (ADS)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104-5  ×  107 microbubbles ml-1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s-1, prior to the onset of

  20. Ultrasound

    MedlinePlus

    ... called multiples) To screen for birth defects, like spina bifida or heart defects . Screening means seeing if your ... example, if the ultrasound shows your baby has spina bifida, she may be treated in the womb before ...

  1. Ultrasound

    MedlinePlus Videos and Cool Tools

    ... baby's development in the uterus. Ultrasound uses inaudible sound waves to produce a two-dimensional image of the baby while inside the mother's uterus. The sound waves bounce off solid structures in the body ...

  2. Research on the noise induced by cavitation under the asymmetric cavitation condition in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Lu, J. X.; Yuan, S. Q.; Yuan, J. P.; Ren, X. D.; Pei, J.; Si, Q. R.

    2015-12-01

    An experimental investigation has been carried out to research the noise induced by cavitation under the asymmetric cavitation (AC) condition in a centrifugal pump. The acoustic pressure signals at the pump inlet and outlet were measured respectively during the development of cavitation in a closed hydraulic test rig. It could be found that both the pump inlet and outlet acoustic pressures changed obviously with the development of cavitation. The time domain and the power spectrum density of the pump inlet and outlet acoustic pressure pulsations were analyzed. The broadband pulses of the acoustic pressure pulsations were found and the reasons for the phenomenon were given.

  3. Targeted therapy of animal eyes with tumors by laser-generated focused ultrasound (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lee, Taehwa; Luo, Wei; Demirci, Hakan; Guo, L. Jay

    2016-03-01

    Cavitation therapy based on high-amplitude focused ultrasound (e.g., Histotripsy) has shown great promise in clinical trials. The technique realizes localized treatments of tissues and diseased cells by controlling cavitation zones, which can be even smaller than its acoustic spot sizes. Also, the short pressure pulse used in the technique can minimize the unwanted heat accumulation, which the conventional piezoelectric transducers suffer from due to low operating frequencies and relatively long acoustic pulses. However, this modality requires bulky system composed of array of piezoelectric elements and electric amplifiers in order to obtain high pressure amplitude. Moreover, especially when treating an area much smaller than the acoustic spot size, this approach may be vulnerable to nucleation sites within the focal volume, which can potentially induce cavitation and thus enlarge the total treatment area. Here, we show targeted cell-level therapy by using laser generated ultrasound. By employing a concave lens coated by a carbon nanotube (CNT)-polymer composite, high-amplitude acoustic pressure can be obtained at a tight focal spot (<100 um). The small focal spot, comparable to cavitation zone, lead to controlled cavitation treatment. Such feature can be exploited for treating intraocular tumors but without harming other parts of the eye (e.g. healthy retina and choroid) and therefore preserve the vision of the patients. We demonstrate that the localized disruption effects can be used for cell-level surgery to remove cells and to kill cells. Some experimental examples are shown using animal eyeballs.

  4. Controlled Cavitation to Augment SWL Stone Comminution: Mechanistic Insights In-Vitro

    PubMed Central

    Duryea, Alexander P.; Roberts, William W.; Cain, Charles A.; Hall, Timothy L.

    2013-01-01

    Stone comminution in shock wave lithotripsy (SWL) has been documented to result from mechanical stresses conferred directly to the stone, as well as the activity of cavitational microbubbles. Studies have demonstrated that the presence of this cavitation activity is crucial for stone subdivision; however, its exact role in the comminution process remains somewhat weakly defined, in part due to the fact that it is difficult to isolate the cavitational component from the shock waves themselves. In this study, we further explored the importance of cavitation in SWL stone comminution through the use of histotripsy ultrasound therapy. Histotripsy was utilized to target model stones designed to mimic the mid-range tensile fracture strength of naturally occurring cystine calculi with controlled cavitation at strategic time points in the SWL comminution process. All SWL was applied at a peak-positive pressure (p+) of 34 MPa and a peak-negative pressure (p−) of 8 MPa; a shock rate of 1 Hz was used. Histotripsy pulses had a p− of 33 MPa and were applied at a pulse repetition frequency (PRF) of 100 Hz. Ten model stones were sonicated in-vitro with each of five different treatment schemes: A. 10 minutes SWL (600 shocks) with 0.7 seconds of histotripsy interleaved between successive shocks (totaling to 42,000 pulses); B. 10 minutes SWL (600 shocks) followed by 10 minutes histotripsy applied in 0.7 second bursts (1 burst per second, totaling to 42,000 pulses); C. 10 minutes histotripsy applied in 0.7 second bursts (42,000 pulses) followed by 10 minutes SWL (600 shocks); D. 10 minutes SWL-only (600 shocks); E. 10 minutes histotripsy-only applied in 0.7 second bursts (42,000 pulses). Following sonication, debris was collected and sieved through 8, 6, 4, and 2 mm filters. It was found that SWL-only generated a broad range of fragment sizes, with an average of 14.9 ± 24.1% of the original stone mass remaining >8 mm. Histotripsy-only eroded the surface of stones to tiny

  5. Cavitation and non-cavitation regime for large-scale ultrasonic standing wave particle separation systems--In situ gentle cavitation threshold determination and free radical related oxidation.

    PubMed

    Johansson, Linda; Singh, Tanoj; Leong, Thomas; Mawson, Raymond; McArthur, Sally; Manasseh, Richard; Juliano, Pablo

    2016-01-01

    We here suggest a novel and straightforward approach for liter-scale ultrasound particle manipulation standing wave systems to guide system design in terms of frequency and acoustic power for operating in either cavitation or non-cavitation regimes for ultrasound standing wave systems, using the sonochemiluminescent chemical luminol. We show that this method offers a simple way of in situ determination of the cavitation threshold for selected separation vessel geometry. Since the pressure field is system specific the cavitation threshold is system specific (for the threshold parameter range). In this study we discuss cavitation effects and also measure one implication of cavitation for the application of milk fat separation, the degree of milk fat lipid oxidation by headspace volatile measurements. For the evaluated vessel, 2 MHz as opposed to 1 MHz operation enabled operation in non-cavitation or low cavitation conditions as measured by the luminol intensity threshold method. In all cases the lipid oxidation derived volatiles were below the human sensory detection level. Ultrasound treatment did not significantly influence the oxidative changes in milk for either 1 MHz (dose of 46 kJ/L and 464 kJ/L) or 2 MHz (dose of 37 kJ/L and 373 kJ/L) operation.

  6. Study of the inactivation of spoilage microorganisms in apple juice by pulsed light and ultrasound.

    PubMed

    Ferrario, Mariana; Alzamora, Stella Maris; Guerrero, Sandra

    2015-04-01

    The aim of this study was to evaluate the effect of ultrasound (US) (600 W, 20 kHz and 95.2 μm wave amplitude; 10 or 30 min at 20, 30 or 44 ± 1 °C) and pulsed light (PL) (Xenon lamp; 3 pulses/s; 0.1 m distance; 2.4 J/cm(2)-71.6 J/cm(2); initial temperature 2, 30, 44 ± 1 °C) on the inactivation of Alicyclobacillus acidoterrestris ATCC 49025 spores and Saccharomyces cerevisiae KE162 inoculated in commercial (pH: 3.5; 12.5 °Brix) and natural squeezed (pH: 3.4; 11.8 °Brix) apple juices. Inactivation depended on treatment time, temperature, microorganism and matrix. Combination of these technologies led up to 3.0 log cycles of spore reduction in commercial apple juice and 2.0 log cycles in natural juice; while for S. cerevisiae, 6.4 and 5.8 log cycles of reduction were achieved in commercial and natural apple juices, respectively. In natural apple juice, the combination of US + 60 s PL at the highest temperature build-up (56 ± 1 °C) was the most effective treatment for both strains. In commercial apple juice, US did not contribute to further inactivation of spores, but significantly reduced yeast population. Certain combinations of US + PL kept on good microbial stability under refrigerated conditions for 15 days.

  7. Enhancement of cardiomyogenesis in stem cells by low intensity pulsed ultrasound

    NASA Astrophysics Data System (ADS)

    Teo, Ailing; Morshedi, Amir; Wang, Jen-Chieh; Lim, Mayasari; Zhou, Yufeng

    2017-03-01

    Low intensity pulsed ultrasound (LIPUS) has been shown to enhance bone and cartilage regeneration from stem cells. Gene expression of angiotensin II type 1 (AT1) receptor can be increased in LIPUS-treated osteoblasts. The AT1 receptor is a known mechanoreceptor in cardiomyocytes. It suggests that LIPUS may enhance cardiomyogenesis via mechanotransduction by increasing AT1 expression. Murine embryonic stem cells (ESCs) were treated daily by 10-min 1MHz LIPUS at spatial-average temporal-peak acoustic intensities of 30 mW/cm2 and 300 mW/cm2 in both continuous and pulsed wave (20% duty cycle) for 10 days. Polymerase chain reaction (PCR), immunocytochemistry, and beating rate were used to evaluate the cardiac viability quantitatively. After the treatment of LIPUS, beating rate of contractile areas and cardiac gene expression, such as α- and β-myosin heavy chain, were improved. Furthermore, no deleterious effects to the development of cardiac proteins were observed. All results suggest that LIPUS stimulation has the capacity of enhancing cardiomyogenesis from embryonic stem cells. With the benefit and the ease in incorporating LIPUS into various culture platforms, LIPUS has the potential to produce cardiomyocytes for clinical use in the future.

  8. Localized Tissue Surrogate Deformation due to Controlled Single Bubble Cavitation

    DTIC Science & Technology

    2014-08-27

    dissolved gasses, and cavitation can be induced within CSF or other fluid compartments within the brain when exposed to relatively low blast...particulate surfaces. However, pre-existing gas nuclei can act as another source 5. Previous hyperbaric decompression and ultrasound studies suggest that...studies using ultrasound shock waves also support cavitation induced damage, e.g. hemorrhage and cellular membrane poration 26-28. In addition

  9. Cavitation bioeffects.

    PubMed

    Kimmel, Eitan

    2006-01-01

    Acoustic cavitation takes place when tiny gas bubbles oscillate, grow, and collapse in liquid under the influence of ultrasonic field. This study reviews cavitation bioeffects that are found both in vivo and in vitro when exposed to either low- or high-power acoustics. Proposed mechanisms are discussed here as well based on theoretical studies, simulations and test bench experiments. Bioeffects are induced in living tissue once the gas bubble is, for instance, within a blood vessel in close vicinity to the endothelium or to the red blood cells. Conditions for inducing various bioeffects are discussed - from severe damage, such as cell necrosis, to delicate alterations, such as increased permeability of cell membrane. Present and potential applications for therapeutic purpose from stone pulverization and tissue ablation to gene transfection and transdermal delivery are reviewed including the growing use of artificial microbubbles.

  10. THE ROLE OF INERTIAL CAVITATION IN ACOUSTIC DROPLET VAPORIZATION

    PubMed Central

    Fabiilli, Mario L.; Haworth, Kevin J.; Fakhri, Nasir H.; Kripfgans, Oliver D.; Carson, Paul L.; Fowlkes, J. Brian

    2011-01-01

    The vaporization of a superheated droplet emulsion into gas bubbles using ultrasound – termed acoustic droplet vaporization (ADV) – has potential therapeutic applications in embolotherapy and drug delivery. The optimization of ADV for therapeutic applications can be enhanced by understanding the physical mechanisms underlying ADV, which are currently not clearly elucidated. Acoustic cavitation is one possible mechanism. This paper investigates the relationship between the ADV and inertial cavitation (IC) thresholds (measured as peak rarefactional pressures) by studying parameters that are known to influence the IC threshold. These parameters include bulk fluid properties such as gas saturation, temperature, viscosity, and surface tension; droplet parameters such as degree of superheat, surfactant type, and size; and acoustic properties such as pulse repetition frequency and pulse width. In all cases the ADV threshold occurred at a lower rarefactional pressure than the IC threshold indicating that the phase-transition occurs before IC events. The viscosity and temperature of the bulk fluid are shown to influence both thresholds directly and inversely, respectively. An inverse trend is observed between threshold and diameter for droplets in the 1 to 2.5 μ range. Based on a choice of experimental parameters, it is possible to achieve ADV with or without IC. PMID:19473917

  11. Photoacoustic cavitation for theranostics: mechanism, current progress and applications

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Qin, D.; Wan, M.

    2015-12-01

    As an emerging cavitation technology, photoacoustic cavitation (PAC) means the formation of bubbles in liquids using focused laser and pre-established ultrasound synchronously. Its significant advantages include the decreased threshold of each modality and the precise location of cavitation determined by the focused laser. In this paper, a brief review of PAC is presented, including the physical mechanism description, the classic experimental technology, the representative results in variety of media, and its applications in biomedical imaging and therapy. Moreover, some preliminary results of PAC in perfluoropentane (PFP) liquid and PFP droplets investigated by passive cavitation detection (PCD) in our group are also presented.

  12. Use of Ultrasound Pulses Combined with Definity for Targeted Blood-Brain Barrier Disruption

    NASA Astrophysics Data System (ADS)

    McDannold, Nathan; Vykhodtseva, Natalia; Hynynen, Kullervo

    2007-05-01

    We have developed a method to combine an ultrasound contrast agent (USCA) with low-intensity focused ultrasound pulses combined to produce temporary blood-brain barrier disruption (BBBD), a potential non-invasive means for targeted drug delivery in the brain. All of our previous work used the USCA Optison. The purpose of this work was to test the feasibility of using the USCA Definity for BBBD. Thirty-six non-overlapping locations were sonicated through a craniotomy in experiments in the brains of nine rabbits (4 locations per rabbit; US frequency: 0.69MHz, burst: 10ms, PRF: 1Hz, duration: 20s; pressure amplitude: 0.2-1.5 MPa). Eleven locations were sonicated using Optison at 0.5 MPa. For both agents, the probability for BBBD was estimated to be 50% at 0.4 MPa using probit regression. In histology, small isolated areas of extravasated erythrocytes were observed in some locations. At 0.8 MPa and above, this extravasation was sometimes accompanied by tiny (dimensions of 100 μm or less) regions of damaged brain parenchyma. The magnitude of the BBBD was larger with Optison than with Definity at 0.5 MPa (P=0.04), and more areas with extravasated erythrocytes were observed (P=0.03). We conclude that BBBD is possible using Definity for the dosage of USCA and the acoustic parameters tested in this study. While the probability for BBBD as a function of pressure amplitude and the type of acute tissue effects was similar to findings with Optison, under these experimental conditions, Optison produced a larger effect.

  13. Detection of acoustic emission from cavitation in tissue during clinical extracorporeal lithotripsy.

    PubMed

    Coleman, A J; Choi, M J; Saunders, J E

    1996-01-01

    A 1-MHz focused hydrophone has been used to search for acoustic emission expected to arise from cavitation occurring in tissue during clinical extracorporeal shock-wave lithotripsy (ESWL). The hydrophone is acoustically coupled to the patient's skin and the focus directed at depth in tissue under ultrasound guidance. The measured amplitude-time variation of the acoustic emission from tissue near the shock-wave focus of the Storz Modulith SL20 lithotripter has been examined in four patients. There is evidence of increased amplitude acoustic emission at 1 MHz from regions within tissue that also appear hyperechoic in simultaneously acquired ultrasound images. The acoustic emission from these regions decays from an initial peak to the noise level in about 500 microseconds following each shock-wave pulse. Within this period, a second peak, often of higher amplitude than the first, is typically observed about 100 microseconds after the shockwave. The time between the initial and second peaks is found to increase with increasing shock-wave amplitude. The results are similar to those previously observed from cavitation induced by shock-wave exposure in water and indicate that the 1-MHz acoustic emission arises from inertial cavitation in tissue during clinical ESWL.

  14. Impact of acoustic cavitation on food emulsions.

    PubMed

    Krasulya, Olga; Bogush, Vladimir; Trishina, Victoria; Potoroko, Irina; Khmelev, Sergey; Sivashanmugam, Palani; Anandan, Sambandam

    2016-05-01

    The work explores the experimental and theoretical aspects of emulsification capability of ultrasound to deliver stable emulsions of sunflower oil in water and meat sausages. In order to determine optimal parameters for direct ultrasonic emulsification of food emulsions, a model was developed based on the stability of emulsion droplets in acoustic cavitation field. The study is further extended to investigate the ultrasound induced changes to the inherent properties of raw materials under the experimental conditions of sono-emulsification.

  15. Enzymolysis kinetics, thermodynamics and model of porcine cerebral protein with single-frequency countercurrent and pulsed ultrasound-assisted processing.

    PubMed

    Zou, Ye; Ding, Yangyang; Feng, Weiwei; Wang, Wei; Li, Qian; Chen, Yao; Wu, Huiyu; Wang, Xintong; Yang, Liuqing; Wu, Xiangyang

    2016-01-01

    The present work investigated the enzymolysis kinetics, thermodynamics and model of porcine cerebral protein (PCP) which was pretreated by single-frequency countercurrent and pulsed ultrasound. The kinetic constants for ultrasonic pretreated and traditional enzymolysis have been determined. Results showed that the value of KM in ultrasonic PCP (UPCP) enzymolysis decreased by 9% over that in the traditional enzymolysis. The values of reaction rate constant (k) for UPCP enzymolysis increased by 207%, 121%, 62%, and 45% at 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased activation energy (Ea), change in enthalpy (ΔH) and entropy (ΔS) by 76%, 82% and 31% in PCP, respectively. However, ultrasound had little change in Gibbs free energy (ΔG) value in the temperature range of 293-323 K. Therefore, a general kinetic equation for the enzymolysis model of UPCP by a simple empirical equation was suggested. The experimental values fits with the enzymolysis kinetic model with a low average relative error (4%) confirmed that the kinetic model was accurate to reflect the enzymolysis process. The positive effect of single-frequency countercurrent and pulsed ultrasound in this study and application of the kinetic model may be useful for the release of bioactive peptides from meat processing by-products.

  16. Pulsed low-intensity ultrasound: a new salvage procedure for delayed unions and nonunions after leg lengthening in children.

    PubMed

    Gebauer, Dieter; Correll, Johannes

    2005-01-01

    From 1998 to 2001, 112 lengthening procedures with or without deformity correction were performed in 108 children by external fixation with the Ilizarov method. Of these cases, 16.9% did not lead to a solid bone consolidation. Two children were operated the second time, mainly because of the parent's decision. Seventeen delayed unions or nonunions in 13 children were treated with low-intensity pulsed ultrasound. All 17 cases healed within 3 to 12 months without any risk of surgical intervention.

  17. Heating of tissues in vivo by pulsed focused ultrasound to stimulate enhanced HSP expression

    NASA Astrophysics Data System (ADS)

    Kujawska, Tamara; Wójcik, Janusz; Nowicki, Andrzej

    2011-09-01

    The main aim of this work was numerical modeling of temperature fields induced in soft tissues in vivo by pulsed focused ultrasound during neurodegenerative disease treatment and experimental verification of the proposed model for a rat liver. The new therapeutic approach to neurodegenerative diseases consists of stimulation of enhanced expression of the Heat Shock Proteins (HSP) which are responsible for immunity of cells to stress. During therapy the temperature rise in tissues in vivo should not exceed 6 °C above level of the thermal norm (37 °C). First, the 3D acoustic pressure field, and the rate of heat production per unit volume due to that field, were calculated using our 3D numerical solver capable of predicting nonlinear propagation of pulsed high intensity waves generated from circular focused acoustic sources in multilayer configuration of attenuating media. The two-layer configuration of media (water—rat liver) assumed in calculations fairly well approximated both the real anatomic dimensions of rat liver and the geometric scheme of our experimental set-up. A numerical solution of the Pennes bio-heat transfer equation which accounted for the effects of heat diffusion, blood perfusion and metabolism rates, was employed to calculate the temperature fields induced in the rat liver by the ultrasonic beam. The numerical simulation results were verified experimentally using a thermocouple inserted in the liver of a rat under anesthesia at the beam focus. The quantitative analysis of the obtained results enabled estimation of the effects of several acoustic and thermal parameters of the rat liver in vivo on the temperature rise, as well as determination of exposure time for ultrasonic beams with varied acoustic power generated by a 2-MHz circular transducer of 15-mm diameter and 25-mm focal length, in order to avoid the tissue overheating that leads to cells necrosis, which would be unacceptable in neurodegenerative disease treatment.

  18. Low intensity pulsed ultrasound increases the mechanical properties of the healing tissues at bone-tendon junction.

    PubMed

    Lu, Min-Hua; Zheng, Yong-Ping; Huang, Qing-Hua; Lu, Hong-Bin; Qin, Ling

    2009-01-01

    The re-establishment of bone-tendon junction (BTJ) tissues is involved in many trauma and reconstructive surgeries. A direct BTJ repair requires a long period of immobilization which may be associated with a postoperative weak knee. In this study, we investigated if low-intensity pulsed ultrasound treatment increases the material properties of healing tissues at bone-tendon junction (BTJ) after partial patellectomy using rabbit models. Standard partial patellectomy was conducted on one knee of twenty four rabbits which were randomly divided into an ultrasound group and a control group. The bony changes of BTJ complexes around the BTJ healing interface were measured by anteroposterior x-ray radiographs; then the volumetric bone-mineral density (BMD) of the new bone was assessed using a peripheral computed tomography scanner (pQCT). The stiffness of patellar cartilage, fibrocartilage at the healing interface and the tendon were measured in situ using a novel noncontact ultrasound water jet indentation system. Not only significantly more newly formed bone at the BTJ healing interface but also increased stiffness of the junction tissues were found in the ultrasound group compared with the controls at week 18. In addition, the ultrasound group also showed significantly 44% higher BMD at week 6 than controls.

  19. Design evolution enhances patient compliance for low-intensity pulsed ultrasound device usage

    PubMed Central

    Pounder, Neill M; Jones, John T; Tanis, Kevin J

    2016-01-01

    Poor patient compliance or nonadherence with prescribed treatments can have a significant unfavorable impact on medical costs and clinical outcomes. In the current study, voice-of-the-customer research was conducted to aid in the development of a next-generation low-intensity pulsed ultrasound (LIPUS) bone healing product. An opportunity to improve patient compliance reporting was identified, resulting in the incorporation into the next-generation device of a visual calendar that provides direct feedback to the patient, indicating days for which they successfully completed treatment. Further investigation was done on whether inclusion of the visual calendar improved patient adherence to the prescribed therapy (20 minutes of daily treatment) over a 6-month period. Thus, 12,984 data files were analyzed from patients prescribed either the earlier- or the next-generation LIPUS device. Over the 6-month period, overall patient compliance was 83.8% with the next-generation LIPUS device, compared with 74.2% for the previous version (p<0.0001). Incorporation of the calendar feature resulted in compliance never decreasing below 76% over the analysis period, whereas compliance with the earlier-generation product fell to 51%. A literature review on the LIPUS device shows a correlation between clinical effectiveness and compliance rates more than 70%. Incorporation of stakeholder feedback throughout the design and innovation process of a next-generation LIPUS device resulted in a measurable improvement in patient adherence, which may help to optimize clinical outcomes. PMID:27942237

  20. Effects of beam steering in pulsed-wave ultrasound velocity estimation.

    PubMed

    Steinman, Aaron H; Yu, Alfred C H; Johnston, K Wayne; Cobbold, Richard S C

    2005-08-01

    Experimental and computer simulation methods have been used to investigate the significance of beam steering as a potential source of error in pulsed-wave flow velocity estimation. By simulating a typical linear-array transducer system as used for spectral flow estimation, it is shown that beam steering can cause an angle offset resulting in a change in the effective beam-flow angle. This offset primarily depends on the F-number and the nominal steering angle. For example, at an F-number of 3 and a beam-flow angle of 70 degrees , the velocity error changed from -5% to + 5% when the steering angle changed from -20 degrees to + 20 degrees . Much higher errors can occur at higher beam-flow angles, with smaller F-numbers and greater steering. Our experimental study used a clinical ultrasound system, a tissue-mimicking phantom and a pulsatile waveform to determine peak flow velocity errors for various steering and beam-flow angles. These errors were found to be consistent with our simulation results.

  1. Clinical and immunohistopathological aspects of venous ulcers treatment by Low-Intensity Pulsed Ultrasound (LIPUS).

    PubMed

    de Ávila Santana, Luísiane; Alves, José Marcos; Andrade, Thiago Antônio Moretti; Kajiwara, João Kazuyuki; Garcia, Sérgio Britto; Gomes, Fernanda Guzzo; Frade, Marco Andrey Cipriani

    2013-04-01

    The immunological mechanisms that are triggered by Low-Intensity Pulsed Ultrasound (LIPUS) in wound healing are unknown. In the present study, experimental groups were used to assess the treatment of chronic venous ulcers with 30mW/cm(2) SATA peripheral LIPUS three times per week compared to a daily treatment of 1% silver sulfadiazine (SDZ). The ulcers of the SDZ group (n=7) (G1) and LIPUS group (n=9) (G2) were photographed five times three months, and the images were analyzed using ImageJ software to quantify the total area (S), fibrin/sphacel area (yellow) and granulation area (red). The healing process was evaluated by the wound healing rate (WHR), granulation tissue rate (GTR) and fibrin/sphacel tissue rate (FTR). The ulcers were biopsied on days 1 and 45 and stained for collagen fiber quantification (picrosirius) and CD68(+) protein and VEGF (vascular endothelial growth factor) expression using HRP-streptavidin (horseradish peroxidase-streptavidin). On day 90, G2 had a mean 41% decrease in the ulcer area, while no decrease was observed in G1 (p<0.05). An increased tendency toward positive labeling of collagen fibers and VEGF (p>0.05) was observed in G2 compared to G1, and the number of CD68(+) cells was greater in G2 than in G1 (p<0.05). LIPUS presents superior activity compared to SDZ in stimulating the inflammatory and proliferative (angiogenesis and collagenesis, respectively) phases of chronic venous wound healing.

  2. Low-Intensity Pulsed Ultrasound Improves the Functional Properties of Cardiac Mesoangioblasts.

    PubMed

    Bernal, Aurora; Pérez, Laura M; De Lucas, Beatriz; Martín, Nuria San; Kadow-Romacker, Anke; Plaza, Gustavo; Raum, Kay; Gálvez, Beatriz G

    2015-12-01

    Cell-based therapy is a promising approach for many diseases, including ischemic heart disease. Cardiac mesoangioblasts are committed vessel-associated progenitors that can restore to a significant, although partial, extent, heart structure and function in a murine model of myocardial infarction. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive form of mechanical energy that can be delivered into biological tissues as acoustic pressure waves, and is widely used for clinical applications including bone fracture healing. We hypothesized that the positive effects of LIPUS on bone and soft tissue, such as increased cell differentiation and cytoskeleton reorganization, could be applied to increase the therapeutic potential of mesoangioblasts for heart repair. In this work, we show that LIPUS stimulation of cardiac mesoangioblasts isolated from mouse and human heart results in significant cellular modifications that provide beneficial effects to the cells, including increased malleability and improved motility. Additionally, LIPUS stimulation increased the number of binucleated cells and induced cardiac differentiation to an extent comparable with 5'-azacytidine treatment. Mechanistically, LIPUS stimulation activated the BMP-Smad signalling pathway and increased the expression of myosin light chain-2 together with upregulation of β1 integrin and RhoA, highlighting a potentially important role for cytoskeleton reorganization. Taken together, these results provide functional evidence that LIPUS might be a useful tool to explore in the field of heart cell therapy.

  3. Low-intensity pulsed ultrasound therapy: a potential strategy to stimulate tendon-bone junction healing.

    PubMed

    Ying, Zhi-min; Lin, Tiao; Yan, Shi-gui

    2012-12-01

    Incorporation of a tendon graft within the bone tunnel represents a challenging clinical problem. Successful anterior cruciate ligament (ACL) reconstruction requires solid healing of the tendon graft in the bone tunnel. Enhancement of graft healing to bone is important to facilitate early aggressive rehabilitation and a rapid return to pre-injury activity levels. No convenient, effective or inexpensive procedures exist to enhance tendon-bone (T-B) healing after surgery. Low-intensity pulsed ultrasound (LIPUS) improves local blood perfusion and angiogenesis, stimulates cartilage maturation, enhances differentiation and proliferation of osteoblasts, and motivates osteogenic differentiation of mesenchymal stem cells (MSCs), and therefore, appears to be a potential non-invasive tool for T-B healing in early stage of rehabilitation of ACL reconstruction. It is conceivable that LIPUS could be used to stimulate T-B tunnel healing in the home, with the aim of accelerating rehabilitation and an earlier return to normal activities in the near future. The purpose of this review is to demonstrate how LIPUS stimulates T-B healing at the cellular and molecular levels, describe studies in animal models, and provide a future direction for research.

  4. Low-intensity pulsed ultrasound therapy: a potential strategy to stimulate tendon-bone junction healing*

    PubMed Central

    Ying, Zhi-min; Lin, Tiao; Yan, Shi-gui

    2012-01-01

    Incorporation of a tendon graft within the bone tunnel represents a challenging clinical problem. Successful anterior cruciate ligament (ACL) reconstruction requires solid healing of the tendon graft in the bone tunnel. Enhancement of graft healing to bone is important to facilitate early aggressive rehabilitation and a rapid return to pre-injury activity levels. No convenient, effective or inexpensive procedures exist to enhance tendon-bone (T-B) healing after surgery. Low-intensity pulsed ultrasound (LIPUS) improves local blood perfusion and angiogenesis, stimulates cartilage maturation, enhances differentiation and proliferation of osteoblasts, and motivates osteogenic differentiation of mesenchymal stem cells (MSCs), and therefore, appears to be a potential non-invasive tool for T-B healing in early stage of rehabilitation of ACL reconstruction. It is conceivable that LIPUS could be used to stimulate T-B tunnel healing in the home, with the aim of accelerating rehabilitation and an earlier return to normal activities in the near future. The purpose of this review is to demonstrate how LIPUS stimulates T-B healing at the cellular and molecular levels, describe studies in animal models, and provide a future direction for research. PMID:23225850

  5. Design evolution enhances patient compliance for low-intensity pulsed ultrasound device usage.

    PubMed

    Pounder, Neill M; Jones, John T; Tanis, Kevin J

    2016-01-01

    Poor patient compliance or nonadherence with prescribed treatments can have a significant unfavorable impact on medical costs and clinical outcomes. In the current study, voice-of-the-customer research was conducted to aid in the development of a next-generation low-intensity pulsed ultrasound (LIPUS) bone healing product. An opportunity to improve patient compliance reporting was identified, resulting in the incorporation into the next-generation device of a visual calendar that provides direct feedback to the patient, indicating days for which they successfully completed treatment. Further investigation was done on whether inclusion of the visual calendar improved patient adherence to the prescribed therapy (20 minutes of daily treatment) over a 6-month period. Thus, 12,984 data files were analyzed from patients prescribed either the earlier- or the next-generation LIPUS device. Over the 6-month period, overall patient compliance was 83.8% with the next-generation LIPUS device, compared with 74.2% for the previous version (p<0.0001). Incorporation of the calendar feature resulted in compliance never decreasing below 76% over the analysis period, whereas compliance with the earlier-generation product fell to 51%. A literature review on the LIPUS device shows a correlation between clinical effectiveness and compliance rates more than 70%. Incorporation of stakeholder feedback throughout the design and innovation process of a next-generation LIPUS device resulted in a measurable improvement in patient adherence, which may help to optimize clinical outcomes.

  6. Effect of low-intensity pulsed ultrasound on orthodontically induced root resorption in beagle dogs.

    PubMed

    Al-Daghreer, Saleh; Doschak, Michael; Sloan, Alastair J; Major, Paul W; Heo, Giseon; Scurtescu, Cristian; Tsui, Ying Y; El-Bialy, Tarek

    2014-06-01

    We investigated the effect of low-intensity pulsed ultrasound (LIPUS) on orthodontically induced inflammatory root resorption in vivo. Ten beagle dogs were treated with an orthodontic appliance to move the mandibular fourth premolars bodily. The orthodontic movement was carried out for 4 wk with a continuous force of 1 N/side; using a split-mouth model, LIPUS was applied daily for 20 min. Fourth premolar and surrounding periodontal tissue were evaluated with micro-computed tomography and hematoxylin and eosin and tartrate-resistant acid phosphatase staining. We calculated the number, volume and distribution of root resorption lacunae and their percentage relative to total root volume, orthodontic tooth movement and periodontal ligament space. There was no significant difference in orthodontic tooth movement between the two sides. LIPUS significantly reduced the number of orthodontically induced inflammatory root resorption initiation areas by 71%, reduced their total volume by 68% and reduced their volume relative to the affected root total volume by 70%. LIPUS induced the formation of a precementum layer, thicker cementum and reparative cellular cementum.

  7. Interactions of inertial cavitation bubbles with stratum corneum lipid bilayers during low-frequency sonophoresis.

    PubMed

    Tezel, Ahmet; Mitragotri, Samir

    2003-12-01

    Interactions of acoustic cavitation bubbles with biological tissues play an important role in biomedical applications of ultrasound. Acoustic cavitation plays a particularly important role in enhancing transdermal transport of macromolecules, thereby offering a noninvasive mode of drug delivery (sonophoresis). Ultrasound-enhanced transdermal transport is mediated by inertial cavitation, where collapses of cavitation bubbles microscopically disrupt the lipid bilayers of the stratum corneum. In this study, we describe a theoretical analysis of the interactions of cavitation bubbles with the stratum corneum lipid bilayers. Three modes of bubble-stratum corneum interactions including shock wave emission, microjet penetration into the stratum corneum, and impact of microjet on the stratum corneum are considered. By relating the mechanical effects of these events on the stratum corneum structure, the relationship between the number of cavitation events and collapse pressures with experimentally measured increase in skin permeability was established. Theoretical predictions were compared to experimentally measured parameters of cavitation events.

  8. Temporal Trends in the Histology of the Rabbit Kidney after Cavitational Tissue Ablation

    NASA Astrophysics Data System (ADS)

    Hall, Timothy L.; Kieran, Kathleen; Fowlkes, J. Brian; Cain, Charles A.; Roberts, William W.

    2007-05-01

    Tissue can be mechanically ablated through inertial cavitation generated by high intensity pulsed ultrasound. The ablation appears acutely as a fine slurry with absent cellular structure. Long-term effects and the evolution of histologic changes in disrupted tissue remain poorly understood. This study aimed to characterize the 0-60 day histology of cavitational ablation in a rabbit model. 29 New Zealand White rabbits were anesthetized and exposed to high intensity pulses of ultrasound (60000 pulses, 20 usec duration, 750 kHz, 1 kHz PRF, 18 MPa peak rarefactional pressure, lower pole, left kidney). Kidneys were harvested immediately from five rabbits. The others were recovered and the kidneys were harvested 1, 2, 7, 20, or 60 days after treatment. Grossly, kidneys from 0-2 days displayed subcapsular bruising near the exposure site and some hemorrhage in the adjacent perirenal fat; microscopically, a disrupted, acellular zone measuring 3-5 mm by 5-10 mm accompanied by local infiltration of neutrophils (acute inflammation) was seen. Kidneys harvested after 7 days displayed tubular dilatation adjacent to the targeted area and collagen deposition consistent with scar formation. Decreased collagen deposition, decreased size of the disrupted zone, and regeneration of the tubular basal cell layer of dilated tubules was evident by day 20. Kidneys harvested at 20 and 60 days had contour defects near the exposure site with an apparent volume loss. Cavitation causes orderly and predictable histologic changes. Local renal damage induced during histotripsy may be partially reversible. Further research is needed to identify the clinical correlates of the observed histologic findings.

  9. Effects of varying duty cycle and pulse width on high-intensity focused ultrasound (HIFU)-induced transcranial thrombolysis.

    PubMed

    Hölscher, Thilo; Raman, Rema; Fisher, David J; Ahadi, Golnaz; Zadicario, Eyal; Voie, Arne

    2013-01-01

    The goal was to test the effects of various combinations of pulse widths (PW) and duty cycles (DC) on high-intensity focused ultrasound (HIFU)-induced sonothrombolysis efficacy using an in vitro flow model. An ExAblate™ 4000 HIFU headsystem (InSightec, Inc., Israel) was used. Artificial blood clots were placed into test tubes inside a human calvarium and exposed to pulsatile flow. Four different duty cycles were tested against four different pulse widths. For all study groups, an increase in thrombolysis efficacy could be seen in association with increasing DC and/or PW (p < 0.0001). Using transcranial HIFU, significant thrombolysis can be achieved within seconds and without the use of lytic drugs in vitro. Longer duty cycles in combination with longer pulse widths seem to have the highest potential to optimize clot lysis efficacy.

  10. Treatment of hepatic tumors by thermal versus mechanical effects of pulsed high intensity focused ultrasound in vivo

    NASA Astrophysics Data System (ADS)

    Peng, Song; Zhou, Ping; He, Wei; Liao, Manqiong; Chen, Lili; Ma, C.-M.

    2016-09-01

    The purpose of this study is to comparatively assess the thermal versus mechanical effects of pulsed high intensity focused ultrasound (HIFU) treatment on hepatic tumors in vivo. Forty-five rabbits with hepatic VX2 tumors were randomly separated into three groups (15 animals per group) before HIFU ablation. The total HIFU energy (in situ) of 1250 J was used for each tumor for three groups. In groups I and II, animals were treated with 1 MHz pulsed ultrasound at 1 Hz pulsed repetition frequency (PRF), 0.5 duty cycle (0.5 s on and 0.5 s off) and10 s duration for one spot sonication. For group II, in addition to HIFU treatment, microbubbles (SonoVue, Bracco, Milan, Italy) were injected via vein before sonication acting as a synergist. In group III, animals were treated with 1 MHz pulsed ultrasound at 10 Hz PRF, 0.1 duty cycle (0.1 s on and 0.9 s off) and 10 s duration for one sonication. The total treatment spots were calculated according to the tumor volume. Tumors were examined with contrast-enhanced computed tomography (CECT) immediately prior to and post HIFU treatment. Histopathologic assessment was performed 3 h after treatment. Our study showed that all animals tolerated the HIFU treatment well. Our data showed that mechanical HIFU could lead to controlled injury in rabbit hepatic tumors with different histological changes in comparison to thermal HIFU with or without microbubbles.

  11. Flow rate and duty cycle effects in lysis of Chlamydomonas reinhardtii using high-energy pulsed focused ultrasound.

    PubMed

    Riesberg, Grant; Bigelow, Timothy A; Stessman, Dan J; Spalding, Martin H; Yao, Linxing; Wang, Tong; Xu, Jin

    2014-06-01

    To consider microalgae lipid biofuel as a viable energy source, it is a necessity to maximize algal cell lysis, lipid harvest, and thus biofuel production versus the energy used to lyse the cells. Previous techniques have been to use energy consumptive ultrasound waves in the 10-40 kHz range in a stationary exposure environment. This study evaluated the potential of using 1.1 MHz ultrasound pulses in a new flow through type chamber on Chlamydomonas reinhardtii as a model organism for cell breakage. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34 cm and an active diameter of 6.36 cm driven by 20 cycle sine-wave tone bursts at varied pulse repetition frequencies. First, variations in flow rate were examined at a constant duty cycle of 3.6%. After assessing flow rates, the duty cycle was varied to further explore the dependence on the tone burst parameters. Cell lysis was assessed by quantifying protein and chlorophyll release into the supernatant as well as by lipid extractability. Appropriate flow rates with higher duty cycles led to statistically significant increases in cell lysis relative to controls and other exposure conditions.

  12. Why Current Doppler Ultrasound Methodology Is Inaccurate in Assessing Cerebral Venous Return: The Alternative of the Ultrasonic Jugular Venous Pulse

    PubMed Central

    2016-01-01

    Assessment of cerebral venous return is growing interest for potential application in clinical practice. Doppler ultrasound (DUS) was used as a screening tool. However, three meta-analyses of qualitative DUS protocol demonstrate a big heterogeneity among studies. In an attempt to improve accuracy, several authors alternatively measured the flow rate, based on the product of the time average velocity with the cross-sectional area (CSA). However, also the quantification protocols lacked of the necessary accuracy. The reasons are as follows: (a) automatic measurement of the CSA assimilates the jugular to a circle, while it is elliptical; (b) the use of just a single CSA value in a pulsatile vessel is inaccurate; (c) time average velocity assessment can be applied only in laminar flow. Finally, the tutorial describes alternative ultrasound calculation of flow based on the Womersley method, which takes into account the variation of the jugular CSA overtime. In the near future, it will be possible to synchronize the electrocardiogram with the brain inflow (carotid distension wave) and with the outflow (jugular venous pulse) in order to nicely have a noninvasive ultrasound picture of the brain-heart axis. US jugular venous pulse may have potential use in neurovascular, neurocognitive, neurosensorial, and neurodegenerative disorders. PMID:27006525

  13. Controlled tissue emulsification produced by high intensity focused ultrasound shock waves and millisecond boiling.

    PubMed

    Khokhlova, Tatiana D; Canney, Michael S; Khokhlova, Vera A; Sapozhnikov, Oleg A; Crum, Lawrence A; Bailey, Michael R

    2011-11-01

    In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound.

  14. Detection of tissue harmonic motion induced by ultrasonic radiation force using pulse-echo ultrasound and Kalman filter.

    PubMed

    Zheng, Yi; Chen, Shigao; Tan, Wei; Kinnick, Randall; Greenleaf, James F

    2007-02-01

    A method using pulse echo ultrasound and the Kalman filter is developed for detecting submicron harmonic motion induced by ultrasonic radiation force. The method estimates the amplitude and phase of the motion at desired locations within a tissue region with high sensitivity. The harmonic motion generated by the ultrasound radiation force is expressed as extremely small oscillatory Doppler frequency shifts in the fast time (A-line) of ultrasound echoes, which are difficult to estimate. In slow time (repetitive ultrasound echoes) of the echoes, the motion also is presented as oscillatory phase shifts, from which the amplitude and phase of the harmonic motion can be estimated with the least mean squared error by Kalman filter. This technique can be used to estimate the traveling speed of a harmonic shear wave by tracking its phase changes during propagation. The shear wave propagation speed can be used to solve for the elasticity and viscosity of tissue as reported in our earlier study. Validation and in vitro experiments indicate that the method provides excellent estimations for very small (submicron) harmonic vibrations and has potential for noninvasive and quantitative stiffness measurements of tissues such as artery.

  15. Low-intensity pulsed ultrasound regulates proliferation and differentiation of osteoblasts through osteocytes

    SciTech Connect

    Li, Lei; Yang, Zheng; Zhang, Hai; Chen, Wenchuan; Chen, Mengshi; Zhu, Zhimin

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer CM from LIPUS-stimulated osteocytes inhibits proliferation of osteoblasts. Black-Right-Pointing-Pointer CM from LIPUS-stimulated osteocytes enhances differentiation of osteoblasts. Black-Right-Pointing-Pointer LIPUS stimulates MLO-Y4 cells to secrete PGE{sub 2} and NO. -- Abstract: Low-intensity pulsed ultrasound (LIPUS) has been used as a safe and effective modality to enhance fracture healing. As the most abundant cells in bone, osteocytes orchestrate biological activities of effector cells via direct cell-to-cell contacts and by soluble factors. In this study, we have used the osteocytic MLO-Y4 cells to study the effects of conditioned medium from LIPUS-stimulated MLO-Y4 cells on proliferation and differentiation of osteoblastic MC3T3-E1 cells. Conditioned media from LIPUS-stimulated MLO-Y4 cells (LIPUS-Osteocyte-CM) were collected and added on MC3T3-E1 cell cultures. MC3T3-E1 cells cultured in LIPUS-Osteocyte-CM demonstrated a significant inhibition of proliferation and an increased alkaline phosphatase activity. The results of PGE{sub 2} and NO assay showed that LIPUS could enhance PGE{sub 2} and NO secretion from MLO-Y4 cells at all time points within 24 h after LIPUS stimulation. We conclude that LIPUS regulates proliferation and differentiation of osteoblasts through osteocytes in vitro. Increased secretion of PGE{sub 2} from osteocytes may play a role in this effect.

  16. Assessment of aortic pulse wave velocity by ultrasound: a feasibility study in mice

    NASA Astrophysics Data System (ADS)

    Faita, Francesco; Di Lascio, Nicole; Stea, Francesco; Kusmic, Claudia; Sicari, Rosa

    2014-03-01

    Pulse wave velocity (PWV) is considered a surrogate marker of arterial stiffness and could be useful for characterizing cardiovascular disease progression even in mouse models. Aim of this study was to develop an image process algorithm for assessing arterial PWV in mice using ultrasound (US) images only and test it on the evaluation of age-associated differences in abdominal aorta PWV (aaPWV). US scans were obtained from six adult (7 months) and six old (19 months) wild type male mice (strain C57BL6) under gaseous anaesthesia. For each mouse, diameter and flow velocity instantaneous values were achieved from abdominal aorta B-mode and PW-Doppler images; all measurements were obtained using edge detection and contour tracking techniques. Single-beat mean diameter and velocity were calculated and time-aligned, providing the lnD-V loop. aaPWV values were obtained from the slope of the linear part of the loop (the early systolic phase), while relative distension (relD) measurements were calculated from the mean diameter signal. aaPWV values for young mice (3.5±0.52 m/s) were lower than those obtained for older ones (5.12±0.98 m/s) while relD measurements were higher in young (25%±7%) compared with older animals evaluations (15%±3%). All measurements were significantly different between the two groups (P<0.01 both). In conclusion, the proposed image processing technique well discriminate between age groups. Since it provides PWV assessment just from US images, it could represent a simply and useful system for vascular stiffness evaluation at any arterial site in the mouse, even in preclinical small animal models.

  17. Radiation induced cavitation: A possible phenomenon in liquid targets?

    SciTech Connect

    West, C.D.

    1998-07-01

    The proposed design of a new, short-pulse spallation neutron source includes a liquid mercury target irradiated with a 1 GeV proton beam. This paper explores the possibility that cavitation bubbles may be formed in the mercury and briefly discusses some design features that could avoid harmful effects should cavitation take place.

  18. A 3D time reversal cavity for the focusing of high-intensity ultrasound pulses over a large volume

    NASA Astrophysics Data System (ADS)

    Robin, J.; Arnal, B.; Tanter, M.; Pernot, M.

    2017-02-01

    Shock wave ultrasound therapy techniques, increasingly used for non-invasive surgery, require extremely high pressure amplitudes in precise focal spots, and large high-power transducers arranged on a spherical shell are usually used to achieve that. This solution allows limited steering of the beam around the geometrical focus of the device at the cost of a large number of transducer elements, and the treatment of large and moving organs like the heart is challenging or impossible. This paper validates numerically and experimentally the possibility of using a time reversal cavity (TRC) for the same purpose. A 128-element, 1 MHz power transducer combined with different multiple scattering media in a TRC was used. We were able to focus high-power ultrasound pulses over a large volume in a controlled manner, with a limited number of transducer elements. We reached sufficiently high pressure amplitudes to erode an Ultracal® target over a 10 cm2 area.

  19. Low-Power 2-MHz Pulsed-Wave Transcranial Ultrasound Reduces Ischemic Brain Damage in Rats.

    PubMed

    Alexandrov, Andrei V; Barlinn, Kristian; Strong, Roger; Alexandrov, Anne W; Aronowski, Jaroslaw

    2011-09-01

    It is largely unknown whether prolonged insonation with ultrasound impacts the ischemic brain tissue by itself. Our goal was to evaluate safety and the effect of high-frequency ultrasound on infarct volume in rats. Thirty-two Long-Evans rats with permanent middle cerebral and carotid artery occlusions received either 2-MHz ultrasound at two levels of insonation power (128 or 10 mW) or no ultrasound (controls). We measured cerebral hemorrhage, indirect and direct infarct volume as well as edema volume at 24 h. No cerebral hemorrhages were detected in all animals. Exposure to low-power (10 mW) ultrasound resulted in a significantly decreased indirect infarct volume (p = 0.0039), direct infarct volume (p = 0.0031), and brain edema volume (p = 0.01) compared with controls. High-power (128 mW) ultrasound had no significant effects. An additional experiment with India ink showed a greater intravascular penetration of dye into ischemic tissues exposed to low-power ultrasound. Insonation with high-frequency, low-power ultrasound reduces ischemic brain damage in rat. Its effect on edema reduction and possible promotion of microcirculation could be used to facilitate drug and nutrient delivery to ischemic areas.

  20. Comparison of the Effects of Ultrasound-Guided Interfascial Pulsed Radiofrequency and Ultrasound-Guided Interfascial Injection on Myofascial Pain Syndrome of the Gastrocnemius

    PubMed Central

    2016-01-01

    Objective To investigate the comparative treatment effects of ultrasound-guided pulsed radiofrequency treatment (UG-PRF) in the gastrocnemius interfascial space and ultrasound-guided interfascial injection (UG-INJ) on myofascial pain syndrome. Methods Forty consecutive patients with myofascial pain syndrome of the gastrocnemius were enrolled and were allocated to one of the two groups. Twenty patients were treated by UG-PRF delivered to the gastrocnemius interfascial space (UG-PRF group) and the other 20 patients were treated by interfascial injection (UG-INJ group). The primary outcome measure was the numeric rating score (NRS) for pain on pressing the tender point in the gastrocnemius, and the secondary outcome measure was health-related quality of life as determined by the Short Form-36 questionnaire (SF-36). NRSs were obtained at the first visit, immediately after treatment, and at 2 and 4 weeks post-treatment, and physical component summary scores (PCS) and mental component summary scores (MCS) of the SF-36 questionnaire were measured at the first visit and at 4 weeks post-treatment. Results Immediately after treatments, mean NRS in the UG-PRF group was significantly higher than that in the UG-INJ group (p<0.0001). However, at 2 and 4 weeks post-treatment, the mean NRS was significantly lower in the UG-PRF group (both p<0.0001). Similarly, at 4 weeks post-treatment, mean PCS and MCS were significantly higher in the UG-PRF group (p<0.0001 and p=0.002, respectively). Conclusion Based on these results, the authors conclude that ultrasound-guided gastrocnemius interfascial PRF provides an attractive treatment for myofascial pain syndrome of the gastrocnemius. PMID:27847719

  1. Low-Intensity Pulsed Ultrasound Stimulation Facilitates Osteogenic Differentiation of Human Periodontal Ligament Cells

    PubMed Central

    Hu, Bo; Zhang, Yuanyuan; Zhou, Jie; Li, Jing; Deng, Feng; Wang, Zhibiao; Song, Jinlin

    2014-01-01

    Human periodontal ligament cells (hPDLCs) possess stem cell properties, which play a key role in periodontal regeneration. Physical stimulation at appropriate intensities such as low-intensity pulsed ultrasound (LIPUS) enhances cell proliferation and osteogenic differentiation of mesechymal stem cells. However, the impacts of LIPUS on osteogenic differentiation of hPDLCs in vitro and its molecular mechanism are unknown. This study was undertaken to investigate the effects of LIPUS on osteogenic differentiation of hPDLCs. HPDLCs were isolated from premolars of adolescents for orthodontic reasons, and exposed to LIPUS at different intensities to determine an optimal LIPUS treatment dosage. Dynamic changes of alkaline phosphatase (ALP) activities in the cultured cells and supernatants, and osteocalcin production in the supernatants after treatment were analyzed. Runx2 and integrin β1 mRNA levels were assessed by reverse transcription polymerase chain reaction analysis after LIPUS stimulation. Blocking antibody against integrinβ1 was used to assess the effects of integrinβ1 inhibitor on LIPUS-induced ALP activity, osteocalcin production as well as calcium deposition. Our data showed that LIPUS at the intensity of 90 mW/cm2 with 20 min/day was more effective. The ALP activities in lysates and supernatants of LIPUS-treated cells started to increase at days 3 and 7, respectively, and peaked at day 11. LIPUS treatment significantly augmented the production of osteocalcin after day 5. LIPUS caused a significant increase in the mRNA expression of Runx2 and integrin β1, while a significant decline when the integrinβ1 inhibitor was used. Moreover, ALP activity, osteocalcin production as well as calcium nodules of cells treated with both daily LIPUS stimulation and integrinβ1 antibody were less than those in the LIPUS-treated group. In conclusion, LIPUS promotes osteogenic differentiation of hPDLCs, which is associated with upregulation of Runx2 and integrin β1, which

  2. Fundamental studies on cavitation melt processing

    NASA Astrophysics Data System (ADS)

    Tzanakis, I.; Hodnett, M.; Lebon, G. S. B.; Eskin, D. G.; Pericleous, K.

    2016-05-01

    The application of ultrasound to industrial casting processes has attracted research interest during the last 50 years. However, the transfer and scale-up of this advanced and promising technology to industry has been hindered by difficulties in treating large volumes of liquid metal due to the lack of understanding of certain fundamentals. In the current study experimental results on ultrasonic processing in deionised water and in liquid aluminium (Al) are reported. Cavitation activity was determined in both liquid environments and acoustic pressures were successfully measured using an advanced high-temperature cavitometer sensor. Results showed that highest cavitation intensity in the liquid bulk is achieved at lower amplitudes of the sonotrode tip than the maximum available, suggesting nonlinearity in energy transfer to the liquid, while the location of the sonotrode is seen to substantially affect cavitation activity within the liquid. Estimation of real-time acoustic pressures distributed inside a crucible with liquid Al was performed for the first time.

  3. Lipid Coated Microbubbles and Low Intensity Pulsed Ultrasound Enhance Chondrogenesis of Human Mesenchymal Stem Cells in 3D Printed Scaffolds

    PubMed Central

    Aliabouzar, Mitra; Zhang, Lijie Grace; Sarkar, Kausik

    2016-01-01

    Lipid-coated microbubbles are used to enhance ultrasound imaging and drug delivery. Here we apply these microbubbles along with low intensity pulsed ultrasound (LIPUS) for the first time to enhance proliferation and chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in a 3D printed poly-(ethylene glycol)-diacrylate (PEG-DA) hydrogel scaffold. The hMSC proliferation increased up to 40% after 5 days of culture in the presence of 0.5% (v/v) microbubbles and LIPUS in contrast to 18% with LIPUS alone. We systematically varied the acoustic excitation parameters—excitation intensity, frequency and duty cycle—to find 30 mW/cm2, 1.5 MHz and 20% duty cycle to be optimal for hMSC proliferation. A 3-week chondrogenic differentiation results demonstrated that combining LIPUS with microbubbles enhanced glycosaminoglycan (GAG) production by 17% (5% with LIPUS alone), and type II collagen production by 78% (44% by LIPUS alone). Therefore, integrating LIPUS and microbubbles appears to be a promising strategy for enhanced hMSC growth and chondrogenic differentiation, which are critical components for cartilage regeneration. The results offer possibilities of novel applications of microbubbles, already clinically approved for contrast enhanced ultrasound imaging, in tissue engineering. PMID:27883051

  4. Porous resins as a cavitation enhancer for low-frequency sonophoresis.

    PubMed

    Terahara, Takaaki; Mitragotri, Samir; Langer, Robert

    2002-03-01

    The application of low-frequency ultrasound enhances drug transport through the skin, a phenomenon referred to as low-frequency sonophoresis. This enhancement is mediated through cavitation, the formation and collapse of gaseous bubbles. We hypothesized that the efficacy of low-frequency sonophoresis can be significantly enhanced by provision of nuclei for cavitation. In this study, we used two porous resins, Diaion HP20 and Diaion HP2MG (2MG), as cavitation nuclei. We measured the effect of these resins on cavitation using pitting of aluminum foil. 2MG showed a higher efficacy in enhancing cavitation compared with Diaion HP20. 2MG was also effective in enhancing transdermal mannitol transport. These results confirm that the addition of cavitation nuclei such as porous resins further increases the effect of low-frequency ultrasound on skin permeability.

  5. Cavitation-induced drug delivery in tumors for cancer chemotherapy: phantom studies

    NASA Astrophysics Data System (ADS)

    Larina, Irina V.; Bartels, Christian; Larin, Kirill V.; Esenaliev, Rinat O.

    2001-07-01

    One of the major problems of cancer chemotherapy is slow diffusion of anti-cancer drugs in the interstitium and their poor penetration from blood through tumor capillary wall and cancer cell membrane. To enhance delivery of the drugs in cancer cells we proposed to use interaction of exogenous microparticles with laser or ultrasonic radiation. This interaction results in cavitation near the particles upon certain irradiation conditions. Our previous pilot studies demonstrated feasibility of enhanced delivery of model and real anti-cancer conditions. Our previous pilot studies demonstrated feasibility of enhanced delivery of model and real anti-cancer drugs in tissues in vitro and in vivo if laser pulsed or ultrasonic radiation is applied. In this work we performed studies in tissue phantoms in order to find optimal parameters that can be used for safe and efficient delivery of anti-cancer drugs in tumors. Water solutions and gelatin were used as tissue phantoms with well-controlled parameters. Cavitation in the phantoms was studied by using optical dn ultrasound techniques. Results of our studies indicate that efficient cavitation-driven drug delivery can be achieved with no or minimal damage to normal tissues.

  6. Transcranial Cavitation Detection in Primates during Blood-Brain Barrier Opening – A Performance Assessment Study

    PubMed Central

    Wu, Shih-Ying; Tung, Yao-Sheng; Marquet, Fabrice; Downs, Matthew Eric; Sanchez, Carlos Sierra; Chen, Cherry Chen; Ferrera, Vincent

    2014-01-01

    Focused ultrasound (FUS) has been shown promise in treating the brain locally and noninvasively. Transcranial passive cavitation detection (PCD) provides methodology of monitoring the treatment in real time, while the skull effects remain a major challenge for its translation to the clinic. In this study, we investigated the sensitivity, reliability, and limitations of PCD through primate (macaque and human) skulls in vitro. The results were further correlated with the in vivo macaque studies including the transcranial PCD calibration and real-time monitoring of BBB opening, with magnetic resonance imaging assessing the opening and safety. The stable cavitation doses using harmonics (SCDh) and ultraharmonics (SCDu), the inertial cavitation dose (ICD), and the cavitation signal-to-noise ratio (SNR) were quantified based on the PCD signals. Results showed that through the macaque skull the pressure threshold for detecting the SCDh remained the same as without the skull in place, while it increased for the SCDu and ICD; through the human skull, it increased for all cavitation doses. The transcranial PCD was found reliable both in vitro and in vivo when the transcranial cavitation SNR exceeded the 1-dB detection limit through the in vitro macaque (attenuation: 4.92 dB/mm) and human (attenuation: 7.33 dB/mm) skull. In addition, using long pulses enabled reliable PCD monitoring and facilitate BBB opening at low pressures. The in vivo results showed that the SCDh became detectable at pressures as low as 100 kPa; the ICD, at 250 kPa while it could occur at lower pressures; the SCDu, at 700 kPa and was less reliable at lower pressures. Real-time monitoring of PCD was further implemented during BBB opening, with successful and safe opening achieved at 250–600 kPa in both the thalamus and the putamen. In conclusion, this study shows that transcranial PCD in macaques in vitro and in vivo as well as humans in vitro is reliable by improving the cavitation SNR beyond the 1-d

  7. Free radical generation by ultrasound in aqueous and nonaqueous solutions.

    PubMed Central

    Riesz, P; Berdahl, D; Christman, C L

    1985-01-01

    The physical principles underlying the oscillatory behavior of minute gas bubbles in liquids exposed to ultrasound are reviewed. Results from mathematical analyses suggest that these oscillations sometimes become unstable leading to transient cavitation in which a bubble violently collapses during a single acoustic half-cycle producing high temperatures and pressures. The role that micronuclei, resonant bubble size, and rectified diffusion play in the initiation of transient cavitation is explained. Evidence to support these theoretical predictions is presented with particular emphasis on sonoluminescence which provides some non-chemical evidence for the formation of free radicals. Acoustic methods for conducting sonochemical investigations are discussed. In aqueous solutions transient cavitation initially generates hydrogen atoms and hydroxyl radicals which may recombine to form hydrogen and hydrogen peroxide or may react with solutes in the gas phase, at the gas-liquid boundary or in the bulk of the solution. The analogies and differences between sonochemistry and ionizing radiation chemistry are explored. The use of spin trapping and electron spin resonance to identify hydrogen atoms and hydroxyl radicals conclusively and to detect transient cavitation produced by continuous wave and by pulsed ultrasound is described in detail. The study of the chemical effects of cavitation in organic liquids is a relatively unexplored area which has recently become the subject of renewed interest. Examples of the decomposition of solvent and solute, of ultrasonically initiated free-radical polymerization and polymer degradation are presented. Spin trapping has been used to identify radicals in organic liquids, in polymer degradation and in the decomposition of organometallic compounds. PMID:3007091

  8. Control of acoustic cavitation with application to lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael Rollins

    Control of acoustic cavitation, which is sound-induced growth and collapse of bubbles, is the subject of this dissertation. Application is to extracorporeal shock wave lithotripsy (ESWL), used to treat kidney stones. Cavitation is thought to help comminute stones yet may damage tissue. Can cavitation be controlled? The acoustic source in a widely used clinical lithotripter is an electrical spark at the near focus of an underwater ellipsoidal reflector. To control cavitation, we used rigid reflectors, pressure release reflectors, and pairs of reflectors aligned to have a common focus and a controlled delay between sparks. Cavitation was measured with aluminum foil, which was placed along the axis at the far focus of the reflector(s). Collapsing bubbles pitted the foil. Pit depth measured with a profilometer provided a relative measure of cavitation intensity. Cavitation was also measured with a focused hydrophone, which detected the pressure pulse radiated in bubble collapse. Acoustic pressure signals produced by the reflectors were measured with a PVdF membrane hydrophone, digitally recorded, and input into a numerical version of the Gilmore equation (F. R. Gilmore, 'The growth or collapse of a spherical bubble in a viscous compressible liquid,' Rep#26-4, California Institute of Technology, Pasadena (1952), pp.1-40.). Maximum pressure produced in a spherical bubble was calculated and employed as a relative measure of collapse intensity. Experimental and numerical results demonstrate cavitation can be controlled by an appropriately delayed auxiliary pressure pulse. When two rigid-reflector pulses are used, a long interpulse delay (150-200 μs) of the second pulse 'kicks' the collapsing bubble and intensifies cavitation. Foil pit depth and computed pressure three times single pulse values were obtained. Conversely, a short delay (<90 μs) 'stifles' bubble growth and weakens cavitation. A single pressure release reflector time- reverses the rigid-reflector waveform

  9. A randomized, double-blind clinical trial comparing the effects of continuous and pulsed ultrasound in patients with chronic rhinosinusitis.

    PubMed

    Ansari, Noureddin Nakhostin; Fathali, Mojtaba; Naghdi, Soofia; Hasson, Scott; Jalaie, Shohreh; Rastak, Mohammad Saeed

    2012-02-01

    The objective of the present study was to compare the effects of continuous ultrasound (CUS) with pulsed ultrasound (PUS) in patients with chronic rhinosinusitis (CRS). In this prospective, randomized, double-blind, parallel group study, 40 patients (10 losses) with CRS participated. Patients received either continuous or pulsed (1:9) 1 MHz ultrasound (US) using a US head of 1 cm2 at 1 W/cm2 and 0.5 W/cm2 for the maxillary and frontal sinuses, respectively. Treatment was performed in 10 sessions, 3 days per week, with US given every other day. The primary outcome measure was percent improvement in the Sinusitis Symptom Score. Measurements were taken before and after 10 treatment sessions. The patients were followed up monthly for 2 months. After treatment, both groups improved significantly on the Sinusitis Symptoms Score. Patients who received PUS had significantly decreased total symptom scores compared with patients receiving CUS (mean change 9.8 vs. 5.6, p = 0.049). The percent improvement in the Sinusitis Symptom Score between the PUS group (65.2 SD 23.1) and the CUS group (43.9 SD 40.7) was not statistically significant (p = 0.09). The effect size for each treatment was large; PUS: d = 3.92 and CUS: d = 1.93. Symptom improvement in both groups was similar at the 2-month follow-up. These results support the use of therapeutic US for CRS. This pilot study gives only marginal evidence to favor PUS over CUS.

  10. Hot spot conditions during cavitation in water

    SciTech Connect

    Didenko, Y.T.; McNamara, W.B. III; Suslick, K.S.

    1999-06-23

    Liquids irradiated with high-intensity ultrasound undergo acoustic cavitation--the formation, growth, and implosive collapse of bubbles. The energy stored during the growth of the bubble in the rarefaction phase of the acoustic field is released when the bubble violently collapses in the compression phase of the acoustic field, as acoustic noise, shock waves, chemical reactions, and the emission of light (sonoluminescence, SL). This violent collapse is predicted to generate a hot spot of thousands of Kelvin within the bubble, but, to date, there have been only a limited number of experimental measurements of the temperature of this hot spot. Although the SL of water has been studied for more than 50 years, the effective hot spot temperature during aqueous cavitation remains unresolved. Given the importance of aqueous cavitation (sonography and bioeffects of ultrasound, sonochemical remediation of aqueous pollutants, synthetic applications of sonochemistry, etc.), the authors decided to apply previous spectroscopic analysis of SL of nonaqueous liquids to aqueous solutions doped with small amounts of hydrocarbons. The authors have collected and analyzed excited-state C{sub 2} NBSL (multi-bubble sonoluminescence, light emission from the clouds of cavitating bubbles) spectra from mixtures of organic liquids in water at 20 kHz and find an effective emission temperature of 4,300 {+-} 200 K.

  11. Dynamics of Cavitation Clouds within a High-Intensity Focused Ultrasonic Beam

    DTIC Science & Technology

    2012-03-01

    the cloud size. I. INTRODUCTION High-intensity focused ultrasound (HIFU), along with the associated cavitation , is used in a variety of fields. The...Article 3. DATES COVERED (From - To) March 2012- May 2012 4. TITLE AND SUBTITLE Dynamics of Cavitation Clouds within a High-Intensity Focused...in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line

  12. Enhancement of Focused Ultrasound Treatment by Acoustically Generated Microbubbles

    NASA Astrophysics Data System (ADS)

    Umemura, Shin-ichiro; Yoshizawa, Shin; Takagi, Ryo; Inaba, Yuta; Yasuda, Jun

    2013-07-01

    Microbubbles, whether introduced from outside the body or ultrasonically generated in situ, are known to significantly enhance the biological effects of ultrasound, including the mechanical, thermal, and sonochemical effects. Phase-change nanodroplets, which selectively accumulate in tumor tissue and whose phase changes to microbubbles can be induced by ultrasonic stimulation, have been proposed for high-intensity focused ultrasound (HIFU) tumor treatment with enhanced selectivity and efficiency. In this paper, a purely acoustic approach to generate microbubble clouds in the tissue to be treated is proposed. Short pulses of focused ultrasound with extremely high intensity, named trigger pulses, are used for exposure. They are immediately followed by focused ultrasound for heating with an intensity similar to or less than that of normal HIFU treatment. The localized generation of microbubble clouds by the trigger pulses is observed in a polyarylamide gel by a high-speed camera, and the effectiveness of the generated clouds in accelerating ultrasonically induced thermal coagulation is confirmed in excised chicken breast tissue. The use of second-harmonic superimposed waves as the trigger pulses is also proposed. The highly reproducible initiation of cavitation by waves with the negative peak pressure emphasized and the efficient expansion of the generated microbubble clouds by waves with the positive peak pressure emphasized are also observed by a high-speed camera in partially degassed water.

  13. PULSED FOCUSED ULTRASOUND TREATMENT OF MUSCLE MITIGATES PARALYSIS-INDUCED BONE LOSS IN THE ADJACENT BONE: A STUDY IN A MOUSE MODEL

    PubMed Central

    Poliachik, Sandra L.; Khokhlova, Tatiana D.; Wang, Yak-Nam; Simon, Julianna C.; Bailey, Michael R.

    2015-01-01

    Bone loss can result from bed rest, space flight, spinal cord injury or age-related hormonal changes. Current bone loss mitigation techniques include pharmaceutical interventions, exercise, pulsed ultrasound targeted to bone and whole body vibration. In this study, we attempted to mitigate paralysis-induced bone loss by applying focused ultrasound to the midbelly of a paralyzed muscle. We employed a mouse model of disuse that uses onabotulinumtoxinA-induced paralysis, which causes rapid bone loss in 5 d. A focused 2 MHz transducer applied pulsed exposures with pulse repetition frequency mimicking that of motor neuron firing during walking (80 Hz), standing (20 Hz), or the standard pulsed ultrasound frequency used in fracture healing (1 kHz). Exposures were applied daily to calf muscle for 4 consecutive d. Trabecular bone changes were characterized using micro-computed tomography. Our results indicated that application of certain focused pulsed ultrasound parameters was able to mitigate some of the paralysis-induced bone loss. PMID:24857416

  14. Ultrasound physics.

    PubMed

    Shriki, Jesse

    2014-01-01

    Bedside ultrasound has become an important modality for obtaining critical information in the acute care of patients. It is important to understand the physics of ultrasound in order to perform and interpret images at the bedside. The physics of both continuous wave and pulsed wave sound underlies diagnostic ultrasound. The instrumentation, including transducers and image processing, is important in the acquisition of appropriate sonographic images. Understanding how these concepts interplay with each other enables practitioners to obtain the best possible images.

  15. Synchronized passive imaging of single cavitation events

    NASA Astrophysics Data System (ADS)

    Gateau, Jérôme; Aubry, Jean-François; Pernot, Mathieu; Chauvet, Daurian; Boch, Anne-Laure; Fink, Mathias; Tanter, Mickaël

    2011-09-01

    Passive cavitation detection techniques are usually of relatively low sensitivity to single cavitation events. Moreover, a single-element transducer is generally used, so that the spatial localization of these cavitation events is not possible, or is limited to the probing volume. To both detect and localize single cavitation events over an extended volume, the following experimental set-up has been used and validated: cavitation is induced with a focused single-element transducer (mean frequency 660 kHz, f♯ = 1) driven by a high power (up to 5 kW) electric burst of a few cycles, and the acoustic emission of the bubbles is recorded on a standard linear array (4-7 MHz), mounted on the side of the single element to probe its focal spot. Both the frequencies and the geometry used are appropriate to in vivo implementation. The recording of ultrasonic radio-frequency (RF) data was performed simultaneously on 64 channels of the array and was synchronized with the pulsed excitation. A single cavitation event results in a high frequency and coherent wave front on the RF data. Thanks to synchronization, these RF data are beam-formed to localize the event with a axial resolution of 0.3 mm. A small number of discrete events could also be separated with this method. Besides, B-mode images obtained with the linear array prior to passive detection allowed the positioning of the events within the tissue structure. This technique has been used first ex vivo on freshly harve pig and sheep thigh muscle: with a two cycle excitation, a 9 MPa cavitation threshold was found. Cavitation detection was also achieved in vivo with a five cycle burst excitation in sheep thigh muscle for a peak acoustic pressure of 11MPa. This technique could provide useful information in order to better understand, control and monitor the initiation phase of the histotripsy process.

  16. A preliminary study into the effect of low-intensity pulsed ultrasound on chronic maxillary and frontal sinusitis.

    PubMed

    Ansari, Noureddin Nakhostin; Naghdi, Soofia; Farhadi, Mohammad; Jalaie, Shohreh

    2007-01-01

    Sinusitis is a very common acute or chronic illness that affects a significant percentage of individuals. Recently, therapeutic ultrasound was reported as a treatment for chronic sinusitis. The purpose of this study was twofold: 1) to evaluate the effectiveness of low-intensity pulsed ultrasound (US) in chronic sinusitis using a pretest-posttest research design and 2) to determine the level of association between the independent variables of initial presence of symptoms, age, gender, and duration of disease and the dependent variable of improvement of symptoms. Patients with chronic sinusitis were treated with low-intensity pulsed US, 3 days per week for 15 sessions. Fifty-seven patients (18 females and 39 males; mean age, 35 years) were included in the study. The results of the McNemar test showed a significant change in proportions of post nasal drip and nasal obstruction, two common leading symptoms of patients with chronic sinusitis (p < 0.001). Most of the major and minor symptoms showed significant changes after US therapy (p < 0.05). The total improvement of symptoms was 81.3%. The greatest improvement in symptoms was observed in nasal discharge (100%), followed by facial pain (95.4%) and postnasal drip (82.7%), three major factors in sinusitis. There was a significant, low association between the initial presence of symptoms and the improvement of symptoms after US therapy (chi(2) = 30.352; df = 12; p = 0.002; phi value = 0.356). A significant, low association was also noted between the age and the improvement of symptoms after intervention (chi(2) = 17.548; df = 6; p = 0.007; phi value = 0.270). It may be concluded that low-intensity pulsed US has a significant effect on chronic sinusitis and improves patient symptoms in our study group.

  17. Characterizing the cavitation development and acoustic spectrum in various liquids.

    PubMed

    Tzanakis, I; Lebon, G S B; Eskin, D G; Pericleous, K A

    2017-01-01

    A bespoke cavitometer that measures acoustic spectrum and is capable of operating in a range of temperatures (up to 750°C) was used to study the cavitation behaviour in three transparent liquids and in molten aluminium. To relate these acoustic measurements to cavitation development, the dynamics of the cavitation bubble structures was observed in three Newtonian, optically transparent liquids with significantly different physical properties: water, ethanol, and glycerine. Each liquid was treated at 20kHz with a piezoelectric ultrasonic transducer coupled to a titanium sonotrode with a tip diameter of 40mm. Two different transducer power levels were deployed: 50% and 100%, with the maximum power corresponding to a peak-to-peak amplitude of 17μm. The cavitation structures and the flow patterns were filmed with a digital camera. To investigate the effect of distance from the ultrasound source on the cavitation intensity, acoustic emissions were measured with the cavitometer at two points: below the sonotrode and near the edge of the experimental vessel. The behaviour of the three tested liquids was very different, implying that their physical parameters played a decisive role in the establishment of the cavitation regime. Non dimensional analysis revealed that water shares the closest cavitation behaviour with liquid aluminium and can therefore be used as its physical analogue in cavitation studies; this similarity was also confirmed when comparing the measured acoustic spectra of water and liquid aluminium.

  18. Cavitation-based hydro-fracturing simulator

    DOEpatents

    Wang, Jy-An John; Wang, Hong; Ren, Fei; Cox, Thomas S.

    2016-11-22

    An apparatus 300 for simulating a pulsed pressure induced cavitation technique (PPCT) from a pressurized working fluid (F) provides laboratory research and development for enhanced geothermal systems (EGS), oil, and gas wells. A pump 304 is configured to deliver a pressurized working fluid (F) to a control valve 306, which produces a pulsed pressure wave in a test chamber 308. The pulsed pressure wave parameters are defined by the pump 304 pressure and control valve 306 cycle rate. When a working fluid (F) and a rock specimen 312 are included in the apparatus, the pulsed pressure wave causes cavitation to occur at the surface of the specimen 312, thus initiating an extensive network of fracturing surfaces and micro fissures, which are examined by researchers.

  19. Trapping of embolic particles in a vessel phantom by cavitation-enhanced acoustic streaming

    NASA Astrophysics Data System (ADS)

    Maxwell, Adam D.; Park, Simone; Vaughan, Benjamin L.; Cain, Charles A.; Grotberg, James B.; Xu, Zhen

    2014-09-01

    Cavitation clouds generated by short, high-amplitude, focused ultrasound pulses were previously observed to attract, trap, and erode thrombus fragments in a vessel phantom. This phenomenon may offer a noninvasive method to capture and eliminate embolic fragments flowing through the bloodstream during a cardiovascular intervention. In this article, the mechanism of embolus trapping was explored by particle image velocimetry (PIV). PIV was used to examine the fluid streaming patterns generated by ultrasound in a vessel phantom with and without crossflow of blood-mimicking fluid. Cavitation enhanced streaming, which generated fluid vortices adjacent to the focus. The focal streaming velocity, uf, was as high as 120 cm/s, while mean crossflow velocities, uc, were imposed up to 14 cm/s. When a solid particle 3-4 mm diameter was introduced into crossflow, it was trapped near the focus. Increasing uf promoted particle trapping while increasing uc promoted particle escape. The maximum crossflow Reynolds number at which particles could be trapped, Rec, was approximately linear with focal streaming number, Ref, i.e. Rec = 0.25Ref + 67.44 (R2 = 0.76) corresponding to dimensional velocities uc = 0.084uf + 3.122 for 20 < uf < 120 cm/s. The fluidic pressure map was estimated from PIV and indicated a negative pressure gradient towards the focus, trapping the embolus near this location.

  20. Trapping of Embolic Particles in a Vessel Phantom by Cavitation-Enhanced Acoustic Streaming

    PubMed Central

    Maxwell, Adam D.; Park, Simone; Vaughan, Benjamin L.; Cain, Charles A.; Grotberg, James B.; Xu, Zhen

    2014-01-01

    Cavitation clouds generated by short, high-amplitude, focused ultrasound pulses were previously observed to attract, trap, and erode thrombus fragments in a vessel phantom. This phenomenon may offer a noninvasive method to capture and eliminate embolic fragments flowing through the bloodstream during a cardiovascular intervention. In this article, the mechanism of embolus trapping was explored by particle image velocimetry (PIV). PIV was used to examine the fluid streaming patterns generated by ultrasound in a vessel phantom with and without crossflow of blood-mimicking fluid. Cavitation enhanced streaming, which generated fluid vortices adjacent to the focus. The focal streaming velocity, uf, was as high as 120 cm/s, while mean crossflow velocities, uc, were imposed up to 14 cm/s. When a solid particle 3-4 mm diameter was introduced into crossflow, it was trapped near the focus. Increasing uf promoted particle trapping while increasing uc promoted particle escape. The maximum crossflow Reynolds number at which particles could be trapped, Rec, was approximately linear with focal streaming number, Ref, i.e. Rec = 0.25Ref + 67.44 (R2=0.76) corresponding to dimensional velocities uc=0.084uf + 3.122 for 20 < uf < 120 cm/s. The fluidic pressure map was estimated from PIV and indicated a negative pressure gradient towards the focus, trapping the embolus near this location. PMID:25109407

  1. Trapping of embolic particles in a vessel phantom by cavitation-enhanced acoustic streaming.

    PubMed

    Maxwell, Adam D; Park, Simone; Vaughan, Benjamin L; Cain, Charles A; Grotberg, James B; Xu, Zhen

    2014-09-07

    Cavitation clouds generated by short, high-amplitude, focused ultrasound pulses were previously observed to attract, trap, and erode thrombus fragments in a vessel phantom. This phenomenon may offer a noninvasive method to capture and eliminate embolic fragments flowing through the bloodstream during a cardiovascular intervention. In this article, the mechanism of embolus trapping was explored by particle image velocimetry (PIV). PIV was used to examine the fluid streaming patterns generated by ultrasound in a vessel phantom with and without crossflow of blood-mimicking fluid. Cavitation enhanced streaming, which generated fluid vortices adjacent to the focus. The focal streaming velocity, uf, was as high as 120 cm/s, while mean crossflow velocities, uc, were imposed up to 14 cm/s. When a solid particle 3-4 mm diameter was introduced into crossflow, it was trapped near the focus. Increasing uf promoted particle trapping while increasing uc promoted particle escape. The maximum crossflow Reynolds number at which particles could be trapped, Rec, was approximately linear with focal streaming number, Ref, i.e. Rec = 0.25Ref + 67.44 (R(2) = 0.76) corresponding to dimensional velocities uc = 0.084uf + 3.122 for 20 < uf < 120 cm/s. The fluidic pressure map was estimated from PIV and indicated a negative pressure gradient towards the focus, trapping the embolus near this location.

  2. Synchrotron x-ray imaging of acoustic cavitation bubbles induced by acoustic excitation

    NASA Astrophysics Data System (ADS)

    Jung, Sung Yong; Park, Han Wook; Park, Sung Ho; Lee, Sang Joon

    2017-04-01

    The cavitation induced by acoustic excitation has been widely applied in various biomedical applications because cavitation bubbles can enhance the exchanges of mass and energy. In order to minimize the hazardous effects of the induced cavitation, it is essential to understand the spatial distribution of cavitation bubbles. The spatial distribution of cavitation bubbles visualized by the synchrotron x-ray imaging technique is compared to that obtained with a conventional x-ray tube. Cavitation bubbles with high density in the region close to the tip of the probe are visualized using the synchrotron x-ray imaging technique, however, the spatial distribution of cavitation bubbles in the whole ultrasound field is not detected. In this study, the effects of the ultrasound power of acoustic excitation and working medium on the shape and density of the induced cavitation bubbles are examined. As a result, the synchrotron x-ray imaging technique is useful for visualizing spatial distributions of cavitation bubbles, and it could be used for optimizing the operation conditions of acoustic cavitation.

  3. Continuous and pulsed ultrasound-assisted extractions of antioxidants from pomegranate peel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a great demand for developing efficient extraction methods in order to reduce extraction time and increase the yield and activity of functional antioxidants. The yields, activities, and extraction kinetics of antioxidants from dry peel of pomegranate marc were studied using ultrasound assis...

  4. Continuous and pulsed ultrasound-assisted extractions of antioxidants from pomegranate peel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a great demand for developing efficient extraction methods in order to reduce extraction time and increase the yield and activity of functional antioxidants. The yields, activities, and extraction kinetics of antioxidants from dry peel of pomegranate marc were studied using ultrasound-assis...

  5. Enhancement of Small Molecule Delivery by Pulsed-High Intensity Focused Ultrasound (pHIFU): A Parameter Exploration

    PubMed Central

    Zhou, Yufeng; Wang, Yak-Nam; Farr, Navid; Zia, Jasmine; Chen, Hong; Ko, Bong Min; Khokhlova, Tatiana; Li, Tong; Hwang, Joo Ha

    2015-01-01

    Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug dose would result in systemic toxicity. The use of high-intensity focused ultrasound (HIFU) has the potential to enhance penetration of small molecules. However, operation parameters need to be optimized before the use of chemotherapeutic drug in vivo and translation to clinical trial. In this study, the effects of pulsed-HIFU (pHIFU) parameters (spatial-average pulse-average intensity, duty factor, and pulse repetition frequency) to the penetration as well as content of small molecules were evaluated in ex vivo porcine kidneys. Specific HIFU parameters resulted in over 40 times greater Evans blue content and 3.5 times the penetration depth compared to untreated samples. When selected parameters were applied to porcine kidneys in vivo, a 2.3-fold increase in concentration was obtained after a 2-minute pHIFU exposure. Altogether, pHIFU has shown to be an effective modality to enhance both the concentration and penetration depth of small molecules into tissue using the optimized HIFU parameters. Although, performed in normal tissue, this study has the promise of translation into tumor tissue. PMID:26803389

  6. Management of pudendal neuralgia using ultrasound-guided pulsed radiofrequency: a report of two cases and discussion of pudendal nerve block techniques.

    PubMed

    Hong, Myong-Joo; Kim, Yeon-Dong; Park, Jeong-Ki; Hong, Hyon-Joo

    2016-04-01

    Pudendal neuralgia is characterized by chronic pain or discomfort in the area innervated by the pudendal nerve, with no obvious cause. A successful pudendal nerve block is crucial for the diagnosis of pudendal neuralgia. Blind or fluoroscopy-guided pudendal nerve blocks have been conventionally used for diagnosis and treatment; however, ultrasound-guided pudendal nerve blocks were also reported recently. With regard to the achievement of long-term effects, although pulsed radiofrequency performed under fluoroscopic guidance has been reported, that performed under ultrasound guidance is not well reported. This report describes two cases of pudendal neuralgia that were successfully managed using ultrasound-guided pulsed radiofrequency and presents a literature review of pudendal nerve block techniques. However, in the management of chronic neuropathic pain, physicians should keep in mind that the placebo effect related to invasive approaches must not be neglected.

  7. Effects of Low-intensity Pulsed Ultrasound and Cryotherapy on Recovery of Joint Function and C-reactive Protein Levels in Patients after Total Knee Replacement Surgery

    PubMed Central

    Kang, Jeong Il; Kim, Yong-Nam; Choi, Hyun

    2014-01-01

    [Purpose] We investigated the effect of low-intensity pulsed ultrasound and cryotherapy on joint function recovery and C-reactive protein (CRP) levels of patients with total knee replacement. [Subjects] Forty-six patients with total knee replacement were recruited and allocated to either low-intensity pulsed ultrasound therapy (n=15), cryotherapy (n=15), or a combination of both (n=16). Therapy was administered once a day, 5 times a week for 3 weeks. To determine functional joint recovery and reduction of inflammation, changes in the Korean Western Ontario and McMaster Universities Arthritis Index (K-WOMAC), range of motion (ROM), and CRP were assessed postsurgically and four times over a 3-week period. Using one-way analysis of variance (ANOVA), homogeneity tests were performed based on participants’ general characteristics. To recognize changes in time-variant K-WOMAC, ROM, and CRP values between groups, repeated measures ANOVA was performed, and Tukey’s test was used for post-test analysis. Values at α=0.05 were considered significant. [Results] We found a difference between groups and times, and the group that received the combined therapies showed greater changes in outcomes than the group that received low-intensity pulsed ultrasound therapy alone. [Conclusion] Applying both low-intensity pulsed ultrasound and cryotherapy can relieve inflammation and enhance joint function in patients who undergo total knee replacement. PMID:25140090

  8. A two-pulse technique for extracting 3rd harmonic from ultrasound contrast agent echo signal.

    PubMed

    Song, Jae-hee; Kim, Sang-min; Song, Tai-kyong

    2008-01-01

    Multi-pulse techniques like CPS (contrast pulse sequence) and TPS (triplet pulse sequence) are the most popular methods for separating the 3rd harmonic signals from received signal. Those two methods, however, transmit a pulse at least three times along each scanline with different phase and amplitude, which results in the frame rate reduction. In this paper, we propose a technique using two pulses whose phase difference is 90 degrees and a simple digital filter. The second harmonic signal is eliminated by summing two received signals as their phase difference becomes 180 degrees and then the fundamental signals are eliminated by using a digital filter. Computer simulations are performed for different values of signal bandwidths and filter specifications. The results show the maximum error is -35.5 dB compared to TPS.

  9. Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

    PubMed

    Lu, Hongbin; Zheng, Cheng; Wang, Zhanwen; Chen, Can; Chen, Huabin; Hu, Jianzhong

    2015-01-01

    This study was designed to evaluate the effects of low-intensity pulsed ultrasound on bone regeneration during the bone-tendon junction healing process and to explore the application of synchrotron radiation micro computed tomography in three dimensional visualization of the bone-tendon junction to evaluate the microarchitecture of new trabecular bone. Twenty four mature New Zealand rabbits underwent partial patellectomy to establish a bone-tendon junction injury model at the patella-patellar tendon complex. Animals were then divided into low-intensity pulsed ultrasound treatment (20 min/day, 7 times/week) and placebo control groups, and were euthanized at week 8 and 16 postoperatively (n = 6 for each group and time point). The patella-patellar tendon specimens were harvested for radiographic, histological and synchrotron radiation micro computed tomography detection. The area of the newly formed bone in the ultrasound group was significantly greater than that of control group at postoperative week 8 and 16. The high resolution three dimensional visualization images of the bone-tendon junction were acquired by synchrotron radiation micro computed tomography. Low-intensity pulsed ultrasound treatment promoted dense and irregular woven bone formation at week 8 with greater bone volume fraction, number and thickness of new trabecular bone but with lower separation. At week 16, ultrasound group specimens contained mature lamellar bone with higher bone volume fraction and thicker trabeculae than that of control group; however, there was no significant difference in separation and number of the new trabecular bone. This study confirms that low-intensity pulsed ultrasound treatment is able to promote bone formation and remodeling of new trabecular bone during the bone-tendon junction healing process in a rabbit model, and the synchrotron radiation micro computed tomography could be applied for three dimensional visualization to quantitatively evaluate the

  10. Ultrasound assisted reduction of graphene oxide to graphene in L-ascorbic acid aqueous solutions: kinetics and effects of various factors on the rate of graphene formation.

    PubMed

    Abulizi, Abulikemu; Okitsu, Kenji; Zhu, Jun-Jie

    2014-05-01

    The reduction of graphene oxide (GO) to graphene (rGO) was achieved by using 20 kHz ultrasound in L-ascorbic acid (L-AA, reducing agent) aqueous solutions under various experimental conditions. The effects of ultrasound power, ultrasound pulse mode, reaction temperature, pH value and L-AA amount on the rates of rGO formation from GO reduction were investigated. The rates of rGO formation were found to be enhanced under the following conditions: high ultrasound power, long pulse mode, high temperature, high pH value and large amount of L-AA. It was also found that the rGO formation under ultrasound treatment was accelerated in comparison with a conventional mechanical mixing treatment. The pseudo rate and pseudo activation energy (Ea) of rGO formation were determined to discuss the reaction kinetics under both treatment. The Ea value of rGO formation under ultrasound treatment was clearly lower than that obtained under mechanical mixing treatment at the same condition. We proposed that physical effects such as shear forces, microjets and shock waves during acoustic cavitation enhanced the mass transfer and reaction of L-AA with GO to form rGO as well as the change in the surface morphology of GO. In addition, the rates of rGO formation were suggested to be affected by local high temperatures of cavitation bubbles.

  11. Low-intensity pulsed ultrasound (LIPUS) prevents periprosthetic inflammatory loosening through FBXL2-TRAF6 ubiquitination pathway.

    PubMed

    Zhao, Xiang; Zhao, Gangsheng; Shi, Zhongli; Zhou, Chenhe; Chen, Yunlin; Hu, Bin; Yan, Shigui

    2017-04-05

    Previous studies have shown that Low intensity pulsed ultrasound(LIPUS) prevents polyethylene-debris-induced periprosthetic loosening in vivo, but the details of the mechanism by which it does so remain unclear. In this article, we used polyethylene debris induced RAW 264.7 cells as the in vitro model, and tested the effect of LIPUS on this model. Changes in the level of inflammatory cytokines, cell proliferation, and apoptosis were assessed. Gene overexpression and siRNA technique were applied, and the levels of expression of FBXL2, TRAF6, ERK, and related inflammatory cytokines were also measured. Results indicated that FBXL2-mediated TRAF6 ubiquitination and degradation also plays an important role in aseptic periprosthetic loosening process, and LIPUS prevents such loosening by strengthening this pathway.

  12. Effects and Mechanisms of Low-Intensity Pulsed Ultrasound for Chronic Prostatitis and Chronic Pelvic Pain Syndrome.

    PubMed

    Lin, Guiting; Reed-Maldonado, Amanda B; Lin, Maofan; Xin, Zhongcheng; Lue, Tom F

    2016-07-01

    Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) is one of the most common urologic diseases, and no curative treatments have been identified. Low-intensity pulsed ultrasound (LIPUS) has been successfully used in promoting tissue healing, inhibiting inflammation and pain, differentiating stem cells, and stimulating nerve regeneration/muscle regeneration, as well as enhancing angiogenesis. Very recently, LIPUS has been proven an effective approach for CP/CPPS. This review summarizes the possible mechanisms responsible for the therapeutic effect of LIPUS for CP/CPPS. To search publications relevant to the topics of this review, the search engine for life sciences of Entrez was used. We reviewed the available evidence from 1954 through 2015 concerning LIPUS for CP/CPPS. According to the literature, both transrectal and transperineal approaches of LIPUS are effective for CP/CPPS.

  13. Effects and Mechanisms of Low-Intensity Pulsed Ultrasound for Chronic Prostatitis and Chronic Pelvic Pain Syndrome

    PubMed Central

    Lin, Guiting; Reed-Maldonado, Amanda B.; Lin, Maofan; Xin, Zhongcheng; Lue, Tom F.

    2016-01-01

    Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) is one of the most common urologic diseases, and no curative treatments have been identified. Low-intensity pulsed ultrasound (LIPUS) has been successfully used in promoting tissue healing, inhibiting inflammation and pain, differentiating stem cells, and stimulating nerve regeneration/muscle regeneration, as well as enhancing angiogenesis. Very recently, LIPUS has been proven an effective approach for CP/CPPS. This review summarizes the possible mechanisms responsible for the therapeutic effect of LIPUS for CP/CPPS. To search publications relevant to the topics of this review, the search engine for life sciences of Entrez was used. We reviewed the available evidence from 1954 through 2015 concerning LIPUS for CP/CPPS. According to the literature, both transrectal and transperineal approaches of LIPUS are effective for CP/CPPS. PMID:27376284

  14. Osteogenic activity of human fracture haematoma-derived progenitor cells is stimulated by low-intensity pulsed ultrasound in vitro.

    PubMed

    Hasegawa, T; Miwa, M; Sakai, Y; Niikura, T; Kurosaka, M; Komori, T

    2009-02-01

    The haematoma occurring at the site of a fracture is known to play an important role in bone healing. We have recently shown the presence of progenitor cells in human fracture haematoma and demonstrated that they have the capacity for multilineage mesenchymal differentiation. There have been many studies which have shown that low-intensity pulsed ultrasound (LIPUS) stimulates the differentiation of a variety of cells, but none has investigated the effects of LIPUS on cells derived from human fracture tissue including human fracture haematoma-derived progenitor cells (HCs). In this in vitro study, we investigated the effects of LIPUS on the osteogenic activity of HCs. Alkaline phosphatase activity, osteocalcin secretion, the expression of osteoblast-related genes and the mineralisation of HCs were shown to be significantly higher when LIPUS had been applied but without a change in the proliferation of the HCs. These findings provide evidence in favour of the use of LIPUS in the treatment of fractures.

  15. Low-intensity pulsed ultrasound (LIPUS) prevents periprosthetic inflammatory loosening through FBXL2-TRAF6 ubiquitination pathway

    PubMed Central

    Zhao, Xiang; Zhao, Gangsheng; Shi, Zhongli; Zhou, Chenhe; Chen, Yunlin; Hu, Bin; Yan, Shigui

    2017-01-01

    Previous studies have shown that Low intensity pulsed ultrasound(LIPUS) prevents polyethylene-debris-induced periprosthetic loosening in vivo, but the details of the mechanism by which it does so remain unclear. In this article, we used polyethylene debris induced RAW 264.7 cells as the in vitro model, and tested the effect of LIPUS on this model. Changes in the level of inflammatory cytokines, cell proliferation, and apoptosis were assessed. Gene overexpression and siRNA technique were applied, and the levels of expression of FBXL2, TRAF6, ERK, and related inflammatory cytokines were also measured. Results indicated that FBXL2-mediated TRAF6 ubiquitination and degradation also plays an important role in aseptic periprosthetic loosening process, and LIPUS prevents such loosening by strengthening this pathway. PMID:28378753

  16. Directivity patterns and pulse profiles of ultrasound emitted by laser action on interface between transparent and opaque solids: Analytical theory

    SciTech Connect

    Nikitin, Sergey M. E-mail: vitali.goussev@univ-lemans.fr; Tournat, Vincent; Chigarev, Nikolay; Castagnede, Bernard; Gusev, Vitalyi E-mail: vitali.goussev@univ-lemans.fr; Bulou, Alain; Zerr, Andreas

    2014-01-28

    The analytical theory for the directivity patterns of ultrasounds emitted from laser-irradiated interface between two isotropic solids is developed. It is valid for arbitrary combinations of transparent and opaque materials. The directivity patterns are derived both in two-dimensional and in three-dimensional geometries, by accounting for the specific features of the sound generation by the photo-induced mechanical stresses distributed in the volume, essential in the laser ultrasonics. In particular, the theory accounts for the contribution to the emitted propagating acoustic fields from the converted by the interface evanescent photo-generated compression-dilatation waves. The precise analytical solutions for the profiles of longitudinal and shear acoustic pulses emitted in different directions are proposed. The developed theory can be applied for dimensional scaling, optimization, and interpretation of the high-pressure laser ultrasonics experiments in diamond anvil cell.

  17. Optimization of Contrast-to-Tissue Ratio by Adaptation of Transmitted Ternary Signal in Ultrasound Pulse Inversion Imaging

    PubMed Central

    Girault, Jean-Marc

    2013-01-01

    Ultrasound contrast imaging has provided more accurate medical diagnoses thanks to the development of innovating modalities like the pulse inversion imaging. However, this latter modality that improves the contrast-to-tissue ratio (CTR) is not optimal, since the frequency is manually chosen jointly with the probe. However, an optimal choice of this command is possible, but it requires precise information about the transducer and the medium which can be experimentally difficult to obtain, even inaccessible. It turns out that the optimization can become more complex by taking into account the kind of generators, since the generators of electrical signals in a conventional ultrasound scanner can be unipolar, bipolar, or tripolar. Our aim was to seek the ternary command which maximized the CTR. By combining a genetic algorithm and a closed loop, the system automatically proposed the optimal ternary command. In simulation, the gain compared with the usual ternary signal could reach about 3.9 dB. Another interesting finding was that, in contrast to what is generally accepted, the optimal command was not a fixed-frequency signal but had harmonic components. PMID:23573167

  18. Improved Human Bone Marrow Mesenchymal Stem Cell Osteogenesis in 3D Bioprinted Tissue Scaffolds with Low Intensity Pulsed Ultrasound Stimulation.

    PubMed

    Zhou, Xuan; Castro, Nathan J; Zhu, Wei; Cui, Haitao; Aliabouzar, Mitra; Sarkar, Kausik; Zhang, Lijie Grace

    2016-09-06

    3D printing and ultrasound techniques are showing great promise in the evolution of human musculoskeletal tissue repair and regeneration medicine. The uniqueness of the present study was to combine low intensity pulsed ultrasound (LIPUS) and advanced 3D printing techniques to synergistically improve growth and osteogenic differentiation of human mesenchymal stem cells (MSC). Specifically, polyethylene glycol diacrylate bioinks containing cell adhesive Arginine-Glycine-Aspartic acid-Serene (RGDS) peptide and/or nanocrystalline hydroxyapatite (nHA) were used to fabricate 3D scaffolds with different geometric patterns via novel table-top stereolithography 3D printer. The resultant scaffolds provide a highly porous and interconnected 3D environment to support cell proliferation. Scaffolds with small square pores were determined to be the optimal geometric pattern for MSC attachment and growth. The optimal LIPUS working parameters were determined to be 1.5 MHz, 20% duty cycle with 150 mW/cm(2) intensity. Results demonstrated that RGDS peptide and nHA containing 3D printed scaffolds under LIPUS treatment can greatly promote MSC proliferation, alkaline phosphatase activity, calcium deposition and total protein content. These results illustrate the effectiveness of the combination of LIPUS and biomimetic 3D printing scaffolds as a valuable combinatorial tool for improved MSC function, thus make them promising for future clinical and various regenerative medicine application.

  19. Improved Human Bone Marrow Mesenchymal Stem Cell Osteogenesis in 3D Bioprinted Tissue Scaffolds with Low Intensity Pulsed Ultrasound Stimulation

    PubMed Central

    Zhou, Xuan; Castro, Nathan J.; Zhu, Wei; Cui, Haitao; Aliabouzar, Mitra; Sarkar, Kausik; Zhang, Lijie Grace

    2016-01-01

    3D printing and ultrasound techniques are showing great promise in the evolution of human musculoskeletal tissue repair and regeneration medicine. The uniqueness of the present study was to combine low intensity pulsed ultrasound (LIPUS) and advanced 3D printing techniques to synergistically improve growth and osteogenic differentiation of human mesenchymal stem cells (MSC). Specifically, polyethylene glycol diacrylate bioinks containing cell adhesive Arginine-Glycine-Aspartic acid-Serene (RGDS) peptide and/or nanocrystalline hydroxyapatite (nHA) were used to fabricate 3D scaffolds with different geometric patterns via novel table-top stereolithography 3D printer. The resultant scaffolds provide a highly porous and interconnected 3D environment to support cell proliferation. Scaffolds with small square pores were determined to be the optimal geometric pattern for MSC attachment and growth. The optimal LIPUS working parameters were determined to be 1.5 MHz, 20% duty cycle with 150 mW/cm2 intensity. Results demonstrated that RGDS peptide and nHA containing 3D printed scaffolds under LIPUS treatment can greatly promote MSC proliferation, alkaline phosphatase activity, calcium deposition and total protein content. These results illustrate the effectiveness of the combination of LIPUS and biomimetic 3D printing scaffolds as a valuable combinatorial tool for improved MSC function, thus make them promising for future clinical and various regenerative medicine application. PMID:27597635

  20. Controllable permeability of blood-brain barrier and reduced brain injury through low-intensity pulsed ultrasound stimulation.

    PubMed

    Su, Wei-Shen; Tsai, Min-Lan; Huang, Sin-Luo; Liu, Shing-Hwa; Yang, Feng-Yi

    2015-12-08

    It has been shown that the blood-brain barrier (BBB) can be locally disrupted by focused ultrasound (FUS) in the presence of microbubbles (MB) while sustaining little damage to the brain tissue. Thus, the safety issue associated with FUS-induced BBB disruption (BBBD) needs to be investigated for future clinical applications. This study demonstrated the neuroprotective effects induced by low-intensity pulsed ultrasound (LIPUS) against brain injury in the sonicated brain. Rats subjected to a BBB disruption injury received LIPUS exposure for 5 min after FUS/MB application. Measurements of BBB permeability, brain water content, and histological analysis were then carried out to evaluate the effects of LIPUS. The permeability and time window of FUS-induced BBBD can be effectively modulated with LIPUS. LIPUS also significantly reduced brain edema, neuronal death, and apoptosis in the sonicated brain. Our results show that brain injury in the FUS-induced BBBD model could be ameliorated by LIPUS and that LIPUS may be proposed as a novel treatment modality for controllable release of drugs into the brain.

  1. Accuracy of velocity and shear rate measurements using pulsed Doppler ultrasound: a comparison of signal analysis techniques.

    PubMed

    Markou, C P; Ku, D N

    1991-01-01

    An experimental investigation was instituted to evaluate the performance of Doppler ultrasound signal processing techniques for measuring fluid velocity under well-defined flow conditions using a 10-MHz multigated pulsed ultrasound instrument. Conditions of fully developed flow in a rigid, circular tube were varied over a Reynolds number range between 500 and 8000. The velocity across the tube was determined using analog and digital zero crossing detectors and three digital spectrum estimators. Determination of the Doppler frequency from analog or digital zero crossing detectors gave accurate velocity values for laminar and moderately turbulent flow away from the wall (0.969 less than or equal to r less than or equal to 0.986). Three digital spectrum estimators, Fast Fourier Transform, Burg autoregressive method, and minimum variance method, were slightly more accurate than the zero crossing detector (0.984 less than or equal to r less than or equal to 0.994), especially at points close to the walls and with higher levels of turbulence. Steep velocity gradients and transit-time-effects from high velocities produced significantly larger errors in velocity measurement. Wall shear rate estimates were most precise when calculated using the position of the wall and two velocity points. The calculated wall shears were within 20%-30% of theoretically predicted values.

  2. Low intensity pulse ultrasound stimulate chondrocytes growth in a 3-D alginate scaffold through improved porosity and permeability.

    PubMed

    Guo, Gepu; Lu, Lu; Ji, Hongfei; Ma, Yong; Dong, Rui; Tu, Juan; Guo, Xiasheng; Qiu, Yuanyuan; Wu, Junru; Zhang, Dong

    2015-04-01

    A 3-D scaffold culture system has been used to promote in producing functional chondrocytes for repairing damaged cartilage. In the present study, the low intensity pulse ultrasound (LIPUS) (P(-)=0, 0.055, 0.085 and 0.11 MPa) was applied to improve the porosity and permeability of a 3-D alginate scaffold which was beneficial for the nutrition supply and metabolism during cell growth in 3-D alginate scaffold. The porosity and permeability of the scaffold was quantitatively analyzed based on scanning electron microscopy examination and fluorescence image observation. The results suggest that, for the scaffold exposed to LIPUS, its porosity and permeability could be significantly enhanced by the increasing LIPUS amplitude, which might be induced by the microstreaming shear stress generated by ultrasound-driven microbubble oscillations. Furthermore, the assessments of cell proliferation and collagen II expression confirmed that chondrocytes growth could be effectively promoted in 3-D alginate scaffolds treated by LIPUS, because of the improved scaffold porosity and permeability might benefit cell growth space and nutrition supply. It should also be noticed that appropriate LIPUS driving parameters should be adapted to achieve optimized chondrocytes culture effect in 3-D alginate scaffold.

  3. Heating simulations of pulsed high-intensity focused ultrasound in the presence of heterogeneous tissue

    NASA Astrophysics Data System (ADS)

    Zhou, Hao; Zheng, Yinfei; Duan, Huilong

    2017-03-01

    A numerical model for evaluating the distribution of the acoustic pressure and temperature beneath the abdominal wall or the chest wall under nonablative high-intensity ultrasound treatments is proposed. The nonlinear propagation of the ultrasound wave was simulated using a k-space pseudo-spectral method. The abdominal wall (heterogeneous medium) was presented by the digital tissue cross sections. The heating process was modeled by solving the bioheat equation using a finite difference time domain (FDTD) method. As indicated in the simulation, the presents of the heterogeneous tissue can influence the distribution of the acoustic intensity. The intensity beneath the abdominal wall was decreased by 2.2 dB on the focal point compared with homogeneous tissue and the temperature of the focused region in the tissue is reduced as a result. Furthermore, compared with conventional 2-order FDTD methods, the proposed model is still stable when the high dissipative tissue (e.g., bone) presents.

  4. The leicester Doppler phantom--a digital electronic phantom for ultrasound pulsed Doppler system testing.

    PubMed

    Gittins, John; Martin, Kevin

    2010-04-01

    Doppler flow and string phantoms have been used to assess the performance of ultrasound Doppler systems in terms of parameters such as sensitivity, velocity accuracy and sample volume registration. However, because of the nature of their construction, they cannot challenge the accuracy and repeatability of modern digital ultrasound systems or give objective measures of system performance. Electronic Doppler phantoms are able to make use of electronically generated test signals, which may be controlled precisely in terms of frequency, amplitude and timing. The Leicester Electronic Doppler Phantom uses modern digital signal processing methods and field programmable gate array technology to overcome some of the limitations of previously described electronic phantoms. In its present form, it is able to give quantitative graphical assessments of frequency response and range gate characteristics, as well as measures of dynamic range and velocity measurement accuracy. The use of direct acoustic coupling eliminates uncertainties caused by Doppler beam effects, such as intrinsic spectral broadening, but prevents their evaluation.

  5. CONTRAST-ENHANCED INTRAVASCULAR ULTRASOUND PULSE SEQUENCES FOR BANDWIDTH-LIMITED TRANSDUCERS

    PubMed Central

    Maresca, David; Renaud, Guillaume; van Soest, Gijs; Li, Xiang; Zhou, Qifa; Shung, K. Kirk; de Jong, Nico; van der Steen, Antonius F. W.

    2013-01-01

    We demonstrate two methods for vasa vasorum imaging using contrast-enhanced intravascular ultrasound, which can be performed using commercial catheters. Plaque neovascularization was recognized as an independent marker of coronary artery plaque vulnerability. IVUS-based methods to image the microvessels available to date require high bandwidth (−6 dB relative frequency bandwidth >70%), which are not routinely available commercially. We explored the potential of ultraharmonic imaging and chirp reversal imaging for vasa vasorum imaging. In vitro recordings were performed on a tissue-mimicking phantom using a commercial ultrasound contrast agent and a transducer with a center frequency of 34 MHz and a −6 dB relative bandwidth of 56%. Acoustic peak pressures <500 kPa were used. A tissue-mimicking phantom with channels down to 200 μm in diameter was successfully imaged by the two contrast detection sequences while the smallest channel stayed invisible in conventional intravascular ultrasound images. Ultraharmonic imaging provided the best contrast agent detection. PMID:23384459

  6. Analysis of ultrasound pulse-echo images for characterization of muscle disease

    NASA Astrophysics Data System (ADS)

    Leeman, Sidney; Heckmatt, John Z.

    1996-04-01

    This study aims to extract quantifiable indices characterizing ultrasound propagation and scattering in skeletal muscle, from data acquired using a real-time linear array scanner in a paediatric muscle clinic, in order to establish early diagnosis of Duchenne muscular dystrophy in young children, as well as to chart the progressive severity of the disease. Approximately 40 patients with gait disorders, aged between 1 and 11 years, were scanned with a real-time linear array ultrasound scanner, at 5 MHz. A control group consisted of approximately 50 boys, in the same age range, with no evidence or history of muscle disease. Results show that ultrasound quantitative methods can provide a tight clustering of normal data, and also provide a basis for charting the degree of change in diseased muscle. The most significant (quantitative) parameters derive from the frequency of the attenuation and the muscle echogenicity. The approach provides a discrimination method that is more sensitive than visual assessment of the corresponding image by even an experienced observer. There are also indications that the need for traumatic muscle biopsy may be obviated in some cases.

  7. Cavitational hydrothermal oxidation: A new remediation process. 1998 annual progress report

    SciTech Connect

    Suslick, K.S.

    1998-06-01

    'The primary goal is to develop a quantitative understanding of cavitation phenomena in aqueous media and the development of applications of cavitation to remediation processes. Efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions. This report summarizes work after one year of a three year project. In order to gain further understanding of the conditions present during cavitation, the author has continued his studies of sonoluminescence. He has made recent breakthroughs in the use of emission spectroscopy for temperature and pressure measurement of cavitation events, which he expects to publish shortly. He has been able to measure for the first time the temperature of cavitation in water during multi-bubble cavitation in the presence of aromatic hydrocarbons. The emission from excited states of C{sub 2} in water gives temperatures that are consistent with adiabatic compressional heating, with maximum temperatures of 4,300 K. Prior measurements of cavitation temperatures in low vapor pressure nonaqueous media gave somewhat higher temperatures of 5,000 K. This work lays permanently to rest exotic mechanisms for cavitational chemistry, at least for cavitation fields.'

  8. Cavitational hydrothermal oxidation: A new remediation process. Annual progress report, September 1996--August 1997

    SciTech Connect

    Suslick, K.S.

    1997-11-21

    'During the past year, the authors have continued to make substantial scientific progress on the understanding of cavitation phenomena in aqueous media and applications of cavitation to remediation processes. The efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions. In order to gain further understanding of the conditions present during cavitation, the author has continued his studies of sonoluminescence. He has made recent breakthroughs in the use of emission spectroscopy for temperature and pressure measurement of cavitation events, which he expects to publish shortly. He has been able to measure for the first time the temperature of cavitation in water during multi-bubble cavitation in the presence of aromatic hydrocarbons. The emission from excited states of C{sub 2} in water gives temperatures that are consistent with adiabatic compressional heating, with maximum temperatures of 4,300 K. Prior measurements of cavitation temperatures in low vapor pressure nonaqueous media gave somewhat higher temperatures of 5,000 K. This work lays permanently to rest exotic mechanisms for cavitational chemistry, at least for cavitation fields.'

  9. Characterization of the HIFU-induced cloud cavitation for the optimization of high pressure concentration for lithotripsy

    NASA Astrophysics Data System (ADS)

    Ikeda, Teiichiro; Yoshizawa, Shin; Kaneko, Yukio; Matsumoto, Yoichiro

    2006-05-01

    The bubble cloud is a highly scattering object; to the contrary, it is also a strong pressure wave enhancer, if the wavelength and amplitude of the wave is appropriate ones. We've been investigated the stone erosion enhancement in the existence of bubble cloud on the stone surface by using high frequency waveform that immediately followed by low frequency trailing pulse (C-C waveform; Cavitation Control waveform). For the optimization of the high pressure concentration it is needed to know, "how the enhancement of the pressure wave through the bubble cloud" and "how we can estimate the efficiency thorough the passive detection of the reflected signal from the bubble cloud". We measured the "Transmittance" and "Reflection" by two types of acoustic emission sensors, PCD (Passive Cavitation Detector) and DCD (Direct Collapse Detector). The results well depict the characteristics of the HIFU-induced bubble cloud responses. The response curves reveal that the local maxima of the "Transmittance" and "Reflection" occur at the different bubble cloud volume. The PCD signal is higher in the larger bubble cloud band. The DCD signal is larger in the smaller bubble cloud band. These tendencies imply the therapeutic effect through the bubble cloud is optimized in the small bubble cloud region and too much bubbles scatter the incoming ultrasound wave and the ultrasound wave does not efficiently propagates inward the bubble cloud. Thus, for the optimization of the bubble cloud collapse, the cavitation threshold can be the lower limit and the large scattering amplitude from bubble cloud can be the upper limit of the ultrasound conditions.

  10. Modeling and experimental analysis of acoustic cavitation bubbles for Burst Wave Lithotripsy

    PubMed Central

    Maeda, Kazuki; Colonius, Tim; Kreider, Wayne; Maxwell, Adam; Cunitz, Bryan; Bailey, Michael

    2016-01-01

    A combined modeling and experimental study of acoustic cavitation bubbles that are initiated by focused ultrasound waves is reported. Focused ultrasound waves of frequency 335 kHz and peak negative pressure 8 MPa are generated in a water tank by a piezoelectric transducer to initiate cavitation. The resulting pressure field is obtained by direct numerical simulation (DNS) and used to simulate single bubble oscillation. The characteristics of cavitation bubbles observed by high-speed photography qualitatively agree withs the simulation result. Finally, bubble clouds are captured using acoustic B-mode imaging that works in synchronization with high-speed photography. PMID:27087826

  11. Ultrasound pregnancy

    MedlinePlus

    Pregnancy sonogram; Obstetric ultrasonography; Obstetric sonogram; Ultrasound - pregnancy; IUGR - ultrasound; Intrauterine growth - ultrasound; Polyhydramnios - ultrasound; Oligohydramnios - ultrasound; ...

  12. Transvaginal ultrasound

    MedlinePlus

    ... Uterine bleeding - transvaginal ultrasound; Menstrual bleeding - transvaginal ultrasound; Infertility - transvaginal ultrasound; Ovarian - transvaginal ultrasound; Abscess - transvaginal ultrasound

  13. Use of hydrodynamic cavitation in (waste)water treatment.

    PubMed

    Dular, Matevž; Griessler-Bulc, Tjaša; Gutierrez-Aguirre, Ion; Heath, Ester; Kosjek, Tina; Krivograd Klemenčič, Aleksandra; Oder, Martina; Petkovšek, Martin; Rački, Nejc; Ravnikar, Maja; Šarc, Andrej; Širok, Brane; Zupanc, Mojca; Žitnik, Miha; Kompare, Boris

    2016-03-01

    The use of acoustic cavitation for water and wastewater treatment (cleaning) is a well known procedure. Yet, the use of hydrodynamic cavitation as a sole technique or in combination with other techniques such as ultrasound has only recently been suggested and employed. In the first part of this paper a general overview of techniques that employ hydrodynamic cavitation for cleaning of water and wastewater is presented. In the second part of the paper the focus is on our own most recent work using hydrodynamic cavitation for removal of pharmaceuticals (clofibric acid, ibuprofen, ketoprofen, naproxen, diclofenac, carbamazepine), toxic cyanobacteria (Microcystis aeruginosa), green microalgae (Chlorella vulgaris), bacteria (Legionella pneumophila) and viruses (Rotavirus) from water and wastewater. As will be shown, hydrodynamic cavitation, like acoustic, can manifest itself in many different forms each having its own distinctive properties and mechanisms. This was until now neglected, which eventually led to poor performance of the technique. We will show that a different type of hydrodynamic cavitation (different removal mechanism) is required for successful removal of different pollutants. The path to use hydrodynamic cavitation as a routine water cleaning method is still long, but recent results have already shown great potential for optimisation, which could lead to a low energy tool for water and wastewater cleaning.

  14. Cell mechanics in biomedical cavitation

    PubMed Central

    Wang, Qianxi; Manmi, Kawa; Liu, Kuo-Kang

    2015-01-01

    Studies on the deformation behaviours of cellular entities, such as coated microbubbles and liposomes subject to a cavitation flow, become increasingly important for the advancement of ultrasonic imaging and drug delivery. Numerical simulations for bubble dynamics of ultrasound contrast agents based on the boundary integral method are presented in this work. The effects of the encapsulating shell are estimated by adapting Hoff's model used for thin-shell contrast agents. The viscosity effects are estimated by including the normal viscous stress in the boundary condition. In parallel, mechanical models of cell membranes and liposomes as well as state-of-the-art techniques for quantitative measurement of viscoelasticity for a single cell or coated microbubbles are reviewed. The future developments regarding modelling and measurement of the material properties of the cellular entities for cutting-edge biomedical applications are also discussed. PMID:26442142

  15. Investigations of the Cavitation and Damage Thresholds of Histotripsy and Applications in Targeted Tissue Ablation

    NASA Astrophysics Data System (ADS)

    Vlaisavljevich, Eli

    Histotripsy is a noninvasive ultrasound therapy that controls acoustic cavitation to mechanically fractionate soft tissue. This dissertation investigates the physical thresholds to initiate cavitation and produce tissue damage in histotripsy and factors affecting these thresholds in order to develop novel strategies for targeted tissue ablation. In the first part of this dissertation, the effects of tissue properties on histotripsy cavitation thresholds and damage thresholds were investigated. Results demonstrated that the histotripsy shock scattering threshold using multi-cycle pulses increases in stiffer tissues, while the histotripsy intrinsic threshold using single-cycle pulses is independent of tissue stiffness. Further, the intrinsic threshold slightly decreases with lower frequencies and significantly decreases with increasing temperature. The effects of tissue properties on the susceptibility to histotripsy-induced tissue damage were also investigated, demonstrating that stiffer tissues are more resistant to histotripsy. Two strategies were investigated for increasing the effectiveness of histotripsy for the treatment of stiffer tissues, with results showing that thermal preconditioning may be used to alter tissue susceptibility to histotripsy and that lower frequency treatments may increase the efficiency of histotripsy tissue ablation due to enhanced bubble expansion. In the second part of this dissertation, the feasibility of using histotripsy for targeted liver ablation was investigated in an intact in vivo porcine model, with results demonstrating that histotripsy was capable of non-invasively creating precise lesions throughout the entire liver. Additionally, a tissue selective ablation approach was developed, where histotripsy completely fractionated the liver tissue surrounding the major hepatic vessels and gallbladder while being self-limited at the boundaries of these critical structures. Finally, the long-term effects of histotripsy liver

  16. Can Cavitation Be Anticipated?

    SciTech Connect

    Allgood, G.O.; Dress, W.B.; Hylton, J.O.; Kercel, S.W.

    1999-04-25

    The major problem with cavitation in pumps and hydraulic systems is that there is no effective (conventional) method for detecting or predicting its inception. The traditional method of recognizing cavitation in a pump is to declare the event occurring when the total head drops by some arbitrary value (typically 3%) in response to a pressure reduction at the pump inlet. However, the device is already seriously cavitating when this happens. What is actually needed is a practical method to detect impending rather than incipient cavitation. Whereas the detection of incipient cavitation requires the detection of features just after cavitation starts, the anticipation of cavitation requires the detection and identification of precursor features just before it begins. Two recent advances that make this detection possible. The first is acoustic sensors with a bandwidth of 1 MHz and a dynamic range of 80 dB that preserve the fine details of the features when subjected to coarse vibrations. The second is the application of Bayesian parameter estimation which makes it possible to separate weak signals, such as those present in cavitation precursors, from strong signals, such as pump vibration. Bayesian parameter estimation derives a model based on cavitation hydrodynamics and produces a figure of merit of how well it fits the acquired data. Applying this model to an anticipatory engine should lead to a reliable method of anticipating cavitation before it occurs. This paper reports the findings of precursor features using high-performance sensors and Bayesian analysis of weak acoustic emissions in the 100-1000kHz band from an experimental flow loop.

  17. A piezoelectric polymer cavitation sensor installed in an emulsion generation microchannel device and an evaluation of cavitation state

    NASA Astrophysics Data System (ADS)

    Kanda, Takefumi; Yabumoto, Masaki; Suzumori, Koichi

    2016-07-01

    In previous works, ultrasonic emulsification was realized using small microchannel devices oscillated by piezoelectric transducers. By using the devices, the emulsification in the flow process was also realized. In these devices, the driving frequency was higher than 2 MHz. This value is higher than the maximum audible field. On the other hand, the frequency is too high to utilize the cavitation effect. This is because the cavitation threshold depends on the frequency. The aim of this study is to confirm the cavitation state in the microchannel device using a piezoelectric polymer sensor. A micropatterned cavitation detection sensor has been fabricated by a photolithography technique and evaluated in a high-intensity ultrasound field. The emulsification state in the microchannel device has been evaluated using the fabricated sensor.

  18. Mechanisms of thrombolysis acceleration by cavitation

    NASA Astrophysics Data System (ADS)

    Weiss, Hope; Selvaraj, Prashanth; Ahadi, Golnaz; Voie, Arne; Hoelscher, Thilo; Okita, Kohei; Matsumoto, Yoichiro; Szeri, Andrew

    2012-11-01

    Recent studies, in vitro and in vivo, have shown that High Intensity Focused Ultrasound (HIFU) accelerates thrombolysis, the dissolution of blood clots, for ischemic stroke. Although the mechanisms are not fully understood, cavitation is thought to play an important role in sonothrombolysis. The damage to a blood clot's fibrin fiber network from cavitation in a HIFU field is studied using two independent approaches for an embedded bubble. One method is extended to the more important scenario of a bubble outside a blood clot that collapses asymmetrically creating a jet towards the clot. There is significantly more damage potential from a bubble undergoing cavitation collapse outside the clot compared to a rapidly expanding bubble embedded within the clot structure. Also, the effects of the physical properties of skull bone when a HIFU wave propagates through it are examined by use of computer simulation. The dynamics of a test bubble placed at the focus is used in understanding of the pressure field. All other things being equal, the analysis suggests that skull thickness can alter the wave at the focus, which in turn can change the nature of cavitation bubble dynamics and the amount of energy available for clot damage. Now at MSOE.

  19. Visualization of Electrical Trees by 80 MHz-band Pulsed Ultrasound

    NASA Astrophysics Data System (ADS)

    Kida, Satoshi; Murakami, Yoshinobu; Nagao, Masayuki; Hozumi, Naohiro

    Power modules are often molded with a resin, such as epoxy, for their protection and downsizing. The resin, which contains inorganic filler, is usually non-transparent. As optical inspection is not realistic, non-destructive inspections using X-ray or ultrasound is being performed. As for cracks and so-called “electrical tree” in the insulation, ultrasound may bring a good contrast, because there is a big difference in acoustic impedance between resin and air. There are some reports on ultrasonic observation for electrical trees, however, as thick specimens were employed, the spatial resolution was very poor due to the limitation of available frequency range. However, the diameter of electrical tree path is as thin as 5 μm. Enough resolution can't be obtained by the measurement with a low frequency range. Based on the above background, we tried to observe a “close but small” tree by ultrasonic imaging. Using the wide-band ultrasonic microscope, it was examined if a tree with 0.5 mm in scale could be observed with its fine structure. An ultrasonic image, in which branching in the tree can be discriminated. The spatial resolution was determined as 40∼50 μm. An image processing was carried out in order to acquire a clearer image. Assuming the Gaussian as a blur function, the original image was deconvolved.

  20. Acoustic cavitation as an enhancing mechanism of low-frequency sonophoresis for transdermal drug delivery.

    PubMed

    Ueda, Hideo; Mutoh, Mizue; Seki, Toshinobu; Kobayashi, Daisuke; Morimoto, Yasunori

    2009-05-01

    We investigated the role of acoustic cavitation on sonophoretic skin permeation of calcein, a model permeant, across excised hairless rat skin. Three different frequencies (41, 158, 445 kHz) and various intensities (60 to 300 mW/cm(2)) of ultrasound were applied. Cavitation generation in degassed and undegassed (normal) water was monitored using a commercially available cavitation meter, then compared with skin permeability from calcein solution consistent of them. In addition, the penetration of a fluorescent dye, rhodamine B, into gelatin gel as a skin alternative was observed to estimate the role of cavitation collapse in the solution at or near the skin surface. Cavitation generation in the undegassed water was dependent on the ultrasound frequency, and the rank order of the cavitation was 41 kHz>158 kHz>445 kHz. At 41 kHz, cavitation generation in degassed water was clearly lower than that in undegassed water. Calcein permeability during ultrasound application correlated well with the cavitation generation in the medium, suggesting the important role of the indirect actions of cavitation collapse which occurred in the applied solution rather than the direct action in the skin. When ultrasound (41 or 158 kHz) was applied to the gelatin gels covered with rhodamine B solution, alteration in the surface configuration, like spots, and the coincident penetration of the dye were observed only at 41 kHz, while no alteration in the surface configuration was evident at 158 kHz. These results suggest that cavitation collapses in the vicinity of the skin surface might be more important for solute penetration in addition to skin permeabilization.

  1. [Effects of low-frequency pulsed wave ultrasound on the shear properties of the interface of vancomycin-loaded acrylic bone cement-stem].

    PubMed

    Zhao, Q H; Zhu, F B; Cai, X Z; Yan, S G; He, R X

    2017-02-21

    Objective: To investigate the effects of low-frequency pulsed wave ultrasound on the shear properties of interface of the vancomycin -loaded acrylic bone cement-stem. Methods: The interfaces of 1% vancomycin-loaded acrylic bone cement-stem specimences were successfully manufactured and randomly divided into three groups: the control group, 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) ultrasound group, each group consisted of eight samples.Two ultrasound groups were exposed to a local ultrasonic field for 7 d, then immersed in PBS for 23 d, and the control groups were immersed in PBS for 30 d. After curing in air for 24 h, the shear strength of the stem-cement interface was determined by push-out test.The specimens were then photographed using SEM and analysed using Image-Pro Plus 6.0 to determine the porosity at the stem-cement interface. Results: The mean shear strength of stem-cement interface additionally decreased by 9% (P>0.05) and 17% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, but no significant difference was found between the two ultrasound groups.The porosity at the stem-cement interface additionally increased by 44% (P>0.05) and 110% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, furthermore.The porosity in 1 200 mW/cm(2) ultrasound group increased by 46% (P<0.05) comparing with the 450 mW/cm(2) group. There are much more fluid penetration along the stem-cement interface in ultrasound group . Conclusion: Low-frequency pulsed wave ultrasound signifiantly enhanced porosity and fluid penetration interface, and reduced the interface shear strength and initial stability.

  2. Ultrasound-guided delivery of microRNA loaded nanoparticles into cancer.

    PubMed

    Wang, Tzu-Yin; Choe, Jung Woo; Pu, Kanyi; Devulapally, Rammohan; Bachawal, Sunitha; Machtaler, Steven; Chowdhury, Sayan Mullick; Luong, Richard; Tian, Lu; Khuri-Yakub, Butrus; Rao, Jianghong; Paulmurugan, Ramasamy; Willmann, Jürgen K

    2015-04-10

    Ultrasound induced microbubble cavitation can cause enhanced permeability across natural barriers of tumors such as vessel walls or cellular membranes, allowing for enhanced therapeutic delivery into the target tissues. While enhanced delivery of small (<1nm) molecules has been shown at acoustic pressures below 1MPa both in vitro and in vivo, the delivery efficiency of larger (>100nm) therapeutic carriers into cancer remains unclear and may require a higher pressure for sufficient delivery. Enhanced delivery of larger therapeutic carriers such as FDA approved pegylated poly(lactic-co-glycolic acid) nanoparticles (PLGA-PEG-NP) has significant clinical value because these nanoparticles have been shown to protect encapsulated drugs from degradation in the blood circulation and allow for slow and prolonged release of encapsulated drugs at the target location. In this study, various acoustic parameters were investigated to facilitate the successful delivery of two nanocarriers, a fluorescent semiconducting polymer model drug nanoparticle as well as PLGA-PEG-NP into human colon cancer xenografts in mice. We first measured the cavitation dose produced by various acoustic parameters (pressure, pulse length, and pulse repetition frequency) and microbubble concentration in a tissue mimicking phantom. Next, in vivo studies were performed to evaluate the penetration depth of nanocarriers using various acoustic pressures, ranging between 1.7 and 6.9MPa. Finally, a therapeutic microRNA, miR-122, was loaded into PLGA-PEG-NP and the amount of delivered miR-122 was assessed using quantitative RT-PCR. Our results show that acoustic pressures had the strongest effect on cavitation. An increase of the pressure from 0.8 to 6.9MPa resulted in a nearly 50-fold increase in cavitation in phantom experiments. In vivo, as the pressures increased from 1.7 to 6.9MPa, the amount of nanoparticles deposited in cancer xenografts was increased from 4- to 14-fold, and the median penetration depth of

  3. The influence of air content in water on ultrasonic cavitation field.

    PubMed

    Liu, Liyan; Yang, Yang; Liu, Penghong; Tan, Wei

    2014-03-01

    Cavitation is a complex physical phenomenon affected by many factors, one of which is the gas dissolved in the medium. Researchers have given some efforts to the influence of gas content on sonoluminescence or some specific chemical reactions in and around the bubble, but limited work has been reported about the influence on the ultrasonic cavitation field distribution. In this work, the intensity distribution of the ultrasound field in a cleaning tank has been measured with the hydrophone. After analysed and visualised by MATLAB software, it was found that the cavitation intensity distribution in degassed water was much better than that in tap water. And further study proved that degassing process can improve the cavitation effect dramatically both in intensity and scope. Finally, the cavitation fields in mediums with different gas content were measured and the specific influence of air content on cavitation field was discussed.

  4. Investigations of the role of cavitation in low-frequency sonophoresis using acoustic spectroscopy.

    PubMed

    Tezel, Ahmet; Sens, Ashley; Mitragotri, Samir

    2002-02-01

    Application of low-frequency ultrasound significantly enhances skin permeability. The enhancement of skin permeability is mediated by cavitation, oscillation, and collapse of gaseous cavities. In this article, we report detailed investigations of the occurrence of cavitation during low-frequency sonophoresis. Cavitation was monitored by recording pressure amplitudes of subharmonic emission and broadband noise at four different ultrasound frequencies in the range of 20-100 kHz and at various intensities in the range of 0-2.6 W/cm(2). Enhancement of skin conductivity, in the presence of sodium lauryl sulfate (SLS), was also measured under the same ultrasound conditions. Enhancement of skin conductivity correlated well with the amplitude of broadband noise, which suggests the role of transient cavitation in low-frequency sonophoresis. No correlation was found between the subharmonic pressure amplitude and conductivity enhancement.

  5. Cavitation in flowing superfluid helium

    NASA Technical Reports Server (NTRS)

    Daney, D. E.

    1988-01-01

    Flowing superfluid helium cavitates much more readily than normal liquid helium, and there is a marked difference in the cavitation behavior of the two fluids as the lambda point is traversed. Examples of cavitation in a turbine meter and centrifugal pump are given, together with measurements of the cavitation strength of flowing superfluid helium. The unusual cavitation behavior of superfluid helium is attributed to its immense thermal conductivity .

  6. Cell-Type-Selective Effects of Intramembrane Cavitation as a Unifying Theoretical Framework for Ultrasonic Neuromodulation123

    PubMed Central

    2016-01-01

    Abstract Diverse translational and research applications could benefit from the noninvasive ability to reversibly modulate (excite or suppress) CNS activity using ultrasound pulses, however, without clarifying the underlying mechanism, advanced design-based ultrasonic neuromodulation remains elusive. Recently, intramembrane cavitation within the bilayer membrane was proposed to underlie both the biomechanics and the biophysics of acoustic bio-effects, potentially explaining cortical stimulation results through a neuronal intramembrane cavitation excitation (NICE) model. Here, NICE theory is shown to provide a detailed predictive explanation for the ability of ultrasonic (US) pulses to also suppress neural circuits through cell-type-selective mechanisms: according to the predicted mechanism T-type calcium channels boost charge accumulation between short US pulses selectively in low threshold spiking interneurons, promoting net cortical network inhibition. The theoretical results fit and clarify a wide array of earlier empirical observations in both the cortex and thalamus regarding the dependence of ultrasonic neuromodulation outcomes (excitation-suppression) on stimulation and network parameters. These results further support a unifying hypothesis for ultrasonic neuromodulation, highlighting the potential of advanced waveform design for obtaining cell-type-selective network control. PMID:27390775

  7. Treatment of Breast Tumors using Pulsed HIFU for Delivery and Activation of Sonosensitizers

    DTIC Science & Technology

    2009-08-01

    done. Using similar treatment parameters in vivo necessitated the use of ultrasound contrast agents to initiate cavitation . When this was done, we...ablation for breast cancer treatment. 15. SUBJECT TERMS high intensity focused ultrasound , sonodynamic, cavitation , free radicals, chemotherapy...40 W (abou 8.6 MPa peak negative pressure). Targeting and cavitation monitoring was via ultrasonic b-mode imaging. After the ultrasound treatment

  8. Reduction in mechanical allodynia in complex regional pain syndrome patients with ultrasound-guided pulsed radiofrequency treatment of the superficial peroneal nerve

    PubMed Central

    Chae, Won Soek; Kim, Sang Hyun; Cho, Sung Hwan; Lee, Mi Sun

    2016-01-01

    The superficial peroneal nerve is vulnerable to damage from ankle sprain injuries and fractures as well as surgery to this region. And it is also one of the most commonly involved nerves in complex regional pain syndrome type II in the foot and ankle region. We report two cases of ultrasound-guided pulsed radiofrequency treatment of superficial peroneal nerve for reduction of allodynia in CRPS patients. PMID:27738506

  9. Two-Color Laser High-Harmonic Generation in Cavitated Plasma Wakefields

    SciTech Connect

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2016-10-03

    A method is proposed for producing coherent x-rays via high-harmonic generation using a laser interacting with highly-stripped ions in cavitated plasma wakefields. Two laser pulses of different colors are employed: a long-wavelength pulse for cavitation and a short-wavelength pulse for harmonic generation. This method enables efficient laser harmonic generation in the sub-nm wavelength regime.

  10. Temporally-Specific Modification of Myelinated Axon Excitability In Vitro Following a Single Ultrasound Pulse

    DTIC Science & Technology

    1990-01-01

    corresponding to local temperature rises of the nerve trunk of no more than 0.25* C per pulse, thereby precluding bulk heating as a basis of this effect... Henneman 19Ua.. 1961b: Fry et al. 1958). and direct modification of A great deal of investigation concerning the effects of receptor potentials in...in vitro R. T. MlHRAf4 et aL V Z a S C 0. 0 20 40 s0 so 100 (a) Paet-Pulee Stliaton Delay (mus) 10 . c 1.6 c 4 at 0. 0 20 40 60 60 100 (b) paut

  11. Three-dimensional noninvasive ultrasound Joule heat tomography based on the acousto-electric effect using unipolar pulses: a simulation study.

    PubMed

    Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang

    2012-11-21

    Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on the acousto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on the acousto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high-resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of a priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations.

  12. Bubble Dynamics and Cavitation Inception Theory.

    DTIC Science & Technology

    1986-07-30

    appearing in the forcing function, with the result that this problem involves only a soft excitation. Expanding the forced Rayleigh - Plesset equation and...Expanding the forced Rayleigh - Plesset equation and its initial conditions to the second order in 6, we find that the zeroth-order problem is the well...involves only an ordinary pulsed (e) This interaction causes the cavitation Rayleigh - Plesset differential equation. bubble to be removed from the

  13. Low frequency cavitation erosion

    NASA Astrophysics Data System (ADS)

    Pardue, Sally J.; Chandekar, Gautam

    2002-11-01

    Damage of diesel engine piston sleeve liners due to cavitation of the coolant fluid can be severe. Coolant fluid additives are used to inhibit cavitation damage, and are evaluated by industry suppliers using ASTM G32-98 Standard Test Method for Cavitation Erosion Using Vibratory Apparatus. The ASTM G32-98 test procedure uses an ultrasonic horn at 20 kHz to vibrate a test button in the coolant. The test button mass loss and surface appearance are studied to sort the performance of new coolant additives. Mismatch between good lab performers and actual engine test runs has raised concerns over the current lab test. The frequency range of the current test has been targeted for investigation. A low frequency, less than 2000 Hz, test rig was built to explore the cavitation damage. The test system did produce cavitation on the surface of the test button for a period of 36 h, with minimal mass loss. The test rig experienced cyclic fatigue when test times were extended. The work is now focusing on designing a better test rig for long duration tests and on developing numerical models in order to explore the effects of cavitation excitation frequency on surface erosion.

  14. Effect of gold nanoparticle size on acoustic cavitation using chemical dosimetry method.

    PubMed

    Shanei, Ahmad; Shanei, Mohammad Mahdi

    2017-01-01

    When a liquid is irradiated with high intensities of ultrasound irradiation, acoustic cavitation occurs. Acoustic cavitation generates free radicals from the breakdown of water and other molecules. Cavitation can be fatal to cells and is utilized to destroy cancer tumors. The existence of particles in liquid provides nucleation sites for cavitation bubbles and leads to decrease the ultrasonic intensity threshold needed for cavitation onset. In the present investigation, the effect of gold nanoparticles with appropriate amount and size on the acoustic cavitation activity has been shown by determining hydroxyl radicals in terephthalic acid solutions containing 15, 20, 28 and 35nm gold nanoparticles sizes by using 1MHz low level ultrasound. The effect of sonication intensity in hydroxyl radical production was considered. The recorded fluorescence signal in terephthalic acid solutions containing gold nanoparticles was considerably higher than the terephthalic acid solutions without gold nanoparticles at different intensities of ultrasound irradiation. Also, the results showed that the recorded fluorescence signal intensity in terephthalic acid solution containing finer size of gold nanoparticles was lower than the terephthalic acid solutions containing larger size of gold nanoparticles. Acoustic cavitation in the presence of gold nanoparticles can be used as a way for improving therapeutic effects on the tumors.

  15. Photoacoustic measurement for glucose solution concentration based on tunable pulsed laser induced ultrasound

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Huang, Zhen; Zhao, Dengji

    2012-12-01

    Noninvasive measurement of blood glucose concentration (BGC) has become a research hotspot. BGC measurement based on photoacoustic spectroscopy (PAS) was employed to detect the photoacoustic (PA) signal of blood glucose due to the advantages of avoiding the disturbance of optical scattering. In this paper, a set of custom-built BGC measurement system based on tunable optical parametric oscillator (OPO) pulsed laser and ultrasonic transducer was established to test the PA response effect of the glucose solution. In the experiments, we successfully acquired the time resolved PA signals of distilled water and glucose aqueous solution, and the PA peak-to-peak values(PPV) were gotten under the condition of excitated pulsed laser with changed wavelength from 1340nm to 2200nm by increasing interval of 10nm, the optimal characteristic wavelengths of distilled water and glucose solution were determined. Finally, to get the concentration prediction error, we used the linear fitting of ordinary least square (OLS) algorithm to fit the PPV of 1510nm, and we got the predicted concentration error was about 0.69mmol/L via the fitted linear equation. So, this system and scheme have some values in the research of noninvasive BGC measurement.

  16. Effect of low-intensity pulsed ultrasound (LIPUS) on mandibular condyle growth in rats analyzed with micro-CT.

    PubMed

    Sasaki, Kyozo; Motoyoshi, Mitsuru; Horinuki, Eri; Arai, Yoshinori; Shimizu, Noriyoshi

    2016-01-01

    This study examined the effects of a bite-jumping appliance combined with low-intensity pulsed ultrasound (LIPUS) stimulation on the mandibular condyle of growing rats using micro CT (mCT) and histological examinations. Twelve Wistar rats were divided into three groups of four individuals each: Group 1 was an untreated control group, Group 2 received bite-jumping appliances, and Group 3 received bite-jumping appliances and LIPUS stimulation (15 min/day, 2 weeks) to the temporomandibular region. We measured the length and three-dimensional bone volume of each rat's mandibular condyle using mCT. The condylar cartilage was observed after the rats had been sacrificed. There was no significant difference in condylar sagittal width among the groups. The bite-jumping appliance combined with LIPUS stimulation increased the condylar major axis, mandibular sagittal length and condylar bone volume to a greater degree than use of the bite-jumping appliance alone. Histological examination demonstrated hypertrophy of the condylar cartilage layers, the fibrous layer and hypertrophic cell layer of the rats treated with bite-jumping appliances combined with LIPUS stimulation in comparison to rats treated with bite-jumping appliances alone. (J Oral Sci 58, 415-422, 2016).

  17. Low-intensity pulsed ultrasound (LIPUS) and cell-to-cell communication in bone marrow stromal cells.

    PubMed

    Sena, Kotaro; Angle, Siddhesh R; Kanaji, Arihiko; Aher, Chetan; Karwo, David G; Sumner, Dale R; Virdi, Amarjit S

    2011-07-01

    Low-intensity pulsed ultrasound (LIPUS) is an established therapy for fracture repair and has been used widely in the clinics, but its underlying mechanism of action remains unclear. The aim of the current research was to determine the effect of LIPUS on gap junctional cell-to-cell intercellular communication in rat bone marrow stromal cells (BMSC) in vitro and to determine whether the ability of BMSCs to communicate by gap junctions would affect their response to LIPUS. Single or daily-multiple LIPUS treatment at 1.5MHz, 30mW/cm(2), for 20min was applied to BMSC. We demonstrated that BMSC form functional gap junctions and single LIPUS treatment significantly increased the intracellular dye transfer between BMSC. In addition, activated phosphorylation of ERK1/2 and p38 by LIPUS stimulation was diminished when cells were treated with a gap junction inhibitor 18β-glycyrrhetinic acid (18β). We further demonstrated that 18β diminished the significant increase in alkaline phosphatase activity following LIPUS stimulation. These results suggest a potential role of gap junctional cell-to-cell intercellular communication on the effects of LIPUS in BMSC.

  18. Protective effects of low-intensity pulsed ultrasound on aluminum-induced cerebral damage in Alzheimer's disease rat model

    NASA Astrophysics Data System (ADS)

    Lin, Wei-Ting; Chen, Ran-Chou; Lu, Wen-Wei; Liu, Shing-Hwa; Yang, Feng-Yi

    2015-04-01

    The protein expressions of neurotrophic factors can be enhanced by low-intensity pulsed ultrasound (LIPUS) stimulation in the brain. The purpose of this study was to demonstrate the protective effect of LIPUS stimulation against aluminum-induced cerebral damage in Alzheimer's disease rat model. LIPUS was administered 7 days before each aluminum chloride (AlCl3) administration, and concomitantly given with AlCl3 daily for a period of 6 weeks. Neurotrophic factors in hippocampus were measured by western blot analysis. Behavioral changes in the Morris water maze and elevated plus maze were examined in rats after administration of AlCl3. Various biochemical analyses were performed to evaluate the extent of brain damages. LIPUS is capable of prompting levels of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor (VEGF) in rat brain. AlCl3 administration resulted in a significant increase in the aluminum concentration, acetylcholinesterase activity and beta-amyloid (Aβ) deposition in AlCl3 treated rats. LIPUS stimulation significantly attenuated aluminum concentration, acetylcholinesterase activity, Aβ deposition and karyopyknosis in AlCl3 treated rats. Furthermore, LIPUS significantly improved memory retention in AlCl3-induced memory impairment. These experimental results indicate that LIPUS has neuroprotective effects against AlCl3-induced cerebral damages and cognitive dysfunction.

  19. Effect of low-intensity pulsed ultrasound on biocompatibility and cellular uptake of chitosan-tripolyphosphate nanoparticles

    PubMed Central

    Wu, Junyi; Liu, Gaojun; Qin, Yi-Xian; Meng, Yizhi

    2014-01-01

    Using low molecular weight chitosan nanoparticles (CNPs) prepared by an ionic gelation method, the authors report the effect of low-intensity pulsed ultrasound (US) on cell viability and nanoparticle uptake in cultured murine preosteoblasts. Particle size and zeta potential are measured using dynamic light scattering, and cell viability is evaluated using the of [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] assay. Results show that 30 min delivery of CNPs at 0.5 mg/mL is able to prevent loss of cell viability due to either serum starvation or subsequent exposure to US (1 W/cm2 or 2 W/cm2, up to 1 min). Additionally, flow cytometry data suggest that there is a close association between cellular membrane integrity and the presence of CNPs when US at 2 W/cm2 is administered. PMID:25280857

  20. Comparison between ultrasound-guided interfascial pulsed radiofrequency and ultrasound-guided interfascial block with local anesthetic in myofascial pain syndrome of trapezius muscle

    PubMed Central

    Cho, Ik Tae; Cho, Yun Woo; Kwak, Sang Gyu; Chang, Min Cheol

    2017-01-01

    Abstract Myofascial pain syndrome (MPS) of the trapezius muscle (TM) is a frequently occurring musculoskeletal disorder. However, the treatment of MPS of the TM remains a challenge. We investigated the effects of ultrasound (US)-guided pulsed radiofrequency (PRF) stimulation on the interfascial area of the TM. In addition, we compared its effect with that of interfascial block (IFB) with 10 mL of 0.6% lidocaine on the interfascial area of the TM. Thirty-six patients with MPS of the TM were included and randomly assigned into 2 groups. Eighteen patients underwent PRF stimulation on the interfascial area of the TM (PRF group) and 18 patients underwent IFB with lidocaine on the same area (IFB group). Pain intensity was evaluated using a numerical rating scale (NRS) at pretreatment, 2, 4, and 8 weeks after treatment. At pretreatment and 8 weeks after treatment, quality of life was assessed using the Short Form-36 Health Survey (SF-36), which includes the physical component score (PCS) and the mental component score (MCS). One patient in the PRF group was lost to follow-up. Patients in both groups showed a significant decrease in NRS scores at 2, 4, and 8 weeks after treatments and a significant increase in PCS and MCS of the SF-36 at 8 weeks after treatments. Two weeks after each treatment, the decrements of NRS scores were not significantly different between the 2 groups. However, 4 and 8 weeks after the procedures, we found that the NRS score was significantly lower in the PRF group than in the IFB group. At 8 weeks after the treatments, PCS and MCS of the SF-36 in the PRF group were significantly higher than those in the IFB group. For the management of MPS of the TM, US-guided interfascial PRF had a better long-term effect on reducing the pain and the quality of life compared to US-guided IFB. Therefore, we think US-guided PRF stimulation on the interfascial area of the TM can be a beneficial alternative to manage the pain following MPS of the TM. PMID:28151904

  1. Application of cavitation promoting surfaces in management of acute ischemic stroke.

    PubMed

    Soltani, Azita

    2013-02-01

    High frequency, low intensity ultrasound has the potential to accelerate the clearance of thrombotic occlusion in the absence of cavitation. At high frequency ultrasound, high acoustic pressures, >5.2MPa, are required to generate cavitation in thrombus. The focus of this study was to reduce the cavitation threshold by applying materials with appropriate nucleation sites at the transducer-thrombus boundary to further augment sonothrombolysis. Heterogeneous and homogenous nucleation sites were generated on the outer surface of a polyimide tube (PI) using microfringed (MPI) and laser induced (LPI) microcavities. The cavitation threshold of these materials was determined using a passive cavitation detection system. Furthermore, the biological impact of both materials was investigated in vitro. The results revealed that both MPI and LPI have the potential to induce cavitation at acoustic pressure levels as low as 2.3MPa. In the presence of cavitation, thrombolysis rate could be enhanced by up to two times without any evidence of hemolysis that is generally associated with cavitation activities in blood. A prototype ultrasonic catheter operating at 1.7MHz frequency and acoustic pressure of 2.3MPa with either of MPI or LPI could be considered as a viable option for treatment of acute ischemic stroke.

  2. Laser-enhanced high-intensity focused ultrasound heating in an in vivo small animal model

    NASA Astrophysics Data System (ADS)

    Jo, Janggun; Yang, Xinmai

    2016-11-01

    The enhanced heating effect during the combination of high-intensity focused ultrasound (HIFU) and low-optical-fluence laser illumination was investigated by using an in vivo murine animal model. The thighs of murine animals were synergistically irradiated by HIFU and pulsed nano-second laser light. The temperature increases in the target region were measured by a thermocouple under different HIFU pressures, which were 6.2, 7.9, and 9.8 MPa, in combination with 20 mJ/cm2 laser exposures at 532 nm wavelength. In comparison with conventional laser therapies, the laser fluence used here is at least one order of magnitude lower. The results showed that laser illumination could enhance temperature during HIFU applications. Additionally, cavitation activity was enhanced when laser and HIFU irradiation were concurrently used. Further, a theoretical simulation showed that the inertial cavitation threshold was indeed decreased when laser and HIFU irradiation were utilized concurrently.

  3. Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction

    PubMed Central

    Hodges, Ryan; Endo, Masayuki; La Gerche, Andre; Eixarch, Elisenda; DeKoninck, Philip; Ferferieva, Vessilina; D'hooge, Jan; Wallace, Euan M.; Deprest, Jan

    2013-01-01

    Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ultrasound and fetal echocardiography. Increasingly, these imaging modalities are being employed clinically to examine cardiac function and assess wellbeing in utero, thereby guiding timing of birth decisions. Here, we used a rabbit model of IUGR that allows analysis of cardiac function in a clinically relevant way. Using isoflurane induced anesthesia, IUGR is surgically created at gestational age day 25 by performing a laparotomy, exposing the bicornuate uterus and then ligating 40-50% of uteroplacental vessels supplying each gestational sac in a single uterine horn. The other horn in the rabbit bicornuate uterus serves as internal control fetuses. Then, after recovery at gestational age day 30 (full term), the same rabbit undergoes examination of fetal cardiac function. Anesthesia is induced with ketamine and xylazine intramuscularly, then maintained by a continuous intravenous infusion of ketamine and xylazine to minimize iatrogenic effects on fetal cardiac function. A repeat laparotomy is performed to expose each gestational sac and a microultrasound examination (VisualSonics VEVO 2100) of fetal cardiac function is performed. Placental insufficiency is evident by a raised pulsatility index or an absent or reversed end diastolic flow of the umbilical artery Doppler waveform. The ductus venosus and middle cerebral artery Doppler is then examined. Fetal echocardiography is performed by recording B mode, M mode and flow velocity waveforms in lateral and apical views. Offline calculations determine standard M-mode cardiac variables, tricuspid and mitral annular plane systolic excursion, speckle tracking and strain analysis, modified myocardial performance index and vascular flow velocity waveforms of interest. This small animal model of IUGR therefore affords examination of in utero cardiac function that is

  4. Cavitation guide for control valves

    SciTech Connect

    Tullis, J.P.

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  5. Cavitation in medicine

    PubMed Central

    Brennen, Christopher Earls

    2015-01-01

    We generally think of bubbles as benign and harmless and yet they can manifest the most remarkable range of physical effects. Some of those effects are the stuff of our everyday experience as in the tinkling of a brook or the sounds of breaking waves at the beach. But even these mundane effects are examples of the ability of bubbles to gather, focus and radiate energy (acoustic energy in the above examples). In other contexts that focusing of energy can lead to serious technological problems as when cavitation bubbles eat great holes through ships' propeller blades or cause a threat to the integrity of the spillways at the Hoover Dam. In liquid-propelled rocket engines, bubbles pose a danger to the stability of the propulsion system, and in artificial heart valves they can cause serious damage to the red blood cells. In perhaps the most extraordinary example of energy focusing, collapsing cavitation bubbles can emit not only sound, but also light with black body radiation temperatures equal to that of the sun (Brennen 1995 Cavitation and bubble dynamics). But, harnessed carefully, this almost unique ability to focus energy can also be put to remarkably constructive use. Cavitation bubbles are now used in a remarkable range of surgical and medical procedures, for example to emulsify tissue (most commonly in cataract surgery or in lithotripsy procedures for the reduction of kidney and gall stones) or to manipulate the DNA in individual cells. By creating cavitation bubbles non-invasively thereby depositing and focusing energy non-intrusively, one can generate minute incisions or target cancer cells. This paper will begin by briefly reviewing the history of cavitation phenomena and will end with a vision of the new horizons for the amazing cavitation bubble. PMID:26442145

  6. Cavitation in medicine.

    PubMed

    Brennen, Christopher Earls

    2015-10-06

    We generally think of bubbles as benign and harmless and yet they can manifest the most remarkable range of physical effects. Some of those effects are the stuff of our everyday experience as in the tinkling of a brook or the sounds of breaking waves at the beach. But even these mundane effects are examples of the ability of bubbles to gather, focus and radiate energy (acoustic energy in the above examples). In other contexts that focusing of energy can lead to serious technological problems as when cavitation bubbles eat great holes through ships' propeller blades or cause a threat to the integrity of the spillways at the Hoover Dam. In liquid-propelled rocket engines, bubbles pose a danger to the stability of the propulsion system, and in artificial heart valves they can cause serious damage to the red blood cells. In perhaps the most extraordinary example of energy focusing, collapsing cavitation bubbles can emit not only sound, but also light with black body radiation temperatures equal to that of the sun (Brennen 1995 Cavitation and bubble dynamics). But, harnessed carefully, this almost unique ability to focus energy can also be put to remarkably constructive use. Cavitation bubbles are now used in a remarkable range of surgical and medical procedures, for example to emulsify tissue (most commonly in cataract surgery or in lithotripsy procedures for the reduction of kidney and gall stones) or to manipulate the DNA in individual cells. By creating cavitation bubbles non-invasively thereby depositing and focusing energy non-intrusively, one can generate minute incisions or target cancer cells. This paper will begin by briefly reviewing the history of cavitation phenomena and will end with a vision of the new horizons for the amazing cavitation bubble.

  7. Effects of low intensity pulsed ultrasound with and without increased cortical porosity on structural bone allograft incorporation

    PubMed Central

    Santoni, Brandon G; Ehrhart, Nicole; Turner, A Simon; Wheeler, Donna L

    2008-01-01

    Background Though used for over a century, structural bone allografts suffer from a high rate of mechanical failure due to limited graft revitalization even after extended periods in vivo. Novel strategies that aim to improve graft incorporation are lacking but necessary to improve the long-term clinical outcome of patients receiving bone allografts. The current study evaluated the effect of low-intensity pulsed ultrasound (LIPUS), a potent exogenous biophysical stimulus used clinically to accelerate the course of fresh fracture healing, and longitudinal allograft perforations (LAP) as non-invasive therapies to improve revitalization of intercalary allografts in a sheep model. Methods Fifteen skeletally-mature ewes were assigned to five experimental groups based on allograft type and treatment: +CTL, -CTL, LIPUS, LAP, LIPUS+LAP. The +CTL animals (n = 3) received a tibial ostectomy with immediate replacement of the resected autologous graft. The -CTL group (n = 3) received fresh frozen ovine tibial allografts. The +CTL and -CTL groups did not receive LAP or LIPUS treatments. The LIPUS treatment group (n = 3), following grafting with fresh frozen ovine tibial allografts, received ultrasound stimulation for 20 minutes/day, 5 days/week, for the duration of the healing period. The LAP treatment group (n = 3) received fresh frozen ovine allografts with 500 μm longitudinal perforations that extended 10 mm into the graft. The LIPUS+LAP treatment group (n = 3) received both LIPUS and LAP interventions. All animals were humanely euthanized four months following graft transplantation for biomechanical and histological analysis. Results After four months of healing, daily LIPUS stimulation of the host-allograft junctions, alone or in combination with LAP, resulted in 30% increases in reconstruction stiffness, paralleled by significant increases (p < 0.001) in callus maturity and periosteal bridging across the host/allograft interfaces. Longitudinal perforations extending 10

  8. Modern spectral analysis techniques for blood flow velocity and spectral measurements with pulsed Doppler ultrasound.

    PubMed

    David, J Y; Jones, S A; Giddens, D P

    1991-06-01

    Four spectral analysis techniques were applied to pulsed Doppler ultrasonic quadrature signals to compare the relative merits of each technique for estimation of flow velocity and Doppler spectra. The four techniques were 1) the fast Fourier transform method, 2) the maximum likelihood method, 3) the Burg autoregressive algorithm, and 4) the modified covariance approach to autoregressive modeling. Both simulated signals and signals obtained from an in vitro flow system were studied. Optimal parameter values (e.g., model orders) were determined for each method, and the effects of signal-to-noise ratio and signal bandwidth were investigated. The modern spectral analysis techniques were shown to be superior to Fourier techniques in most circumstances, provided the model order was chosen appropriately. Robustness considerations tended to recommend the maximum likelihood method for both velocity and spectral estimation. Despite the restrictions of steady laminar flow, the results provide important basic information concerning the applicability of modern spectral analysis techniques to Doppler ultrasonic evaluation of arterial disease.

  9. Pulsed counter-current ultrasound-assisted extraction and characterization of polysaccharides from Boletus edulis.

    PubMed

    You, Qinghong; Yin, Xiulian; Ji, Chaowen

    2014-01-30

    Four methods for extracting polysaccharides from Boletus edulis, namely, hot-water extraction, ultrasonic clearer extraction, static probe ultrasonic extraction, and pulsed counter-current probe ultrasonic extraction (CCPUE), were studied. Results showed that CCPUE has the highest extraction efficiency among the methods studied. Under optimal CCPUE conditions, a B. edulis polysaccharide (BEP) yield of 8.21% was obtained. Three purified fractions, BEP-I, BEP-II, and BEP-III, were obtained through sequential purification by DEAE-52 and Sephadex G-75 chromatography. The average molecular weights of BEP-I, BEP-II, and BEP-III were 10,278, 23,761, and 42,736 Da, respectively. The polysaccharides were mainly composed of xylose, mannose, galactose, and glucose; of these, mannose contents were the highest. The antioxidant activities of the BEPs were further investigated by measurement of their ability to scavenge DPPH and hydroxyl radicals as well as their reducing power. The results indicated that the BEPs have good antioxidant activity.

  10. Exploration and Practice in Photoacoustic Measurement for Glucose Concentration Based on Tunable Pulsed Laser Induced Ultrasound

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Huang, Zhen; Zhao, Dengji; Xiong, Zhihua

    2015-07-01

    In this article, a tunable pulsed laser induced photoacoustic measurement setup of monitoring glucose concentration was established in the forward mode. In experiments, the time-resolved photoacoustic signal of glucose aqueous solution with different concentrations of 0-300 mg/dl were captured and averaged 512 times, and the photoacoustic peak-to-peak values were recorded using the wavelength scan in NIR region of 1300-2300 nm. The optimal characteristic wavelengths of glucose were determined via the difference spectral and the first derivative spectral algorithm, and correction models between peak-to-peak values of optimal wavelengths and concentration gradients were established using multivariate linear regression algorithm. Experimental results demonstrated that the profile and logarithm shape of time-resolved photoacoustic signal for glucose solutions were in good agreement with photoacoustic theories. The prediction effect of optimal wavelength of 1510 nm was best, its root-mean-square errors of correction and prediction were 12.14 and 8.45 mg/dl, respectively, the correlation coefficient reached 0.9856.

  11. Prediction of pump cavitation performance

    NASA Technical Reports Server (NTRS)

    Moore, R. D.

    1974-01-01

    A method for predicting pump cavitation performance with various liquids, liquid temperatures, and rotative speeds is presented. Use of the method requires that two sets of test data be available for the pump of interest. Good agreement between predicted and experimental results of cavitation performance was obtained for several pumps operated in liquids which exhibit a wide range of properties. Two cavitation parameters which qualitatively evaluate pump cavitation performance are also presented.

  12. Detecting Cavitation Pitting Without Disassembly

    NASA Technical Reports Server (NTRS)

    Barkhoudarian, S.

    1986-01-01

    Technique for detecting cavitation pitting in pumps, turbines, and other machinery uses low-level nuclear irradiation. Isotopes concentrated below surface emit gamma radiation, a portion of which is attenuated by overlying material. Where there are cavitation pits, output of gamma-ray detector fluctuates as detector is scanned near pits. Important to detect cavitation pits because nozzle, turbine blade, or other pump component weakened by cavitation could fail catastrophically and cause machine to explode.

  13. Experimental determination of cavitation thresholds in liquid water and mercury

    SciTech Connect

    Taleyarkhan, R.P.; Gulec, K.; West, C.D.; Haines, J.

    1998-09-01

    It is well-known that fluids (like solids) will break apart or form voids when put under sufficient tension. The present study has been motivated by the need to evaluate the impact of fluid cavitation in spallation neutron source target systems, more specifically for the proposed 1-MW Spallation Neutron Source (SNS) project, which is being designed in collaboration between Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory, Lawrence Berkeley National Laboratory, Brookhaven National Laboratory, and Argonne National Laboratory. Indeed, results of SNS-specific simulations have indicated that the onset of cavitation could play a very significant role in reducing imposed stresses in structural components of the SNS. In general, the cavitation of fluids is target systems is important to consider for a variety of reasons. Its occurrence can have significant impact on heat transfer, pressure pulse generation, fluid jetting on to structures, surface erosion, stresses induced in enclosures, etc. Therefore, it is important to evaluate the threshold pressure under which the fluid in tension will undergo cavitation. Another major aspect concerns the possible onset of cavitation in an oscillating pressure field; i.e., one would need to know if fluids such as mercury and water will cavitate if the imposed tensile pressure in the fluid is of short duration. If indeed it takes sufficiently long for cavitation bubbles to nucleate, then it would be possible to disregard the complexities involved with addressing cavitation-related issues. This paper provides an overview of preliminary work done to date to derive information on cavitation onset in a relatively static and in a high-frequency environment.

  14. Hysteresis of inertial cavitation activity induced by fluctuating bubble size distribution.

    PubMed

    Muleki Seya, Pauline; Desjouy, Cyril; Béra, Jean-Christophe; Inserra, Claude

    2015-11-01

    Amongst the variety of complex phenomena encountered in nonlinear physics, a hysteretic effect can be expected on ultrasound cavitation due to the intrinsic nonlinearity of bubble dynamics. When applying successive ultrasound shots for increasing and decreasing acoustic intensities, a hysteretic behaviour is experimentally observed on inertial cavitation activity, with a loop area sensitive to the inertial cavitation threshold. To get a better insight of the phenomena underlying this hysteretic effect, the evolution of the bubble size distribution is studied numerically by implementing rectified diffusion, fragmentation process, rising and dissolution of bubbles from an initial bubble size distribution. When applying increasing and decreasing acoustic intensities, the numerical distribution exhibits asymmetry in bubble number and distribution. The resulting inertial cavitation activity is assessed through the numerical broadband noise of the emitted acoustic radiation of the bubble cloud dynamics. This approach allows obtaining qualitatively the observed hysteretic effect and its interest in terms of control is discussed.

  15. Acoustic signal characteristics of laser induced cavitation in DDFP droplet: Spectrum and time-frequency analysis.

    PubMed

    Feng, Yi; Qin, Dui; Zhang, Jun; Ma, Chenxiang; Wan, Mingxi

    2015-01-01

    Cavitation has great application potential in microvessel damage and targeted drug delivery. Concerning cavitation, droplet vaporization has been widely investigated in vitro and in vivo with plasmonic nanoparticles. Droplets with a liquid dodecafluoropentane (DDFP) core enclosed in an albumin shell have a stable and simple structure with good characteristics of laser absorbing; thus, DDFP droplets could be an effective aim for laser-induced cavitation. The DDPF droplet was prepared and perfused in a mimic microvessel in the optical microscopic system with a passive acoustic detection module. Three patterns of laser-induced cavitation in the droplets were observed. The emitted acoustic signals showed specific spectrum components at specific time points. It was suggested that a nanosecond laser pulse could induce cavitation in DDPF droplets, and specific acoustic signals would be emitted. Analyzing its characteristics could aid in monitoring the laser-induced cavitation process in droplets, which is meaningful to theranostic application.

  16. Enhancement of cell ingrowth, proliferation, and early differentiation in a three-dimensional silicon carbide scaffold using low-intensity pulsed ultrasound.

    PubMed

    Wu, Lin; Lin, Liangjun; Qin, Yi-Xian

    2015-01-01

    Concerns over the use of autografts or allografts have necessitated the development of biomaterials for bone regeneration. Various studies have been performed to optimize the cultivation of osteogenic cells using osteoconductive porous scaffolds. The aim of this study was to evaluate the osteogenic efficiency of bone cell ingrowth, proliferation, and early differentiation in a silicon carbide (SiC) porous ceramic scaffold promoted with low-intensity pulsed ultrasound. MC3T3-E1 mouse preosteoblasts were seeded onto scaffolds and cultured for 4 and 7 days with daily of 20-min ultrasound treatment. The cells were evaluated for cell attachment, morphology, viability, ingrowth depth, volumetric proliferation, and early differentiation. After 4 and 7 days of culture and ultrasound exposure, the cell density was higher in the ultrasound-treated group compared with the sham-treated group on SiC scaffolds. The cell ingrowth depths inside the SiC scaffolds were 149.2±27.3 μm at 1 day, 310.1±12.6 μm for the ultrasound-treated group and 248.0±19.7 μm for the sham control at 4 days, and 359.6±18.5 μm for the ultrasound-treated group and 280.0±17.7 μm for the sham control at 7 days. They were significantly increased, that is, 25% (p=0.0029) and 28% (p=0.0008) increase, respectively, with ultrasound radiation force as compared with those in sham control at 4 and 7 days postseeding. The dsDNA contents were 583.5±19.1 ng/scaffold at 1 day, 2749.9±99.9 ng/scaffold for the ultrasound-treated group and 2514.9±114.7 ng/scaffold for the sham control at 4 days, and 3582.3±325.3 ng/scaffold for the ultrasound-treated group and 2825.7±134.3 ng/scaffold for the sham control at 7 days. There was a significant difference in the dsDNA content between the ultrasound- and sham-treated groups at 4 and 7 days. The ultrasound-treated group with the SiC construct showed a 9% (p=0.00029) and 27% (p=0.00017) increase in the average dsDNA content at 4 and 7 days over

  17. Enhancement of Cell Ingrowth, Proliferation, and Early Differentiation in a Three-Dimensional Silicon Carbide Scaffold Using Low-Intensity Pulsed Ultrasound

    PubMed Central

    Lin, Liangjun

    2015-01-01

    Concerns over the use of autografts or allografts have necessitated the development of biomaterials for bone regeneration. Various studies have been performed to optimize the cultivation of osteogenic cells using osteoconductive porous scaffolds. The aim of this study was to evaluate the osteogenic efficiency of bone cell ingrowth, proliferation, and early differentiation in a silicon carbide (SiC) porous ceramic scaffold promoted with low-intensity pulsed ultrasound. MC3T3-E1 mouse preosteoblasts were seeded onto scaffolds and cultured for 4 and 7 days with daily of 20-min ultrasound treatment. The cells were evaluated for cell attachment, morphology, viability, ingrowth depth, volumetric proliferation, and early differentiation. After 4 and 7 days of culture and ultrasound exposure, the cell density was higher in the ultrasound-treated group compared with the sham-treated group on SiC scaffolds. The cell ingrowth depths inside the SiC scaffolds were 149.2±27.3 μm at 1 day, 310.1±12.6 μm for the ultrasound-treated group and 248.0±19.7 μm for the sham control at 4 days, and 359.6±18.5 μm for the ultrasound-treated group and 280.0±17.7 μm for the sham control at 7 days. They were significantly increased, that is, 25% (p=0.0029) and 28% (p=0.0008) increase, respectively, with ultrasound radiation force as compared with those in sham control at 4 and 7 days postseeding. The dsDNA contents were 583.5±19.1 ng/scaffold at 1 day, 2749.9±99.9 ng/scaffold for the ultrasound-treated group and 2514.9±114.7 ng/scaffold for the sham control at 4 days, and 3582.3±325.3 ng/scaffold for the ultrasound-treated group and 2825.7±134.3 ng/scaffold for the sham control at 7 days. There was a significant difference in the dsDNA content between the ultrasound- and sham-treated groups at 4 and 7 days. The ultrasound-treated group with the SiC construct showed a 9% (p=0.00029) and 27% (p=0.00017) increase in the average dsDNA content at 4 and 7 days over

  18. Improving the therapeutic efficacy of mesenchymal stromal cells to restore perfusion in critical limb ischemia through pulsed focused ultrasound

    PubMed Central

    Tebebi, Pamela A.; Kim, Saejeong J.; Williams, Rashida A.; Milo, Blerta; Frenkel, Victor; Burks, Scott R.; Frank, Joseph A.

    2017-01-01

    Mesenchymal stem cells (MSC) are promising therapeutics for critical limb ischemia (CLI). Mechanotransduction from pulsed focused ultrasound (pFUS) upregulates local chemoattractants to enhance homing of intravenously (IV)-infused MSC and improve outcomes. This study investigated whether pFUS exposures to skeletal muscle would improve local homing of iv-infused MSCs and their therapeutic efficacy compared to iv-infused MSCs alone. CLI was induced by external iliac arterial cauterization in 10–12-month-old mice. pFUS/MSC treatments were delayed 14 days, when surgical inflammation subsided. Mice were treated with iv-saline, pFUS alone, IV-MSC, or pFUS and IV-MSC. Proteomic analyses revealed pFUS upregulated local chemoattractants and increased MSC tropism to CLI muscle. By 7 weeks post-treatment, pFUS + MSC significantly increased perfusion and CD31 expression, while reducing fibrosis compared to saline. pFUS or MSC alone reduced fibrosis, but did not increase perfusion or CD31. Furthermore, MSCs homing to pFUS-treated CLI muscle expressed more vascular endothelial growth factor (VEGF) and interleukin-10 (IL-10) than MSCs homing to non-pFUS-treated muscle. pFUS + MSC improved perfusion and vascular density in this clinically-relevant CLI model. The molecular effects of pFUS increased both MSC homing and MSC production of VEGF and IL-10, suggesting microenvironmental changes from pFUS also increased potency of MSCs in situ to further enhance their efficacy. PMID:28169278

  19. Enhanced Therapeutic Epidermal Growth Factor Receptor (EGFR) Antibody Delivery via Pulsed Ultrasound with Targeting Microbubbles for Glioma Treatment.

    PubMed

    Liao, Ai-Ho; Chou, Hsin-Yi; Hsieh, Yi-Lei; Hsu, Sheng-Chieh; Wei, Kuo-Chen; Liu, Hao-Li

    Pulsed-mode ultrasound (pUS) in combination with intravenously (IV) administered microbubbles (MBs) can enhance local drug delivery by temporarily enhancing capillary permeability. This study evaluates the use of epidermal growth factor receptor (EGFR)-targeting MBs after pUS treatment to enhance the effects of therapeutic-EGFR antibody delivery to glioma tumor cells in mice. Three animal groups were compared: (1) IV-injected non-targeting MBs, (2) IV-injected targeting MBs, and (3) IV-injected targeting MBs combined with pUS treatment. All animals were analyzed using high-frequency small-animal US imaging. The mean halftime of circulating targeting MBs was significantly increased from 3.13 min of targeting bubble alone to 5.86 min by targeting MBs combined with pUS treatment, compared to 2.34 min for non-targeting MBs. Compared to targeting bubble administration alone, pUS exposure prior to injection of targeting MBs was also significantly better at suppressing tumor growth when monitored for up to 35 days (p < 0.05). The final relative tumor volumes were 2664, 700, and 188 mm(3) for non-targeting MBs, targeting MBs, and targeting MBs combined with pUS treatment, respectively. pUS treatment prolonged the mean circulatory halftime of targeting MBs and enhanced the anti-tumor effect of EGFR antibodies in a human glioma model in mice. Targeting MBs combined with pUS treatment thus has potential for enhanced therapeutic antibody delivery for facilitating anti-glioma treatment.

  20. Improving the therapeutic efficacy of mesenchymal stromal cells to restore perfusion in critical limb ischemia through pulsed focused ultrasound.

    PubMed

    Tebebi, Pamela A; Kim, Saejeong J; Williams, Rashida A; Milo, Blerta; Frenkel, Victor; Burks, Scott R; Frank, Joseph A

    2017-02-07

    Mesenchymal stem cells (MSC) are promising therapeutics for critical limb ischemia (CLI). Mechanotransduction from pulsed focused ultrasound (pFUS) upregulates local chemoattractants to enhance homing of intravenously (IV)-infused MSC and improve outcomes. This study investigated whether pFUS exposures to skeletal muscle would improve local homing of iv-infused MSCs and their therapeutic efficacy compared to iv-infused MSCs alone. CLI was induced by external iliac arterial cauterization in 10-12-month-old mice. pFUS/MSC treatments were delayed 14 days, when surgical inflammation subsided. Mice were treated with iv-saline, pFUS alone, IV-MSC, or pFUS and IV-MSC. Proteomic analyses revealed pFUS upregulated local chemoattractants and increased MSC tropism to CLI muscle. By 7 weeks post-treatment, pFUS + MSC significantly increased perfusion and CD31 expression, while reducing fibrosis compared to saline. pFUS or MSC alone reduced fibrosis, but did not increase perfusion or CD31. Furthermore, MSCs homing to pFUS-treated CLI muscle expressed more vascular endothelial growth factor (VEGF) and interleukin-10 (IL-10) than MSCs homing to non-pFUS-treated muscle. pFUS + MSC improved perfusion and vascular density in this clinically-relevant CLI model. The molecular effects of pFUS increased both MSC homing and MSC production of VEGF and IL-10, suggesting microenvironmental changes from pFUS also increased potency of MSCs in situ to further enhance their efficacy.

  1. Low-intensity pulsed ultrasound enhances bone morphogenetic protein expression of human mandibular fracture haematoma-derived cells.

    PubMed

    Huang, W; Hasegawa, T; Imai, Y; Takeda, D; Akashi, M; Komori, T

    2015-07-01

    We previously demonstrated that human mandibular fracture haematoma-derived cells (MHCs) play an important role in mandibular fracture healing and that low-intensity pulsed ultrasound (LIPUS) accelerates this effect by stimulating various osteogenic cytokines. In the present study, we investigated how LIPUS affects the expression of bone morphogenetic proteins (BMPs), which are also known to have the ability to induce bone formation. MHCs were isolated from human mandibular fracture haematomas and the cells were divided into two groups: a LIPUS (+) group and a LIPUS (-) group, both of which were cultured in osteogenic medium. LIPUS was applied to the LIPUS (+) group 20 min a day for 4, 8, 14, and 20 days (1.5 MHz, 30 mW/cm(2)). Real-time PCR and immunofluorescence studies were carried out to determine the expression of BMP-2, 4, and 7. Compared to the LIPUS (-) group, gene expression levels were significantly increased in the LIPUS (+) group for BMP-2 on day 20 (67.38 ± 26.59 vs. 11.52 ± 3.42, P < 0.001), for BMP-4 on days 14 (45.12 ± 11.06 vs. 9.20 ± 2.88, P = 0.045) and 20 (40.96 ± 24.81 vs. 3.22 ± 1.53, P = 0.035), and for BMP-7 on day 8 (48.11 ± 35.36 vs. 7.03 ± 3.96, P = 0.034). These findings suggest that BMP-2, 4, and 7 may be mediated by LIPUS therapy during the bone repair process.

  2. Nonlinear simultaneous reconstruction of inhomogeneous compressibility and mass density distributions in unidirectional pulse-echo ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Hesse, Markus C.; Salehi, Leili; Schmitz, Georg

    2013-09-01

    In diagnostic ultrasound imaging, the image reconstruction quality is crucial for reliable diagnosis. Applying reconstruction algorithms based on the acoustic wave equation, the obtained image quality depends significantly on the physical material parameters accounted for in the equation. In this contribution, we extend a proposed iterative nonlinear one-parameter compressibility reconstruction algorithm by the additional reconstruction of the object’s inhomogeneous mass density distribution. The improved iterative algorithm is able to reconstruct inhomogeneous maps of the object’s compressibility and mass density simultaneously using only one conventional linear transducer array at a fixed location for wave transmission and detection. The derived approach is based on an acoustic wave equation including spatial compressibility and mass density variations, and utilizes the Kaczmarz method for iterative material parameter reconstruction. We validate our algorithm numerically for an unidirectional pulse-echo breast imaging application, and thus generate simulated measurements acquired from a numerical breast phantom with realistic compressibility and mass density values. Applying these measurements, we demonstrate with two reconstruction experiments the necessity to calculate the mass density in case of tissues with significant mass density inhomogeneities. When reconstructing spatial mass density variations, artefacts in the breast’s compressibility image are reduced resulting in improved spatial resolution. Furthermore, the compressibility relative error magnitude within a diagnostically significant region of interest (ROI) decreases from 3.04% to 2.62%. Moreover, a second image showing the breast’s inhomogeneous mass density distribution is given to provide additional diagnostic information. In the compressibility image, a spatial resolution moderately higher than the classical half-wavelength limit is observed.

  3. Optic cavitation with CW lasers: A review

    NASA Astrophysics Data System (ADS)

    Padilla-Martinez, J. P.; Berrospe-Rodriguez, C.; Aguilar, G.; Ramirez-San-Juan, J. C.; Ramos-Garcia, R.

    2014-12-01

    The most common method to generate optic cavitation involves the focusing of short-pulsed lasers in a transparent liquid media. In this work, we review a novel method of optic cavitation that uses low power CW lasers incident in highly absorbing liquids. This novel method of cavitation is called thermocavitation. Light absorbed heats up the liquid beyond its boiling temperature (spinodal limit) in a time span of microseconds to milliseconds (depending on the optical intensity). Once the liquid is heated up to its spinodal limit (˜300 °C for pure water), the superheated water becomes unstable to random density fluctuations and an explosive phase transition to vapor takes place producing a fast-expanding vapor bubble. Eventually, the bubble collapses emitting a strong shock-wave. The bubble is always attached to the surface taking a semi-spherical shape, in contrast to that produced by pulsed lasers in transparent liquids, where the bubble is produced at the focal point. Using high speed video (105 frames/s), we study the bubble's dynamic behavior. Finally, we show that heat diffusion determines the water superheated volume and, therefore, the amplitude of the shock wave. A full experimental characterization of thermocavitation is described.

  4. Duplex ultrasound

    MedlinePlus

    Vascular ultrasound; Peripheral vascular ultrasound ... A duplex ultrasound combines: Traditional ultrasound: This uses sound waves that bounce off blood vessels to create pictures. Doppler ultrasound: This ...

  5. Laser-induced cavitation based micropump.

    PubMed

    Dijkink, Rory; Ohl, Claus-Dieter

    2008-10-01

    Lab-on-a-chip devices are in strong demand as versatile and robust pumping techniques. Here, we present a cavitation based technique, which is able to pump a volume of 4000 microm3 within 75 micros against an estimated pressure head of 3 bar. The single cavitation event is created by focusing a laser pulse in a conventional PDMS microfluidic chip close to the channel opening. High-speed photography at 1 million frames s(-1) resolves the flow in the supply channel, pump channel, and close to the cavity. The elasticity of the material affects the overall fluid flow. Continuous pumping at repetition rates of up to 5 Hz through 6 mm long square channels of 20 microm width is shown. A parameter study reveals the key-parameters for operation: the distance between the laser focus and the channel, the maximum bubble size, and the chamber geometry.

  6. A Study of Cavitation Erosion

    SciTech Connect

    Hiromu Isaka; Masatsugu Tsutsumi; Tadashi Shiraishi; Hiroyuki Kobayashi

    2002-07-01

    The authors performed experimental study for the purpose of the following two items from a viewpoint of cavitation erosion of a cylindrical orifice in view of a problem at the letdown orifice in PWR (Pressurized Water Reactor). 1. To get the critical cavitation parameter of the cylindrical orifice to establish the design criteria for prevention of cavitation erosion, and 2. to ascertain the erosion rate in such an eventuality that the cavitation erosion occurs with the orifice made of stainless steel with precipitation hardening (17-4-Cu hardening type stainless steel), so that we confirm the appropriateness of the design criteria. Regarding the 1. item, we carried out the cavitation tests to get the critical cavitation parameters inside and downstream of the orifice. The test results showed that the cavitation parameter at inception is independent of the length or the diameter of the orifice. Moreover, the design criteria of cavitation erosion of cylindrical orifices have been established. Regarding the 2. item, we tested the erosion rate under high-pressure conditions. The cavitation erosion actually occurred in the cylindrical orifice at the tests that was strongly resemble to the erosion occurred at the plant. It will be seldom to reproduce resemble cavitation erosion in a cylindrical orifice with the hard material used at plants. We could establish the criteria for preventing the cavitation erosion from the test results. (authors)

  7. Comparative study of the effects of low-intensity pulsed ultrasound and low-level laser therapy on injured muscle repair

    NASA Astrophysics Data System (ADS)

    Renno, Ana Claudia Muniz; Toma, Renata Luri; Feitosa, Suellen Maurin; Fernandes, Kelly; de Oliveira, Poliani; Parizotto, N.; Ribeiro, Daniel Araki

    2011-03-01

    Muscle tissue is one of the most frequently affected by injury, whether during sports activities, or work activities. In this context, biochemical and biophysical resources have been studied to minimize the time of muscle regeneration. Among these, low intensity pulsed ultrasound (US) and low level laser therapy (LLLT) may be highlighted. Despite a series of evidences about the positive effects of these resources in the process of tissue regeneration, the cellular and morphological changes triggered by LLLT and U.S. are still largely unknown. Thus, the aim of this study was to investigate the effects of US and LLLT on muscle repair after cryolesion by means of histopathological analysis and immunohistochemistry for COX-2. A total of thirty five male Wistar rats were randomly distributed into 4 groups: intact control group; injured control group: muscle injured animals without any treatment; laser treated group: muscle injured animals treated with 830 nm laser and ultra-sound treated group: muscle injured animals treated with US. The treatments started 24 hours post-surgery and were performed during 6 sessions. The animals exposed to lasertherapy pointed out minor degenerative changes of muscle tissue. In the same way, exposure to ultrasound was able to reduce tissue injuries induced by cryolesion, but less intense than laser therapy. Strong COX-2 positive cells were found in rats submitted to cryolesion only, whereas COX-2 immunoexpression was lower in laser treated or ultrasound treated groups. In summary, this study reveals that both lasertherapy and ultrasound have positive effects on muscle repair in rats.

  8. Cavitation damage prediction for the JSNS mercury target vessel

    NASA Astrophysics Data System (ADS)

    Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Teshigawara, Makoto; Kinoshita, Hidetaka; Takada, Hiroshi; Futakawa, Masatoshi

    2016-01-01

    The liquid mercury target system for the Japan Spallation Neutron Source (JSNS) at the Materials and Life science experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) is designed to produce pulsed neutrons. The mercury target vessel in this system, which is made of type 316L stainless steel, is damaged by pressure wave-induced cavitation due to proton beam bombardment. Currently, cavitation damage is considered to be the dominant factor influencing the service life of the target vessel rather than radiation damage. In this study, cavitation damage to the interior surface of the target vessel was predicted on the basis of accumulated damage data from off-beam and on-beam experiments. The predicted damage was compared with the damage observed in a used target vessel. Furthermore, the effect of injecting gas microbubbles on cavitation damage was predicted through the measurement of the acoustic vibration of the target vessel. It was shown that the predicted depth of cavitation damage is reasonably coincident with the observed results. Moreover, it was confirmed that the injection of gas microbubbles had an effect on cavitation damage.

  9. Cavitation during wire brushing

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zou, Jun; Ji, Chen

    2016-11-01

    In our daily life, brush is often used to scrub the surface of objects, for example, teeth, pots, shoes, pool, etc. And cleaning rust and stripping paint are accomplished using wire brush. Wire brushes also can be used to clean the teeth for large animals, such as horses, crocodiles. By observing brushing process in water, we capture the cavitation phenomenon on the track of moving brush wire. It shows that the cavitation also can affect the surface. In order to take clear and entire pictures of cavity, a simplified model of one stainless steel wire brushing a boss is adopted in our experiment. A transparent organic tank filled with deionized water is used as a view box. And a high speed video camera is used to record the sequences. In experiment, ambient pressure is atmospheric pressure and deionized water temperature is kept at home temperature. An obvious beautiful flabellate cavity zone appears behind the moving steel wire. The fluctuation of pressure near cavity is recorded by a hydrophone. More movies and pictures are used to show the behaviors of cavitation bubble following a restoring wire. Beautiful tracking cavitation bubble cluster is captured and recorded to show.

  10. Ozone and Cavitation Combination

    NASA Astrophysics Data System (ADS)

    Carreon, Ernestina; Traversoni, Leonardo

    2009-09-01

    From laboratory measurements it is well known that the addition of ozone and cavitation enhances the properties of both, understanding for that the ones related to disinfection and carbon removal from waste water. This paper shows modeling of such phenomena that gives some light to the understanding of it and also provides the opportunity to improve the effectiveness of the current procedures.

  11. Quantitative observations of cavitation activity in a viscoelastic medium.

    PubMed

    Collin, Jamie R T; Coussios, Constantin C

    2011-11-01

    Quantitative experimental observations of single-bubble cavitation in viscoelastic media that would enable validation of existing models are presently lacking. In the present work, single bubble cavitation is induced in an agar gel using a 1.15 MHz high intensity focused ultrasound transducer, and observed using a focused single-element passive cavitation detection (PCD) transducer. To enable quantitative observations, a full receive calibration is carried out of a spherically focused PCD system by a bistatic scattering substitution technique that uses an embedded spherical scatterer and a hydrophone. Adjusting the simulated pressure received by the PCD by the transfer function on receive and the frequency-dependent attenuation of agar gel enables direct comparison of the measured acoustic emissions with those predicted by numerical modeling of single-bubble cavitation using a modified Keller-Miksis approach that accounts for viscoelasticity of the surrounding medium. At an incident peak rarefactional pressure near the cavitation threshold, period multiplying is observed in both experiment and numerical model. By comparing the two sets of results, an estimate of the equilibrium bubble radius in the experimental observations can be made, with potential for extension to material parameter estimation. Use of these estimates yields good agreement between model and experiment.

  12. Shock Waves in Bubbly Cavitating Flows: Part I. Shock Waves in Cloud Cavitation. Part II. Bubbly Cavitating Flows Through a Converging-Diverging Nozzle.

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Chun

    Two problems are considered in this thesis: the nonlinear dynamics of a cloud of cavitation bubbles, and bubbly cavitating flows through a converging-diverging nozzle. The focus of the first problem is to explore the characteristics of the growth and collapse of a spherical cloud of bubbles. This is typical of the transient behaviour exhibited by a bubble cloud as it passes a body or the blade of a ship propeller. The simulations employ the fully nonlinear, non-barotropic, homogeneous two-phase flow equations coupled with the Rayleigh-Plesset equation for the dynamics of individual bubbles. It was found that the collapse of the cloud is accompanied by the formation of an inward propagating bubbly shock wave. The focusing of the shock is responsible for the severe noise and damage potential in cloud cavitation. The second problem investigates the nonlinear behavior of bubbly cavitating flows through a converging -diverging nozzle. Two different flow regimes are found from steady state solutions: quasi-steady and quasi-unsteady. Bifurcation occurs as the flow transitions from one regime to the other. Unsteady solutions in a period of consecutive times are also presented. These solutions are characterized by large pressure pulses changing in both magnitude and location with time downstream of the throat. The characteristics of these pulses are similar to the shock pulses of the first problem and are produced by the local violent collapse of the bubbles in the flow.

  13. Pulse

    MedlinePlus

    ... the underside of the opposite wrist, below the base of the thumb. Press with flat fingers until ... determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately ...

  14. Physical acoustics of ultrasound-assisted lipoplasty.

    PubMed

    Weninger, K; Camara, C; Putterman, S

    1999-07-01

    The acoustic fields generated by probes and cannulas used for ultrasound-assisted lipoplasty (UAL) are sources of cavitation and sonoluminescence. The localized stress fields and heating caused by cavitation are strong enough to lyse cells and, in the authors' opinion, constitute the means of therapeutic action of UAL. The spectrum of sonoluminescence extends into the ultraviolet. Various devices have been calibrated and various issues relating to health risks are discussed.

  15. Sizing of Emboli in Flowing Blood Using Pulse Doppler Ultrasound and the Embolus-To Power Ratio.

    NASA Astrophysics Data System (ADS)

    Moehring, Mark Alan

    The embolus to blood ratio (EBR) theoretical model describing pulse Doppler ultrasound observations of emboli in flowing blood is summarized. The EBR model uses the backscattered signal power from blood in the Doppler sample volume as a reference from which to assess embolus size and composition. This EBR is independent of attenuation and reflection loss in intervening tissues between probe and bloodflow. An in vitro investigation is presented that tests the validity of the EBR model. The experimental apparatus includes a novel phantom for Doppler observation of circulating emboli and a Doppler system which uses 1.6 and 2.4 MHz concurrently for interrogation of an embolus. The phantom contains a tubeless flow conduit inside a polyacrylamide gel and a blood-mimicking fluid flowing in the conduit. Time series Doppler shift data which are gathered while polystyrene microsphere "emboli" transit the sample volume are post -processed to calculate the EBR on each embolic signature. EBR measurements from microspheres of three different diameters are summarized and shown to contain pronounced and systematic variability. The hypothesis is presented that this variability is due to a small speed of sound mismatch between the gel and the blood-mimicking fluid, a phenomenon anticipated in vivo. This speed of sound mismatch results in beam refraction and a non-uniformly insonated sample volume (thereby causing variability in embolus signatures). A three dimensional theoretical study is presented that models beam refraction resulting from speed of sound mismatch between the blood mimicking fluid and the surrounding gel. A Monte Carlo study of the EBR behavior in the presence of beam refraction is performed and yields similar results to the data obtained in vitro. This study is evidence that the experimental signal variability is due to speed of sound mismatch between blood-mimicking fluid and gel. A method of extracting embolus size from the dual frequency EBR data based on the

  16. Low Intensity Pulsed Ultrasound Enhanced Mesenchymal Stem Cell Recruitment through Stromal Derived Factor-1 Signaling in Fracture Healing

    PubMed Central

    Wei, Fang-Yuan; Leung, Kwok-Sui; Li, Gang; Qin, Jianghui; Chow, Simon Kwoon-Ho; Huang, Shuo; Sun, Ming-Hui; Qin, Ling; Cheung, Wing-Hoi

    2014-01-01

    Low intensity pulsed ultrasound (LIPUS) has been proven effective in promoting fracture healing but the underlying mechanisms are not fully depicted. We examined the effect of LIPUS on the recruitment of mesenchymal stem cells (MSCs) and the pivotal role of stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) pathway in response to LIPUS stimulation, which are essential factors in bone fracture healing. For in vitro study, isolated rat MSCs were divided into control or LIPUS group. LIPUS treatment was given 20 minutes/day at 37°C for 3 days. Control group received sham LIPUS treatment. After treatment, intracellular CXCR4 mRNA, SDF-1 mRNA and secreted SDF-1 protein levels were quantified, and MSCs migration was evaluated with or without blocking SDF-1/CXCR4 pathway by AMD3100. For in vivo study, fractured 8-week-old young rats received intracardiac administration of MSCs were assigned to LIPUS treatment, LIPUS+AMD3100 treatment or vehicle control group. The migration of transplanted MSC to the fracture site was investigated by ex vivo fluorescent imaging. SDF-1 protein levels at fracture site and in serum were examined. Fracture healing parameters, including callus morphology, micro-architecture of the callus and biomechanical properties of the healing bone were investigated. The in vitro results showed that LIPUS upregulated SDF-1 and CXCR4 expressions in MSCs, and elevated SDF-1 protein level in the conditioned medium. MSCs migration was promoted by LIPUS and partially inhibited by AMD3100. In vivo study demonstrated that LIPUS promoted MSCs migration to the fracture site, which was associated with an increase of local and serum SDF-1 level, the changes in callus formation, and the improvement of callus microarchitecture and mechanical properties; whereas the blockade of SDF-1/CXCR4 signaling attenuated the LIPUS effects on the fractured bones. These results suggested SDF-1 mediated MSCs migration might be one of the crucial mechanisms

  17. Effects of High Intensity Focused Ultrasound on the Brain

    NASA Astrophysics Data System (ADS)

    Vykhodtseva, Natalia; McDannold, Nathan; Hynynen, Kullervo

    2007-05-01

    Bio-effects in the brain resulting from short focused ultrasound (FUS) pulses (1-10 ms, PRF=0.5, 1.0, and 2.0 Hz, frequency=1.63 MHz) at high acoustic power (up to 700W) were examined. Fifty-seven locations were targeted through a craniotomy in the brains of 11 rabbits. Temperature rise was measured with MRI-based thermometry. The animals were sacrificed 4 h or 48 h after sonications for histological evaluations. A range of effects was observed: (1) Vascular changes (vasoconstriction/occlusion). (2) Homogenization of tissue. (3) Concentric circular lesions; (4) Hemorrhagic lesions similar to what was described earlier as inertial cavitation effects. Overall, the type of damage correlated with the acoustical power, with substantial overlapping among categories. Vascular changes were found at ˜140-180W, the thresholds for homogenized tissue and hemorrhagic lesions were approximately 200W and 350W, respectively. Some of these effects might be exploited for new therapies. Vascular occlusion might also be exploited for therapy; the lesions with homogenized tissue may suggest a new mechanism for non-thermal tissue ablation; small ones for ophthalmology and for functional neurosurgery (if produced in nerve tracts). The mechanism for this effect is unknown, but with the acoustic intensities used, non-linear absorption, strong radiation forces and microbubble activity were likely to have been present. MRI-based temperature changes suggest that thermal effects were probably not responsible for these lesions, as the average focal temperature (approximately 47°C) was slightly below the threshold for thermal damage. The overlap between types of tissue effects for a given acoustic intensity indicates that a method to guide such cavitation-based therapies is needed. MRI was promising in some ways — we can detect where the effects were happening and whether or not cavitation occurred. While the artifacts in temperature mappings will make temperature measurements problematic

  18. Ultrasound-Propelled Nanocups for Drug Delivery

    PubMed Central

    Kwan, James J; Myers, Rachel; Coviello, Christian M; Graham, Susan M; Shah, Apurva R; Stride, Eleanor; Carlisle, Robert C; Coussios, Constantin C

    2015-01-01

    Ultrasound-induced bubble activity (cavitation) has been recently shown to actively transport and improve the distribution of therapeutic agents in tumors. However, existing cavitation-promoting agents are micron-sized and cannot sustain cavitation activity over prolonged time periods because they are rapidly destroyed upon ultrasound exposure. A novel ultrasound-responsive single-cavity polymeric nanoparticle (nanocup) capable of trapping and stabilizing gas against dissolution in the bloodstream is reported. Upon ultrasound exposure at frequencies and intensities achievable with existing diagnostic and therapeutic systems, nanocups initiate and sustain readily detectable cavitation activity for at least four times longer than existing microbubble constructs in an in vivo tumor model. As a proof-of-concept of their ability to enhance the delivery of unmodified therapeutics, intravenously injected nanocups are also found to improve the distribution of a freely circulating IgG mouse antibody when the tumor is exposed to ultrasound. Quantification of the delivery distance and concentration of both the nanocups and coadministered model therapeutic in an in vitro flow phantom shows that the ultrasound-propelled nanocups travel further than the model therapeutic, which is itself delivered to hundreds of microns from the vessel wall. Thus nanocups offer considerable potential for enhanced drug delivery and treatment monitoring in oncological and other biomedical applications. PMID:26296985

  19. Pulsatility Produced by the Hemodialysis Roller Pump as Measured by Doppler Ultrasound.

    PubMed

    Fulker, David; Keshavarzi, Gholamreza; Simmons, Anne; Pugh, Debbie; Barber, Tracie

    2015-11-01

    Microbubbles have previously been detected in the hemodialysis extracorporeal circuit and can enter the blood vessel leading to potential complications. A potential source of these microbubbles is highly pulsatile flow resulting in cavitation. This study quantified the pulsatility produced by the roller pump throughout the extracorporeal circuit. A Sonosite S-series ultrasound probe (FUJIFILM Sonosite Inc., Tokyo, Japan) was used on a single patient during normal hemodialysis treatment. The Doppler waveform showed highly pulsatile flow throughout the circuit with the greatest pulse occurring after the pump itself. The velocity pulse after the pump ranged from 57.6 ± 1.74 cm/s to -72 ± 4.13 cm/s. Flow reversal occurred when contact between the forward roller and tubing ended. The amplitude of the pulse was reduced from 129.6 cm/s to 16.25 cm/s and 6.87 cm/s following the dialyzer and venous air trap. This resulted in almost nonpulsatile, continuous flow returning to the patient through the venous needle. These results indicate that the roller pump may be a source of microbubble formation from cavitation due to the highly pulsatile blood flow. The venous air trap was identified as the most effective mechanism in reducing the pulsatility. The inclusion of multiple rollers is also recommended to offer an effective solution in dampening the pulse produced by the pump.

  20. Dynamics of Isolated Tip Vortex Cavitation

    NASA Astrophysics Data System (ADS)

    Pennings, Pepijn; Bosschers, Johan; van Terwisga, Tom

    2014-11-01

    Performance of ship propellers and comfort levels in the surroundings are limited by various forms of cavitation. Amongst these forms tip vortex cavitation is one of the first appearing forms and is expected to be mainly responsible for the emission of broadband pressure fluctuations typically occurring between the 4th to the 7th blade passing frequency (approx. 40--70 Hz). These radiated pressure pulses are likely to excite parts of the hull structure resulting in a design compromise between efficiency and comfort. Insight is needed in the mechanism of acoustic emission from the oscillations by a tip vortex cavity. In the current experimental study the tip vortex cavity from a blade with an elliptic planform and sections based on NACA 662 - 415 with meanline a = 0 . 8 is observed using high speed shadowgraphy in combination with blade force and acoustic measurements. An analytic model describing three main cavity deformation modes is verified and used to explain the origin of a cavity eigenfrequency or ``vortex singing'' phenomenon observed by Maines and Arndt (1997) on the tip vortex cavity originating from the same blade. As no hydrodynamic sound originating from the tip vortex cavity was observed it is posed that a tip flow instability is essential for ``vortex singing.'' This research was funded by the Lloyd's Register Foundation as part of the International Institute for Cavitation Research.

  1. Controlled multibubble surface cavitation.

    PubMed

    Bremond, Nicolas; Arora, Manish; Ohl, Claus-Dieter; Lohse, Detlef

    2006-06-09

    Heterogeneous bubble nucleation at surfaces has been notorious because of its irreproducibility. Here controlled multibubble surface cavitation is achieved by using a hydrophobic surface patterned with microcavities. The expansion of the nuclei in the microcavities is triggered by a fast lowering of the liquid pressure. The procedure allows us to control and fix the bubble distance within the bubble cluster. We observe a perfect quantitative reproducibility of the cavitation events where the inner bubbles in the two-dimensional cluster are shielded by the outer ones, reflected by their later expansion and their delayed collapse. Apart from the final bubble collapse phase (when jetting flows directed towards the cluster's center develop), the bubble dynamics can be quantitatively described by an extended Rayleigh-Plesset equation, taking pressure modification through the surrounding bubbles into account.

  2. Controlled Multibubble Surface Cavitation

    NASA Astrophysics Data System (ADS)

    Bremond, Nicolas; Arora, Manish; Ohl, Claus-Dieter; Lohse, Detlef

    2006-06-01

    Heterogeneous bubble nucleation at surfaces has been notorious because of its irreproducibility. Here controlled multibubble surface cavitation is achieved by using a hydrophobic surface patterned with microcavities. The expansion of the nuclei in the microcavities is triggered by a fast lowering of the liquid pressure. The procedure allows us to control and fix the bubble distance within the bubble cluster. We observe a perfect quantitative reproducibility of the cavitation events where the inner bubbles in the two-dimensional cluster are shielded by the outer ones, reflected by their later expansion and their delayed collapse. Apart from the final bubble collapse phase (when jetting flows directed towards the cluster’s center develop), the bubble dynamics can be quantitatively described by an extended Rayleigh-Plesset equation, taking pressure modification through the surrounding bubbles into account.

  3. Bubbly Cavitation Flows.

    DTIC Science & Technology

    1991-03-31

    and 12. Comparison is also made with analytical predictions based on the Rayleigh - Plesset equations. In addition to the single bubble studies, the...bubble maximum size distributions and those predicted using the measured nuclei number distribution and the Rayleigh - Plesset model for the bubble dyna...tions 7, 9, 11, 12, 13 examined travelling bubble cavitation on two classic axisymmetric headforms (a Schiebe body and the ITTC headform) and, with the

  4. Shock Induced Cavitation

    DTIC Science & Technology

    1991-02-01

    Rehak, Margareta L, Frank L. DiMaggio and Ivan S. Sandler, "Interactive Ap- proximations for a Cavitating Fluid around a Floating Structure...INC ATTN: LIBRARY ATTN: R FRANK DEPARTMENT OF THE AIR FORCE BDM INTERNATIONAL INC ATTN: E DORCHAK AIR FORCE INSTITUTE OF TECHNOLOGY/EN ATTN: COMMANDER...F SHELTON ATTN: LIBRARY B KINSLOW SCIENCE APPLICATIONS INTL CORP ATTN: J R BRITT KAMAN SCIENCES CORP ATTN: DASIAC SRI INTERNATIONAL ATTN: E CONRAD

  5. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin

    NASA Astrophysics Data System (ADS)

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C.

    2015-03-01

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure—PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  6. Cavitation-enhanced delivery of insulin in agar and porcine models of human skin.

    PubMed

    Feiszthuber, Helga; Bhatnagar, Sunali; Gyöngy, Miklós; Coussios, Constantin-C

    2015-03-21

    Ultrasound-assisted transdermal insulin delivery offers a less painful and less invasive alternative to subcutaneous insulin injections. However, ultrasound-based drug delivery, otherwise known as sonophoresis, is a highly variable phenomenon, in part dependent on cavitation. The aim of the current work is to investigate the role of cavitation in transdermal insulin delivery. Fluorescently stained, soluble Actrapid insulin was placed on the surface of human skin-mimicking materials subjected to 265 kHz, 10% duty cycle focused ultrasound. A confocally and coaxially aligned 5 MHz broadband ultrasound transducer was used to detect cavitation. Two different skin models were used. The first model, 3% agar hydrogel, was insonated with a range of pressures (0.25-1.40 MPa peak rarefactional focal pressure-PRFP), with and without cavitation nuclei embedded within the agar at a concentration of 0.05% w/v. The second, porcine skin was insonated at 1.00 and 1.40 MPa PRFP. In both models, fluorescence measurements were used to determine penetration depth and concentration of delivered insulin. Results show that in agar gel, both insulin penetration depth and concentration only increased significantly in the presence of inertial cavitation, with up to a 40% enhancement. In porcine skin the amount of fluorescent insulin was higher in the epidermis of those samples that were exposed to ultrasound compared to the control samples, but there was no significant increase in penetration distance. The results underline the importance of instigating and monitoring inertial cavitation during transdermal insulin delivery.

  7. Generation and Quantitative Analysis of Pulsed Low Frequency Ultrasound to Determine the Sonic Sensitivity of Untreated and Treated Neoplastic Cells

    PubMed Central

    Trendowski, Matthew; Christen, Timothy D.; Zoino, Joseph N.; Acquafondata, Christopher; Fondy, Thomas P.

    2015-01-01

    Low frequency ultrasound in the 20 to 60 kHz range is a novel physical modality by which to induce selective cell lysis and death in neoplastic cells. In addition, this method can be used in combination with specialized agents known as sonosensitizers to increase the extent of preferential damage exerted by ultrasound against neoplastic cells, an approach referred to as sonodynamic therapy (SDT). The methodology for generating and applying low frequency ultrasound in a preclinical in vitro setting is presented to demonstrate that reproducible cell destruction can be attained in order to examine and compare the effects of sonication on neoplastic and normal cells. This offers a means by which to reliably sonicate neoplastic cells at a level of consistency required for preclinical therapeutic assessment. In addition, the effects of cholesterol-depleting and cytoskeletal-directed agents on potentiating ultrasonic sensitivity in neoplastic cells are discussed in order to elaborate on mechanisms of action conducive to sonochemotherapeutic approaches. PMID:26274053

  8. An ultrasound tomography system with polyvinyl alcohol (PVA) moldings for coupling: in vivo results for 3-D pulse-echo imaging of the female breast.

    PubMed

    Koch, Andreas; Stiller, Florian; Lerch, Reinhard; Ermert, Helmut

    2015-02-01

    Full-angle spatial compounding (FASC) is a concept for pulse-echo imaging using an ultrasound tomography (UST) system. With FASC, resolution is increased and speckles are suppressed by averaging pulse-echo data from 360°. In vivo investigations have already shown a great potential for 2-D FASC in the female breast as well as for finger-joint imaging. However, providing a small number of images of parallel cross-sectional planes with enhanced image quality is not sufficient for diagnosis. Therefore, volume data (3-D) is needed. For this purpose, we further developed our UST add-on system to automatically rotate a motorized array (3-D probe) around the object of investigation. Full integration of external motor and ultrasound electronics control in a custom-made program allows acquisition of 3-D pulse-echo RF datasets within 10 min. In case of breast cancer imaging, this concept also enables imaging of near-thorax tissue regions which cannot be achieved by 2-D FASC. Furthermore, moldings made of polyvinyl alcohol hydrogel (PVA-H) have been developed as a new acoustic coupling concept. It has a great potential to replace the water bath technique in UST, which is a critical concept with respect to clinical investigations. In this contribution, we present in vivo results for 3-D FASC applied to imaging a female breast which has been placed in a PVA-H molding during data acquisition. An algorithm is described to compensate time-of-flight and consider refraction at the water-PVA-H molding and molding-tissue interfaces. Therefore, the mean speed of sound (SOS) for the breast tissue is estimated with an image-based method. Our results show that the PVA-H molding concept is applicable and feasible and delivers good results. 3-D FASC is superior to 2-D FASC and provides 3-D volume data at increased image quality.

  9. Influence of mixing and ultrasound frequency on antisolvent crystallisation of sodium chloride.

    PubMed

    Lee, Judy; Ashokkumar, Muthupandian; Kentish, Sandra E

    2014-01-01

    Ultrasound is known to promote nucleation of crystals and produce a narrower size distribution in a controlled and reproducible manner for the crystallisation process. Although there are various theories that suggest cavitation bubbles are responsible for sonocrystallisation, most studies use power ultrasonic horns that generate both intense shear and cavitation and this can mask the role that cavitation bubbles play. High frequency ultrasound from a plate transducer can be used to examine the effect of cavitation bubbles without the intense shear effect. This study reports the crystal size and morphology with various mixing speeds and ultrasound frequencies. The results show high frequency ultrasound produced sodium chloride crystals of similar size distribution as an ultrasonic horn. In addition, ultrasound generated sodium chloride crystals having a more symmetrical cubic structure compared to crystals produced by a high shear mixer.

  10. Re-evaluation of low intensity pulsed ultrasound in treatment of tibial fractures (TRUST): randomized clinical trial

    PubMed Central

    Bhandari, Mohit; Einhorn, Thomas A; Schemitsch, Emil; Heckman, James D; Tornetta, Paul; Leung, Kwok-Sui; Heels-Ansdell, Diane; Makosso-Kallyth, Sun; Della Rocca, Gregory J; Jones, Clifford B; Guyatt, Gordon H

    2016-01-01

    Objective To determine whether low intensity pulsed ultrasound (LIPUS), compared with sham treatment, accelerates functional recovery and radiographic healing in patients with operatively managed tibial fractures. Design A concealed, randomized, blinded, sham controlled clinical trial with a parallel group design of 501 patients, enrolled between October 2008 and September 2012, and followed for one year. Setting 43 North American academic trauma centers. Participants Skeletally mature men or women with an open or closed tibial fracture amenable to intramedullary nail fixation. Exclusions comprised pilon fractures, tibial shaft fractures that extended into the joint and required reduction, pathological fractures, bilateral tibial fractures, segmental fractures, spiral fractures >7.5 cm in length, concomitant injuries that were likely to impair function for at least as long as the patient’s tibial fracture, and tibial fractures that showed <25% cortical contact and >1 cm gap after surgical fixation. 3105 consecutive patients who underwent intramedullary nailing for tibial fracture were assessed, 599 were eligible and 501 provided informed consent and were enrolled. Interventions Patients were allocated centrally to self administer daily LIPUS (n=250) or use a sham device (n=251) until their tibial fracture showed radiographic healing or until one year after intramedullary fixation. Main outcome measures Primary registry specified outcome was time to radiographic healing within one year of fixation; secondary outcome was rate of non-union. Additional protocol specified outcomes included short form-36 (SF-36) physical component summary (PCS) scores, return to work, return to household activities, return to ≥80% of function before injury, return to leisure activities, time to full weight bearing, scores on the health utilities index (mark 3), and adverse events related to the device. Results SF-36 PCS data were acquired from 481/501 (96%) patients, for whom

  11. Cavitation studies in microgravity

    NASA Astrophysics Data System (ADS)

    Kobel, Philippe; Obreschkow, Danail; Farhat, Mohamed; Dorsaz, Nicolas; de Bosset, Aurele

    The hydrodynamic cavitation phenomenon is a major source of erosion for many industrial systems such as cryogenic pumps for rocket propulsion, fast ship propellers, hydraulic pipelines and turbines. Erosive processes are associated with liquid jets and shockwaves emission fol-lowing the cavity collapse. Yet, fundamental understanding of these processes requires further cavitation studies inside various geometries of liquid volumes, as the bubble dynamics strongly depends the surrounding pressure field. To this end, microgravity represents a unique platform to produce spherical fluid geometries and remove the hydrostatic pressure gradient induced by gravity. The goal of our first experiment (flown on ESA's parabolic flight campaigns 2005 and 2006) was to study single bubble dynamics inside large spherical water drops (having a radius between 8 and 13 mm) produced in microgravity. The water drops were created by a micro-pump that smoothly expelled the liquid through a custom-designed injector tube. Then, the cavitation bubble was generated through a fast electrical discharge between two electrodes immersed in the liquid from above. High-speed imaging allowed to analyze the implications of isolated finite volumes and spherical free surfaces on bubble evolution, liquid jets formation and shock wave dynamics. Of particular interest are the following results: (A) Bubble lifetimes are shorter than in extended liquid volumes, which could be explain by deriving novel corrective terms to the Rayleigh-Plesset equation. (B) Transient crowds of micro-bubbles (smaller than 1mm) appeared at the instants of shockwaves emission. A comparison between high-speed visualizations and 3D N-particle simulations of a shock front inside a liquid sphere reveals that focus zones within the drop lead to a significantly increased density of induced cavitation. Considering shock wave crossing and focusing may hence prove crucially useful to understand the important process of cavitation erosion

  12. Cavitation bubble dynamics during thulium fiber laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Hardy, Luke A.; Kennedy, Joshua D.; Wilson, Christopher R.; Irby, Pierce B.; Fried, Nathaniel M.

    2016-02-01

    The Thulium fiber laser (TFL) is being explored for lithotripsy. TFL parameters differ from standard Holmium:YAG laser in several ways, including smaller fiber delivery, more strongly absorbed wavelength, low pulse energy/high pulse rate operation, and more uniform temporal pulse structure. High speed imaging of cavitation bubbles was performed at 105,000 fps and 10 μm spatial resolution to determine influence of these laser parameters on bubble formation. TFL was operated at 1908 nm with pulse energies of 5-75 mJ, and pulse durations of 200-1000 μs, delivered through 100-μm-core fiber. Cavitation bubble dynamics using Holmium laser at 2100 nm with pulse energies of 200-1000 mJ and pulse duration of 350 μs was studied, for comparison. A single, 500 μs TFL pulse produced a bubble stream extending 1090 +/- 110 μm from fiber tip, and maximum bubble diameters averaged 590 +/- 20 μm (n=4). These observations are consistent with previous studies which reported TFL ablation stallout at working distances < 1.0 mm. TFL bubble dimensions were five times smaller than for Holmium laser due to lower pulse energy, higher water absorption coefficient, and smaller fiber diameter used.

  13. Transient cavitation and acoustic emission produced by different laser lithotripters.

    PubMed

    Zhong, P; Tong, H L; Cocks, F H; Pearle, M S; Preminger, G M

    1998-08-01

    Transient cavitation and shockwave generation produced by pulsed-dye and holmium:YAG laser lithotripters were studied using high-speed photography and acoustic emission measurements. In addition, stone phantoms were used to compare the fragmentation efficiency of various laser and electrohydraulic lithotripters. The pulsed-dye laser, with a wavelength (504 nm) strongly absorbed by most stone materials but not by water, and a short pulse duration of approximately 1 microsec, induces plasma formation on the surface of the target calculi. Subsequently, the rapid expansion of the plasma forms a cavitation bubble, which expands spherically to a maximum size and then collapses violently, leading to strong shockwave generation and microjet impingement, which comprises the primary mechanism for stone fragmentation with short-pulse lasers. In contrast, the holmium laser, with a wavelength (2100 nm) most strongly absorbed by water as well as by all stone materials and a long pulse duration of 250 to 350 microsec, produces an elongated, pear-shaped cavitation bubble at the tip of the optical fiber that forms a vapor channel to conduct the ensuing laser energy to the target stone (Moss effect). The expansion and subsequent collapse of the elongated bubble is asymmetric, resulting in weak shockwave generation and microjet impingement. Thus, stone fragmentation in holmium laser lithotripsy is caused primarily by thermal ablation (drilling effect).

  14. Bulk cavitation extent modeling: An energy-based approach

    NASA Astrophysics Data System (ADS)

    Esplin, J. James

    Bulk cavitation is a phenomenon that occurs when a negative-pressure or tension wave causes a liquid to rupture, or cavitate, over space. It is a process which causes resident microbubbles to grow to many times their original size, forming a bubble cloud. Such bubble clouds are observed in shallow underwater explosions, where negative-pressure waves are formed after shock waves reflect off the water surface; they are also observed in shock wave lithotripsy, shock wave histotripsy, ultrasonic cleaning, and other applications. Models had been developed for predicting the size and shape of such bulk cavitation regions. This work introduces a model that accounts for energy "lost" to bulk cavitation which in turn influences the extent that is dependent on the rate at which the passing negative-pressure wave dissipates. In-laboratory underwater experiments utilizing a spark source for high-amplitude pressure pulse generation, hydrophones and high-speed videography validate the energy transfer from tension wave to bubble cloud formation. These experiments are supplemented by computational fluid dynamics simulations. A cavitation absorption coefficient is introduced and parameterized for accurate prediction of cloud extent.

  15. Cavitation microstreaming and material transport around microbubbles

    NASA Astrophysics Data System (ADS)

    Manasseh, Richard; Tho, Paul; Ooi, Andrew; Petkovic-Duran, Karolina; Zhu, Yonggang

    2010-01-01

    It has been suggested that cavitation microstreaming plays a role in the therapeutic action of microbubbles driven by ultrasound, such as the sonothrombolytic and sonoporative phenomena. Microscopic particle-image velocimetry experiments are presented, showing that many different microstreaming patterns are possible around a microbubble when it is on a surface. Each pattern is associated with a particular oscillation mode of the bubble and generates a different shear stress distribution. It was found that it is possible to change the flow pattern by changing the sound frequency. Microstreaming flows around bubbles could be responsible for mixing therapeutic agents into the surrounding blood, as well as assisting sonoporative delivery of molecules across cell membranes. Appropriate tuning of the driving frequency may benefit therapies.

  16. Cavitation damage in blood clots under HIFU

    NASA Astrophysics Data System (ADS)

    Weiss, Hope; Ahadi, Golnaz; Hoelscher, Thilo; Szeri, Andrew

    2010-11-01

    High Intensity Focused Ultrasound (HIFU) has been shown to accelerate thrombolysis, the dissolution of blood clots, in vitro and in vivo, for treatment of ischemic stroke. Cavitation in sonothrombolysis is thought to play an important role, although the mechanisms are not fully understood. The damage to a blood clot associated with bubble collapses in a HIFU field is studied. The region of damage caused by a bubble collapse on the fibrin network of the blood clot exposed to HIFU is estimated, and compared with experimental assessment of the damage. The mechanical damage to the network caused by a bubble is probed using two independent approaches, a strain based method and an energy based method. Immunoflourescent fibrin staining is used to assess the region of damage experimentally.

  17. Anti-tumor efficacy of ultrasonic cavitation is potentiated by concurrent delivery of anti-angiogenic drug in colon cancer.

    PubMed

    Zhang, Chao; Huang, Pintong; Zhang, Ying; Chen, Jian; Shentu, Weihui; Sun, Yu; Yang, Zhijian; Chen, Shuyuan

    2014-05-28

    This study investigated the efficacy of concurrent delivery of an anti-angiogenic drug and ultrasonic cavitation therapy in a mouse model of human colon cancer. A biotinylated form of the anti-angiogenic drug Endostar was conjugated to a streptavidin-coated microbubble (MB). Mice bearing subcutaneous tumors (HT29) were divided into 4 groups. Group 1 served as an untreated control. Group 2 served as a cavitation control and received naked microbubbles and sham ultrasonic cavitation (MB+sham cavitation). Group 3 received naked microbubbles and ultrasonic cavitation (MB+cavitation). Group 4 received Endostar loaded microbubbles and ultrasonic cavitation (Endostar-MB+cavitation). Ultrasonic cavitation was performed using a high-power custom built sonicator. Contrast-enhanced ultrasound imaging (CEUS) was used to measure tumor blood flow before and after ultrasonic cavitation. In vivo fluorescence imaging was performed to monitor changes in tumor volume. Immunohistochemistry was performed to assess CD31, VEGFR-2 and alpha-v beta-3 integrin expression within the tumor. Apoptosis of the tumor cells was determined by TUNEL assay, and ultrastructural changes within the tumor were examined by electron microcopy. Ultrasonic cavitation with Endostar-MB demonstrated a significantly greater inhibition of tumor blood flow on day 7 and tumor growth on day 16 compared with naked MB and control groups. The Endostar-MB treated mice showed significantly decreased expression VEGFR-2 and alpha-v beta-3 integrin, and increased apoptosis of tumor cells and degradation of the tumor ultrastructure. Our findings indicated that the anti-vascular and anti-tumor effects of ultrasonic cavitation could be potentiated by simultaneously delivering an anti-angiogenic drug in colon cancer.

  18. Acceleration of lithotripsy using cavitation bubbles induced by second-harmonic superimposition

    NASA Astrophysics Data System (ADS)

    Osuga, Masamizu; Yasuda, Jun; Jimbo, Hayato; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Shock wave lithotripsy potentially produces residual stone fragments too large to pass through ureters and significant injury to the normal tissue surrounding the stone. Previous works have shown that the collapse of cavitation bubbles induced by high-intensity focused ultrasound can produce small stone fragments via cavitation erosion. However, the erosion rate is hypothesized to be reduced by ultrasound attenuation by excessively generated bubble clouds. If so, it is important to generate the bubbles only on the stone surface. The effects of peak-negative-enhanced (PNE) and peak-positive-enhanced (PPE) waves obtained by second-harmonic superimposition were investigated to control cavitation bubbles. With the PNE waves, the bubbles were generated only on the stone surface and the maximum erosion rate was 232 ± 32 mg/min. All the fragments were smaller than 2 mm, which makes them pass through ureters naturally. The proposed method shows the potential to significantly improve the speed of lithotripsy.

  19. Reversible and irreversible vascular bioeffects induced by ultrasound and microbubbles in chorioallantoic membrane model

    NASA Astrophysics Data System (ADS)

    Tarapacki, Christine; Kuebler, Wolfgang M.; Tabuchi, Arata; Karshafian, Raffi

    2017-03-01

    Background: The application of ultrasound and microbubbles at therapeutic conditions has been shown to improve delivery of molecules, cause vasoconstriction, modulate blood flow and induce a vascular shut down in in vivo cancerous tissues. The underlying mechanism has been associated with the interaction of ultrasonically-induced microbubble oscillation and cavitation with the blood vessel wall. In this study, the effect of ultrasound and microbubbles on blood flow and vascular architecture was studied using a fertilized chicken egg CAM (chorioallantoic membrane) model. Methods: CAM at day 12 of incubation (Hamburger-Hamilton stage 38-40) were exposed to ultrasound at varying acoustic pressures (160, 240 and 320 kPa peak negative pressure) in the presence of Definity microbubbles and 70 kDa FITC dextran fluorescent molecules. A volume of 50 µL Definity microbubbles were injected into a large anterior vein of the CAM prior to ultrasound exposure. The ultrasound treatment sequence consisted of 5 s exposure at 500 kHz frequency, 8 cycles and 1 kHz pulse repetition frequency with 5 s off for a total exposure of 2 minutes. Fluorescent videos and images of the CAM vasculature were acquired using intravital microscopy prior, during and following the ultrasound exposure. Perfusion was quantified by measuring the length of capillaries in a region of interest using Adobe Illustrator. Results and Discussion: The vascular bioeffects induced by USMB increased with acoustic peak negative pressure. At 160 kPa, no visible differences were observed compared to the control. At 240 kPa, a transient decrease in perfusion with subsequent recovery within 15 minutes was observed, whereas at 320 kPa, the fluorescent images showed an irreversible vascular damage. The study indicates that a potential mechanism for the transient decrease in perfusion may be related to blood coagulation. The results suggest that ultrasound and microbubbles can induce reversible and irreversible vascular

  20. Evaluation of inertial cavitation activity in tissue through measurement of oxidative stress.

    PubMed

    Prieur, Fabrice; Pialoux, Vincent; Mestas, Jean-Louis; Mury, Pauline; Skinner, Sarah; Lafon, Cyril

    2015-09-01

    Ultrasound cavitation is an essential mechanism involved in the therapeutic local enhancement of drug delivery by ultrasound for cancer treatment. Inertial cavitation also triggers chemical reactions that generate free radicals and subsequent oxidative stress in the tissue. The aim of this study was to measure the oxidative stress induced by inertial cavitation in ex vivo tissue and to test the association between the exposure conditions and the oxidative stress. A confocal ultrasound setup was used to sonicate and create inertial cavitation in freshly excised adipose pig tissue. The ex vivo tissue samples were then processed to measure the quantity of malondialdehyde (MDA), an end-product of polyunsaturated free fatty acid oxidation. The creation of hydroxyterephthalic acid (HTA) from the reaction of terephthalic acid (TA) with free radicals in water was also quantified in vitro. Samples were sonicated for different durations using various amplitudes for the applied pressure. The results showed a minimum 2-fold increase in the amount of detected MDA in the sonicated tissue samples compared to baseline clearly suggesting the generation of free radicals by inertial cavitation. The method exhibited a moderate dependence of MDA generated upon the duration of exposure (R(2)=057,p<0.0001). The average increase in MDA concentration was approximately 2-fold, 5-fold, 6-fold, and 9-fold for exposure durations per unit of volume of 0.13, 0.17, 0.25, and 0.50s/mm(3), respectively. The results showed no statistically significant dependence on the amplitude of the pressure within the used range. Both pressure amplitude and exposure duration, however, influenced the HTA concentration (R(2)>0.95,p<0.0001). This biochemical method can be used on ex vivo tissue to detect the generation of free radicals induced by inertial cavitation. In large enough sample populations, the cavitation activity is linked to the exposure conditions of the sonication.

  1. Controlled effect of ultrasonic cavitation on hydrophobic/hydrophilic surfaces.

    PubMed

    Belova, Valentina; Gorin, Dmitry A; Shchukin, Dmitry G; Möhwald, Helmuth

    2011-02-01

    Controlling cavitation at the solid surface is of increasing interest, as it plays a major role in many physical and chemical processes related to the modification of solid surfaces and formation of multicomponent nanoparticles. Here, we show a selective control of ultrasonic cavitation on metal surfaces with different hydrophobicity. By applying a microcontact printing technique we successfully formed hydrophobic/hydrophilic alternating well-defined microstructures on aluminium surfaces. Fabrication of patterned surfaces provides the unique opportunity to verify a model of heterogeneous nucleation of cavitation bubbles near the solid/water interface by varying the wettability of the surface, temperature and ultrasonic power. At the initial stage of sonication (up to 30 min), microjets and shock waves resulting from the collapsing bubbles preferably impact the hydrophobic surface, whereas the hydrophilic areas of the patterned Al remain unchanged. Longer sonication periods affect both surfaces. These findings confirm the expectation that higher contact angle causes a lower energy barrier, thus cavitation dominates at the hydrophobic surfaces. Experimental results are in good agreement with expectations from nucleation theory. This paper illustrates a new approach to ultrasound induced modification of solid surfaces resulting in the formation of foam-structured metal surfaces.

  2. Quantitative assessment of reactive oxygen sonochemically generated by cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Miyashita, Takuya; Taguchi, Kei; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-07-01

    Acoustic cavitation bubbles can induce not only a thermal bioeffect but also a chemical bioeffect. When cavitation bubbles collapse and oscillate violently, they produce reactive oxygen species (ROS) that cause irreversible changes to the tissue. A sonosensitizer can promote such ROS generation. A treatment method using a sonosensitizer is called sonodynamic treatment. Rose bengal (RB) is one of the sonosensitizers whose in vivo and in vitro studies have been reported. In sonodynamic treatment, it is important to produce ROS at a high efficiency. For the efficient generation of ROS, a triggered high-intensity focused ultrasound (HIFU) sequence has been proposed. In this study, cavitation bubbles were generated in a chamber where RB solution was sealed, and a high-speed camera captured the behavior of these cavitation bubbles. The amount of ROS was also quantified by a potassium iodide (KI) method and compared with high-speed camera pictures to investigate the effectiveness of the triggered HIFU sequence. As a result, ROS could be obtained efficiently by this sequence.

  3. Cavitation-resistant inducer

    DOEpatents

    Dunn, Charlton; Subbaraman, Maria R.

    1989-01-01

    An improvement in an inducer for a pump wherein the inducer includes a hub, a plurality of radially extending substantially helical blades and a wall member extending about and encompassing an outer periphery of the blades. The improvement comprises forming adjacent pairs of blades and the hub to provide a substantially rectangular cross-sectional flow area which cross-sectional flow area decreases from the inlet end of the inducer to a discharge end of the inducer, resulting in increased inducer efficiency improved suction performance, reduced susceptibility to cavitation, reduced susceptibility to hub separation and reduced fabrication costs.

  4. Cavitation-resistant inducer

    DOEpatents

    Dunn, C.; Subbaraman, M.R.

    1989-06-13

    An improvement in an inducer for a pump is disclosed wherein the inducer includes a hub, a plurality of radially extending substantially helical blades and a wall member extending about and encompassing an outer periphery of the blades. The improvement comprises forming adjacent pairs of blades and the hub to provide a substantially rectangular cross-sectional flow area which cross-sectional flow area decreases from the inlet end of the inducer to a discharge end of the inducer, resulting in increased inducer efficiency improved suction performance, reduced susceptibility to cavitation, reduced susceptibility to hub separation and reduced fabrication costs. 11 figs.

  5. In vivo real-time cavitation imaging in moving organs

    NASA Astrophysics Data System (ADS)

    Arnal, B.; Baranger, J.; Demene, C.; Tanter, M.; Pernot, M.

    2017-02-01

    The stochastic nature of cavitation implies visualization of the cavitation cloud in real-time and in a discriminative manner for the safe use of focused ultrasound therapy. This visualization is sometimes possible with standard echography, but it strongly depends on the quality of the scanner, and is hindered by difficulty in discriminating from highly reflecting tissue signals in different organs. A specific approach would then permit clear validation of the cavitation position and activity. Detecting signals from a specific source with high sensitivity is a major problem in ultrasound imaging. Based on plane or diverging wave sonications, ultrafast ultrasonic imaging dramatically increases temporal resolution, and the larger amount of acquired data permits increased sensitivity in Doppler imaging. Here, we investigate a spatiotemporal singular value decomposition of ultrafast radiofrequency data to discriminate bubble clouds from tissue based on their different spatiotemporal motion and echogenicity during histotripsy. We introduce an automation to determine the parameters of this filtering. This method clearly outperforms standard temporal filtering techniques with a bubble to tissue contrast of at least 20 dB in vitro in a moving phantom and in vivo in porcine liver.

  6. Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

    PubMed Central

    Pflieger, Rachel; Chave, Tony; Virot, Matthieu; Nikitenko, Sergey I.

    2014-01-01

    The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects. PMID:24747272

  7. Activating molecules, ions, and solid particles with acoustic cavitation.

    PubMed

    Pflieger, Rachel; Chave, Tony; Virot, Matthieu; Nikitenko, Sergey I

    2014-04-11

    The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

  8. Ultrasound-Mediated Polymeric Micelle Drug Delivery.

    PubMed

    Xia, Hesheng; Zhao, Yue; Tong, Rui

    2016-01-01

    The synthesis of multi-functional nanocarriers and the design of new stimuli-responsive means are equally important for drug delivery. Ultrasound can be used as a remote, non-invasive and controllable trigger for the stimuli-responsive release of nanocarriers. Polymeric micelles are one kind of potential drug nanocarrier. By combining ultrasound and polymeric micelles, a new modality (i.e., ultrasound-mediated polymeric micelle drug delivery) has been developed and has recently received increasing attention. A major challenge remaining in developing ultrasound-responsive polymeric micelles is the improvement of the sensitivity or responsiveness of polymeric micelles to ultrasound. This chapter reviews the recent advance in this field. In order to understand the interaction mechanism between ultrasound stimulus and polymeric micelles, ultrasound effects, such as thermal effect, cavitation effect, ultrasound sonochemistry (including ultrasonic degradation, ultrasound-initiated polymerization, ultrasonic in-situ polymerization and ultrasound site-specific degradation), as well as basic micellar knowledge are introduced. Ultrasound-mediated polymeric micelle drug delivery has been classified into two main streams based on the different interaction mechanism between ultrasound and polymeric micelles; one is based on the ultrasound-induced physical disruption of the micelle and reversible release of payload. The other is based on micellar ultrasound mechanochemical disruption and irreversible release of payload.

  9. High-intensity focused ultrasound sonothrombolysis: the use of perfluorocarbon droplets to achieve clot lysis at reduced acoustic power.

    PubMed

    Pajek, Daniel; Burgess, Alison; Huang, Yuexi; Hynynen, Kullervo

    2014-09-01

    The purpose of this study was to evaluate use of intravascular perfluorocarbon droplets to reduce the sonication power required to achieve clot lysis with high-intensity focused ultrasound. High-intensity focused ultrasound with droplets was initially applied to blood clots in an in vitro flow apparatus, and inertial cavitation thresholds were determined. An embolic model for ischemic stroke was used to illustrate the feasibility of this technique in vivo. Recanalization with intravascular droplets was achieved in vivo at 24 ± 5% of the sonication power without droplets. Recanalization occurred in 71% of rabbits that received 1-ms pulsed sonications during continuous intravascular droplet infusion (p = 0.041 vs controls). Preliminary experiments indicated that damage was confined to the ultrasonic focus, suggesting that tolerable treatments would be possible with a more tightly focused hemispheric array that allows the whole focus to be placed inside of the main arteries in the human brain.

  10. Conformal drug delivery and instantaneous monitoring based on an inverse synthesis method at a diagnostic ultrasound platform

    NASA Astrophysics Data System (ADS)

    Xu, Shanshan; Zong, Yujin; Liu, Xiaodong; Lu, Mingzhu; Wan, Mingxi

    2017-03-01

    In this paper, based on a programmable diagnostic ultrasound scanner, a combined approach was proposed, in which a variable-sized focal region wherein the acoustic pressure is above the ultrasound contrast agents (UCA) fragmentation threshold is synthesized by reasonably matching the excitation voltage and the transmit aperture of the linear array at 5MHz, the UCAs' temporal and spatial distribution before and after the microbubbles fragmentation is monitored using the plane-wave transmission and reception at 400Hz and, simultaneously, the broadband noise emission during the microbubbles fragmentation is extracted using the backscattering of focused release bursts (destruction pulse) themselves on the linear array. Then, acquired radio frequency (RF) data are processed to draw parameters which can be correlated with the indicator of broadband noise emission level, namely inertial cavitation dose (ICD) and microbubble fragmentation efficiency, namely decay rate of microbubbles.

  11. Anticipatory model of cavitation

    NASA Astrophysics Data System (ADS)

    Kercel, Stephen W.; Allgood, Glenn O.; Dress, William B.; Hylton, James O.

    1999-03-01

    The Anticipatory System (AS) formalism developed by Robert Rosen provides some insight into the problem of embedding intelligent behavior in machines. AS emulates the anticipatory behavior of biological systems. AS bases its behavior on its expectations about the near future and those expectations are modified as the system gains experience. The expectation is based on an internal model that is drawn from an appeal to physical reality. To be adaptive, the model must be able to update itself. To be practical, the model must run faster than real-time. The need for a physical model and the requirement that the model execute at extreme speeds, has held back the application of AS to practical problems. Two recent advances make it possible to consider the use of AS for practical intelligent sensors. First, advances in transducer technology make it possible to obtain previously unavailable data from which a model can be derived. For example, acoustic emissions (AE) can be fed into a Bayesian system identifier that enables the separation of a weak characterizing signal, such as the signature of pump cavitation precursors, from a strong masking signal, such as a pump vibration feature. The second advance is the development of extremely fast, but inexpensive, digital signal processing hardware on which it is possible to run an adaptive Bayesian-derived model faster than real-time. This paper reports the investigation of an AS using a model of cavitation based on hydrodynamic principles and Bayesian analysis of data from high-performance AE sensors.

  12. Current Status in Cavitation Modeling

    NASA Technical Reports Server (NTRS)

    Singhal, Ashok K.; Avva, Ram K.

    1993-01-01

    Cavitation is a common problem for many engineering devices in which the main working fluid is in liquid state. In turbomachinery applications, cavitation generally occurs on the inlet side of pumps. The deleterious effects of cavitation include: lowered performance, load asymmetry, erosion and pitting of blade surfaces, vibration and noise, and reduction of the overall machine life. Cavitation models in use today range from rather crude approximations to sophisticated bubble dynamics models. Details about bubble inception, growth and collapse are relevant to the prediction of blade erosion, but are not necessary to predict the performance of pumps. An engineering model of cavitation is proposed to predict the extent of cavitation and performance. The vapor volume fraction is used as an indicator variable to quantify cavitation. A two-phase flow approach is employed with the assumption of the thermal equilibrium between liquid and vapor. At present velocity slip between the two phases is selected. Preliminary analyses of 2D flows shows qualitatively correct results.

  13. Nuclei and propeller cavitation inception

    SciTech Connect

    Gindroz, B.; Billet, M.L.

    1994-12-31

    Propeller cavitation inception tests were conducted in the Grand Tunnel Hydrodynamique (GTH) of the Bassin d`Essaid des Carenes. Both acoustic and visual cavitation inception were determined for leading-edge sheet, travelling bubble, and tip vortex. These data were obtained for specific water quality conditions. The water quality was determined from cavitation susceptibility meter measurements for degassed water (maximum liquid tension, few nuclei), low injection rate of microbubbles (medium liquid tension, low nuclei concentration), medium injection rate of microbubbles (medium liquid tension, high nuclei concentration) and high injection rate of microbubbles (minimum liquid tension, high nuclei concentration). Results clearly demonstrate a different influence of water quality for each type of cavitation. Little variation in cavitation inception index for a significant increase in liquid tension and microbubble size distribution was found for leading-edge sheet; however, tip vortex cavitation inception index decreased significantly for an increase in liquid tension. In addition, a dependency on event rate was determined for tip vortex cavitation inception.

  14. Bubble dynamics in high-amplitude ultrasound therapies

    NASA Astrophysics Data System (ADS)

    Johnsen, Eric; Mancia, Lauren

    2015-11-01

    Cavitation plays an important role in certain therapeutic ultrasound procedures, such as histotripsy in which megahertz pressure pulses are used to destroy tissue. The large tensions (> 25 MPa) nucleate bubbles in the tissue, which rapidly grow to radii on the order of hundreds of microns and subsequently collapse. To better understand potential cavitation-induced damage, we developed a numerical framework for spherical bubble dynamics in soft tissue that includes liquid compressibility and full thermal effects, as well as a comprehensive viscoelastic model with elasticity, relaxation, viscosity and various nonlinearities. This framework has enabled us to understand the effects of the viscoelastic and thermal properties of the tissue on the bubble dynamics, and compute stress and temperature fields in the surroundings. Results indicate that different viscoelastic properties affect the bubble dynamics differently, but that overall the viscoelastic nature of tissue produces larger stresses and increased heating on the surroundings, compared to bubble dynamics in purely viscous liquids. This work was supported by NSF grant number CBET 1253157 and NIH grant number 1R01HL110990-01A1.

  15. Study of cavitation bubble dynamics during Ho:YAG laser lithotripsy by high-speed camera

    NASA Astrophysics Data System (ADS)

    Zhang, Jian J.;