WorldWideScience

Sample records for focused ultrasound transducer

  1. Focused ultrasound transducer for thermal treatment.

    Science.gov (United States)

    Umemura, Shin-ichiro

    2015-03-01

    Air-backed transducers have been employed for thermal ultrasonic treatment including both ablation and hyperthermia because the power efficiency rather than the bandwidth is a main concern, unlike a typical imaging transducer working in a pulse mode. The characteristic of an air-backed piezoelectric transducer with a matching layer is analysed, and the role and choice of the matching layer is discussed. An element size of a focused array transducer, appropriate for such thermal treatment, is then estimated, and the characteristic of a piezoceramic transducer element of such a size was numerically analysed using a finite element code. The characteristic of a piezocomposite transducer element is also numerically analysed and its suitability to such a therapeutic array transducer is discussed.

  2. Focusing of ferroelectret air-coupled ultrasound transducers

    Science.gov (United States)

    Gaal, Mate; Bartusch, Jürgen; Dohse, Elmar; Schadow, Florian; Köppe, Enrico

    2016-02-01

    Air-coupled ultrasound has been applied increasingly as a non-destructive testing method for lightweight construction in recent years. It is particularly appropriate for composite materials being used in automotive and aviation industry. Air-coupled ultrasound transducers mostly consist of piezoelectric materials and matching layers. However, their fabrication is challenging and their signal-to-noise ratio often not sufficient for many testing requirements. To enhance the efficiency, air-coupled ultrasound transducers made of cellular polypropylene have been developed. Because of its small density and sound velocity, this piezoelectric ferroelectret matches the small acoustic impedance of air much better than matching layers applied in conventional transducers. In our contribution, we present two different methods of spherical focusing of ferroelectret transducers for the further enhancement of their performance in NDT applications. Measurements on carbon-fiber-reinforced polymer (CFRP) samples and on metal adhesive joints performed with commercially available focused air-coupled ultrasound transducers are compared to measurements executed with self-developed focused ferroelectret transducers.

  3. Oblong-Shaped-Focused Transducers for Intravascular Ultrasound Imaging.

    Science.gov (United States)

    Lee, Junsu; Jang, Jihun; Chang, Jin Ho

    2017-03-01

    In intravascular ultrasound (IVUS) imaging, a transducer is inserted into a blood vessel and rotated to obtain image data. For this purpose, the transducer aperture is typically less than 0.5 mm in diameter, which causes natural focusing to occur in the imaging depth ranging from 1 to 5 mm. Due to the small aperture, however, it is not viable to conduct geometric focusing in order to enhance the spatial resolution of IVUS images. Furthermore, this hampers narrowing the slice thickness of a cross-sectional scan plane in the imaging depth, which leads to lowering spatial and contrast resolutions of IVUS images. To solve this problem, we propose an oblong-shaped-focused transducer for IVUS imaging. Unlike the conventional IVUS transducers with either a circular or a square flat aperture, the proposed transducer has an oblong aperture of which long side is positioned along a blood vessel. This unique configuration makes it possible to conduct geometric focusing at a desired depth in the elevation direction. In this study, furthermore, it is demonstrated that a spherically shaped aperture in both lateral and elevation directions also improves lateral resolution, compared to the conventional flat aperture. To ascertain this, the conventional and the proposed IVUS transducers were designed and fabricated to evaluate and to compare their imaging performances through wire phantom and tissue-mimicking phantom experiments. For the proposed 50-MHz IVUS transducer, a PZT piece of 0.5 × 1.0 mm(2) was spherically shaped for elevation focus at 3 mm by using the conventional press-focusing technique whereas the conventional one has a flat aperture of 0.5 × 0.5 mm(2). The experimental results demonstrated that the proposed IVUS transducer is capable of improving spatial and contrast resolutions of IVUS images.

  4. Design and implementation of capacitive micromachined ultrasonic transducers for high intensity focused ultrasound

    OpenAIRE

    Yamaner, Yalçın Feysel; Yamaner, Yalcin Feysel

    2011-01-01

    High intensity focused ultrasound (HIFU) is a medical procedure for noninvasive treatment of cancers. High intensity focused ultrasound is used to heat and destroy the diseased tissue. Piezoelectricity has been the core mechanism for generation of ultrasound waves in the treatment. Focusing can be done by using spherically curved transducers or using a lens or electronically steering sound waves by using phased arrays. Current research in HIFU technology targets the development of MR-guided m...

  5. Experimental analysis of 1-3 piezocomposites for high-intensity focused ultrasound transducer applications.

    Science.gov (United States)

    Chen, Gin-Shin; Liu, Hsin-Chih; Lin, Yu-Cheng; Lin, Yu-Li

    2013-01-01

    Piezocomposites with 1-3 connectivity have been extensively used in medical imaging transducers and high-intensity focused ultrasound transducers, but most studies of 1-3 piezocomposites address medical imaging applications. The purpose of this study was to completely investigate 1-3 composites specifically for high-power ultrasonic transducer applications via a series of experimental analyses. PZT4-epoxy composite focused transducers with various aspect ratios and volume fractions were constructed in-house for the evaluation of the coupling factor, dielectric loss tangent, quality factor, bandwidth, acoustic impedance, and electroacoustic efficiency. The experimental analyses demonstrated that although the coupling factor of composite transducers was higher than that of the ceramic transducer, the composite transducers had a lower efficiency due to the high dielectric loss and high mechanical energy loss of the composites. In addition, the bandwidth and acoustic impedance of composite transducers were superior to the ceramic transducer. For the composite transducers, the efficiency and acoustic impedance were inversely proportional to the aspect ratio and linearly proportional to the volume fraction. The coupling of inter pillars that are too close to each other could cause a significant decrease in the efficiency of the composite transducer. With an appropriate design in terms of the aspect ratio, volume fraction, and PZT-pillar spacing, a high-efficiency composite high-intensity focused ultrasound transducer can be achieved.

  6. Modeling of ultrasound transducers

    DEFF Research Database (Denmark)

    Bæk, David

    deviation of 5.5 % to 11.0 %. Finite element modeling of piezoceramics in combination with Field II is addressed and reveals the influence of restricting the modeling of transducers to the one-dimensional case. An investigation on modeling capacitive micromachined ultrasonic transducers (CMUT)s with Field......This Ph.D. dissertation addresses ultrasound transducer modeling for medical ultrasound imaging and combines the modeling with the ultrasound simulation program Field II. The project firstly presents two new models for spatial impulse responses (SIR)s to a rectangular elevation focused transducer...... II is addressed. It is shown how a single circular CMUT cell can be well approximated with a simple square transducer encapsulating the cell, and how this influence the modeling of full array elements. An optimal cell discretization with Field II’s mathematical elements is addressed as well...

  7. DUAL-FOCUS THERAPEUTIC ULTRASOUND TRANSDUCER FOR PRODUCTION OF BROAD TISSUE LESIONS

    Science.gov (United States)

    Jeong, Jong Seob; Cannata, Jonathan M.; Shung, K. Kirk

    2011-01-01

    In noninvasive high-intensity focused ultrasound (HIFU) treatment, formation of a large tissue lesion per sonication is desirable for reducing the overall treatment time. The goal of this study is to show the feasibility of enlarging tissue lesion size with a dual-focus therapeutic ultrasound transducer (DFTUT) by increasing the depth-of-focus (DOF). The proposed transducer consists of a disc- and an annular-type element of different radii of curvatures to produce two focal zones. To increase focal depth and to maintain uniform beamwidth of the elongated DOF, each element transmits ultrasound of a different center frequency: the inner element at a higher frequency for near field focusing and the outer element at a lower frequency for far field focusing. By activating two elements at the same time with a single transmitter capable of generating a dual-frequency mixed signal, the overall DOF of the proposed transducer may be extended considerably. A prototype transducer composed of a 4.1 MHz inner element and a 2.7 MHz outer element was fabricated to obtain preliminary experimental results. The feasibility the proposed technique was demonstrated through sound field, temperature and thermal dose simulations. The performance of the prototype transducer was verified by hydrophone measurements and tissue ablation experiments on a beef liver specimen. When several factors affecting the length and the uniformity of elongated DOF of the DFTUT are optimized, the proposed therapeutic ultrasound transducer design may increase the size of ablated tissues in the axial direction and, thus, decreasing the treatment time for a large volume of malignant tissues especially deep-seated targets. PMID:20870346

  8. Angled-focused 45 MHz PMN-PT single element transducer for intravascular ultrasound imaging.

    Science.gov (United States)

    Yoon, Sangpil; Williams, Jay; Kang, Bong Jin; Yoon, Changhan; Cabrera-Munoz, Nestor; Jeong, Jong Seob; Lee, Sang Goo; Shung, K Kirk; Kim, Hyung Ham

    2015-06-01

    A transducer with an angled and focused aperture for intravascular ultrasound imaging has been developed. The acoustic stack for the angled-focused transducer was made of PMN-PT single crystal with one matching layer, one protective coating layer, and a highly damped backing layer. It was then press-focused to a desired focal length and inserted into a thin needle housing with an angled tip. A transducer with an angled and unfocused aperture was also made, following the same fabrication procedure, to compare the performance of the two transducers. The focused and unfocused transducers were tested to measure their center frequencies, bandwidths, and spatial resolutions. Lateral resolution of the angled-focused transducer (AFT) improved more than two times compared to that of the angled-unfocused transducer (AUT). A tissue-mimicking phantom in water and a rabbit aorta tissue sample in rabbit blood were scanned using AFT and AUT. Imaging with AFT offered improved contrast, over imaging with AUT, of the tissue-mimicking phantom and the rabbit aorta tissue sample by 23 dB and 8 dB, respectively. The results show that AFT has strong potential to provide morphological and pathological information of coronary arteries with high resolution and high contrast.

  9. Single-element focused ultrasound transducer method for harmonic motion imaging.

    Science.gov (United States)

    Maleke, Caroline; Pernot, Mathieu; Konofagou, Elisa E

    2006-07-01

    The harmonic motion imaging (HMI) technique for simultaneous monitoring and generation of ultrasound therapy using two separate focused ultrasound transducer elements was previously demonstrated. In this study, a new HMI technique is described that images tissue displacement induced by a harmonic radiation force using a single focused-ultrasound element. A wave propagation simulation model first indicated that, unlike in the two-beam configuration, the amplitude-modulated beam produced a stable focal zone for the applied harmonic radiation force. The AM beam thus offered the unique advantage of sustaining the application of the spatially-invariant radiation force. Experiments were performed on gelatin phantoms and ex vivo tissues. The radiation force was generated by a 4.68 MHz focused ultrasound (FUS) transducer using a 50 Hz amplitude-modulated wave. A 7.5 MHz pulse-echo transducer was used to acquire rf echoes during the application of the harmonic radiation force. Consecutive rf echoes were acquired with a pulse repetition frequency (PRF) of 6.5 kHz and 1D cross-correlation was performed to estimate the resulting axial tissue displacement. The HMI technique was shown capable of estimating stiffness-dependent displacement amplitudes. Finally, taking advantage of the real-time capability of the HMI technique, temperature-dependent measurements enabled monitoring ofHIFU sonication in ex vivo tissues. The new HMI method may thus enable a highly-localized force and stiffness-dependent measurements as well as real-time and low-cost HIFU monitoring.

  10. Numerical simulation of ultrasound thermotherapy of brain with a scanned focus transducer

    Science.gov (United States)

    Behnia, Sohrab; Ghalichi, Farzan; Jafari, Amin; Bonabi, Ashkan

    2005-04-01

    Brain tumors are one of the most difficult ones to treat. The margin between destruction of the tumor and damage to the surrounding tissue is narrow in the brain. Ultrasound could be an effective treatment because of its ability to propagate deep in tissue and induce temperature rise at the focus while leaving the surrounding tissue intact. This study investigates whether using a fix-focus transducer could destroy brain tumor cells, in a cost effective manner which reduces the treatment time significantly. In this work an appropriate fix-focus transducer was designed considering effective parameters and limitations which are dominant in this case. Then a real 2-D brain model was constructed from a MR image. A piece of the skull bone has been removed to allow ultrasound to propagate into the brain. The resultant pressure field and the temperature rise were calculated by Rayleigh integral and bio-heat equation on the model. The obtained results were promising indicating that toxic temperatures could be obtained in short treatment times. This could be of great advantage especially in treating primary brain tumors.

  11. Photoacoustic tomography with a high lateral resolution and a large field of view using a rectangular focused ultrasound transducer

    Science.gov (United States)

    Zhang, Shangyu; Cheng, Renxiang; Tao, Chao; Liu, Xiaojun

    2016-04-01

    The enlargement of the field of view (FOV) of a photoacoustic (PA) tomography (PAT) system and the improvement of its lateral resolution are often two conflicting goals. A rectangular focused transducer is proposed to solve this problem. An asymmetric geometry of the transducer results in its asymmetric characteristics of the ultrasound (US) field. Both simulation and experiments confirm that the rectangular focused transducer can improve the FOV and lateral resolution of PAT systems simultaneously. The US transducer proposed in this study has the potential to improve the performance of a PAT system for practical biomedical applications.

  12. Evaluation of a novel therapeutic focused ultrasound transducer based on Fermat’s spiral

    Science.gov (United States)

    Ramaekers, P.; de Greef, M.; Berriet, R.; Moonen, C. T. W.; Ries, M.

    2017-06-01

    The purpose of this study was to evaluate a novel phased array transducer design rule for therapeutic focused ultrasound applications. This design rule uses the discretized Fermat’s spiral to determine the positioning of the transducer elements for a given number of elements and f-number. Using this principle, three variations of Fermat’s spiral were generated, aimed at (1) grating lobe minimization, (2) side lobe minimization, and (3) an optimized element packing efficiency. For each spiral, sparse layouts using identical circular elements and fully populated layouts based on additional Voronoi tessellation were evaluated numerically. Evaluation criteria included the element size distribution, beam steering capabilities, focal plane pressure distribution, prefocal pressure distribution, and practical considerations. Finally, one Voronoi-tessellated design with a focal length and aperture diameter of 16 cm and a natural frequency of 1.3 MHz was evaluated experimentally through hydrophone measurements. The numerical evaluation showed that while sparse arrays possess superior beam steering capabilities for a given number of elements, the focal point quality and prefocal pressure distribution is substantially more favorable when using the Voronoi-tessellated designs. Beam steering was shown to be feasible with the tessellated designs for lateral deflections up to 10 mm and axial deflections up to 20 mm. The experimental evaluation showed that such a transducer is capable of inducing 40.00 MPa rarefactional and 237.50 MPa compressional peak pressure levels at 800 W instantaneous acoustic output power under free-field conditions, making the system potentially relevant for thermal ablation therapy, histotripsy applications, and shockwave-enhanced heating.

  13. Photoacoustic Tomography Imaging of the Adult Zebrafish by Using Unfocused and Focused High-Frequency Ultrasound Transducers

    Directory of Open Access Journals (Sweden)

    Yubin Liu

    2016-11-01

    Full Text Available The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based on available optical imaging techniques. In this study, photoacoustic tomography (PAT was utilized for high-resolution imaging of adult zebrafish by using focused and unfocused high-frequency (10 MHz ultrasound transducers. We examined and compared the imaging results from the two categories of transducers with in vivo experimental tests, in which we discovered that the unfocused transducer is able to identify the inner organs of adult zebrafish with higher contrast but limited regional resolution, whereas the findings from the focused transducer were with high resolution but limited regional contrast for the recovered inner organs.

  14. Monitoring of high-intensity focused ultrasound treatment by shear wave elastography induced by two-dimensional-array therapeutic transducer

    Science.gov (United States)

    Iwasaki, Ryosuke; Takagi, Ryo; Nagaoka, Ryo; Jimbo, Hayato; Yoshizawa, Shin; Saijo, Yoshifumi; Umemura, Shin-ichiro

    2016-07-01

    Shear wave elastography (SWE) is expected to be a noninvasive monitoring method of high-intensity focused ultrasound (HIFU) treatment. However, conventional SWE techniques encounter difficulty in inducing shear waves with adequate displacements in deep tissue. To observe tissue coagulation at the HIFU focal depth via SWE, in this study, we propose using a two-dimensional-array therapeutic transducer for not only HIFU exposure but also creating shear sources. The results show that the reconstructed shear wave velocity maps detected the coagulated regions as the area of increased propagation velocity even in deep tissue. This suggests that “HIFU-push” shear elastography is a promising solution for the purpose of coagulation monitoring in deep tissue, because push beams irradiated by the HIFU transducer can naturally reach as deep as the tissue to be coagulated by the same transducer.

  15. Setting boundary conditions on the Khokhlov-Zabolotskaya equation for modeling ultrasound fields generated by strongly focused transducers

    Science.gov (United States)

    Rosnitskiy, P. B.; Yuldashev, P. V.; Vysokanov, B. A.; Khokhlova, V. A.

    2016-03-01

    An equivalent source model is developed for setting boundary conditions on the parabolic diffraction equation in order to simulate ultrasound fields radiated by strongly focused medical transducers. The equivalent source is defined in a plane; corresponding boundary conditions for pressure amplitude, aperture, and focal distance are chosen so that the axial solution to the parabolic model in the focal region of the beam matches the solution to the full diffraction model (Rayleigh integral) for a spherically curved uniformly vibrating source. It is shown that the proposed approach to transferring the boundary condition from a spherical surface to a plane makes it possible to match the solutions over an interval of several diffraction maxima around the focus even for focused sources with F-numbers less than unity. This method can be used to accurately simulate nonlinear effects in the fields of strongly focused therapeutic transducers using the parabolic Khokhlov-Zabolotskaya equation.

  16. Focused ultrasound in ophthalmology

    Directory of Open Access Journals (Sweden)

    Silverman RH

    2016-09-01

    Full Text Available Ronald H Silverman1,2 1Department of Ophthalmology, Columbia University Medical Center, 2F.L. Lizzi Center for Biomedical Engineering, Riverside Research, New York, NY, USA Abstract: The use of focused ultrasound to obtain diagnostically significant information about the eye goes back to the 1950s. This review describes the historical and technological development of ophthalmic ultrasound and its clinical application and impact. Ultrasound, like light, can be focused, which is crucial for formation of high-resolution, diagnostically useful images. Focused, single-element, mechanically scanned transducers are most common in ophthalmology. Specially designed transducers have been used to generate focused, high-intensity ultrasound that through thermal effects has been used to treat glaucoma (via cilio-destruction, tumors, and other pathologies. Linear and annular transducer arrays offer synthetic focusing in which precise timing of the excitation of independently addressable array elements allows formation of a converging wavefront to create a focus at one or more programmable depths. Most recently, linear array-based plane-wave ultrasound, in which the array emits an unfocused wavefront and focusing is performed solely on received data, has been demonstrated for imaging ocular anatomy and blood flow. While the history of ophthalmic ultrasound extends back over half-a-century, new and powerful technologic advances continue to be made, offering the prospect of novel diagnostic capabilities. Keywords: ophthalmic ultrasound, ultrasound biomicroscopy (UBM, high-intensity focused ultrasound (HIFU, ultrafast imaging, Doppler imaging 

  17. Ultrasound transducer assembly and method for manufacturing an ultrasound transducer assembly

    NARCIS (Netherlands)

    Dekker, R.; Henneken, V.A.; Louwerse, M.C.; Raganato, M.F.

    2015-01-01

    The present invention relates to an ultrasound transducer assembly (10), in particular for intravascular ultrasound systems. The ultrasound transducer assembly comprises at least one silicon substrate element (30) including an ultrasound transducer element (14) for emitting and receiving ultrasound

  18. Ultrasound transducer assembly and method for manufacturing an ultrasound transducer assembly

    NARCIS (Netherlands)

    Dekker, R.; Henneken, V.A.; Louwerse, M.C.; Raganato, M.F.

    2015-01-01

    The present invention relates to an ultrasound transducer assembly (10), in particular for intravascular ultrasound systems. The ultrasound transducer assembly comprises at least one silicon substrate element (30) including an ultrasound transducer element (14) for emitting and receiving ultrasound

  19. Reflection-mode photoacoustic microscopy using a hollow focused ultrasound transducer for in vivo imaging of blood vessels

    Institute of Scientific and Technical Information of China (English)

    Yuan Yi; Yang Si-Hua

    2012-01-01

    A reflection-mode photoacoustic microscope using a hollow focused ultrasound transducer is developed for highresolution in vivo imaging.A confocal structure of the laser and the ultrasound is used to improve the system resolution.The axial and lateral resolutions of the system are measured to be~32 μm and~58 μm,respectively.Ex vivo and in vivo modes are tested to validate the imaging capability of the photoacoustic microscope.The adjacent vein and artery can be seen clearly from the reconstructed photoacoustic images.The results demonstrate that the reflectionmode photoacoustic microscope can be used for high-resolution imaging of micro-blood vessels,which would be of great benefit for monitoring the neovascularization in tumor angiogenesis.

  20. Micromachined Integrated Transducers for Ultrasound Imaging

    DEFF Research Database (Denmark)

    la Cour, Mette Funding

    The purpose of this project is to develop capacitive micromachined ultrasonic transducers (CMUTs) for medical imaging. Medical ultrasound transducers used today are fabricated using piezoelectric materials and bulk processing. To fabricate transducers capable of delivering a higher imaging...... project and collaboration with a lot of partners to improve medical ultrasound imaging. The focus in this part of the project is to design, fabricate and characterize 1D CMUT arrays. Two versions of 1D transducers are made, one at Stanford University and one at DTU. Electrical and acoustical...... resolution it is however necessary to develop new fabrication methods that allows fabrication of transducer elements with smaller dimensions. By using microfabrication technology it is possible to push the dimensions down and provide higher design flexibility. This project is part of a large ultrasound...

  1. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    Science.gov (United States)

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement.

  2. Stress wave focusing transducers

    Energy Technology Data Exchange (ETDEWEB)

    Visuri, S.R., LLNL

    1998-05-15

    Conversion of laser radiation to mechanical energy is the fundamental process behind many medical laser procedures, particularly those involving tissue destruction and removal. Stress waves can be generated with laser radiation in several ways: creation of a plasma and subsequent launch of a shock wave, thermoelastic expansion of the target tissue, vapor bubble collapse, and ablation recoil. Thermoelastic generation of stress waves generally requires short laser pulse durations and high energy density. Thermoelastic stress waves can be formed when the laser pulse duration is shorter than the acoustic transit time of the material: {tau}{sub c} = d/c{sub s} where d = absorption depth or spot diameter, whichever is smaller, and c{sub s} = sound speed in the material. The stress wave due to thermoelastic expansion travels at the sound speed (approximately 1500 m/s in tissue) and leaves the site of irradiation well before subsequent thermal events can be initiated. These stress waves, often evolving into shock waves, can be used to disrupt tissue. Shock waves are used in ophthalmology to perform intraocular microsurgery and photodisruptive procedures as well as in lithotripsy to fragment stones. We have explored a variety of transducers that can efficiently convert optical to mechanical energy. One such class of transducers allows a shock wave to be focused within a material such that the stress magnitude can be greatly increased compared to conventional geometries. Some transducer tips could be made to operate regardless of the absorption properties of the ambient media. The size and nature of the devices enable easy delivery, potentially minimally-invasive procedures, and precise tissue- targeting while limiting thermal loading. The transducer tips may have applications in lithotripsy, ophthalmology, drug delivery, and cardiology.

  3. Heart ablation using a planar rectangular high intensity focused ultrasound transducer and MRI guidance

    Science.gov (United States)

    Couppis, Andreas; Damianou, Christakis; Ioannides, Kleanthis; Mylonas, Nicos; Iosif, Demitris; Kyriakou, Panagiotis; Lafon, Cyril; Chavrier, Francoise; Chapelon, Jean-Yves; Birer, Alain

    2011-09-01

    The aim of this study was to evaluate the performance of a flat rectangular (3×10 mm2) MRI compatible transducer operating at 5 MHz in creating deep lesions in heart at a depth of at least 15 mm. The size of thermal necrosis in heart tissue was estimated as a function of power and time using a simulation model. The system was then tested in freshly excised heart of pig and lamb. In this study we were able to create lesions 15 mm deep with an acoustic power of 6W for an exposure of approximately one minute. The contrast to noise ratio (CNR) between lesion and heart tissue was evaluated using Fast Spin Echo (FSE). With T1W FSE the CNR value was approximately 22. Maximum CNR was achieved with repetition times (TR) between 300 and 800 ms. With T2W FSE the corresponding CNR was approximately 13. The transducer was tested in rabbits in vivo and despite the motion of the heart; it was possible to create thermal lesions.

  4. Transducer for harmonic intravascular ultrasound imaging

    NARCIS (Netherlands)

    Vos, Hendrik J.; Frijlink, Martijn E.; Droog, E.J.; Goertz, David E.; Blacquiere, Gerrit; Gisolf, Anton; de Jong, N.; van der Steen, Antonius F.W.

    2005-01-01

    A recent study has shown the feasibility of tissue harmonic imaging (THI) using an intravascular ultrasound (IVUS) transducer. This correspondence describes the design, fabrication, and characterization of a THI-optimized piezoelectric transducer with oval aperture of 0.75 mm by 1 mm. The transducer

  5. New piezoelectric transducers for therapeutic ultrasound.

    Science.gov (United States)

    Chapelon, J Y; Cathignol, D; Cain, C; Ebbini, E; Kluiwstra, J U; Sapozhnikov, O A; Fleury, G; Berriet, R; Chupin, L; Guey, J L

    2000-01-01

    Therapeutic ultrasound (US) has been of increasing interest during the past few years. However, the development of this technique depends on the availability of high-performance transducers. These transducers have to be optimised for focusing and steering high-power ultrasonic energy within the target volume. Recently developed high-power 1-3 piezocomposite materials bring to therapeutic US the exceptional electroacoustical properties of piezocomposite technology: these are high efficiency, large bandwidth, predictable beam pattern, more flexibility in terms of shaping and definition of sampling in annular arrays, linear arrays or matrix arrays. The construction and evaluation of several prototypes illustrates the benefit of this new approach that opens the way to further progress in therapeutic US.

  6. Glass-windowed ultrasound transducers.

    Science.gov (United States)

    Yddal, Tostein; Gilja, Odd Helge; Cochran, Sandy; Postema, Michiel; Kotopoulis, Spiros

    2016-05-01

    In research and industrial processes, it is increasingly common practice to combine multiple measurement modalities. Nevertheless, experimental tools that allow the co-linear combination of optical and ultrasonic transmission have rarely been reported. The aim of this study was to develop and characterise a water-matched ultrasound transducer architecture using standard components, with a central optical window larger than 10 mm in diameter allowing for optical transmission. The window can be used to place illumination or imaging apparatus such as light guides, miniature cameras, or microscope objectives, simplifying experimental setups. Four design variations of a basic architecture were fabricated and characterised with the objective to assess whether the variations influence the acoustic output. The basic architecture consisted of a piezoelectric ring and a glass disc, with an aluminium casing. The designs differed in piezoelectric element dimensions: inner diameter, ID=10 mm, outer diameter, OD=25 mm, thickness, TH=4 mm or ID=20 mm, OD=40 mm, TH=5 mm; glass disc dimensions OD=20-50 mm, TH=2-4 mm; and details of assembly. The transducers' frequency responses were characterised using electrical impedance spectroscopy and pulse-echo measurements, the acoustic propagation pattern using acoustic pressure field scans, the acoustic power output using radiation force balance measurements, and the acoustic pressure using a needle hydrophone. Depending on the design and piezoelectric element dimensions, the resonance frequency was in the range 350-630 kHz, the -6 dB bandwidth was in the range 87-97%, acoustic output power exceeded 1 W, and acoustic pressure exceeded 1 MPa peak-to-peak. 3D stress simulations were performed to predict the isostatic pressure required to induce material failure and 4D acoustic simulations. The pressure simulations indicated that specific design variations could sustain isostatic pressures up to 4.8 MPa.The acoustic simulations were able to

  7. Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers

    Science.gov (United States)

    Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

    2016-04-01

    Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a

  8. Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers.

    Science.gov (United States)

    Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

    2016-04-07

    Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a

  9. Ultrasound transducer selection in clinical imaging practice.

    Science.gov (United States)

    Szabo, Thomas L; Lewin, Peter A

    2013-04-01

    Many types of medical ultrasound transducers are used in clinical practice. They operate at different center frequencies, have different physical dimensions, footprints, and shapes, and provide different image formats. However, little information is available about which transducers are most appropriate for a given application, and the purpose of this article is to address this deficiency. Specifically, the relationship between the transducer, imaging format, and clinical applications is discussed, and systematic selection criteria that allow matching of transducers to specific clinical needs are presented. These criteria include access to and coverage of the region of interest, maximum scan depth, and coverage of essential diagnostic modes required to optimize a patient's diagnosis. Three comprehensive figures organize and summarize the imaging planes, scanning modes, and types of diagnostic transducers to facilitate their selection in clinical diagnosis.

  10. Design considerations for piezoelectric polymer ultrasound transducers.

    Science.gov (United States)

    Brown, L F

    2000-01-01

    Much work has been published on the design of ultrasound transducers using piezoelectric ceramics, but a great deal of this work does not apply when using the piezoelectric polymers because of their unique electrical and mechanical properties. The purpose of this paper is to review and present new insight into seven important considerations for the design of active piezoelectric polymer ultrasound transducers: piezoelectric polymer materials selection, transducer construction and packaging requirements, materials characterization and modeling, film thickness and active area design, electroding selection, backing material design, and front protection/matching layer design. Besides reviewing these design considerations, this paper also presents new insight into the design of active piezoelectric polymer ultrasonic transducers. The design and fabrication of an immersible ultrasonic transducer, which has no adhesive layer between the active element and backing layer, is included. The transducer features direct deposition of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer onto an insulated aluminum backing substrate. Pulse-echo tests indicated a minimum insertion loss of 37 dB and -6 dB bandwidth of 9.8 to 22 MHz (71%). The use of polymer wear-protection/quarter-wave matching layers is also discussed. Test results on a P(VDF-TrFE) transducer showed that a Mylar/sup TM/ front layer provided a slight increase in pulse-echo amplitude of 15% (or 1.2 dB) and an increase in -6 dB pulse-echo fractional bandwidth from 86 to 95%. Theoretical derivations are reported for optimizing the active area of the piezoelectric polymer element for maximum power transfer at resonance. These derivations are extended to the special case for a low profile (i.e., thin) shielded transducer. A method for modeling the non-linear loading effects of a commercial pulser-receiver is also included.

  11. Current Research Situation of High-intensity Focused Ultrasound Transducer for Oncotherapy%肿瘤治疗用高强度聚焦超声换能器的研究现状

    Institute of Scientific and Technical Information of China (English)

    刘刚; 尹军刚

    2012-01-01

    高强度聚集超声(High-intensity Focused Ultrasound,HIFU)作为一种非侵入性、无毒副作用、具有巨大潜力的肿瘤治疗手段,近年来已经越来越受到国内外学者的广泛关注.高强度聚焦超声换能器是HIFU肿瘤治疗设备的核心部件,直接影响治疗的效果.因此,本文就其发展过程、治疗机制及应用等相关问题做一综述.%As non-invasive technique with non-toxic side effects and great potential, high-intensity focused ultrasound(HIFU) has received widespread attention from scholars both at home and abroad in recent years. Higb- intensity focused ultrasound transducer is the core component of HIFU treatment equipment for oncotherapy, which chould affect the therapeutical result directly. Therefore, this paper summarizes some related issues of high-intensity focused ultrasound transducer, including its development, working principle, applications and so on.

  12. Spatial filters for focusing ultrasound images

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gori, Paola

    2001-01-01

    . A new method for making spatial matched filter focusing of RF ultrasound data is proposed based on the spatial impulse response description of the imaging. The response from a scatterer at any given point in space relative to the transducer can be calculated, and this gives the spatial matched filter...

  13. Ultrasonic transducer chip assembly, ultrasound probe, ultrasonic imaging system and ultrasound assembly and probe manufacturing methods

    NARCIS (Netherlands)

    Weekamp, J.W.; Henneken, V.A.; Groenland, A.W.; Louwerse, M.C.

    2015-01-01

    Disclosed is an ultrasonic transducer assembly comprising an ultrasonic transducer chip (100) having a main surface comprising a plurality of ultrasound transducer elements (112) and a plurality of first contacts (120) for connecting to said ultrasound transducer elements; a contact chip (400) havin

  14. Micromachined capacitive transducer arrays for intravascular ultrasound

    Science.gov (United States)

    Degertekin, F. Levent; Guldiken, R. Oytun; Karaman, Mustafa

    2005-01-01

    Intravascular ultrasound (IVUS) imaging has become an essential imaging modality for the effective diagnosis and treatment of cardiovascular diseases during the past decade enabled by innovative applications of piezoelectric transducer technology. The limitations in the manufacture and performance of the same piezoelectric transducers have also impeded the improvement of IVUS for emerging clinically important applications such as forward viewing arrays for guiding interventions and high resolution imaging of arterial structure such as vulnerable plaque and fibrous cap, and also implementation of techniques such as harmonic imaging of the tissue and of the contrast agents. Capacitive micromachined ultrasonic transducer (CMUT) technology shows great potential for transforming IVUS not only to satisfy these clinical needs but also to open up possibilities for low-cost imaging devices integrated to therapeutic tools. We have developed manufacturing processes with a maximum process temperature of 250°C to build CMUTs on the same silicon chip with integrated electronics. Using these processes we fabricated CMUT arrays suitable for forward viewing IVUS in the 10-20MHz range. We characterized these array elements in terms of pulse-echo response, radiation pattern measurements and demonstrated its volumetric imaging capabilities on various imaging targets.

  15. High intensity ultrasound transducer used in gene transfection

    Science.gov (United States)

    Morrison, Kyle P.; Keilman, George W.; Noble, Misty L.; Brayman, Andrew A.; Miao, Carol H.

    2012-11-01

    This paper describes a novel therapeutic high intensity non-focused ultrasound (HIU) transducer designed with uniform pressure distribution to aid in accelerated gene transfer in large animal liver tissues in vivo. The underlying HIU transducer was used to initiate homogeneous cavitation throughout the tissue while delivering up to 2.7 MPa at 1.1 MHz across its radiating surface. The HIU transducer was built into a 6 cm diameter x 1.3 cm tall housing ergonomically designed to avoid collateral damage to the surrounding anatomy during dynamic motion. The ultrasound (US) radiation was applied in a 'paintbrush-like' manner to the surface of the liver. The layers and geometry of the transducer were carefully selected to maximize the active diameter (5.74 cm), maximize the electrical to acoustic conversion efficiency (85%) to achieve 2.7 MPa of peak negative pressure, maximize the frequency operating band at the fundamental resonance to within a power transfer delta of 1 dB, and reduce the pressure delta to within 2 dB across the radiating surface. For maximum peak voltage into the transducer, a high performance piezoceramic was chosen and a DC bias circuit was built integral to the system. An apodized two element annular pattern was made from a single piezoceramic element, resulting in significant pressure uniformity enhancement. In addition to using apodization for pressure uniformity, a proprietary multi-layered structure was used to improve efficiency while sustaining an operating band from 900 kHz to 1.3 MHz. The resultant operating band allowed for dithering techniques using frequency modulation. The underlying HIU transducer for use in large animals enhances gene expression up to 6300-fold.

  16. PMN-PT single crystal focusing transducer fabricated using a mechanical dimpling technique.

    Science.gov (United States)

    Lam, K H; Chen, Y; Cheung, K F; Dai, J Y

    2012-01-01

    A ∼5MHz focusing PMN-PT single crystal ultrasound transducer has been fabricated utilizing a mechanical dimpling technique, where the dimpled crystal wafer was used as an active element of the focusing transducer. For the dimpled focusing transducer, the effective electromechanical coupling coefficient was enhanced significantly from 0.42 to 0.56. The dimpled transducer also yields a -6dB bandwidth of 63.5% which is almost double the bandwidth of the plane transducer. An insertion loss of the dimpled transducer (-18.1dB) is much lower than that of the plane transducer. Finite element simulation also reveals specific focused beam from concave crystal surface. These promising results show that the dimpling technique can be used to develop high-resolution focusing single crystal transducers.

  17. Transducer models in the ultrasound simulation program FIELD II and their accuracy

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Bæk, David

    2010-01-01

    The FIELD II simulation program can be used for simulating any kind of linear ultrasound fields. The program is capable of describing multi-element transducers used with any kind of excitation, apodization, and focusing. The program has been widely used in both academia and by commercial ultrasound...... companies for investigation novel transducer geometries and advanced linear imaging schemes. The program models transducer geometries using a division of the transducer elements into either rectangles, triangles, or bounding lines. The precision of the simulation and the simulation time is intimately linked...

  18. Multilayer Array Transducer for Nonlinear Ultrasound Imaging

    Science.gov (United States)

    Owen, Neil R.; Kaczkowski, Peter J.; Li, Tong; Gross, Dan; Postlewait, Steven M.; Curra, Francesco P.

    2011-09-01

    The properties of nonlinear acoustic wave propagation are known to be able to improve the resolution of ultrasound imaging, and could be used to dynamically estimate the physical properties of tissue. However, transducers capable of launching a wave that becomes nonlinear through propagation do not typically have the necessary bandwidth to detect the higher harmonics. Here we present the design and characterization of a novel multilayer transducer for high intensity transmit and broadband receive. The transmit layer was made from a narrow-band, high-power piezoceramic (PZT), with nominal frequency of 2.0 MHz, that was diced into an array of 32 elements. Each element was 0.300 mm wide and 6.3 mm in elevation, and with a pitch of 0.400 mm the overall aperture width was 12.7 mm. A quarter-wave matching layer was attached to the PZT substrate to improve transmit efficiency and bandwidth. The overlaid receive layer was made from polyvinylidene fluoride (PVDF) that had gold metalization on one side. A custom two-sided flex circuit routed electrical connections to the PZT elements and patterned the PVDF elements; the PZT and PVDF elements had identical apertures. A low viscosity and electrically nonconductive epoxy was used for all adhesion layers. Characterization of electrical parameters and acoustic output were performed per standard methods, where transmit and receive events were driven by a software-controlled ultrasound engine. Echo data, collected from ex vivo tissue and digitized at 45 MS/s, exhibited frequency content up to the 4th harmonic of the 2 MHz transmit frequency.

  19. Piezoelectric micromachined ultrasound transducer (PMUT) arrays for integrated sensing, actuation and imaging

    National Research Council Canada - National Science Library

    Qiu, Yongqiang; Gigliotti, James V; Wallace, Margeaux; Griggio, Flavio; Demore, Christine E M; Cochran, Sandy; Trolier-McKinstry, Susan

    2015-01-01

    .... Piezoelectric micromachined ultrasound transducers (PMUTs), diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays...

  20. Ultrasound transducer function: annual testing is not sufficient.

    Science.gov (United States)

    Mårtensson, Mattias; Olsson, Mats; Brodin, Lars-Åke

    2010-10-01

    The objective was to follow-up the study 'High incidence of defective ultrasound transducers in use in routine clinical practice' and evaluate if annual testing is good enough to reduce the incidence of defective ultrasound transducers in routine clinical practice to an acceptable level. A total of 299 transducers were tested in 13 clinics at five hospitals in the Stockholm area. Approximately 7000-15,000 ultrasound examinations are carried out at these clinics every year. The transducers tested in the study had been tested and classified as fully operational 1 year before and since then been in normal use in the routine clinical practice. The transducers were tested with the Sonora FirstCall Test System. There were 81 (27.1%) defective transducers found; giving a 95% confidence interval ranging from 22.1 to 32.1%. The most common transducer errors were 'delamination' of the ultrasound lens and 'break in the cable' which together constituted 82.7% of all transducer errors found. The highest error rate was found at the radiological clinics with a mean error rate of 36.0%. There was a significant difference in error rate between two observed ways the clinics handled the transducers. There was no significant difference in the error rates of the transducer brands or the transducers models. Annual testing is not sufficient to reduce the incidence of defective ultrasound transducers in routine clinical practice to an acceptable level and it is strongly advisable to create a user routine that minimizes the handling of the transducers.

  1. Synthetic Aperture Focusing for a Single Element Transducer undergoing Helix Motion

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt

    2011-01-01

    This paper describes the application of 3D synthetic aperture focusing (SAF) to a single element trans-rectal ultrasound transducer. The transducer samples a 3D volume by simultaneous rotation and translation giving a helix motion. Two different 3D SAF methods are investigated, a direct and a two...

  2. Integration of Capacitive Micromachined Ultrasound Transducers to Microfluidic Devices

    KAUST Repository

    Viržonis, Darius

    2013-10-22

    The design and manufacturing flexibility of capacitive micromachined ultrasound transducers (CMUT) makes them attractive option for integration with microfluidic devices both for sensing and fluid manipulation. CMUT concept is introduced here by presentin

  3. Transducer combination for high-quality ultrasound tomography based on speed of sound imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Hun; Park, Kwan Kyu [Dept. of Mechanical Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-02-15

    The type of ultrasound transducer used influences the quality of a reconstructed ultrasound image. This study analyzed the effect of transducer type on ultrasound computed tomography (UCT) image quality. The UCT was modeled in an ultrasound simulator by using a 5 cm anatomy model and a ring-shape 5 MHz 128 transducer array, which considered attenuation, refraction, and reflection. Speed-of-sound images were reconstructed by the Radon transform as the UCT image modality. Acoustic impedance images were also reconstructed by the delayand-sum (DAS) method, which considered the speed of sound information. To determine the optimal combination of transducers in observation, point-source, flat, and focused transducers were tested in combination as trasmitters and receivers; UCT images were constructed from each combination. The combination of point-source/flat transducer as transmitting and receiving devices presented the best reconstructed image quality. In UCT implementation, the combination of a flat transducer for transmitting and a point transducer for receiving permitted acceptable image quality.

  4. High frequency PMN-PT single crystal focusing transducer fabricated by a mechanical dimpling technique.

    Science.gov (United States)

    Chen, Y; Lam, K H; Zhou, D; Cheng, W F; Dai, J Y; Luo, H S; Chan, H L W

    2013-02-01

    High frequency (∼30MHz and ∼80MHz) focusing ultrasound transducers were fabricated using a PMN-0.28PT single crystal by a mechanical dimpling technique. The dimpled single crystal was used as an active element for the focusing transducer. Compared with a plane transducer, the focusing transducer fabricated with a dimpled active element exhibits much broader bandwidth and higher sensitivity. Besides, a high quality image can be obtained by the 30MHz focusing transducer, in which the -6dB axial and lateral resolution is 27μm and 139μm, respectively. These results prove that the dimpling technique is capable to fabricate the high frequency focusing transducers with excellent performance for imaging applications.

  5. Development of high frequency annular array ultrasound transducers

    Science.gov (United States)

    Gottlieb, Emanuel John

    The advantage of ultrasonic annular arrays over conventional single element transducers has been in the ability to transmit focus at multiple points throughout the depth of field, as well as receive dynamic focus. Today, annular, linear and multidimensional array imaging systems are not commercially available at frequencies greater than 20 MHz. The fabrication technology used to develop a high frequency (>50 MHz) annular array transducer is presented. A 9 mum P(VDF-TrFE) film was bonded to gold annuli electrodes on the top layer of a two sided polyimide flexible circuit. Each annulus was separated by a 30 mum kerf and had several electroplated micro vias that connected to electrode traces on the bottom side of the polyimide flexible circuit. The array's performance was evaluated by measuring the electrical impedance, pulse echo response and crosstalk measurement for each element in the array. In order to improve device sensitivity each element was electrically matched to an impedance magnitude of 50 O and 0° phase at resonance. The average round trip insertion loss measured for the array and compensated for diffraction effects was -33.5 dB. The measured average center frequency and bandwidth of an element was 55 MHz and 47 respectively. The measured crosstalk between adjacent elements remained below -29 dB at the center frequency in water. A vertical wire phantom was imaged using a single focus transmit beamformer and dynamic focusing receive beamformer. This image showed a significant improvement in lateral resolution over a range of 9 mm after the dynamic focusing receive algorithm was applied. These results correlated well with predictions from a Field II simulation. After beamforming the minimum lateral resolution (-6 dB) was 108 mum at the focus. Preliminary ultrasound B-mode images of the rabbit eye using this transducer were shown in conjunction with a multi-channel digital beamformer. A feasibility study of designing and fabricating tunable copolymer

  6. NONINVASIVE MEASUREMENT OF LOCAL THERMAL DIFFUSIVITY USING BACKSCATTERED ULTRASOUND AND FOCUSED ULTRASOUND HEATING

    OpenAIRE

    2008-01-01

    Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create...

  7. Focused intravascular ultrasonic probe using dimpled transducer elements.

    Science.gov (United States)

    Chen, Y; Qiu, W B; Lam, K H; Liu, B Q; Jiang, X P; Zheng, H R; Luo, H S; Chan, H L W; Dai, J Y

    2015-02-01

    High-frequency focused intravascular ultrasonic probes were fabricated in this study using dimple technique based on PMN-PT single crystal and lead-free KNN-KBT-Mn ceramic. The center frequency, bandwidth, and insertion loss of the PMN-PT transducer were 34 MHz, 75%, and 22.9 dB, respectively. For the lead-free probe, the center frequency, bandwidth, and insertion loss were found to be 40 MHz, 72%, and 28.8 dB, respectively. The ultrasonic images of wire phantom and vessels with good resolution were obtained to evaluate the transducer performance. The -6 dB axial and lateral resolutions of the PMN-PT probe were determined to be 58 μm and 131 μm, respectively. For the lead-free probe, the axial and lateral resolutions were found to be 44 μm and 125 μm, respectively. These results suggest that the mechanical dimpling technique has good potential in preparing focused transducers for intravascular ultrasound applications.

  8. Effects of Non-Elevation-Focalized Linear Array Transducer on Ultrasound Plane-Wave Imaging

    Directory of Open Access Journals (Sweden)

    Congzhi Wang

    2016-11-01

    Full Text Available Plane-wave ultrasound imaging (PWUS has become an important method of ultrasound imaging in recent years as its frame rate has exceeded 10,000 frames per second, allowing ultrasound to be used for two-dimensional shear wave detection and functional brain imaging. However, compared to the traditional focusing and scanning method, PWUS images always suffer from a degradation of lateral resolution and contrast. To improve the image quality of PWUS, many different beamforming algorithms have been proposed and verified. Yet the influence of transducer structure is rarely studied. For this paper, the influence of using an acoustic lens for PWUS was evaluated. Two linear array transducers were fabricated. One was not self-focalized in the elevation direction (non-elevation-focalized transducer, NEFT; the other one was a traditional elevation-focalized transducer (EFT. An initial simulation was conducted to show the influence of elevation focusing. Then the images obtained with NEFT on a standard ultrasound imaging phantom were compared with those obtained with EFT. It was demonstrated that, in a relatively deep region, the contrast of an NEFT image is better than that of an EFT image. These results indicate that a more sophisticated design of ultrasound transducer would further improve the image quality of PWUS.

  9. Transducers in medical ultrasound: Part Three. Transducer applications in echocardiology.

    Science.gov (United States)

    Lancée, C T; Daigle, R; Sahn, D J; Thijssen, J M

    1985-09-01

    A comparison is made between phased arrays and mechanical sector scanners in transcutaneous echocardiographic applications. Aspects such as contact area, beam control, side lobes, grating lobes and image quality are discussed in the context of transducer frequency. The incorporation of simultaneous acquisition of Doppler velocity information and display of M-mode signals is considered. Transoesophageal and intraoperative scanning systems for cardiology are also compared, in particular linear arrays, phased arrays and mechanical scanners, and their advantages and disadvantages in relation to the above mentioned aspects are discussed. The general conclusion is that electronic sector scanners may have a considerably improved cost/benefit ratio in the near future and thereby will become the leading systems for echocardiography.

  10. Ultrasound focusing images in superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Narita, Michiko; Tanaka, Yukihiro; Tamura, Shin-ichiro [Department of Applied Physics, Hokkaido University, Sapporo (Japan)

    2002-03-04

    We study theoretically ultrasound focusing in periodic multilayered structures, or superlattices, by solving the wave equation with the Green function method and calculating the transmitted ultrasound amplitude images of both the longitudinal and transverse modes. The constituent layers assumed are elastically isotropic but the periodically stacked structure is anisotropic. Thus anisotropy of ultrasound propagation is predicted even at low frequencies and it is enhanced significantly at higher frequencies due to the zone-folding effect of acoustic dispersion relations. An additional effect studied is the interference of ultrasound (known as the internal diffraction), which can be recognized when the propagation distance is comparable to the ultrasound wavelength. Numerical examples are developed for millimetre-scale Al/polymer multilayers used recently for imaging experiment with surface acoustic waves. (author)

  11. Broadband electrical impedance matching for piezoelectric ultrasound transducers.

    Science.gov (United States)

    Huang, Haiying; Paramo, Daniel

    2011-12-01

    This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.

  12. Calibration of Field II using a Convex Ultrasound Transducer

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2010-01-01

    Field II is an ultrasound simulation program capable of simulating the pressure scattering from inhomogeneous tissue. The simulations are based on a convolution between spatial impulse responses from the field in front of the transducer and the volt-to-surface acceleration impulse response...... of the transducer. For such simulations to reflect actual measured intensities and pressure levels, the transducer impulse response is to be known. This work presents the results of combining a modified form of a 1D linear transducer model originally suggested by Willatzen with the Field II program to calibrate...... BK-Medical (Herlev, Denmark). As input waveform for the Field model we measured the output voltage of the research amplifier, which peak voltage was limited to 31 V to avoid too high non linear effects. We measured the hydrophone output from three transducer front elements by averaging 40 shoot...

  13. Delimitation of the lung region with distributed ultrasound transducers

    Science.gov (United States)

    Cardona Cárdenas, Diego Armando; Furuie, Sérgio Shiguemi

    2016-04-01

    One technique used to infer and monitor patient's respiratory conditions is the electrical impedance tomography (EIT). This provides images with information about lung function. The EIT image contrast is dependent on the variation of electrical impedance, therefore, this image does not provide anatomical details in border regions of several organs. To contribute to a clinical solution, we propose a new method to delimit regions of interest such as the pulmonary region and to improve the reconstruction quality of the EIT. Using a Matlab Toolbox k-wave, the ultrasound propagation phenomenon in homogeneous medium without patient (Reference) and with thoracic models were simulated, separately via a set of several ultrasound transducers distributed around the chest. After pulse emission by a transducer (TR), all received signals were compared considering the two sets of signals. If the energy relation between parts of the signals does not exceed an empirical threshold (30% in this study), a partial mask is generated between the transmitter and the receptor. This process was repeated until all 128 transducers are considered as TR-emitters. The 128 transducers (150kHz) are uniformly distributed. The evaluation was made by visually comparing the resulting images with the respective simulated object. A simple approach was presented to delimit high contrast organs with ultrasound transducers distributed around the patient. This approach allows other lower contrast objects to become invisible by varying the threshold limit. The investigation, based on numerical simulations of ultrasonic propagation, has shown promising results in the delimitation of the pulmonary region.

  14. Laser-nucleated acoustic cavitation in focused ultrasound.

    Science.gov (United States)

    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. Ultrasound transducer positioning aid for fetal heart rate monitoring.

    Science.gov (United States)

    Hamelmann, Paul; Kolen, Alex; Schmitt, Lars; Vullings, Rik; van Assen, Hans; Mischi, Massimo; Demi, Libertario; van Laar, Judith; Bergmans, Jan

    2016-08-01

    Fetal heart rate (fHR) monitoring is usually performed by Doppler ultrasound (US) techniques. For reliable fHR measurements it is required that the fetal heart is located within the US beam. In clinical practice, clinicians palpate the maternal abdomen to identify the fetal presentation and then the US transducer is fixated on the maternal abdomen where the best fHR signal can be obtained. Finding the optimal transducer position is done by listening to the strength of the Doppler audio output and relying on a signal quality indicator of the cardiotocographic (CTG) measurement system. Due to displacement of the US transducer or displacement of the fetal heart out of the US beam, the fHR signal may be lost. Therefore, it is often necessary that the obstetrician repeats the tedious procedure of US transducer positioning to avoid long periods of fHR signal loss. An intuitive US transducer positioning aid would be highly desirable to increase the work flow for the clinical staff. In this paper, the possibility to determine the fetal heart location with respect to the transducer by exploiting the received signal power in the transducer elements is shown. A commercially available US transducer used for fHR monitoring is connected to an US open platform, which allows individual driving of the elements and raw US data acquisition. Based on the power of the received Doppler signals in the transducer elements, the fetal heart location can be estimated. A beating fetal heart setup was designed and realized for validation. The experimental results show the feasibility of estimating the fetal heart location with the proposed method. This can be used to support clinicians in finding the optimal transducer position for fHR monitoring more easily.

  16. Dissimilar trend of nonlinearity in ultrasound transducers and systems at resonance and non-resonance frequencies

    DEFF Research Database (Denmark)

    Ghasemi, Negareh; Zare, Firuz; Davari, Pooya

    2017-01-01

    Several factors can affect performance of an ultrasound system such as quality of excitation signal and ultrasound transducer behaviour. Nonlinearity of piezoelectric ultrasound transducers is a key determinant in designing a proper driving power supply. Although, the nonlinearity of piezoelectri...... receiver is a function of a voltage across the resistor in the RLC branches and is related to the resonance frequencies of the ultrasound transducer....

  17. Dual-Frequency Piezoelectric Transducers for Contrast Enhanced Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    K. Heath Martin

    2014-11-01

    Full Text Available For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current clinical practices using microbubble contrast agents rely heavily on user training to evaluate degree of localized perfusion. Advances in separating the signals produced from contrast agents versus surrounding tissue backscatter provide unique opportunities for specialized sensors designed to image microbubbles with higher signal to noise and resolution than previously possible. In this review article, we describe the background principles and recent developments of ultrasound transducer technology for receiving signals produced by contrast agents while rejecting signals arising from soft tissue. This approach relies on transmitting at a low-frequency and receiving microbubble harmonic signals at frequencies many times higher than the transmitted frequency. Design and fabrication of dual-frequency transducers and the extension of recent developments in transducer technology for dual-frequency harmonic imaging are discussed.

  18. Breast ultrasound tomography with two parallel transducer arrays: preliminary clinical results

    Science.gov (United States)

    Huang, Lianjie; Shin, Junseob; Chen, Ting; Lin, Youzuo; Intrator, Miranda; Hanson, Kenneth; Epstein, Katherine; Sandoval, Daniel; Williamson, Michael

    2015-03-01

    Ultrasound tomography has great potential to provide quantitative estimations of physical properties of breast tumors for accurate characterization of breast cancer. We design and manufacture a new synthetic-aperture breast ultrasound tomography system with two parallel transducer arrays. The distance of these two transducer arrays is adjustable for scanning breasts with different sizes. The ultrasound transducer arrays are translated vertically to scan the entire breast slice by slice and acquires ultrasound transmission and reflection data for whole-breast ultrasound imaging and tomographic reconstructions. We use the system to acquire patient data at the University of New Mexico Hospital for clinical studies. We present some preliminary imaging results of in vivo patient ultrasound data. Our preliminary clinical imaging results show promising of our breast ultrasound tomography system with two parallel transducer arrays for breast cancer imaging and characterization.

  19. Nakagami imaging for detecting thermal lesions induced by high-intensity focused ultrasound in tissue.

    Science.gov (United States)

    Rangraz, Parisa; Behnam, Hamid; Tavakkoli, Jahan

    2014-01-01

    High-intensity focused ultrasound induces focalized tissue coagulation by increasing the tissue temperature in a tight focal region. Several methods have been proposed to monitor high-intensity focused ultrasound-induced thermal lesions. Currently, ultrasound imaging techniques that are clinically used for monitoring high-intensity focused ultrasound treatment are standard pulse-echo B-mode ultrasound imaging, ultrasound temperature estimation, and elastography-based methods. On the contrary, the efficacy of two-dimensional Nakagami parametric imaging based on the distribution of the ultrasound backscattered signals to quantify properties of soft tissue has recently been evaluated. In this study, ultrasound radio frequency echo signals from ex vivo tissue samples were acquired before and after high-intensity focused ultrasound exposures and then their Nakagami parameter and scaling parameter of Nakagami distribution were estimated. These parameters were used to detect high-intensity focused ultrasound-induced thermal lesions. Also, the effects of changing the acoustic power of the high-intensity focused ultrasound transducer on the Nakagami parameters were studied. The results obtained suggest that the Nakagami distribution's scaling and Nakagami parameters can effectively be used to detect high-intensity focused ultrasound-induced thermal lesions in tissue ex vivo. These parameters can also be used to understand the degree of change in tissue caused by high-intensity focused ultrasound exposures, which could be interpreted as a measure of degree of variability in scatterer concentration in various parts of the high-intensity focused ultrasound lesion.

  20. Non-contact optoacoustic imaging with focused air-coupled transducers

    Energy Technology Data Exchange (ETDEWEB)

    Deán-Ben, X. Luís [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); Pang, Genny A.; Razansky, Daniel, E-mail: dr@tum.de [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); School of Medicine, Technische Universität München (TUM), Munich (Germany); Montero de Espinosa, Francisco [CSIC, Institute of Physics and Communication Technologies, Madrid (Spain)

    2015-08-03

    Non-contact optoacoustic imaging employing raster-scanning of a spherically focused air-coupled ultrasound transducer is showcased herein. Optoacoustic excitation with laser fluence within the maximal permissible human exposure limits in the visible and near-infrared spectra is applied to objects with characteristic dimensions smaller than 1 mm and absorption properties representative of the whole blood at near-infrared wavelengths, and these signals are shown to be detectable without contact to the sample using an air-coupled transducer with reasonable signal averaging. Optoacoustic images of vessel-mimicking tubes embedded in an agar phantom captured with this non-contact sensing technique are also showcased. These initial results indicate that an air-coupled ultrasound detection approach can be suitable for non-contact biomedical imaging with optoacoustics.

  1. Ejection of small droplet from microplate using focused ultrasound

    Science.gov (United States)

    Tanaka, Hiroki; Mizuno, Yosuke; Nakamura, Kentaro

    2017-08-01

    We discussed an ultrasonic system for single-droplet ejection from a microplate, which is one of the basic and important procedures in the noncontact handling of droplets in air. In this system, a 1.5 MHz concave transducer located below the microplate is used for chasing the liquid surface through a pulse echo method, and also for the ejection of a 1 µL single droplet by the burst of focused ultrasound. We investigated the relationship between the droplet ejection characteristics, the distance from the transducer to the surface of liquid, the material property, and the excitation condition of the focused ultrasonic transducer. It was verified that the optimal position of the transducer was off the focal point of sound pressure by ±1 mm, because the sound intensity had to be controlled to eject a single droplet. Subsequently, we confirmed experimentally that the ejected droplet volume linearly depended on the surface tension of the liquid, and that the droplet volume and ejection velocity were determined by the Webber number, Reynolds number, and Ohnesolge number. In addition, by optimizing the duration of the burst ultrasound, the droplet volume and ejection velocity were controlled.

  2. Novice performance of ultrasound-guided needle advancement: standard 38-mm transducer vs 25-mm hockey stick transducer.

    Science.gov (United States)

    Davies, T; Townsley, P; Jlala, H; Dowling, M; Bedforth, N; Hardman, J G; McCahon, R A

    2012-08-01

    The optimal method to develop expertise in ultrasound-guided regional anaesthesia is unknown. Studies of laryngoscopic expertise in novices demonstrate that the choice of laryngoscope affects performance. In this study, we aimed to compare the effect of two different linear array transducers (38-mm standard vs 25-mm hockey stick) on novice performance of ultrasound-guided needle advancement. Following randomisation, participants watched a video model of expert performance of ultrasound-guided needle advancement. Recruits performed the modelled task on a turkey breast model. The median (IQR [range]) composite error score was statistically significantly larger for participants in the hockey stick transducer group compared with the standard transducer group; 10.0 (7.3-14.3 [2.5-29.0]) vs 7.5 (4.5-10.0 [2.0-28.0]) respectively, (p = 0.01). This study has demonstrated that performance of ultrasound-guided needle advancement by novice operators after simple video instruction is better (as assessed using a composite error score) with a standard 38-mm transducer than with a 25-mm hockey stick transducer. Anaesthesia © 2012 The Association of Anaesthetists of Great Britain and Ireland.

  3. Handheld probe integrating laser diode and ultrasound transducer array for ultrasound/photoacoustic dual modality imaging.

    Science.gov (United States)

    Daoudi, K; van den Berg, P J; Rabot, O; Kohl, A; Tisserand, S; Brands, P; Steenbergen, W

    2014-10-20

    Ultrasound and photoacoustics can be utilized as complementary imaging techniques to improve clinical diagnoses. Photoacoustics provides optical contrast and functional information while ultrasound provides structural and anatomical information. As of yet, photoacoustic imaging uses large and expensive systems, which limits their clinical application and makes the combination costly and impracticable. In this work we present and evaluate a compact and ergonomically designed handheld probe, connected to a portable ultrasound system for inexpensive, real-time dual-modality ultrasound/photoacoustic imaging. The probe integrates an ultrasound transducer array and a highly efficient diode stack laser emitting 130 ns pulses at 805 nm wavelength and a pulse energy of 0.56 mJ, with a high pulse repetition frequency of up to 10 kHz. The diodes are driven by a customized laser driver, which can be triggered externally with a high temporal stability necessary to synchronize the ultrasound detection and laser pulsing. The emitted beam is collimated with cylindrical micro-lenses and shaped using a diffractive optical element, delivering a homogenized rectangular light intensity distribution. The system performance was tested in vitro and in vivo by imaging a human finger joint.

  4. Ultrasound transducer modeling--general theory and applications to ultrasound reciprocal systems.

    Science.gov (United States)

    Willatzen, M

    2001-01-01

    A tutorial presentation on the theory of reciprocal ultrasound systems is given, and a complete set of modeling equations for one-dimensional multi-layer ultrasound transducers is derived from first principles. The model includes dielectric losses and mechanical losses in the transducer material layers as well as sound absorption in the transmission medium. First, the so-called constitutive relations of a piezoelectric body are derived based on general thermodynamic considerations, assuming that transducer operation takes place under almost isentropic conditions. Second, full attention is given to transducers oscillating in the thickness mode, discarding all other vibration modes. Dynamic transducer equations are determined using Newton's Second Law, Poisson's equation, and the definition of strain applied to a piezoelectric transducer with one or more non-piezoelectric layers on the front surface (multilayer transducer). Boundary conditions include continuity of normal velocity and stress across material interfaces as well as a subsidiary electrical condition over the piezoceramic electrodes. Sound transmission is assumed to take place in a water bath such that the Rayleigh equation can be used to obtain the incoming pressure at the receiver aperture from the acceleration of the opposing transmitter. This allows, e.g., a detailed treatment of receiver signal variations as the receiver moves from the near-field zone to the far-field zone of the transmitter. In the remaining part of the paper, receiver voltage and current signals are obtained by solving the full set of dynamic equations numerically. Special attention is given to transducers consisting of a) a pure piezoceramic layer only, b) a piezoceramic layer and a quarter-wavelength matching layer of polyphenylensulphide (PPS), c) a piezoceramic layer and a half-wavelength matching layer of stainless steel, and d) a piezoceramic layer and a half-wavelength matching layer of stainless steel tuned to resonance by

  5. Toric focusing for radiation force applications using a toric lens coupled to a spherically focused transducer.

    Science.gov (United States)

    Arnal, Bastien; Nguyen, Thu-Mai; O'Donnell, Matthew

    2014-12-01

    Dynamic elastography using radiation force requires that an ultrasound field be focused during hundreds of microseconds at a pressure of several megapascals. Here, we address the importance of the focal geometry. Although there is usually no control of the elevational focal width in generating a tissue mechanical response, we propose a tunable approach to adapt the focus geometry that can significantly improve radiation force efficiency. Several thin, in-house-made polydimethylsiloxane lenses were designed to modify the focal spot of a spherical transducer. They exhibited low absorption and the focal spot widths were extended up to 8-fold in the elevation direction. Radiation force experiments demonstrated an 8-fold increase in tissue displacements using the same pressure level in a tissue-mimicking phantom with a similar shear wave spectrum, meaning it does not affect elastography resolution. Our results demonstrate that larger tissue responses can be obtained for a given pressure level, or that similar response can be reached at a much lower mechanical index (MI). We envision that this work will impact 3-D elastography using 2-D phased arrays, where such shaping can be achieved electronically with the potential for adaptive optimization.

  6. Optimization of acoustic emitted field of transducer array for ultrasound imaging.

    Science.gov (United States)

    He, Zhengyao

    2014-01-01

    A method is proposed to calculate the weight vector of a transducer array for ultrasound imaging to obtain a low-sidelobe transmitting beam pattern based on the near-field response vector. An optimization problem is established, and the second-order cone (SOC) algorithm is used to solve the problem to obtain the weight vector. The optimized acoustic emitted field of the transducer array is then calculated using the Field II program by applying the obtained weight vector to the array. The simulation results with a 64-element 26 MHz linear phased array show that the proposed method can be used to control the sidelobe of the near-field transmitting beam pattern of the transducer array and achieve a low-sidelobe level. The near-field sound pressure distribution of the transducer array using the proposed method focuses much better than that using the standard delay and sum (DAS) beamforming method. The sound energy is more concentrated using the proposed method.

  7. Simulating arbitrary-geometry ultrasound transducers using triangles

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1996-01-01

    -echo field. The spatial impulse response has only been determined analytically for a few geometries and using apodization over the transducer surface generally makes it impossible to find the response analytically. A popular approach to find the general field is thus to split the aperture into small...... focused at different zones. The time-integrated spatial impulse response is used in the program to minimize the effect of the sharp edges of the spatial impulse response in a sampled signal. Since the integrated response from a triangular element cannot be analytically evaluated, a simple numerical...

  8. Synthetic focusing in ultrasound modulated tomography

    KAUST Repository

    Kuchment, Peter

    2010-09-01

    Several hybrid tomographic methods utilizing ultrasound modulation have been introduced lately. Success of these methods hinges on the feasibility of focusing ultrasound waves at an arbitrary point of interest. Such focusing, however, is difficult to achieve in practice. We thus propose a way to avoid the use of focused waves through what we call synthetic focusing, i.e. by reconstructing the would-be response to the focused modulation from the measurements corresponding to realistic unfocused waves. Examples of reconstructions from simulated data are provided. This non-technical paper describes only the general concept, while technical details will appear elsewhere. © 2010 American Institute of Mathematical Sciences.

  9. A Flexible Ultrasound Transducer Array with Micro-Machined Bulk PZT

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2015-01-01

    Full Text Available This paper proposes a novel flexible piezoelectric micro-machined ultrasound transducer, which is based on PZT and a polyimide substrate. The transducer is made on the polyimide substrate and packaged with medical polydimethylsiloxane. Instead of etching the PZT ceramic, this paper proposes a method of putting diced PZT blocks into holes on the polyimide which are pre-etched. The device works in d31 mode and the electromechanical coupling factor is 22.25%. Its flexibility, good conformal contacting with skin surfaces and proper resonant frequency make the device suitable for heart imaging. The flexible packaging ultrasound transducer also has a good waterproof performance after hundreds of ultrasonic electric tests in water. It is a promising ultrasound transducer and will be an effective supplementary ultrasound imaging method in the practical applications.

  10. Resonant gravimetric immunosensing based on capacitive micromachined ultrasound transducers

    KAUST Repository

    Viržonis, Darius

    2014-04-08

    High-frequency (40 MHz) and low-frequency (7 MHz) capacitive micromachined ultrasound transducers (CMUT) were fabricated and tested for use in gravimetric detection of biomolecules. The low-frequency CMUT sensors have a gold-coated surface, while the high-frequency sensors have a silicon nitride surface. Both surfaces were functionalized with bovine leukemia virus antigen gp51 acting as the antigen. On addition of an a specific antibody labeled with horseradish peroxidase (HRP), the antigen/antibody complex is formed on the surface and quantified by HRP-catalyzed oxidation of tetramethylbenzidine. It has been found that a considerably smaller quantity of immuno complex is formed on the high frequency sensor surface. In parallel, the loading of the surface of the CMUT was determined via resonance frequency and electromechanical resistance readings. Following the formation of the immuno complexes, the resonance frequencies of the low-frequency and high-frequency sensors decrease by up to 420 and 440 kHz, respectively. Finite element analysis reveals that the loading of the (gold-coated) low frequency sensors is several times larger than that on high frequency sensors. The formation of the protein film with pronounced elasticity and stress on the gold surface case is discussed. We also discuss the adoption of this method for the detection of DNA using a hybridization assay following polymerase chain reaction.

  11. First measurements on a novel type of optical micro-machined ultrasound transducer (OMUT)

    NARCIS (Netherlands)

    Leinders, S.M.; Dongen, K.W.A. van; Jong, N. de; Verweij, M.D.; Westerveld, W.J.; Urbach, H.P.; Neer, P.L.M.J. van; Pozo Torres, J.M.

    2014-01-01

    Several types of ultrasound sensors have been developed and are used in the field of medical imaging. Conventional transducers are made of piezo-electric material and show good practical performance. However, when the piezo-electric elements need to be small (below 100 μm × 100 μm), these transducer

  12. First measurements on a novel type of optical micro-machined ultrasound transducer (OMUT)

    NARCIS (Netherlands)

    Leinders, S.M.; Dongen, K.W.A. van; Jong, N. de; Verweij, M.D.; Westerveld, W.J.; Urbach, H.P.; Neer, P.L.M.J. van; Pozo Torres, J.M.

    2014-01-01

    Several types of ultrasound sensors have been developed and are used in the field of medical imaging. Conventional transducers are made of piezo-electric material and show good practical performance. However, when the piezo-electric elements need to be small (below 100 μm × 100 μm), these transducer

  13. Acoustical cross-talk in row–column addressed 2-D transducer arrays for ultrasound imaging

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt; Thomsen, Erik Vilain

    2015-01-01

    The acoustical cross-talk in row–column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed...

  14. Radiation force on a spherical object in the field of a focused cylindrical transducer.

    Science.gov (United States)

    Chen, X; Apfel, R E

    1997-05-01

    An exact solution of the radiation force on a spherical object, when positioned on the acoustic axis of a cylindrical transducer, is provided. The solution is valid for any type of sphere of any size. The radiation force function allows the calibration of high-frequency focused ultrasound fields from radiation force measurements and expands the utility of the elastic sphere radiometer developed by Dunn et al. [Acustica 38, 58-61 (1977)]. Numeral results reveal an oscillatory behavior of the radiation force function for small spheres near the transducer surface and this behavior may present an opportunity for particle sorting based on the mechanical properties of the particle and other types of manipulation.

  15. A numerical study on the oblique focus in MR-guided transcranial focused ultrasound

    Science.gov (United States)

    Hughes, Alec; Huang, Yuexi; Pulkkinen, Aki; Schwartz, Michael L.; Lozano, Andres M.; Hynynen, Kullervo

    2016-11-01

    Recent clinical data showing thermal lesions from treatments of essential tremor using MR-guided transcranial focused ultrasound shows that in many cases the focus is oblique to the main axis of the phased array. The potential for this obliquity to extend the focus into lateral regions of the brain has led to speculation as to the cause of the oblique focus, and whether it is possible to realign the focus. Numerical simulations were performed on clinical export data to analyze the causes of the oblique focus and determine methods for its correction. It was found that the focal obliquity could be replicated with the numerical simulations to within 23.2+/- {{13.6}\\circ} of the clinical cases. It was then found that a major cause of the focal obliquity was the presence of sidelobes, caused by an unequal deposition of power from the different transducer elements in the array at the focus. In addition, it was found that a 65% reduction in focal obliquity was possible using phase and amplitude corrections. Potential drawbacks include the higher levels of skull heating required when modifying the distribution of power among the transducer elements, and the difficulty at present in obtaining ideal phase corrections from CT information alone. These techniques for the reduction of focal obliquity can be applied to other applications of transcranial focused ultrasound involving lower total energy deposition, such as blood-brain barrier opening, where the issue of skull heating is minimal.

  16. High Intensity Focused Ultrasound Tumor Therapy System and Its Application

    Science.gov (United States)

    Sun, Fucheng; He, Ye; Li, Rui

    2007-05-01

    At the end of last century, a High Intensity Focused Ultrasound (HIFU) tumor therapy system was successfully developed and manufactured in China, which has been already applied to clinical therapy. This article aims to discuss the HIFU therapy system and its application. Detailed research includes the following: power amplifiers for high-power ultrasound, ultrasound transducers with large apertures, accurate 3-D mechanical drives, a software control system (both high-voltage control and low-voltage control), and the B-mode ultrasonic diagnostic equipment used for treatment monitoring. Research on the dosage of ultrasound required for tumour therapy in multiple human cases has made it possible to relate a dosage formula, presented in this paper, to other significant parameters such as the volume of thermal tumor solidification, the acoustic intensity (I), and the ultrasound emission time (tn). Moreover, the HIFU therapy system can be applied to the clinical treatment of both benign and malignant tumors in the pelvic and abdominal cavity, such as uterine fibroids, liver cancer and pancreatic carcinoma.

  17. Localized Harmonic Motion Imaging for Focused Ultrasound Surgery Targeting

    Science.gov (United States)

    Curiel, Laura; Hynynen, Kullervo

    2011-01-01

    Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized harmonic motion (LHM) to detect changes in tissues during focused ultrasound surgery (FUS) has been proposed to control the exposure. This technique can potentially be used as well for targeting imaging. In the present study we evaluated the potential of using LHM to detect changes in stiffness and the feasibility of using it for imaging purposes in phantoms and in vivo tumor detection. A single-element FUS transducer (80 mm focal length, 100 mm diameter, 1.485 MHz) was used for inducing a localized harmonic motion and a separate ultrasound diagnostic transducer excited by a pulser/receiver (5 kHz PRF, 5 MHz) was used to track motion. The motion was estimated using cross-correlation techniques on the acquired RF signal. Silicon phantom studies were performed in order to determine the size of inclusion that was possible to detect using this technique. Inclusions were discerned from the surroundings as a reduction on LHM amplitude and it was possible to depict inclusions as small as 4 mm. The amplitude of the induced LHM was always lower at the inclusions as compared with the one obtained at the surroundings. Ten New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region. Tumors (as small as 10 mm in length and 4 mm in width) were discerned from the surroundings as a reduction on LHM amplitude. PMID:21683514

  18. Rapid motion correction in MR-guided high-intensity focused ultrasound heating using real-time ultrasound echo information.

    Science.gov (United States)

    de Oliveira, Philippe Lourenço; de Senneville, Baudouin Denis; Dragonu, Iulius; Moonen, Chrit T W

    2010-11-01

    The objective of this study was to evaluate the feasibility of integrating real-time ultrasound echo guidance in MR-guided high-intensity focused ultrasound (HIFU) heating of mobile targets in order to reduce latency between displacement analysis and HIFU treatment. Experiments on a moving phantom were carried out with MRI-guided HIFU during continuous one-dimensional ultrasound echo detection using separate HIFU and ultrasound imaging transducers. Excellent correspondence was found between MR- and ultrasound-detected displacements. Real-time ultrasound echo-based target tracking during MR-guided HIFU heating is shown with the dimensions of the heated area similar to those obtained for a static target. This work demonstrates that the combination of the two modalities opens up perspectives for motion correction in MRI-guided HIFU with negligible latency.

  19. Noninvasive measurement of local thermal diffusivity using backscattered ultrasound and focused ultrasound heating.

    Science.gov (United States)

    Anand, Ajay; Kaczkowski, Peter J

    2008-09-01

    Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create a brief local temperature rise of no more than 10 degrees C. Beamformed radio-frequency (RF) data are collected during heating and cooling using a clinical ultrasound scanner. Measurements of the time-varying "acoustic strain", that is, spatiotemporal variations in the RF echo shifts induced by the temperature related sound speed changes, are related to a solution of the heat transfer equation to estimate the thermal diffusivity in the heated zone. Numerical simulations and experiments performed in vitro in tissue mimicking phantoms and excised turkey breast muscle tissue demonstrate agreement between the ultrasound derived thermal diffusivity estimates and independent estimates made by a traditional hot-wire technique. The new noninvasive ultrasonic method has potential applications in thermal therapy planning and monitoring, physiological monitoring and as a means of noninvasive tissue characterization.

  20. Optimal experimental design to position transducers in ultrasound breast imaging

    Science.gov (United States)

    Korta Martiartu, Naiara; Boehm, Christian; Vinard, Nicolas; Jovanović Balic, Ivana; Fichtner, Andreas

    2017-03-01

    We present methods to optimize the setup of a 3D ultrasound tomography scanner for breast cancer detection. This approach provides a systematic and quantitative tool to evaluate different designs and to optimize the con- figuration with respect to predefined design parameters. We consider both, time-of-flight inversion using straight rays and time-domain waveform inversion governed by the acoustic wave equation for imaging the sound speed. In order to compare different designs, we measure their quality by extracting properties from the Hessian operator of the time-of-flight or waveform differences defined in the inverse problem, i.e., the second derivatives with respect to the sound speed. Spatial uncertainties and resolution can be related to the eigenvalues of the Hessian, which provide a good indication of the information contained in the data that is acquired with a given design. However, the complete spectrum is often prohibitively expensive to compute, thus suitable approximations have to be developed and analyzed. We use the trace of the Hessian operator as design criterion, which is equivalent to the sum of all eigenvalues and requires less computational effort. In addition, we suggest to take advantage of the spatial symmetry to extrapolate the 3D experimental design from a set of 2D configurations. In order to maximize the quality criterion, we use a genetic algorithm to explore the space of possible design configurations. Numerical results show that the proposed strategies are capable of improving an initial configuration with uniformly distributed transducers, clustering them around regions with poor illumination and improving the ray coverage of the domain of interest.

  1. Numerical simulations of clinical focused ultrasound functional neurosurgery

    Science.gov (United States)

    Pulkkinen, Aki; Werner, Beat; Martin, Ernst; Hynynen, Kullervo

    2014-04-01

    A computational model utilizing grid and finite difference methods were developed to simulate focused ultrasound functional neurosurgery interventions. The model couples the propagation of ultrasound in fluids (soft tissues) and solids (skull) with acoustic and visco-elastic wave equations. The computational model was applied to simulate clinical focused ultrasound functional neurosurgery treatments performed in patients suffering from therapy resistant chronic neuropathic pain. Datasets of five patients were used to derive the treatment geometry. Eight sonications performed in the treatments were then simulated with the developed model. Computations were performed by driving the simulated phased array ultrasound transducer with the acoustic parameters used in the treatments. Resulting focal temperatures and size of the thermal foci were compared quantitatively, in addition to qualitative inspection of the simulated pressure and temperature fields. This study found that the computational model and the simulation parameters predicted an average of 24 ± 13% lower focal temperature elevations than observed in the treatments. The size of the simulated thermal focus was found to be 40 ± 13% smaller in the anterior-posterior direction and 22 ± 14% smaller in the inferior-superior direction than in the treatments. The location of the simulated thermal focus was off from the prescribed target by 0.3 ± 0.1 mm, while the peak focal temperature elevation observed in the measurements was off by 1.6 ± 0.6 mm. Although the results of the simulations suggest that there could be some inaccuracies in either the tissue parameters used, or in the simulation methods, the simulations were able to predict the focal spot locations and temperature elevations adequately for initial treatment planning performed to assess, for example, the feasibility of sonication. The accuracy of the simulations could be improved if more precise ultrasound tissue properties (especially of the

  2. Design of a bullet beam pattern of a micro ultrasound transducer (Conference Presentation)

    Science.gov (United States)

    Roh, Yongrae; Lee, Seongmin

    2016-04-01

    Ultrasonic imaging transducer is often required to compose a beam pattern of a low sidelobe level and a small beam width over a long focal region to achieve good image resolution. Normal ultrasound transducers have many channels along its azimuth, which allows easy formation of the sound beam into a desired shape. However, micro-array transducers have no control of the beam pattern along their elevation. In this work, a new method is proposed to manipulate the beam pattern by using an acoustic multifocal lens and a shaded electrode on top of the piezoelectric layer. The shading technique split an initial uniform electrode into several segments and combined those segments to compose a desired beam pattern. For a given elevation width and frequency, the optimal pattern of the split electrodes was determined by means of the OptQuest-Nonlinear Program (OQ-NLP) algorithm to achieve the lowest sidelobe level. The requirement to achieve a small beam width with a long focal region was satisfied by employing an acoustic lens of three multiple focuses. Optimal geometry of the multifocal lens such as the radius of curvature and aperture diameter for each focal point was also determined by the OQ-NLP algorithm. For the optimization, a new index was devised to evaluate the on-axis response: focal region ratio = focal region / minimum beam width. The larger was the focal region ratio, the better was the beam pattern. Validity of the design has been verified through fabricating and characterizing an experimental prototype of the transducer.

  3. In vitro characterization of perfluorocarbon droplets for focused ultrasound therapy

    Science.gov (United States)

    Schad, Kelly C.; Hynynen, Kullervo

    2010-09-01

    Focused ultrasound therapy can be enhanced with microbubbles by thermal and cavitation effects. However, localization of treatment is difficult as bioeffects can occur outside of the target region. Spatial control of bubbles can be achieved by ultrasound-induced conversion of liquid perfluorocarbon droplets to gas bubbles. This study was undertaken to determine the acoustic parameters for bubble production by droplet conversion and how it depends on the acoustic conditions and droplet physical parameters. Lipid-encapsulated droplets containing dodecafluoropentane were manufactured with sizes ranging from 1.9 to 7.2 µm in diameter and diluted to a concentration of 8 × 106 droplets mL-1. The droplets were sonicated in vitro with a focused ultrasound transducer and varying frequency and exposure under flow conditions through an acoustically transparent vessel. The sonications were 10 ms in duration at frequencies of 0.578, 1.736 and 2.855 MHz. The pressure threshold for droplet conversion was measured with an active transducer operating in pulse-echo mode and simultaneous measurements of broadband acoustic emissions were performed with passive acoustic detection. The results show that droplets cannot be converted at low frequency without broadband emissions occurring. However, the pressure threshold for droplet conversion decreased with increasing frequency, exposure and droplet size. The pressure threshold for broadband emissions was independent of the droplet size and was 2.9, 4.4 and 5.3 MPa for 0.578, 1736 and 2.855 MHz, respectively. In summary, we have demonstrated that droplet conversion is feasible for clinically relevant sized droplets and acoustic exposures.

  4. In vitro characterization of perfluorocarbon droplets for focused ultrasound therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schad, Kelly C; Hynynen, Kullervo, E-mail: khynynen@sri.utoronto.c [Imaging Research, Sunnybrook Health Sciences Centre, 2075 Bayview Ave, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto (Canada)

    2010-09-07

    Focused ultrasound therapy can be enhanced with microbubbles by thermal and cavitation effects. However, localization of treatment is difficult as bioeffects can occur outside of the target region. Spatial control of bubbles can be achieved by ultrasound-induced conversion of liquid perfluorocarbon droplets to gas bubbles. This study was undertaken to determine the acoustic parameters for bubble production by droplet conversion and how it depends on the acoustic conditions and droplet physical parameters. Lipid-encapsulated droplets containing dodecafluoropentane were manufactured with sizes ranging from 1.9 to 7.2 {mu}m in diameter and diluted to a concentration of 8 x 10{sup 6} droplets mL{sup -1}. The droplets were sonicated in vitro with a focused ultrasound transducer and varying frequency and exposure under flow conditions through an acoustically transparent vessel. The sonications were 10 ms in duration at frequencies of 0.578, 1.736 and 2.855 MHz. The pressure threshold for droplet conversion was measured with an active transducer operating in pulse-echo mode and simultaneous measurements of broadband acoustic emissions were performed with passive acoustic detection. The results show that droplets cannot be converted at low frequency without broadband emissions occurring. However, the pressure threshold for droplet conversion decreased with increasing frequency, exposure and droplet size. The pressure threshold for broadband emissions was independent of the droplet size and was 2.9, 4.4 and 5.3 MPa for 0.578, 1736 and 2.855 MHz, respectively. In summary, we have demonstrated that droplet conversion is feasible for clinically relevant sized droplets and acoustic exposures.

  5. Design and fabrication of PIN-PMN-PT single-crystal high-frequency ultrasound transducers.

    Science.gov (United States)

    Sun, Ping; Zhou, Qifa; Zhu, Benpeng; Wu, Dawei; Hu, Changhong; Cannata, Jonathan M; Tian, Jin; Han, Pengdi; Wang, Gaofeng; Shung, K Kirk

    2009-12-01

    High-frequency PIN-PMN-PT single crystal ultrasound transducers at center frequencies of 35 MHz and 60 MHz were successfully fabricated using lead indium niobate-lead magnesium niobate-lead titanate (0.23PIN- 0.5PMN-0.27PT) single crystal. The new PIN-PMN-PT single crystal has higher coercivity (6.0 kV/cm) and higher Curie temperature (160 degrees C) than PMN-PT crystal. Experimental results showed that the PIN-PMN-PT transducers have similar performance but better thermal stability compared with the PMN-PT transducers.

  6. 2D sparse array transducer optimization for 3D ultrasound imaging

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Hoon; Park, Kwan Kyu [Dept. of Mechanical Convergence Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-12-15

    A 3D ultrasound image is desired in many medical examinations. However, the implementation of a 2D array, which is needed for a 3D image, is challenging with respect to fabrication, interconnection and cabling. A 2D sparse array, which needs fewer elements than a dense array, is a realistic way to achieve 3D images. Because the number of ways the elements can be placed in an array is extremely large, a method for optimizing the array configuration is needed. Previous research placed the target point far from the transducer array, making it impossible to optimize the array in the operating range. In our study, we focused on optimizing a 2D sparse array transducer for 3D imaging by using a simulated annealing method. We compared the far-field optimization method with the near-field optimization method by analyzing a point-spread function (PSF). The resolution of the optimized sparse array is comparable to that of the dense array.

  7. Ultrasound transducer shape has no effect on measurements of lumbar multifidus muscle size.

    Science.gov (United States)

    Worsley, Peter R; Smith, Nicholas; Warner, Martin B; Stokes, Maria

    2012-04-01

    Evidence is currently lacking for guidance on ultrasound transducer configuration (shape) when imaging muscle to measure its size. This study compared measurements made of lumbar multifidus on images obtained using curvilinear and linear transducers. Fifteen asymptomatic males (aged 21-32 years) had their right lumbar multifidus imaged at L3. Two transverse images were taken with two transducers (5 MHz curvilinear and 6 MHz linear), and linear and cross-sectional area (CSA) measurements were made off-line. Reliability of image interpretation was shown using intra-class correlation coefficients (0.78-0.99). Muscle measurements were compared between transducers using Bland and Altman plots and paired t-tests. Relationships between CSA and linear measurements were examined using Pearson's Correlation Coefficients. There were no significant differences (p > 0.05) in the measurements of the two transducers. Thickness and CSA measurements had small differences between transducers, with mean differences of 0.01 cm (SDdiff = 0.21 cm) and 0.03 cm(2) (SDdiff = 0.58 cm(2)) respectively. Width measures had a mean difference of 0.14 cm, with the linear transducer giving larger measures. Significant correlations (p transducers (r = 0.78-0.89). Measurements of multifidus at L3 were not influenced by the configuration of transducers of similar frequency. For the purposes of image interpretation, the curvilinear transducer produced better definition of the lateral muscle border, suggesting it as the preferable transducer for imaging lumbar multifidus. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. MR-guided focused ultrasound: a potentially disruptive technology.

    Science.gov (United States)

    Bradley, William G

    2009-07-01

    A disruptive technology is a technological innovation that overturns the existing dominant technologies in a market. Magnetic resonance (MR)-guided focused ultrasound (MRgFUS) is a noninvasive procedure based on the combination of real-time MR anatomic guidance, MR thermometry, and high-intensity focused ultrasound. Several hundred transducer elements become convergent at a point under MR guidance, leading to heating and coagulation necrosis. Outside the focal point, there is no significant heating. There is no need to break the skin for procedures in the body or to perform a craniotomy for procedures in the brain. This lack of invasiveness is what makes MRgFUS so disruptive compared with surgery. At present, MRgFUS has been used for the ablation of uterine fibroids, breast tumors, painful bony metastases, and liver tumors. In the brain, it has been used for the ablation of glioblastomas and for functional neurosurgery. Phantom and animal studies suggest future applications for prostate cancer and acute stroke treatment.

  9. The effect of electronically steering a phased array ultrasound transducer on near-field tissue heating

    Science.gov (United States)

    Payne, Allison; Vyas, Urvi; Todd, Nick; Bever, Joshua de; Christensen, Douglas A.; Parker, Dennis L.

    2011-01-01

    Purpose: This study presents the results obtained from both simulation and experimental techniques that show the effect of mechanically or electronically steering a phased array transducer on proximal tissue heating. Methods: The thermal response of a nine-position raster and a 16-mm diameter circle scanning trajectory executed through both electronic and mechanical scanning was evaluated in computer simulations and experimentally in a homogeneous tissue-mimicking phantom. Simulations were performed using power deposition maps obtained from the hybrid angular spectrum (HAS) method and applying a finite-difference approximation of the Pennes’ bioheat transfer equation for the experimentally used transducer and also for a fully sampled transducer to demonstrate the effect of acoustic window, ultrasound beam overlap and grating lobe clutter on near-field heating. Results: Both simulation and experimental results show that electronically steering the ultrasound beam for the two trajectories using the 256-element phased array significantly increases the thermal dose deposited in the near-field tissues when compared with the same treatment executed through mechanical steering only. In addition, the individual contributions of both beam overlap and grating lobe clutter to the near-field thermal effects were determined through comparing the simulated ultrasound beam patterns and resulting temperature fields from mechanically and electronically steered trajectories using the 256-randomized element phased array transducer to an electronically steered trajectory using a fully sampled transducer with 40 401 phase-adjusted sample points. Conclusions: Three distinctly different three distinctly different transducers were simulated to analyze the tradeoffs of selected transducer design parameters on near-field heating. Careful consideration of design tradeoffs and accurate patient treatment planning combined with thorough monitoring of the near-field tissue temperature will

  10. The effect of electronically steering a phased array ultrasound transducer on near-field tissue heating.

    Science.gov (United States)

    Payne, Allison; Vyas, Urvi; Todd, Nick; de Bever, Joshua; Christensen, Douglas A; Parker, Dennis L

    2011-09-01

    This study presents the results obtained from both simulation and experimental techniques that show the effect of mechanically or electronically steering a phased array transducer on proximal tissue heating. The thermal response of a nine-position raster and a 16-mm diameter circle scanning trajectory executed through both electronic and mechanical scanning was evaluated in computer simulations and experimentally in a homogeneous tissue-mimicking phantom. Simulations were performed using power deposition maps obtained from the hybrid angular spectrum (HAS) method and applying a finite-difference approximation of the Pennes' bioheat transfer equation for the experimentally used transducer and also for a fully sampled transducer to demonstrate the effect of acoustic window, ultrasound beam overlap and grating lobe clutter on near-field heating. Both simulation and experimental results show that electronically steering the ultrasound beam for the two trajectories using the 256-element phased array significantly increases the thermal dose deposited in the near-field tissues when compared with the same treatment executed through mechanical steering only. In addition, the individual contributions of both beam overlap and grating lobe clutter to the near-field thermal effects were determined through comparing the simulated ultrasound beam patterns and resulting temperature fields from mechanically and electronically steered trajectories using the 256-randomized element phased array transducer to an electronically steered trajectory using a fully sampled transducer with 40 401 phase-adjusted sample points. Three distinctly different three distinctly different transducers were simulated to analyze the tradeoffs of selected transducer design parameters on near-field heating. Careful consideration of design tradeoffs and accurate patient treatment planning combined with thorough monitoring of the near-field tissue temperature will help to ensure patient safety during an MRg

  11. Transducer hygiene: comparison of procedures for decontamination of ultrasound transducers and their use in clinical practice.

    Science.gov (United States)

    Häggström, Mikael; Spira, Jack; Edelstam, Greta

    2015-02-01

    To determine whether current hygiene practices are appropriate during sonographic examinations. Five major hospitals in Sweden were investigated with a survey. At each hospital, the departments corresponding to the main types of sonographic examination were chosen. Personnel who were responsible for or acquainted with the local hygiene procedures completed a standardardized questionnaire. The surveys were completed by 25 departments, where the total number of sonographic examinations was approximately 20,000 per month. For transvaginal and transrectal sonographic examinations, the most common method for decontamination of the transducer was barrier protection during the procedure followed by cleansing with alcohol. Latex was the predominant cover material, but one department used polyethylene gloves, and another department used nitrile gloves. Both of these involved transvaginal ultrasonography. In transcutaneous examinations, all hospitals were using alcohol and paper or cloth for decontamination at a minimum. Transesophageal examinations were carried out without barrier protection, and decontamination was performed with an alkylating substance. The hygiene practices appear to be appropriate at most hospitals, but there is a prevalence of transducer cover materials of unacceptable permeability, as well as use of gloves on transducers despite insufficient evidence of safety. © 2015 Wiley Periodicals, Inc.

  12. Ultrasonic measurements of surface defects on flexible circuits using high-frequency focused polymer transducers

    Science.gov (United States)

    Wagle, Sanat; Habib, Anowarul; Melandsø, Frank

    2017-07-01

    High-frequency transducers made from a layer-by-layer deposition method are investigated as transducers for ultrasonic imaging. Prototypes of adhesive-free transducers with four active elements were made on a high-performance poly(ether imide) substrate with precision milled spherical cavities used to produce focused ultrasonic beams. The transducer prototypes were characterized using a pulse-echo experimental setup in a water tank using a glass plate as a reflector. Then, transducer was used in a three-dimensional ultrasonic scanning tank, to produce high-resolution ultrasonic images of flexible electronic circuits with the aim to detect defects in the outermost cover layer.

  13. Dual-frequency super harmonic imaging piezoelectric transducers for transrectal ultrasound

    Science.gov (United States)

    Kim, Jinwook; Li, Sibo; Kasoji, Sandeep; Dayton, Paul A.; Jiang, Xiaoning

    2015-03-01

    In this paper, a 2/14 MHz dual-frequency single-element transducer and a 2/22 MHz sub-array (16/48-elements linear array) transducer were developed for contrast enhanced super-harmonic ultrasound imaging of prostate cancer with the low frequency ultrasound transducer as a transmitter for contrast agent (microbubble) excitation and the high frequency transducer as a receiver for detection of nonlinear responses from microbubbles. The 1-3 piezoelectric composite was used as active materials of the single-element transducers due to its low acoustic impedance and high coupling factor. A high dielectric constant PZT ceramic was used for the sub-array transducer due to its high dielectric property induced relatively low electrical impedance. The possible resonance modes of the active elements were estimated using finite element analysis (FEA). The pulse-echo response, peak-negative pressure and bubble response were tested, followed by in vitro contrast imaging tests using a graphite-gelatin tissue-mimicking phantom. The single-element dual frequency transducer (8 × 4 × 2 mm3) showed a -6 dB fractional bandwidth of 56.5% for the transmitter, and 41.8% for the receiver. A 2 MHz-transmitter (730 μm pitch and 6.5 mm elevation aperture) and a 22 MHz-receiver (240 μm pitch and 1.5 mm aperture) of the sub-array transducer exhibited -6 dB fractional bandwidth of 51.0% and 40.2%, respectively. The peak negative pressure at the far field was about -1.3 MPa with 200 Vpp, 1-cycle 2 MHz burst, which is high enough to excite microbubbles for nonlinear responses. The 7th harmonic responses from micro bubbles were successfully detected in the phantom imaging test showing a contrast-to-tissue ratio (CTR) of 16 dB.

  14. Development of a thermal test object for the measurement of ultrasound intracavity transducer self-heating.

    Science.gov (United States)

    Killingback, Alban L T; Newey, Valentine R; El-Brawany, Mohamed A; Nassiri, Dariush K

    2008-12-01

    The elevated surface temperature of diagnostic ultrasound transducers imposes an important limitation to their safe use in clinical situations. Moreover, particular care should be taken if transvaginal transducers are to be used during routine scans in the first few weeks of pregnancy as the transducer surface can be very close to embryonic/fetal tissues. Published results have shown that the heating of tissue due to transducer self-heating can equal and often exceed the acoustic heating contribution. In this article, we report the development of a portable self contained thermal test object (TTO) capable of assessing the self-heating of intracavity diagnostic ultrasound transducers. The thermal conductivity and volumetric heat capacity of the tissue mimicking material (TMM) used in the TTO were measured, yielding values of (0.56 +/- 0.01) W m(-1) K(-1) and (3.5 +/- 0.8) MJ m(-3) K(-1). The speed of sound of the TMM was measured as 1540 m s(-1) and the attenuation over a frequency range of 2 to 10 MHz was found to be (0.50 +/- 0.01) dB cm(-1) MHz(-1). These results are in excellent agreement with the International Electrotechnical Commission (IEC 60601-2-37) requirements and the previously published properties of biological soft tissue. The temperature stability and uniformity, and suitability of the TTO for the measurement of transducer self-heating were tested and found to be satisfactory. The TTO reached a stable temperature of 37 degrees C in 3 h and the spatial variation in temperature was less than +/- 0.2 degrees C. Lastly, transducer self-heating measurements from a transvaginal transducer exceeded the IEC temperature limit of 43 degrees C in less than 5 min and the temperature reached after 30 min was 47.3 degrees C.

  15. Techniques and physical properties of 10MHz short pulse focused ultrasonic transducer

    Institute of Scientific and Technical Information of China (English)

    ZHU Guozhen; YANG Yong; LU Kean

    2004-01-01

    A focused ultrasonic transducer used for biomedical purposes with a fundamental frequency of 10MHz and a pulse width of one and a half periods is described in this paper. Its physical properties are given including (1) focused acoustic field recorded by an optical means, (2) electric waveform for triggering the transducer and the corresponding waveform of the wave received by another transducer, and (3) result of tests on a sample object.

  16. On the Development of Focused Ultrasound Liquid Atomizers

    Directory of Open Access Journals (Sweden)

    Ahmed M. Al-Jumaily

    2017-01-01

    Full Text Available This paper reviews the evolution of focused ultrasonic transducers of various kinds for fluid atomization and vaporization. Ultrasonic transducers used for atomization purposes in biomedical, pharmaceutical, or industrial applications, such as surface acoustic wave (SAW transducers, array of micromachined nozzles, and Fourier horn micromachined nozzles with or without a central channel, are all presented and compared. For simplicity of manufacturing and low cost, we focus on plates and curved and corrugated structures for biomedical humidification.

  17. The thresholds and mechanisms of tissue injury by focused ultrasound

    Science.gov (United States)

    Simon, Julianna

    Therapeutic ultrasound is used in clinics around the world to treat ailments such as uterine fibroids, kidney stones, and plantar fasciitis. While many of the therapeutic effects of ultrasound are elicited by hyperthermia, bubbles can also interact with tissue to produce beneficial effects. For example, bubbles are used in boiling histotripsy to de-bulk tissue and are used in shock wave lithotripsy to break kidney stones. However, the same bubbles that break the kidney stones also damage the kidney, which is why bubble damage is a concern in every ultrasound application including fetal imaging. Whether the aim is to emulsify a tumor or image a fetus, understanding the thresholds and mechanisms of tissue injury by bubbles in an ultrasound field is important for all ultrasound applications and was the goal of this dissertation. One specific application of therapeutic ultrasound, known as boiling histotripsy, uses shock wave heating to explosively expand a millimeter-size boiling bubble at the transducer focus and fractionate bulk tissue. Yet it was unclear how the millimeter-size boiling or vapor bubble broke down the tissue into its submicron components. In this dissertation, we experimentally tested the hypothesis that ultrasonic atomization, or the emission of fine droplets from an acoustically excited liquid film, is the mechanism by which the millimeter-size boiling bubble in boiling histotripsy fractionates tissue into its submicron components. Using high speed photography, we showed that tissue can behave as a liquid such that a miniature acoustic fountain forms and atomization occurs within a millimeter-size cavity that approximates the boiling or vapor bubble produced by boiling histotripsy. The end result of tissue atomization was a hole in the tissue surface. After showing that tissue can be eroded by atomization, a series of experiments were conducted to determine the tissue properties that influence atomization. The results indicated that highly

  18. TOPICAL REVIEW: Capacitive micromachined ultrasonic transducer arrays for minimally invasive medical ultrasound

    Science.gov (United States)

    Chen, Jingkuang

    2010-02-01

    This paper reviews the minimally invasive capacitive micromachined ultrasonic transducer (CMUT) arrays for medical diagnosis and therapy. While piezoelectric transducers dominate today's medical ultrasound market, the capacitive micromachined ultrasonic transducer has recently emerged as a promising alternative which delivers a comparable device performance to its piezoelectric counterparts, is compatible with front-end circuit integration, allows high-density imager integration and is relative easy in miniaturization. Utilizing MEMS technology, the substrate of CMUT arrays can be micromachined into miniature platforms with various geometrical shapes, which include needles, three-dimensional prisms, as well as other flexible-substrate configurations. These arrays are useful for reaching deep inside the tissue or an organ with a minimally invasive approach. Due to the close proximity of the transducers to the target organ/tissue, a higher resolution/accuracy of diagnostic information can be achieved. In addition to pulse-echo and photoacoustic imaging, high-power CMUT devices capable of delivering ultrasounds with a pressure greater than 1.0 MPa have been monolithically integrated with imager CMUTs for image-guided therapy (IGT). Such miniature devices would facilitate diagnostic and therapy interventions not possible with conventional piezoelectric transducers.

  19. Piezoelectric Micromachined Ultrasound Transducer (PMUT Arrays for Integrated Sensing, Actuation and Imaging

    Directory of Open Access Journals (Sweden)

    Yongqiang Qiu

    2015-04-01

    Full Text Available Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs, diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed.

  20. Piezoelectric micromachined ultrasound transducer (PMUT) arrays for integrated sensing, actuation and imaging.

    Science.gov (United States)

    Qiu, Yongqiang; Gigliotti, James V; Wallace, Margeaux; Griggio, Flavio; Demore, Christine E M; Cochran, Sandy; Trolier-McKinstry, Susan

    2015-04-03

    Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs), diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed.

  1. Thin catheter bending in the direction perpendicular to ultrasound propagation using two-dimensional array transducer

    Science.gov (United States)

    Suzuki, Toshiya; Mochizuki, Takashi; Ushimizu, Hidetaka; Miyazawa, Shinya; Tsurui, Nobuhiro; Masuda, Kohji

    2017-07-01

    Although we have already experimented on the bending of a thin catheter with acoustic radiation force using a single transducer, it is necessary to develop a method of bending a catheter in an arbitrary direction because the installation position of ultrasound transducers on a body surface is limited for application to various shapes of in vivo blood vessels. Therefore, we examined the bending of a thin catheter in the direction perpendicular to ultrasound propagation using a two-dimensional array transducer (1 MHz), which realizes not only the temporospatial design but also the dynamic variation of acoustic fields. Forming two focal points with opposite phases, where the amplitudes of the two points instantaneously have the positive and negative relationship, we confirmed the bending of a thin catheter in the direction perpendicular to ultrasound propagation. We used a thin catheter (diameter, 200 µm length, 50 mm) to obtain the maximum displacement of 220 µm, where the displacement was proportional to the square of the maximum sound pressure and the duty ratio. From these results, the acoustic energy densities observed in front of and behind the catheter are dominant for the bending of the thin catheter independent of ultrasound propagation. We also found that the distance between two focal points may improve the bending performance without requiring a precise position setting.

  2. Acoustical cross-talk in row–column addressed 2-D transducer arrays for ultrasound imaging

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt; Thomsen, Erik Vilain

    2015-01-01

    The acoustical cross-talk in row–column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed...... in the frequency-wavenumber domain. The sources of cross-talk are identified and predicted theoretically. The nearest neighbor cross-talk is 23.9±3.7 dB when the array is used as a 1-D array with the rows functioning as both transmitters and receivers. In the row–column configuration, with the columns transmitting...

  3. Micromachined PIN-PMN-PT Crystal Composite Transducer for High-Frequency Intravascular Ultrasound (IVUS) Imaging

    OpenAIRE

    Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K. Kirk

    2014-01-01

    In this paper, we report the use of micromachined PbIn1/2Nb1/2O3–PbMg1/3Nb2/3O3–PbTiO3 (PIN-PMN-PT) single crystal 1–3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at ...

  4. Design and Fabrication of PIN-PMN-PT Single-Crystal High-Frequency Ultrasound Transducers

    OpenAIRE

    Sun, Ping; Zhou, Qifa; Zhu, Benpeng; WU, DAWEI; Hu, Changhong; Cannata, Jonathan M.; Tian, Jin; Han, Pengdi; Wang, Gaofeng; Shung, K. Kirk

    2009-01-01

    High-frequency PIN-PMN-PT single crystal ultrasound transducers at center frequencies of 35 MHz and 60 MHz were successfully fabricated using lead indium niobate-lead magnesium niobate-lead titanate (0.23PIN-0.5PMN-0.27PT) single crystal. The new PIN-PMN-PT single crystal has higher coercivity (6.0 kV/cm) and higher Curie temperature (160°C) than PMN-PT crystal. Experimental results showed that the PIN-PMN-PT transducers have similar performance but better thermal stability compared with the ...

  5. Note: Comparative experimental studies on the performance of 2-2 piezocomposite for medical ultrasound transducers

    Science.gov (United States)

    Marinozzi, F.; Bini, F.; Biagioni, A.; Grandoni, A.; Spicci, L.

    2013-09-01

    The paper reports the experimental investigation of the behavior of 2-2 Lead Zirconate Titanate (PZT)-polymer composite transducers array for clinical ultrasound equipments. Several 2-2 plate composites having the same dicing pitch of 0.11 mm and different volume fractions were manufactured and investigated. Measurements were performed through different techniques such as electrical impedance, pulse-echo, and Laser Doppler Vibrometer. With the last one, maps of the surface displacement were presented relative to thickness mode and first lateral mode resonance frequencies. The transducers with volume fractions of the 40% resulted markedly inefficient, whereas the largest bandwidth and best band shape were achieved by the 50%.

  6. Treatment of Movement Disorders With Focused Ultrasound

    Directory of Open Access Journals (Sweden)

    Paul S Fishman

    2017-05-01

    Full Text Available Although the use of ultrasound as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists or neurologists are familiar with this technology. Stereotactic brain lesioning had been widely used as a treatment for medically refractory patients with essential tremor (ET, Parkinson disease (PD, and dystonia but has been largely replaced by deep brain stimulation (DBS surgery, with advantages both in safety and efficacy. However, DBS is associated with complications including intracerebral hemorrhage, infection, and hardware malfunction. The occurrence of these complications has spurred interest in less invasive stereotactic brain lesioning methods including magnetic resonance imaging–guided high intensity–focused ultrasound (FUS surgery. Engineering advances now allow sound waves to be targeted noninvasively through the skull to a brain target. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull, recent Food and Drug Administration approval of unilateral thalamotomy for treatment of ET. Clinical studies of stereotactic FUS for aspects of PD are underway. Moderate intensity, pulsed FUS has also demonstrated the potential to safely open the blood-brain barrier for localized delivery of therapeutics including proteins, genes, and cell-based therapy for PD and related disorders. The goal of this review is to provide basic and clinical neuroscientists with a level of understanding to interact with medical physicists, biomedical engineers, and radiologists to accelerate the application of this powerful technology to brain disease

  7. Handheld probe integrating laser diode and ultrasound transducer array for ultrasound/photoacoustic dual modality imaging

    NARCIS (Netherlands)

    Daoudi, K.; Berg, van den P.J.; Rabot, O.; Kohl, A.; Tisserand, S.; Brands, P.J.; Steenbergen, W.

    2014-01-01

    Ultrasound and photoacoustics can be utilized as complementary imaging techniques to improve clinical diagnoses. Photoacoustics provides optical contrast and functional information while ultrasound provides structural and anatomical information. As of yet, photoacoustic imaging uses large and expens

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

    Science.gov (United States)

    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.

  9. Ultrasound backscatter microscope using PZT, fine-grain PZT, and single-crystal perovskite transducers

    Science.gov (United States)

    Olbrish, Kenneth D.; Zipparo, Michael J.; Lopath, Patrick D.; Yu, Clarence; Shrout, Thomas R.; Shung, K. Kirk

    1997-04-01

    Higher frequency ultrasound is rapidly becoming an important tool for dermatologic and ophthalmologic imaging. This brings about a need for improvement in single element transducers operating in the frequency range between 40 MHz and 100 MHz. Several piezoelectric materials may yield improved performance over common lead zirconate titanate (PZT) transducers. This study investigated several different materials incorporated into single element transducers. A static ultrasonic backscatter microscope (UBM) was constructed in the laboratory. This system allowed for a comparative testing of the imaging performance of various transducers. B-mode scans made by individual transducers show differences in image resolution. Clinically, these differences may be important to allow finer detail to be observed in a structure. Not only does this work show differences between transducers constructed from various materials, but it does so in an application-based environment. Previously, only a limited number of materials were used in such a system. This study showed results from several materials that had not been demonstrated before.

  10. Accurate acoustic power measurement for low-intensity focused ultrasound using focal axial vibration velocity

    Science.gov (United States)

    Tao, Chenyang; Guo, Gepu; Ma, Qingyu; Tu, Juan; Zhang, Dong; Hu, Jimin

    2017-07-01

    Low-intensity focused ultrasound is a form of therapy that can have reversible acoustothermal effects on biological tissue, depending on the exposure parameters. The acoustic power (AP) should be chosen with caution for the sake of safety. To recover the energy of counteracted radial vibrations at the focal point, an accurate AP measurement method using the focal axial vibration velocity (FAVV) is proposed in explicit formulae and is demonstrated experimentally using a laser vibrometer. The experimental APs for two transducers agree well with theoretical calculations and numerical simulations, showing that AP is proportional to the square of the FAVV, with a fixed power gain determined by the physical parameters of the transducers. The favorable results suggest that the FAVV can be used as a valuable parameter for non-contact AP measurement, providing a new strategy for accurate power control for low-intensity focused ultrasound in biomedical engineering.

  11. Micromachined ultrasound transducers with improved coupling factors from a CMOS compatible process

    Science.gov (United States)

    Eccardt; Niederer

    2000-03-01

    For medical high frequency acoustic imaging purposes the reduction in size of a single transducer element for one-dimensional and even more for two-dimensional arrays is more and more limited by fabrication and cabling technology. In the fields of industrial distance measurement and simple object recognition low cost phased arrays are lacking. Both problems can be solved with micromachined ultrasound transducers (MUTs). A single transducer is made of a large number of microscopic elements. Because of the array structure of these transducers, groups of elements can be built up and used as a phased array. By integrating parts of the sensor electronics on chip, the cabling effort for arrays can be reduced markedly. In contrast to standard ultrasonic technology, which is based on massive thickness resonators, vibrating membranes are the radiating elements of the MUTs. New micromachining technologies have emerged, allowing a highly reproducible fabrication of electrostatically driven membranes with gap heights below 500 nm. A microelectronic BiCMOS process was extended for surface micromechanics (T. Scheiter et al., Proceedings 11th European Conference on Solid-State Transducers, Warsaw, Vol. 3, 1997, pp. 1595-1598). Additional process steps were included for the realization of the membranes which form sealed cavities with the underlying substrate. Membrane and substrate are the opposite electrodes of a capacitive transducer. The transducers can be integrated monolithically on one chip together with the driving, preamplifying and multiplexing circuitry, thus reducing parasitic capacities and noise level significantly. Owing to their low mass the transducers are very well matched to fluid loads, resulting in a very high bandwidth of 50-100% (C. Eccardt et al., Proceedings Ultrasonics Symposium, San Antonio, Vol. 2, 1996, pp. 959-962; P.C. Eccardt et al., Proceedings of the 1997 Ultrasonics Symposium, Toronto, Vol. 2, 1997, pp. 1609-1618). In the following it is shown how

  12. The ultrasound brain helmet: new transducers and volume registration for in vivo simultaneous multi-transducer 3-D transcranial imaging.

    Science.gov (United States)

    Lindsey, Brooks D; Light, Edward D; Nicoletto, Heather A; Bennett, Ellen R; Laskowitz, Daniel T; Smith, Stephen W

    2011-06-01

    Because stroke remains an important and time-sensitive health concern in developed nations, we present a system capable of fusing 3-D transcranial ultrasound volumes acquired from two sides of the head. This system uses custom sparse array transducers built on flexible multilayer circuits that can be positioned for simultaneous imaging through both temporal acoustic windows, allowing for potential registration of multiple real-time 3-D scans of cerebral vasculature. We examine hardware considerations for new matrix arrays-transducer design and interconnects-in this application. Specifically, it is proposed that SNR may be increased by reducing the length of probe cables. This claim is evaluated as part of the presented system through simulation, experimental data, and in vivo imaging. Ultimately, gains in SNR of 7 dB are realized by replacing a standard probe cable with a much shorter flex interconnect; higher gains may be possible using ribbon-based probe cables. In vivo images are presented, showing cerebral arteries with and without the use of microbubble contrast agent; they have been registered and fused using a simple algorithm which maximizes normalized cross-correlation.

  13. An FPGA-based ultrasound imaging system using capacitive micromachined ultrasonic transducers.

    Science.gov (United States)

    Wong, Lawrence L P; Chen, Albert I; Logan, Andrew S; Yeow, John T W

    2012-07-01

    We report the design and experimental results of a field-programmable gate array (FPGA)-based real-time ultrasound imaging system that uses a 16-element phased-array capacitive micromachined ultrasonic transducer fabricated using a fusion bonding process. The imaging system consists of the transducer, discrete analog components situated on a custom-made circuit board, the FPGA, and a monitor. The FPGA program consists of five functional blocks: a main counter, transmit and receive beamformer, receive signal pre-processing, envelope detection, and display. No dedicated digital signal processor or personal computer is required for the imaging system. An experiment is carried out to obtain the sector B-scan of a 4-wire target. The ultrasound imaging system demonstrates the possibility of an integrated system-in-a-package solution.

  14. Polyimide-etalon all-optical ultrasound transducer for high frequency applications

    Science.gov (United States)

    Sheaff, Clay; Ashkenazi, Shai

    2014-03-01

    We have enhanced our design for an all-optical high frequency ultrasound transducer consisting of a UV-absorbing polyimide film integrated into an etalon receiver operating in the NIR range. A dielectric stack having high NIR reflectivity and high UV transmittance was chosen as the first mirror for increased sensitivity and the allowance of polyimide as the etalon medium. A 13 ns, 0.7 μJ optical pulse at 355 nm and a continuous-wave NIR laser were focused onto the structure with a spot diameter of 120 and 35 μm, respectively. In receive mode the etalon had a noise-equivalent pressure of 4.1 kPa over a bandwidth of 5 - 50 MHz (0.61 Pa/√Hz ). The device generated a pressure of 270 kPa at a depth of 200 μm, and the -3 dB bandwidth of the emission extended from 27 to 60 MHz. In transmit/receive mode, the pulse-echo had a center frequency of 35 MHz with a -6 dB bandwidth of 49 MHz (140 %). Lastly, wire targets were imaged by scanning the UV spot to create a synthetic aperture of transmitters centered upon a single receiver.

  15. Quantitative assessment of photoacoustic tomography systems integrating clinical ultrasound transducers using novel tissue-simulating phantoms

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, Joshua

    2015-03-01

    Photoacoustic Tomography (PAT) systems based on commercial ultrasound instruments have the benefit of dualmodality imaging, which increases their appeal from a clinical standpoint. However, factors that influence PAT system performance have not been thoroughly investigated and standardized test methods have not been established for image quality evaluation. To address these issues we have adapted phantom-based approaches from ultrasound imaging standards and implemented them to assess a PAT system developed for vascular imaging. Our system comprises a tunable near-infrared pulsed laser and a commercial ultrasound imaging system, including four interchangeable linear array clinical ultrasound transducers with varying center frequencies, acoustic bandwidths and geometries. Phantoms consisted of a customized polyvinyl chloride (PVC) plastisol gel that simulates both optical and acoustic properties of breast tissue. One phantom incorporates a sub-resolution filament array suitable for bimodal ultrasound-photoacoustic imaging, while another contains an array of hemoglobin-filled cylindrical inclusions at various depths. Key performance characteristics were evaluated, including spatial resolution, signal uniformity, contrast, and penetration depth. These characteristics were evaluated at 750 nm at radiant exposures below ANSI safety limits. Effects of transducer properties on imaging performance were evaluated. Axial and lateral resolution ranged from 0.27-0.83 mm and 0.28-1.8 mm, respectively, and penetration depths from 1.9-4.2 cm were achieved. These results demonstrate variation in PAT system performance based on clinical transducer selection, as well as the utility of realistic phantom-based test methods in performing benchtop evaluations of system performance.

  16. Lead-Free Intravascular Ultrasound Transducer Using BZT-50BCT Ceramics

    Science.gov (United States)

    Yan, Xingwei; Lam, Kwok Ho; Li, Xiang; Chen, Ruimin; Ren, Wei; Ren, Xiaobing; Zhou, Qifa; Shung, K. Kirk

    2013-01-01

    This paper reports the fabrication and evaluation of a high-frequency ultrasonic transducer based on a new lead-free piezoelectric material for intravascular imaging application. Lead-free 0.5Ba(Zr0.2Ti0.8)O3−0.5(Ba0.7Ca0.3)TiO3 (BZT-50BCT) ceramic with a high dielectric constant (~2800) was employed to develop a high-frequency (~30 MHz) needle-type ultrasonic transducer. With superior piezoelectric performance (piezoelectric coefficient d33 ~ 600 pC/N), the lead-free transducer was found to exhibit a −6-dB bandwidth of 53% with an insertion loss of 18.7 dB. In vitro intravascular ultrasound (IVUS) imaging of a human cadaver coronary artery was performed to demonstrate the potential of the lead-free transducer for biomedical imaging applications. This is the first time that a lead-free transducer has been used for IVUS imaging application. The experimental results suggest that the BZT-50BCT ceramic is a promising lead-free piezoelectric material for high-frequency intravascular imaging applications. PMID:25004492

  17. Histotripsy Lesion Formation Using an Ultrasound Imaging Probe Enabled by a Low-Frequency Pump Transducer.

    Science.gov (United States)

    Lin, Kuang-Wei; Hall, Timothy L; Xu, Zhen; Cain, Charles A

    2015-08-01

    advantages: (i) lesion steering can be achieved using the steering of the imaging transducer (implemented with the beamformer of the accompanying programmable ultrasound system), and (ii) treatment can be simultaneously monitored when the imaging transducer is used in conjunction with an ultrasound imaging system. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  18. Noninvasive skin tightening: focus on new ultrasound techniques

    Directory of Open Access Journals (Sweden)

    Fabi SG

    2015-02-01

    Full Text Available Sabrina Guillen Fabi Goldman, Butterwick, Fitzpatrick, Groff and Fabi, Cosmetic Laser Dermatology, San Diego, CA, USA Abstract: Microfocused ultrasound (MFU has been recently developed to meet the ever-growing public demand for achieving significant, noninvasive skin lifting and tightening. MFU can be focused on subcutaneous tissue where the temperature briefly reaches greater than 60°C, producing small (<1 mm3 thermal coagulation points to a depth of up to 5 mm within the mid-to-deep reticular layer of the dermis and subdermis. The intervening papillary dermal and epidermal layers of skin remain unaffected. The application of heat at these discrete thermal coagulation points causes collagen fibers in the facial planes such as the superficial musculoaponeurotic system and platysma, as well as the deep reticular dermis, to become denatured, contracting and stimulating de novo collagen. A commercially available device combines MFU with high-resolution ultrasound imaging (MFU-V, which enables visualization of tissue planes to a depth of 8 mm and allows the user to see where the MFU energy will be applied (Ultherapy®; Ulthera Inc., Mesa, AZ, USA. Using different transducers, MFU-V treatment can be customized to meet the unique physical characteristics of each patient by adjusting energy and focal depth of the emitted ultrasound. By targeting the facial superficial musculoaponeurotic system, noninvasive tightening and lifting of sagging facial and neck skin and improvements in the appearance of wrinkles can be achieved. MFU-V can also improve lines and wrinkles of the décolleté. Treatment protocols for the use of MFU-V continue to be refined, and its use in combination with other rejuvenation techniques has been demonstrated. Brief discomfort that often occurs during treatment can be minimized with oral nonsteroidal anti-inflammatory drugs. Other treatment-related adverse events include transient erythema, edema, and occasional bruising. MFU-V is

  19. Nonlinear Effects in Ultrasound Fields of Diagnostic-type Transducers Used for Kidney Stone Propulsion: Characterization in Water

    Science.gov (United States)

    Karzova, M.; Cunitz, B.; Yuldashev, P.; Andriyakhina, Y.; Kreider, W.; Sapozhnikov, O.; Bailey, M.; Khokhlova, V.

    2016-01-01

    Newer imaging and therapeutic ultrasound technologies require higher in situ pressure levels compared to conventional diagnostic values. One example is the recently developed use of focused ultrasonic radiation force to move kidney stones and residual fragments out of the urinary collecting system. A commercial diagnostic 2.3 MHz C5-2 array probe is used to deliver the acoustic pushing pulses. The probe comprises 128 elements equally spaced at the 55 mm long convex cylindrical surface with 38 mm radius of curvature. The efficacy of the treatment can be increased by using higher transducer output to provide stronger pushing force; however, nonlinear acoustic saturation effect can be a limiting factor. In this work nonlinear propagation effects were analyzed for the C5-2 transducer using a combined measurement and modeling approach. Simulations were based on the 3D Westervelt equation; the boundary condition was set to match low power pressure beam scans. Focal waveforms simulated for increased output power levels were compared with the fiber-optic hydrophone measurements and were found in good agreement. It was shown that saturation effects do limit the acoustic pressure in the focal region of the transducer. This work has application to standard diagnostic probes and imaging. PMID:27087711

  20. Free Field Reciprocity Calibration in a Convergent Spherical Acoustic Wave of a Focusing Transducer

    Institute of Scientific and Technical Information of China (English)

    寿文德; 严加勇; 王鸿樟; 钱德初

    2002-01-01

    Based on the reciprocity theorem of the acoustic field, we derive the formula of the reciprocity coefficient of a convergent spherical acoustic wave and we calculate a series of diffraction corrective factor curves of the reciprocity coefficient of transducers. Using these formulae and corrective factors, we calibrate the free field transmitting current response and the free field voltage sensitivity of a focusing transducer using the self-reciprocity method.The experimental results of the reciprocity calibration of the focusing transducer in the frequency range of 2 MHz to 5.4 MHz are presented.

  1. Treatment of glaucoma with high intensity focused ultrasound.

    Science.gov (United States)

    Aptel, Florent; Lafon, Cyril

    2015-05-01

    Glaucoma is a common disease mainly due to an increase in pressure inside the eye, leading to a progressive destruction of the optic nerve, potentially to blindness. Intraocular pressure (IOP) is the result of a balance between production of liquid that fills the eye--aqueous humour--and its resorption. All treatments for glaucoma aim to reduce IOP and can therefore have two mechanisms of action: reducing aqueous humour production by the partial destruction or medical inhibition of the ciliary body--the anatomical structure responsible for production of aqueous humour--or facilitating the evacuation of aqueous humour from the eye. Several physical methods can be used to destroy the ciliary body, e.g. laser, cryotherapy, microwave. All these methods have two major drawbacks: they are non-selective for the organ to be treated and they have an unpredictable dose–effect relationship. High intensity focused ultrasound (HIFU) can be used to coagulate the ciliary body and avoid these drawbacks. A commercially available device was marketed in the 1980s, but later abandoned, essentially for technical reasons. A smaller circular device using miniaturised transducers was recently developed and proposed for clinical practice. Experimental studies have shown selective coagulation necrosis of the treated ciliary body. The first three clinical trials in humans have shown that this device was well tolerated and allowed a significant, predictable and sustained reduction of IOP. The aim of this contribution is to present a summary of the work concerning the use of HIFU to treat glaucoma.

  2. Dual-Element Transducer with Phase-Inversion for Wide Depth of Field in High-Frequency Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    Jong Seob Jeong

    2014-08-01

    Full Text Available In high frequency ultrasound imaging (HFUI, the quality of focusing is deeply related to the length of the depth of field (DOF. In this paper, a phase-inversion technique implemented by a dual-element transducer is proposed to enlarge the DOF. The performance of the proposed method was numerically demonstrated by using the ultrasound simulation program called Field-II. A simulated dual-element transducer was composed of a disc- and an annular-type elements, and its aperture was concavely shaped to have a confocal point at 6 mm. The area of each element was identical in order to provide same intensity at the focal point. The outer diameters of the inner and the outer elements were 2.1 mm and 3 mm, respectively. The center frequency of each element was 40 MHz and the f-number (focal depth/aperture size was two. When two input signals with 0° and 180° phases were applied to inner and outer elements simultaneously, a multi-focal zone was generated in the axial direction. The total −6 dB DOF, i.e., sum of two −6 dB DOFs in the near and far field lobes, was 40% longer than that of the conventional single element transducer. The signal to noise ratio (SNR was increased by about two times, especially in the far field. The point and cyst phantom simulation were conducted and their results were identical to that of the beam pattern simulation. Thus, the proposed scheme may be a potential method to improve the DOF and SNR in HFUI.

  3. Optical micromachined ultrasound transducers (OMUT) - a new approach for high resolution imaging

    Science.gov (United States)

    Tadayon, M. A.; Ashkenazi, S.

    2013-03-01

    Piezoelectric ultrasound (US) transducers are at the heart of almost any ultrasonic medical imaging probe. However, their sensitivity and reliability severely degrade in applications requiring high frequency (>20 MHz) and small element size (construct micron-size air cavities capped by an elastic membrane. The membrane functions as the active ultrasound transmitter and receiver. We will describe the design and testing of prototype OMUT devices which implement a receive-only function. The cavity detector is an optical cavity which its top mirror is deflected under the application of pressure. The intensity of a reflected light beam is highly sensitive to displacement of the top membrane if the optical wavelength is at near-resonance condition. Therefore, US pulses can be detected by recording the reflected light intensity. The sensitivity of the device depends on the mechanical properties of the top membrane and optical characteristics of the optical cavity. The device was fabricated using SU8 as a structural material and gold as a mirror. We have developed a new bonding method to fabricate a sealed, low roughness, high quality optical cavity. The 60μm cavity with the 8.5 μm top membrane is tested in water with 25MHz ultrasound transducer. The NEP of the device for bandwidth of 28MHz was 9.25kPa. The optical cavity has a finesse of around 23.

  4. Analysis of acoustic impedance matching in dual-band ultrasound transducers.

    Science.gov (United States)

    Myhre, Ola Finneng; Johansen, Tonni Franke; Johan Angelsen, Bjørn Atle

    2017-02-01

    Dual-frequency band probes are needed for ultrasound (US) reverberation suppression and are useful for image-guided US therapy. A challenge is to design transducer stacks that achieve high bandwidth and efficiency at both operating frequencies when the frequencies are widely separated with a frequency ratio ∼6:1-20:1. This paper studies the loading and backing conditions of transducers in such stacks. Three stack configurations are presented and analyzed using one-dimensional models. It is shown that a configuration with three layers of material separating the transducers is favorable, as it reduces high frequency ringing by ∼20 dB compared to other designs, and matches the low frequency (LF) transducer to the load at a lower frequency. In some cases, the LF load matching is governed by a simple mass-spring interaction in spite of having a complicated matching structure. The proposed design should yield improved performance of reverberation suppression algorithms. Its suitability for reduction of probe heating, also in single-band probes, should be investigated.

  5. Focusing Modeling of OPFC Linear Array Transducer by Using Distributed Point Source Method

    Directory of Open Access Journals (Sweden)

    Ziping Wang

    2014-01-01

    Full Text Available The improvement of ultrasonic phased array detection technology is a major concern of engineering community. Orthotropic piezoelectric fiber composite (OPFC can be constructed to multielement linear array which may be applied conveniently to actuators and sensors. The phased array transducers can generate special directional strong actuator power and high sensitivity for its orthotropic performance. Focusing beam of the linear phased array transducer is obtained simply only by adjusting a parabolic time delay. In this work, the distributed point source method (DPSM is used to model the ultrasonic field. DPSM is a newly developed mesh-free numerical technique that has been developed for solving a variety of engineering problems. This work gives the basic theory of this method and solves the problems from the application of new OPFC phased array transducer. Compared with traditional transducer, the interaction effect of two OPFC linear phased array transducers is also modeled in the same medium, which shows that the pressure beam produced by the new transducer is narrower or more collimated than that produced by the conventional transducer at different angles. DPSM can be used to analyze and optimally design the OPFC linear phased array transducer.

  6. The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound.

    Science.gov (United States)

    Mauldin, F William; Owen, Kevin; Tiouririne, Mohamed; Hossack, John A

    2012-06-01

    The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the linear-array geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bone-like) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact.

  7. Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Svendsen, Niels Bruun

    1992-01-01

    A method for simulation of pulsed pressure fields from arbitrarily shaped, apodized and excited ultrasound transducers is suggested. It relies on the Tupholme-Stepanishen method for calculating pulsed pressure fields, and can also handle the continuous wave and pulse-echo case. The field...... is calculated by dividing the surface into small rectangles and then Summing their response. A fast calculation is obtained by using the far-field approximation. Examples of the accuracy of the approach and actual calculation times are given...

  8. New technique for fabrication of high frequency piezoelectric Micromachined Ultrasound Transducers

    DEFF Research Database (Denmark)

    Pedersen, T; Thomsen, Erik Vilain; Zawada, T

    2008-01-01

    A novel technique for fabrication of linear arrays of high frequency piezoelectric Micromachined Ultrasound Transducers (pMUT) on silicon substrates is presented. Piezoelectric elements are formed by deposition of PZT ((PbZrxTi1-x)O3) into etched features of the silicon substrate...... such that the depth of these features determine the element thickness and hence the resonance frequency. The process leaves a near planar surface which is ideal for further wafer level processing such as top electrode and interconnect formation. A fabricated single element is characterized by pulse echo response....

  9. A New Method of Designing Electrical Impedance Matching Network for Piezoelectric Ultrasound Transducer

    Directory of Open Access Journals (Sweden)

    Jianfei An

    2014-01-01

    Full Text Available A new method that is based on genetic algorithm (GA is developed to design electrical impedance matching network for broadband piezoelectric ultrasound transducer. The new method can both optimize the topology of the matching network and perform optimization on the components at the same time. Results of classical algorithms are referenced to reduce the number of candidate topologies and greatly simplify the calculation process. Some calculation strategies, such as elitist strategy and clearing niche method, are adopted during optimization to make sure that the algorithm can convergence to global optimal result. Simulation results show that the new method has advantages over designing complex impedance matching network.

  10. Calibration of ultrasound backscatter temperature imaging for high-intensity focused ultrasound treatment planning.

    Science.gov (United States)

    Civale, John; Rivens, Ian; Ter Haar, Gail; Morris, Hugh; Coussios, Constantin; Friend, Peter; Bamber, Jeffrey

    2013-09-01

    High-intensity focused ultrasound (HIFU) is rapidly gaining acceptance as a non-invasive method for soft tissue tumor ablation, but improvements in the methods of treatment delivery, planning and monitoring are still required. Backscatter temperature imaging (BTI) uses ultrasound to visualize heating-induced echo strain and may be used to indicate the position of the HIFU focal region using low-power "sub-lesioning" exposure. The technique may also provide a quantitative tool for assessing the efficacy of treatment delivery if apparent strain measurements can be related to the underlying temperature rise. To obtain temperature estimates from strain measurements, the relationship between these variables has to be either measured or otherwise assumed from previous calibrations in similar tissues. This article describes experimental measurements aimed at deriving the relationship between temperature rise and apparent strain in the laboratory environment using both ex vivo bovine liver tissue samples and normothermically perfused porcine livers. A BTI algorithm was applied to radiofrequency ultrasound echo data acquired from a clinical ultrasound scanner (Z.One, Zonare Medical Systems, Mountain View, CA, USA) where the imaging probe was aligned with the focal region of a HIFU transducer. Temperature measurements were obtained using needle thermocouples implanted in the liver tissue. A series of "non-ablative" HIFU exposures giving peak temperatures below 10°C were made in three separate ex vivo bovine livers, yielding an average strain/temperature coefficient of 0.126 ± 0.088 percentage strain per degree Celsius. In the perfused porcine livers at a starting temperature of 38°C (normal body temperature) the strain/temperature coefficients were found to be 0.040 ± 0.029 percentage strain per degree Celsius. The uncertainty in these results is directly linked to the precision of the strain measurement, as well as the naturally occurring variance between different

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

    Science.gov (United States)

    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.

  12. Modeling of Nonlinear Propagation in Multi-layer Biological Tissues for Strong Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    FAN Ting-Bo; LIU Zhen-Bo; ZHANG Zhe; ZHANG DONG; GONG Xiu-Fen

    2009-01-01

    A theoretical model of the nonlinear propagation in multi-layered tissues for strong focused ultrasound is proposed. In this model, the spheroidal beam equation (SBE) is utilized to describe the nonlinear sound propagation in each layer tissue, and generalized oblique incidence theory is used to deal with the sound transmission between two layer tissues. Computer simulation is performed on a fat-muscle-liver tissue model under the irradiation of a 1 MHz focused transducer with a large aperture angle of 35°. The results demonstrate that the tissue layer would change the amplitude of sound pressure at the focal region and cause the increase of side petals.

  13. Nonlinear effects in ultrasound fields of diagnostic-type transducers used for kidney stone propulsion: Characterization in water

    Energy Technology Data Exchange (ETDEWEB)

    Karzova, M., E-mail: masha@acs366.phys.msu.ru [Laboratoire de Mécanique des Fluides et d’Acoustique, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Cunitz, B.; Kreider, W.; Bailey, M. [Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40" t" h Street, Seattle, WA 98105 (United States); Yuldashev, P.; Andriyakhina, Y. [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Sapozhnikov, O.; Khokhlova, V. [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation); Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40" t" h Street, Seattle, WA 98105 (United States)

    2015-10-28

    Newer imaging and therapeutic ultrasound technologies require higher in situ pressure levels compared to conventional diagnostic values. One example is the recently developed use of focused ultrasonic radiation force to move kidney stones and residual fragments out of the urinary collecting system. A commercial diagnostic 2.3 MHz C5-2 array probe is used to deliver the acoustic pushing pulses. The probe comprises 128 elements equally spaced at the 55 mm long convex cylindrical surface with 38 mm radius of curvature. The efficacy of the treatment can be increased by using higher intensity at the focus to provide stronger pushing force; however, nonlinear acoustic saturation can be a limiting factor. In this work nonlinear propagation effects were analyzed for the C5-2 transducer using a combined measurement and modeling approach. Simulations were based on the 3D Westervelt equation; the boundary condition was set to match the focal geometry of the beam as measured at a low power output. Focal waveforms simulated for increased output power levels were compared with the fiber-optic hydrophone measurements and were found in good agreement. It was shown that saturation effects do limit the acoustic pressure in the focal region of the transducer. This work has application to standard diagnostic probes and imaging.

  14. Acoustic characterization of multi-element, dual-frequency transducers for high-intensity contact ultrasound therapy

    Science.gov (United States)

    Burtnyk, M.; N'Djin, W. A.; Persaud, L.; Bronskill, M.; Chopra, R.

    2012-10-01

    High-intensity contact ultrasound therapy can generate precise volumes of thermal damage in deep-seated tissue using interstitial or intracavitary devices. Multi-element, dual-frequency transducers offer increased spatial control of the heating pattern by enabling modulation of ultrasound power and frequency along the device. The performance and acoustic coupling between elements of simple, multi-element, dual-frequency transducers was measured. Transducer arrays were fabricated by cutting halfway through a rectangular plate of PZT, creating individual 4 × 5 mm segments with fundamental frequency (4.1 MHz) and third harmonic (13.3 MHz). Coupling between elements was investigated using a scanning laser vibrometer to measure transducer surface displacements at each frequency and different acoustic powers (0, 10, 20 W/cm2). The measured acoustic power was proportional to the input electrical power with no hysteresis and efficiencies >50% at both frequencies. Maximum transducer surface displacements were observed near element centers, reducing to ˜1/3-maximum near edges. The power and frequency of neighboring transducer segments had little impact on an element's output. In the worst case, an element operating at 4.1 MHz and 20 W/cm2 coupled only 1.5 W/cm2 to its immediate neighboring element. Multi-element, dual-frequency transducers were successfully constructed using a simple dicing method. Coupling between elements was minor, therefore the power and frequency of each transducer element could be considered independent.

  15. Improving the thermal dimensional stability of flexible polymer composite backing materials for ultrasound transducers.

    Science.gov (United States)

    State, Mihai; Brands, Peter J; van de Vosse, Frans N

    2010-04-01

    Novel ultrasound backing materials based on polymer composites with improved dimensional stability and low coefficient of thermal expansion are being developed and analyzed. For this purpose a filled epoxy resin (Stycast(1265)), a commonly used backing material, was considered reference material and polyurethane composites (PU(2305), PU(2350)) were proposed as better alternatives. When compared to the reference, the PU(2350) filled with a mixture of Al(2)O(3) and tungsten exhibited an approximately 15 times lower glassy transition temperature and a 2.5 time lower longitudinal thermal expansion at 20 degrees C. This ensures that within the entire operational temperature range the backing material is flexible, minimizing the thermal stresses induced onto transducer elements soldered joints and piezoceramic core. For the same material, the attenuation at 5MHz was similar to the reference material while at 7 and 8.5MHz it was 33% and 54% higher respectively. From these analyses it is concluded that the newly developed polyurethane composites outperform the reference backing with respect to the thermal dimensional stability as well as to the damping properties. An integrated rigorous mechano-acoustical approach is being proposed as an appropriate passive material design path. It can be easily extended to any other passive materials used for ultrasound transducer conception.

  16. Micromachined PIN-PMN-PT crystal composite transducer for high-frequency intravascular ultrasound (IVUS) imaging.

    Science.gov (United States)

    Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K Kirk

    2014-07-01

    In this paper, we report the use of micromachined PbIn1/2Nb1/2O3-PbMg1/3Nb2/3O3-PbTiO 3 (PIN-PMNPT) single crystal 1-3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT.

  17. Micromachined PIN-PMN-PT Crystal Composite Transducer for High-Frequency Intravascular Ultrasound (IVUS) Imaging

    Science.gov (United States)

    Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K. Kirk

    2015-01-01

    In this paper, we report the use of micromachined PbIn1/2Nb1/2O3–PbMg1/3Nb2/3O3–PbTiO3 (PIN-PMN-PT) single crystal 1–3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT. PMID:24960706

  18. Highly precise acoustic calibration method of ring-shaped ultrasound transducer array for plane-wave-based ultrasound tomography

    Science.gov (United States)

    Terada, Takahide; Yamanaka, Kazuhiro; Suzuki, Atsuro; Tsubota, Yushi; Wu, Wenjing; Kawabata, Ken-ichi

    2017-07-01

    Ultrasound computed tomography (USCT) is promising for a non-invasive, painless, operator-independent and quantitative system for breast-cancer screening. Assembly error, production tolerance, and aging-degradation variations of the hardwire components, particularly of plane-wave-based USCT systems, may hamper cost effectiveness, precise imaging, and robust operation. The plane wave is transmitted from a ring-shaped transducer array for receiving the signal at a high signal-to-noise-ratio and fast aperture synthesis. There are four signal-delay components: response delays in the transmitters and receivers and propagation delays depending on the positions of the transducer elements and their directivity. We developed a highly precise calibration method for calibrating these delay components and evaluated it with our prototype plane-wave-based USCT system. Our calibration method was found to be effective in reducing delay errors. Gaps and curves were eliminated from the plane wave, and echo images of wires were sharpened in the entire imaging area.

  19. The effects of focused transducer geometry and sample size on the measurement of ultrasonic transmission properties

    Energy Technology Data Exchange (ETDEWEB)

    Atkins, T J; Duck, F A; Tooley, M A [Department of Medical Physics and Bioengineering, Royal United Hospital, Combe Park, Bath BA1 3NG (United Kingdom); Humphrey, V F, E-mail: timothy.atkins@nhs.net [Institute of Sound and Vibration Research, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2011-02-01

    The response of two coaxially aligned weakly focused ultrasonic transducers, typical of those employed for measuring the attenuation of small samples using the immersion method, has been investigated. The effects of the sample size on transmission measurements have been analyzed by integrating the sound pressure distribution functions of the radiator and receiver over different limits to determine the size of the region that contributes to the system response. The results enable the errors introduced into measurements of attenuation to be estimated as a function of sample size. A theoretical expression has been used to examine how the transducer separation affects the receiver output. The calculations are compared with an experimental study of the axial response of three unpaired transducers in water. The separation of each transducer pair giving the maximum response was determined, and compared with the field characteristics of the individual transducers. The optimum transducer separation, for accurate estimation of sample properties, was found to fall between the sum of the focal distances and the sum of the geometric focal lengths as this reduced diffraction errors.

  20. Progress in developing a thermal method for measuring the output power of medical ultrasound transducers that exploits the pyroelectric effect.

    Science.gov (United States)

    Zeqiri, Bajram; Zauhar, Gordana; Hodnett, Mark; Barrie, Jill

    2011-05-01

    Progress in developing a new measurement method for ultrasound output power is described. It is a thermal-based technique with the acoustic power generated by a transducer being absorbed within a specially developed polyurethane rubber material, whose high absorption coefficient ensures energy deposition within a few mm of the ultrasonic wave entering the material. The rate of change of temperature at the absorber surface is monitored using the pyroelectric voltage generated from electrodes disposed either side of a 60 mm diameter, 0.061 mm thick membrane of the piezoelectric polymer polyvinylidene fluoride (pvdf) bonded to the absorber. The change in the pyroelectric output voltage generated by the sensor when the transducer is switched ON and OFF is proportional to the delivered ultrasound power. The sensitivity of the device is defined as the magnitude of these switch voltages to a unit input stimulus of power (watt). Three important aspects of the performance of the pyroelectric sensor have been studied. Firstly, measurements have revealed that the temperature dependent sensitivity increases over the range from approximately 20°C to 30°C at a rate of +1.6% °C(-1). Studies point to the key role that the properties of both the absorbing backing layer and pvdf membrane play in controlling the sensor response. Secondly, the high sensitivity of the technique has been demonstrated using an NPL Pulsed Checksource, a 3.5 MHz focused transducer delivering a nominal acoustic power level of 4 mW. Finally, proof-of-concept of a new type of acoustic sensor responding to time-averaged intensity has been demonstrated, through fabrication of an absorber-backed hydrophone of nominal active element diameter 0.4 mm. A preliminary study using such a device to resolve the spatial distribution of acoustic intensity within plane-piston and focused 3.5 MHz acoustic fields has been completed. Derived beam profiles are compared to conventional techniques that depend on deriving

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

    Science.gov (United States)

    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.

  2. IN VIVO MONITORING OF FOCUSED ULTRASOUND SURGERY USING LOCAL HARMONIC MOTION

    Science.gov (United States)

    Curiel, Laura; Chopra, Rajiv; Hynynen, Kullervo

    2009-01-01

    The present study established the feasibility of a technique for monitoring FUS lesion formation in vivo using localized harmonic motion (LHM) measurements. Oscillatory motion (frequencies between 50 and 300 Hz) was generated within tissues by induction of a periodic radiation force with a focused ultrasound (FUS) transducer. The harmonic motion was estimated using cross-correlation of RF ultrasonic signals acquired at different instances during the motion by using a confocal diagnostic ultrasound transducer. The technique was evaluated in vivo in rabbit muscle (14 locations) in an MR imager for simultaneous ultrasound harmonic motion tracking and MR thermometry. The measured maximum amplitude of the induced harmonic motion before and after the lesion formation was significantly different for all the tested motion frequencies and decreased between 17 and 81% depending on the frequency and location. During the FUS exposure a drop in the maximum amplitude value was observed and a threshold value could be associated to the formation of a thermal lesion. A series of controlled sonications was performed by stopping the exposure when the threshold value in LHM amplitude was reached and the presence of a thermal lesion was confirmed by MR imaging. LHM measurements were also used to perform a spatial scan of the tissues across the exposure region and the thermal lesions could be detected as a reduction in the maximum motion amplitude value at the sonication region. PMID:18805626

  3. Implementation of a Rotational Ultrasound Biomicroscopy System Equipped with a High-Frequency Angled Needle Transducer — Ex Vivo Ultrasound Imaging of Porcine Ocular Posterior Tissues

    Directory of Open Access Journals (Sweden)

    Tae-Hoon Bok

    2014-09-01

    Full Text Available The mechanical scanning of a single element transducer has been mostly utilized for high-frequency ultrasound imaging. However, it requires space for the mechanical motion of the transducer. In this paper, a rotational scanning ultrasound biomicroscopy (UBM system equipped with a high-frequency angled needle transducer is designed and implemented in order to minimize the space required. It was applied to ex vivo ultrasound imaging of porcine posterior ocular tissues through a minimal incision hole of 1 mm in diameter. The retina and sclera for the one eye were visualized in the relative rotating angle range of 270° ~ 330° and at a distance range of 6 ~ 7 mm, whereas the tissues of the other eye were observed in relative angle range of 160° ~ 220° and at a distance range of 7.5 ~ 9 mm. The layer between retina and sclera seemed to be bent because the distance between the transducer tip and the layer was varied while the transducer was rotated. Certin features of the rotation system such as the optimal scanning angle, step angle and data length need to be improved for ensure higher accuracy and precision. Moreover, the focal length should be considered for the image quality. This implementation represents the first report of a rotational scanning UBM system.

  4. Photoacoustic imaging of early gastric cancer diagnosis based on long focal area ultrasound transducer

    Science.gov (United States)

    Wu, Huaqin; Li, Zuoran; Liu, Lantian; Li, Zhifang; Wu, Shulian; Li, Hui

    2017-06-01

    We illustrated a novel imaging method to diagnose gastric neoplasms via photoacoustic tomography (PAT). Depending on the structural characteristics of gastric cavity, we used column diffusion fiber to irradiate the stomach tissue through the esophagus, and the externally placed telecentric focus ultrasonic transducer detected photoacoustic signals from the gastric tissue. We reconstructed the distribution of light energy deposition of the simulated gastric tumor, and obtained the location and size information of gastric tumor.

  5. Realtime photoacoustic microscopy in vivo with a 30-MHz ultrasound array transducer.

    Science.gov (United States)

    Zemp, Roger J; Song, Liang; Bitton, Rachel; Shung, K Kirk; Wang, Lihong V

    2008-05-26

    We present a novel high-frequency photoacoustic microscopy system capable of imaging the microvasculature of living subjects in realtime to depths of a few mm. The system consists of a high-repetition-rate Q-switched pump laser, a tunable dye laser, a 30-MHz linear ultrasound array transducer, a multichannel high-frequency data acquisition system, and a shared-RAM multi-core-processor computer. Data acquisition, beamforming, scan conversion, and display are implemented in realtime at 50 frames per second. Clearly resolvable images of 6-microm-diameter carbon fibers are experimentally demonstrated at 80 microm separation distances. Realtime imaging performance is demonstrated on phantoms and in vivo with absorbing structures identified to depths of 2.5-3 mm. This work represents the first high-frequency realtime photoacoustic imaging system to our knowledge.

  6. Reliability of Central Adiposity Assessments Using B-Mode Ultrasound: A Comparison of Linear and Curved Array Transducers.

    Science.gov (United States)

    Stoner, Lee; Geoffron, Morgane; Cornwall, Jon; Chinn, Victoria; Gram, Martin; Credeur, Daniel; Fryer, Simon

    2016-12-01

    Recently, it was reported that intra-abdominal thickness (IAT) assessments using ultrasound are most reliable if measured from the linea alba to the anterior vertebral column. These 2 anatomical sites can be simultaneously visualized using a linear array transducer. Linear array transducers have different operational characteristics when compared with conventional curved array transducers and are more reliable for some ultrasound-derived measures such as abdominal subcutaneous fat thickness. However, it is unknown whether linear array transducers facilitate more reliable IAT measurements than curved array transducers. The purpose of the current study was to (1) compare the reliability of linear and curved array transducer assessments of IAT and maximal abdominal ratio (MAR) and (2) use the findings to update central adiposity measurement guidelines. Fifteen healthy adults (mean [SD], 27 [10] years; 60% female) with a range of somatotypes (body mass index: mean [SD], 24 [4]; range, 19-33 kg/m; waist circumference: mean [SD], 75 [11]; range, 61-96 cm) were tested on 3 mornings under standardized conditions. Intra-abdominal thickness was assessed 2 cm above the umbilicus (transverse plane), measuring from linea alba to the anterior vertebral column. Maximal abdominal ratio was defined as the ratio of IAT to abdominal subcutaneous fat thickness. The IAT range was 25 to 87 mm, and the MAR range was 0.15 to 0.77. Between-day intraclass correlation coefficient values for IAT measurements made were comparable (0.96-0.97) for both transducers, as were MAR values (0.95). In conclusion, while both transducers provided equally reliable measurement of IAT, the use of a single linear array transducer simplifies the assessment of central adiposity.

  7. Effect of Tissue Inhomogeneity on Nonlinear Propagation of Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Bo; FAN Ting-Bo; GUO Xia-Sheng; ZHANG Dong

    2010-01-01

    @@ We study the influence of tissue inhomogeneity on the focused ultrasound based on the phase screen model and the acoustic nonlinear equation.The inhomogeneous tissue is considered as a combination of a homogeneous medium and a phase aberration screen.Six polyethylene(PE)plates with various correlation lengths and standard deviations are made to mimic the inhomogeneity induced by the human body abdominal.Results indicate that the correlation length affects the side lobe structure of the beam pattern; while the standard deviation is associated with the focusing capability.This study provides a theoretical and experimental basis for the development of a precise treatment plan for high intensity focused ultrasound.

  8. Modes of targets in water excited and identified using radiation pressure of modulated focused ultrasound

    Science.gov (United States)

    Daniel, Timothy; Fortuner, Auberry; Abawi, Ahmad; Kirsteins, Ivars; Marston, Philip

    2016-11-01

    The modulated radiation pressure (MRP) of ultrasound has been widely used to selectively excite low frequency modes of fluid objects. We previously used MRP to excite less compliant metallic object in water including the low frequency modes of a circular metal plate in water. A larger focused ultrasonic transducer allows us to drive modes of larger more-realistic targets. In our experiments solid targets are suspended by strings or supported on sand and the modulated ultrasound is focused on the target's surface. Target sound emissions were recorded and a laser vibrometer was used to measure the surface velocity of the target to give the magnitude of the target response. The source transducer was driven with a doublesideband suppressed carrier voltage as in. By varying the modulation frequency and monitoring target response, resonant frequencies can be measured and compared to finite element models. We also demonstrate the radiation torque of a focused first-order acoustic vortex beam associated with power absorption in the Stokes layer adjacent to a sphere. Funded by ONR.

  9. Brachial artery vasomotion and transducer pressure effect on measurements by active contour segmentation on ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Theodore W.; Sultan, Laith R.; Sehgal, Chandra M., E-mail: sehgalc@uphs.upenn.edu [Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Reamer, Courtney B.; Mohler, Emile R. [Department of Medicine, Division of Cardiovascular Medicine, Section of Vascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2014-02-15

    Purpose: To use feed-forward active contours (snakes) to track and measure brachial artery vasomotion on ultrasound images recorded in both transverse and longitudinal views; and to compare the algorithm's performance in each view. Methods: Longitudinal and transverse view ultrasound image sequences of 45 brachial arteries were segmented by feed-forward active contour (FFAC). The segmented regions were used to measure vasomotion artery diameter, cross-sectional area, and distention both as peak-to-peak diameter and as area. ECG waveforms were also simultaneously extracted frame-by-frame by thresholding a running finite-difference image between consecutive images. The arterial and ECG waveforms were compared as they traced each phase of the cardiac cycle. Results: FFAC successfully segmented arteries in longitudinal and transverse views in all 45 cases. The automated analysis took significantly less time than manual tracing, but produced superior, well-behaved arterial waveforms. Automated arterial measurements also had lower interobserver variability as measured by correlation, difference in mean values, and coefficient of variation. Although FFAC successfully segmented both the longitudinal and transverse images, transverse measurements were less variable. The cross-sectional area computed from the longitudinal images was 27% lower than the area measured from transverse images, possibly due to the compression of the artery along the image depth by transducer pressure. Conclusions: FFAC is a robust and sensitive vasomotion segmentation algorithm in both transverse and longitudinal views. Transverse imaging may offer advantages over longitudinal imaging: transverse measurements are more consistent, possibly because the method is less sensitive to variations in transducer pressure during imaging.

  10. Development of a 20-MHz wide-bandwidth PMN-PT single crystal phased-array ultrasound transducer.

    Science.gov (United States)

    Wong, Chi-Man; Chen, Yan; Luo, Haosu; Dai, Jiyan; Lam, Kwok-Ho; Chan, Helen Lai-Wa

    2017-01-01

    In this study, a 20-MHz 64-element phased-array ultrasound transducer with a one-wavelength pitch is developed using a PMN-30%PT single crystal and double-matching layer scheme. High piezoelectric (d33>1000pC/N) and electromechanical coupling (k33>0.8) properties of the single crystal with an optimized fabrication process involving the photolithography technique have been demonstrated to be suitable for wide-bandwidth (⩾70%) and high-sensitivity (insertion loss ⩽30dB) phased-array transducer application. A -6dBbandwidth of 91% and an insertion loss of 29dBfor the 20-MHz 64-element phased-array transducer were achieved. This result shows that the bandwidth is improved comparing with the investigated high-frequency (⩾20MHz) ultrasound transducers using piezoelectric ceramic and single crystal materials. It shows that this phased-array transducer has potential to improve the resolution of biomedical imaging, theoretically. Based on the hypothesis of resolution improvement, this phased-array transducer is capable for small animal (i.e. mouse and zebrafish) studies.

  11. Optimizing MR imaging-guided navigation for focused ultrasound interventions in the brain

    Science.gov (United States)

    Werner, B.; Martin, E.; Bauer, R.; O'Gorman, R.

    2017-03-01

    MR imaging during transcranial MR imaging-guided Focused Ultrasound surgery (tcMRIgFUS) is challenging due to the complex ultrasound transducer setup and the water bolus used for acoustic coupling. Achievable image quality in the tcMRIgFUS setup using the standard body coil is significantly inferior to current neuroradiologic standards. As a consequence, MR image guidance for precise navigation in functional neurosurgical interventions using tcMRIgFUS is basically limited to the acquisition of MR coordinates of salient landmarks such as the anterior and posterior commissure for aligning a stereotactic atlas. Here, we show how improved MR image quality provided by a custom built MR coil and optimized MR imaging sequences can support imaging-guided navigation for functional tcMRIgFUS neurosurgery by visualizing anatomical landmarks that can be integrated into the navigation process to accommodate for patient specific anatomy.

  12. Three-Dimensional Synthetic Aperture Focusing Using a Rocking Convex Array Transducer

    DEFF Research Database (Denmark)

    Andresen, Henrik; Nikolov, Svetoslav; Pedersen, Mads Møller;

    2010-01-01

    Volumetric imaging can be performed using 1-D arrays in combination with mechanical motion. Outside the elevation focus of the array, the resolution and contrast quickly degrade compared with the lateral plane, because of the fixed transducer focus. This paper shows the feasibility of using...... synthetic aperture focusing for enhancing the elevation focus for a convex rocking array. The method uses a virtual source (VS) for defocused multi-element transmit, and another VS in the elevation focus point. This allows a direct time-of-flight to be calculated for a given 3-D point. To avoid artifacts...

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

    Science.gov (United States)

    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. Micromachined Ultrasonic Transducers for 3-D Imaging

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann

    such transducer arrays, capacitive micromachined ultrasonic transducer (CMUT) technology is chosen for this project. Properties such as high bandwidth and high design flexibility makes this an attractive transducer technology, which is under continuous development in the research community. A theoretical...... of state-of-the-art 3-D ultrasound systems. The focus is on row-column addressed transducer arrays. This previously sparsely investigated addressing scheme offers a highly reduced number of transducer elements, resulting in reduced transducer manufacturing costs and data processing. To produce......Real-time ultrasound imaging is a widely used technique in medical diagnostics. Recently, ultrasound systems offering real-time imaging in 3-D has emerged. However, the high complexity of the transducer probes and the considerable increase in data to be processed compared to conventional 2-D...

  15. Ultrasonic atomization of tissue and its role in tissue fractionation by high intensity focused ultrasound

    Science.gov (United States)

    Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Wang, Yak-Nam; Crum, Lawrence A.; Bailey, Michael R.

    2012-12-01

    Atomization and fountain formation is a well-known phenomenon that occurs when a focused ultrasound wave in liquid encounters an air interface. High intensity focused ultrasound (HIFU) has been shown to fractionate a tissue into submicron-sized fragments in a process termed boiling histotripsy, wherein the focused ultrasound wave superheats the tissue at the focus, producing a millimetre-sized boiling or vapour bubble in several milliseconds. Yet the question of how this millimetre-sized boiling bubble creates submicron-sized tissue fragments remains. The hypothesis of this work is that the tissue can behave as a liquid such that it atomizes and forms a fountain within the vapour bubble produced in boiling histotripsy. We describe an experiment, in which a 2 MHz HIFU transducer (maximum in situ intensity of 24 000 W cm-2) was aligned with an air-tissue interface meant to simulate the boiling bubble. Atomization and fountain formation was observed with high-speed photography and resulted in tissue erosion. Histological examination of the atomized tissue showed whole and fragmented cells and nuclei. Air-liquid interfaces were also filmed. Our conclusion was that HIFU can fountain and atomize tissue. Although this process does not entirely mimic what was observed in liquids, it does explain many aspects of tissue fractionation in boiling histotripsy.

  16. Feasibility of MRI-guided Focused Ultrasound as Organ-Sparing Treatment for Testicular Cancer

    Science.gov (United States)

    Staruch, Robert; Curiel, Laura; Chopra, Rajiv; Hynynen, Kullervo

    2009-04-01

    High cure rates for testicular cancer have prompted interest in organ-sparing surgery for patients with bilateral disease or single testis. Focused ultrasound (FUS) ablation could offer a noninvasive approach to organ-sparing surgery. The objective of this study was to determine the feasibility of using MR thermometry to guide organ-sparing focused ultrasound surgery in the testis. The testes of anesthetized rabbits were sonicated in several discrete locations using a single-element focused transducer operating at 2.787MHz. Focal heating was visualized with MR thermometry, using a measured PRF thermal coefficient of -0.0089±0.0003 ppm/° C. Sonications at 3.5-14 acoustic watts applied for 30 seconds produced maximum temperature elevations of 10-80° C, with coagulation verified by histology. Coagulation of precise volumes in the testicle is feasible with MRI-guided focused ultrasound. Variability in peak temperature for given sonication parameters suggests the need for online temperature feedback control.

  17. Portable ultrasound in disaster triage: a focused review.

    Science.gov (United States)

    Wydo, S M; Seamon, M J; Melanson, S W; Thomas, P; Bahner, D P; Stawicki, S P

    2016-04-01

    Ultrasound technology has become ubiquitous in modern medicine. Its applications span the assessment of life-threatening trauma or hemodynamic conditions, to elective procedures such as image-guided peripheral nerve blocks. Sonographers have utilized ultrasound techniques in the pre-hospital setting, emergency departments, operating rooms, intensive care units, outpatient clinics, as well as during mass casualty and disaster management. Currently available ultrasound devices are more affordable, portable, and feature user-friendly interfaces, making them well suited for use in the demanding situation of a mass casualty incident (MCI) or disaster triage. We have reviewed the existing literature regarding the application of sonology in MCI and disaster scenarios, focusing on the most promising and practical ultrasound-based paradigms applicable in these settings.

  18. Harmonic motion imaging for focused ultrasound (HMIFU): a fully integrated technique for sonication and monitoring of thermal ablation in tissues.

    Science.gov (United States)

    Maleke, C; Konofagou, E E

    2008-03-21

    FUS (focused ultrasound), or HIFU (high-intensity-focused ultrasound) therapy, a minimally or non-invasive procedure that uses ultrasound to generate thermal necrosis, has been proven successful in several clinical applications. This paper discusses a method for monitoring thermal treatment at different sonication durations (10 s, 20 s and 30 s) using the amplitude-modulated (AM) harmonic motion imaging for focused ultrasound (HMIFU) technique in bovine liver samples in vitro. The feasibility of HMI for characterizing mechanical tissue properties has previously been demonstrated. Here, a confocal transducer, combining a 4.68 MHz therapy (FUS) and a 7.5 MHz diagnostic (pulse-echo) transducer, was used. The therapy transducer was driven by a low-frequency AM continuous signal at 25 Hz, producing a stable harmonic radiation force oscillating at the modulation frequency. A pulser/receiver was used to drive the pulse-echo transducer at a pulse repetition frequency (PRF) of 5.4 kHz. Radio-frequency (RF) signals were acquired using a standard pulse-echo technique. The temperature near the ablation region was simultaneously monitored. Both RF signals and temperature measurements were obtained before, during and after sonication. The resulting axial tissue displacement was estimated using one-dimensional cross correlation. When temperature at the focal zone was above 48 degrees C during heating, the coagulation necrosis occurred and tissue damage was irreversible. The HMI displacement profiles in relation to the temperature and sonication durations were analyzed. At the beginning of heating, the temperature at the focus increased sharply, while the tissue stiffness decreased resulting in higher HMI displacements. This was confirmed by an increase of 0.8 microm degrees C(-1)(r=0.93, ptissue became irreversibly stiffer, followed by an associated decrease in the HMI displacement (-0.79 microm degrees C(-1), r=-0.92, ptissues during FUS, HIFU or other thermal therapies.

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

    Science.gov (United States)

    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.

  20. Advanced 3-D Ultrasound Imaging: 3-D Synthetic Aperture Imaging using Fully Addressed and Row-Column Addressed 2-D Transducer Arrays

    DEFF Research Database (Denmark)

    Bouzari, Hamed

    with transducer arrays using this addressing scheme, when integrated into probe handles. For that reason, two in-house prototyped 62+62 row-column addressed 2-D array transducer probes were manufactured using capacitive micromachined ultrasonic transducer (CMUT) and piezoelectric transducer (PZT) technology...... in many clinical applications. Real-time 3-D ultrasound imaging is still not as widespread in use in the clinics as 2-D ultrasound imaging. Two limiting factors have traditionally been the low image quality as well as low volume rate achievable with a 2-D transducer array using the conventional 3-D...... and measurements with the ultrasound research scanner SARUS and a 3.8 MHz 1024 element 2-D transducer array. In all investigations, 3-D synthetic aperture imaging achieved a better resolution, lower side-lobes, higher contrast, and better signal to noise ratio than parallel beamforming. This is achieved partly...

  1. Focused Acute Medicine Ultrasound (FAMUS) - point of care ultrasound for the Acute Medical Unit.

    Science.gov (United States)

    Smallwood, Nicholas; Dachsel, Martin; Matsa, Ramprasad; Tabiowo, Eugene; Walden, Andrew

    2016-01-01

    Point of care ultrasound (POCU) is becoming increasingly popular as an extension to clinical examination techniques. Specific POCU training pathways have been developed in specialties such as Emergency and Intensive Care Medicine (CORE Emergency Ultrasound and Core UltraSound Intensive Care, for example), but until this time there has not been a curriculum for the acutely unwell medical patient outside of Critical Care. We describe the development of Focused Acute Medicine Ultrasound (FAMUS), a curriculum designed specifically for the Acute Physician to learn ultrasound techniques to aid in the management of the unwell adult patient. We detail both the outline of the curriculum and the process involved for a candidate to achieve FAMUS accreditation. It is anticipated this will appeal to both Acute Medical Unit (AMU) clinicians and general physicians who deal with the unwell or deteriorating medical or surgical patient. In time, the aspiration is for FAMUS to become a core part of the AIM curriculum.

  2. A 3D reconstruction algorithm for magneto-acoustic tomography with magnetic induction based on ultrasound transducer characteristics

    Science.gov (United States)

    Ma, Ren; Zhou, Xiaoqing; Zhang, Shunqi; Yin, Tao; Liu, Zhipeng

    2016-12-01

    In this study we present a three-dimensional (3D) reconstruction algorithm for magneto-acoustic tomography with magnetic induction (MAT-MI) based on the characteristics of the ultrasound transducer. The algorithm is investigated to solve the blur problem of the MAT-MI acoustic source image, which is caused by the ultrasound transducer and the scanning geometry. First, we established a transducer model matrix using measured data from the real transducer. With reference to the S-L model used in the computed tomography algorithm, a 3D phantom model of electrical conductivity is set up. Both sphere scanning and cylinder scanning geometries are adopted in the computer simulation. Then, using finite element analysis, the distribution of the eddy current and the acoustic source as well as the acoustic pressure can be obtained with the transducer model matrix. Next, using singular value decomposition, the inverse transducer model matrix together with the reconstruction algorithm are worked out. The acoustic source and the conductivity images are reconstructed using the proposed algorithm. Comparisons between an ideal point transducer and the realistic transducer are made to evaluate the algorithms. Finally, an experiment is performed using a graphite phantom. We found that images of the acoustic source reconstructed using the proposed algorithm are a better match than those using the previous one, the correlation coefficient of sphere scanning geometry is 98.49% and that of cylinder scanning geometry is 94.96%. Comparison between the ideal point transducer and the realistic transducer shows that the correlation coefficients are 90.2% in sphere scanning geometry and 86.35% in cylinder scanning geometry. The reconstruction of the graphite phantom experiment also shows a higher resolution using the proposed algorithm. We conclude that the proposed reconstruction algorithm, which considers the characteristics of the transducer, can obviously improve the resolution of the

  3. High-Intensity Focused Ultrasound Therapy: an Overview for Radiologists

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Sun; Rhim, Hyun Chul; Lim, Hyo Keun; Choi, Dong Il [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Choi, Min Joo [College of Medicine, Cheju National University, Jeju (Korea, Republic of)

    2008-08-15

    High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments

  4. High-intensity focused ultrasound therapy: an overview for radiologists.

    Science.gov (United States)

    Kim, Young-sun; Rhim, Hyunchul; Choi, Min Joo; Lim, Hyo Keun; Choi, Dongil

    2008-01-01

    High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments.

  5. Effects of increased compression with an ultrasound transducer on the conspicuity of breast lesions in a phantom

    Science.gov (United States)

    Szczepura, Katy; Faqir, Tahreem; Manning, David

    2017-03-01

    Ultrasound imaging of the breast is highly operator dependent. The amount of pressure applied with the transducer has a direct impact on the lesion visibility in breast ultrasound. The conspicuity index is a quantitative measure of lesion visibility, taking into account more parameters than standard measures that impact on lesion detection. This study assessed the conspicuity of lesions within a breast phantom using increased transducer compression in breast ultrasound. Methods A phantom was constructed of gelatine to represent adipose tissue, steel wool for glandular/blood vessels and silicone spheres to represent lesions, this meant that the lesions were also compressible, but less than the surrounding tissue. The phantom was imaged under increasing transducer compression. The conspicuity index was measured using the Conspicuity Index Software. The distance between the transducer surface and lesion surface was measured as an indication of increased compression. Results When moderate compression (17mm) was applied, the conspicuity index increased resulting in better visualisation of the silicone lesions. However, with increased compression the conspicuity index decreased. New work to be presented The conspicuity index has never been demonstrated in ultrasound imaging before. This is preliminary phantom work to demonstrate the impact of increased transducer compression on quantitative lesion visibility assessment. Conclusion The compression applied should be considered for optimum visualisation, as excessive pressure decreases conspicuity. However, further work needs to be conducted in order to consider other factors, such as density of the breast and lesion location, for a better understanding of the effect of compression on the visualisation of the lesion. A human study is planned.

  6. Continuous monitoring of regional function by a miniaturized ultrasound transducer allows early quantification of low-grade myocardial ischemia.

    Science.gov (United States)

    Hyler, Stefan; Pischke, Søren E; Halvorsen, Per Steinar; Espinoza, Andreas; Bergsland, Jacob; Tønnessen, Tor Inge; Fosse, Erik; Skulstad, Helge

    2015-04-01

    Sensitive methods for the early detection of myocardial dysfunction are still needed, as ischemia is a leading cause of decreased ventricular function during and after heart surgery. The aim of this study was to test the hypothesis that low-grade ischemia could be detected quantitatively by a miniaturized epicardial ultrasound transducer (Ø = 3 mm), allowing continuous monitoring. In 10 pigs, transducers were positioned in the left anterior descending and circumflex coronary artery areas. Left ventricular pressure was obtained by a micromanometer. The left internal mammary artery was grafted to the left anterior descending coronary artery, which was occluded proximal to the anastomosis. Left internal mammary artery flow was stepwise reduced by 25%, 50%, and 75% for 18 min each. From the transducers, M-mode traces were obtained, allowing continuous tissue velocity traces and displacement measurements. Regional work was assessed as left ventricular pressure-displacement loop area. Tissue lactate measured from intramyocardial microdialysis was used as reference method to detect ischemia. All steps of coronary flow reduction demonstrated reduced peak systolic velocity (P transducer allowed the precise detection of different levels of coronary flow reduction. The results also showed a quantitative and linear relationship among coronary flow, ischemia, and myocardial function. Thus, the ultrasound transducer has the potential to improve the monitoring of myocardial ischemia and to detect graft failure during and after heart surgery. Copyright © 2015 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  7. Localized Ablation of Thyroid Tissue by High-Intensity Focused Ultrasound: an Alternative to Surgery?

    Science.gov (United States)

    Esnault, Olivier; Franc, Brigitte; Chapelon, Jean-Yves; Lacoste, Francois

    2006-05-01

    PURPOSE: The aim of this study was to evaluate the feasibility of using a High-intensity focused ultrasound (HIFU) device to obtain a localised destruction of the thyroid with no damage to adjacent tissues. MATERIALS AND METHODS: The ewe model was used because its thyroid gland is easily accessible with ultrasound. The animals were anaesthetised with 10 mg / kg IV injection of Penthothal. The HIFU pulses were generated by a 3-MHz spherical transducer under ultrasound guidance. Macroscopic and microscopic tissue lesions were identified after formalin fixation of the anterior part of the ewe's neck. RESULTS: After determining the optimal instrument settings to obtain localized thyroid ablation, the repeatability of the method was evaluated using a HIFU prototype designed specifically for human use: in 13 ewes (26 treated lobes), an average of 20 (range: 14-27) ultrasound pulses (pulse duration: 3 s) per lobe covering a mean volume of 0.5 cm3 (range: 0.3-0.7 cm3) were delivered. The ewes were sacrificed 2-5 weeks after treatment delivery. No damage to the nerves, trachea, esophagus or muscle was observed. Only 3 ewes suffered superficial skin burns. The desired thyroid lesions were obtained in 25/26 treated lobes, as demonstrated by fibrotic tissues, which replaced necrotic areas. CONCLUSION: These results obtained in the ewe model show that thyroid lesions of defined volume can be induced safely and suggest that the HIFU device is now ready for human trials.

  8. High intensity focused ultrasound (HIFU) focal spot localization using harmonic motion imaging (HMI).

    Science.gov (United States)

    Han, Yang; Hou, Gary Yi; Wang, Shutao; Konofagou, Elisa

    2015-08-07

    Several ultrasound-based imaging modalities have been proposed for image guidance and monitoring of high-intensity focused ultrasound (HIFU) treatment. However, accurate localization and characterization of the effective region of treatment (focal spot) remain important obstacles in the clinical implementation of HIFU ablation. Harmonic motion imaging for focused ultrasound (HMIFU) is a HIFU monitoring technique that utilizes radiation-force-induced localized oscillatory displacement. HMIFU has been shown to correctly identify the formation and extent of HIFU thermal ablation lesions. However a significant problem remains in identifying the location of the HIFU focus, which is necessary for treatment planning. In this study, the induced displacement was employed to localize the HIFU focal spot inside the tissue prior to treatment. Feasibility was shown with two separate systems. The 1D HMIFU system consisted of a HIFU transducer emitting an amplitude-modulated HIFU beam for mechanical excitation and a confocal single-element, pulse-echo transducer for simultaneous RF acquisition. The 2D HIFU system consists of a HIFU phased array, and a co-axial imaging phased array for simultaneous imaging. Initial feasibility was first performed on tissue-mimicking gelatin phantoms and the focal zone was defined as the region corresponding to the -3dB full width at half maximum of the HMI displacement. Using the same parameters, in vitro experiments were performed in canine liver specimens to compare the defined focal zone with the lesion. In vitro measurements showed good agreement between the HMI predicted focal zone and the induced HIFU lesion location. HMIFU was experimentally shown to be capable of predicting and tracking the focal region in both phantoms and in vitro tissues. The accuracy of focal spot localization was evaluated by comparing with the lesion location in post-ablative tissues, with a R(2) = 0.821 at p tissue ablation and can be fully integrated into any HMI

  9. Relationship between the exposure dose of high intensity focused ultrasound and the heated necrosis element

    Institute of Scientific and Technical Information of China (English)

    FENG Ruo; ZHANG Qiang; LI Faqi; ZHENG Xiaozheng; BAI Jin; XU Jianyi; WANG Yaojun; WANG Zhibiao

    2004-01-01

    Heated necrosis element of tissues is the basis for treating tumor by high intensity focused ultrasound (HIFU), so study on the relationship between the HIFU exposure dose and the heated necrosis element of tissues is of great significance for both HIFU clinical applications and basic research. Using Pennes and Rayleigh formulae the relationship between the exposure dose of an annular focused transducer and the heated necrosis element (I.e. Biological focused region) in a bovine liver in vitro at a depth of 2 cm is simulated in an exposure dose range with radiation sound intensity of 7000~25400 W/cm2 and exposure time of 0~20 s. The theoretical results appear to be in quite good agreement with the experimental ones. It is shown that on the basis of existing theories the heated necrosis element produced by HIFU exposure can be predicted. The deviation of the theory from the experiments under higher exposure dose has also been discussed.

  10. Annular spherically focused ring transducers for improved single-beam acoustical tweezers

    Science.gov (United States)

    Mitri, F. G.

    2016-02-01

    The use of ultrasonic transducers with a central hollow is suggested for improved single-beam acoustical tweezers applications. Within the framework of the Fresnel-Kirchhoff parabolic approximation, a closed-form partial-wave series expansion (PWSE) for the incident velocity potential (or pressure) field is derived for an annular spherically focused ring (asfr) with uniform vibration across its surface in spherical coordinates. The Rayleigh-Sommerfeld diffraction integral and the addition theorems for the Legendre and spherical wave functions are used to obtain the PWSE assuming a weakly focused beam (with a focusing angle α ≤ 20°). The PWSE allows evaluating the incident field from the finite asfr in 3D. Moreover, the obtained solution allows computing efficiently the acoustic scattering and radiation force on a sphere centered on the beam's axis of wave propagation. The analytical solution is valid for wavelengths largely exceeding the radius of the asfr and when the viscosity of the surrounding fluid can be neglected. Numerical predictions for the beam-forming, scattering, and axial time-averaged radiation force are performed with particular emphasis on the asfr thickness, the axial distance separating the sphere from the center of the transducer, the (non-dimensional) size of the transducer, as well as the sphere's elastic properties without restriction to the long- (i.e., Rayleigh) or the short-wavelength (i.e., ray acoustics) regimes. Potential applications of the present solution are in beam-forming design, particle tweezing, and manipulation due to negative forces using ultrasonic asfr transducers.

  11. Annular spherically focused ring transducers for improved single-beam acoustical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology—ETC, Santa Fe, New Mexico 87508 (United States)

    2016-02-14

    The use of ultrasonic transducers with a central hollow is suggested for improved single-beam acoustical tweezers applications. Within the framework of the Fresnel-Kirchhoff parabolic approximation, a closed-form partial-wave series expansion (PWSE) for the incident velocity potential (or pressure) field is derived for an annular spherically focused ring (asfr) with uniform vibration across its surface in spherical coordinates. The Rayleigh-Sommerfeld diffraction integral and the addition theorems for the Legendre and spherical wave functions are used to obtain the PWSE assuming a weakly focused beam (with a focusing angle α ≤ 20°). The PWSE allows evaluating the incident field from the finite asfr in 3D. Moreover, the obtained solution allows computing efficiently the acoustic scattering and radiation force on a sphere centered on the beam's axis of wave propagation. The analytical solution is valid for wavelengths largely exceeding the radius of the asfr and when the viscosity of the surrounding fluid can be neglected. Numerical predictions for the beam-forming, scattering, and axial time-averaged radiation force are performed with particular emphasis on the asfr thickness, the axial distance separating the sphere from the center of the transducer, the (non-dimensional) size of the transducer, as well as the sphere's elastic properties without restriction to the long- (i.e., Rayleigh) or the short-wavelength (i.e., ray acoustics) regimes. Potential applications of the present solution are in beam-forming design, particle tweezing, and manipulation due to negative forces using ultrasonic asfr transducers.

  12. Microwave thermal imaging of scanned focused ultrasound heating: animal experiments

    Science.gov (United States)

    Zhou, Tian; Meaney, Paul M.; Hoopes, P. Jack; Geimer, Shireen D.; Paulsen, Keith D.

    2011-03-01

    High intensity focused ultrasound (HIFU) uses focused ultrasound beams to ablate localized tumors noninvasively. Multiple clinical trials using HIFU treatment of liver, kidney, breast, pancreas and brain tumors have been conducted, while monitoring the temperature distribution with various imaging modalities such as MRI, CT and ultrasound. HIFU has achieved only minimal acceptance partially due to insufficient guidance from the limited temperature monitoring capability and availability. MR proton resonance frequency (PRF) shift thermometry is currently the most effective monitoring method; however, it is insensitive in temperature changes in fat, susceptible to motion artifacts, and is high cost. Exploiting the relationship between dielectric properties (i.e. permittivity and conductivity) and tissue temperature, in vivo dielectric property distributions of tissue during heating were reconstructed with our microwave tomographic imaging technology. Previous phantom studies have demonstrated sub-Celsius temperature accuracy and sub-centimeter spatial resolution in microwave thermal imaging. In this paper, initial animal experiments have been conducted to further investigate its potential. In vivo conductivity changes inside the piglet's liver due to focused ultrasound heating were observed in the microwave images with good correlation between conductivity changes and temperature.

  13. A novel image-guided high-intensity focused ultrasound system for tumor treatment

    Science.gov (United States)

    Wu, Zhiqiang; Wu, Puwei; Chen, Bojie; Guan, Jian; Huang, Zheng

    2004-07-01

    A novel ultrasonography-guided high intensity focused ultrasound (HIFU) system (FS-100; Force Electronics Co. Ltd, Chongqing, China) was developed for non-invasive thermal ablation of tumor. The proprietary therapy delivery system is an integration of the digital image progressing, automatic control and the high intensity focused ultrasound thermal ablation devices. The therapeutic ultrasound probe (φ = 240 mm) consists of eight circular HIFU transducers with a curved surface of a diameter of 60 mm. Dual focused beams generated from the probe were used in this system for thermal delivery. The probe has the maximal resonance frequency of 1 MHz, a maximal treatment depth of 160 mm and focal spot diameter of 3 mm. The maximal intensity at the focal spot is 10,000 W/cm2. The imaging and HIFU components are located on top of the device, therefore, the focused ultrasound beams can be delivered to the patient in a supine position. The motion, targeting and localization of the probe are controlled by a PMAC-PC motion controller and an 8-independent-axis mechanical device. The linear motion error of the probe localization is <= 0.1 mm. The ultrasonographic image information is used for treatment planning and therapeutic interventions, such as target definition and registration, visualization of the three-dimensional anatomy of desired target(s), automatic positioning the thermal beams on targets, controlling thermal delivery, and rapid evaluation of target response post-treatment. The preclinical experimental results will be presented. The safety, feasibility and effectiveness of this novel HIFU system will be tested.

  14. Open-source, small-animal magnetic resonance-guided focused ultrasound system.

    Science.gov (United States)

    Poorman, Megan E; Chaplin, Vandiver L; Wilkens, Ken; Dockery, Mary D; Giorgio, Todd D; Grissom, William A; Caskey, Charles F

    2016-01-01

    MR-guided focused ultrasound or high-intensity focused ultrasound (MRgFUS/MRgHIFU) is a non-invasive therapeutic modality with many potential applications in areas such as cancer therapy, drug delivery, and blood-brain barrier opening. However, the large financial costs involved in developing preclinical MRgFUS systems represent a barrier to research groups interested in developing new techniques and applications. We aim to mitigate these challenges by detailing a validated, open-source preclinical MRgFUS system capable of delivering thermal and mechanical FUS in a quantifiable and repeatable manner under real-time MRI guidance. A hardware and software package was developed that includes closed-loop feedback controlled thermometry code and CAD drawings for a therapy table designed for a preclinical MRI scanner. For thermal treatments, the modular software uses a proportional integral derivative controller to maintain a precise focal temperature rise in the target given input from MR phase images obtained concurrently. The software computes the required voltage output and transmits it to a FUS transducer that is embedded in the delivery table within the magnet bore. The delivery table holds the FUS transducer, a small animal and its monitoring equipment, and a transmit/receive RF coil. The transducer is coupled to the animal via a water bath and is translatable in two dimensions from outside the magnet. The transducer is driven by a waveform generator and amplifier controlled by real-time software in Matlab. MR acoustic radiation force imaging is also implemented to confirm the position of the focus for mechanical and thermal treatments. The system was validated in tissue-mimicking phantoms and in vivo during murine tumor hyperthermia treatments. Sonications were successfully controlled over a range of temperatures and thermal doses for up to 20 min with minimal temperature overshoot. MR thermometry was validated with an optical temperature probe, and focus

  15. Ultrasound (US transducer of higher operating frequency detects photoacoustic (PA signals due to the contrast in elastic property

    Directory of Open Access Journals (Sweden)

    Mayanglambam Suheshkumar Singh

    2016-02-01

    Full Text Available We report our study that shows selection in operating frequency of US-transducer used for boundary detection of PA-signals, which result due to the contrast in elastic property distribution ( E ( r → in sample material other than that of optical absorption coefficient (μa. Studies were carried out, experimentally, in tissue-mimicking Agar phantoms employing acoustic resolution photoacoustic microscopy (AR-PAM system as an imaging unit. In the experiments, various transducers having different operating frequencies, ranging from 1MHz to 50MHz, were employed for studying frequency response of the photoacoustic signals. The study shows that, for detecting photoacoustic signals due to the contrast in elastic property, ultrasound transducer with higher operating frequency (∼50MHz is demanded.

  16. X-ray-induced acoustic computed tomography with an ultrasound transducer ring-array

    Science.gov (United States)

    Tang, S.; Nguyen, D. H.; Zarafshani, A.; Ramseyer, C.; Zheng, B.; Liu, H.; Xiang, L.

    2017-03-01

    The objective of this study is to develop and test a unique X-ray-induced acoustic computed tomography system that combines the advantages of high X-ray imaging contrast and high ultrasonic spatial resolution. The system features a 5 MHz 128-element ultrasound transducer ring-array formed into a full circular aperture. A parallel data receiver, which consists of a dedicated 128-channel preamplifier and a 128-channel data acquisition module, provides full tomographic imaging at a speed of up to 25 frames per second. Details of the system design and calibration are presented, along with the characteristic results of the imaging resolution. The tomographic imaging performance is demonstrated through images of a phantom with a spatial resolution up to 138 μm. The study results indicate that this imaging device and the methodology provide a rapid and high resolution approach for the dynamic imaging of information, and it may have the potential for becoming a promising noninvasive imaging modality to be used in future applications.

  17. Feasibility study for removing calcified material using a planar rectangular ultrasound transducer.

    Science.gov (United States)

    Damianou, Christakis; Couppis, Andreas

    2016-01-01

    The aim of the proposed study was to conduct a feasibility study using a flat rectangular (3 mm × 10 mm) MRI compatible transducer operating at 5.3 MHz for destroying calcified material in an in vitro model. The proposed method can be used in the future for treating atherosclerosis plaques of the coronary, carotid or peripheral arteries. The system was tested initially on calcium rods. Another test was performed in a hydroxyapatite-polylactide model. A parametric study was performed where the mass of calcified material removed was studied as a function of intensity, pulse repetition frequency (PRF), duty factor (DF) and presence of bubbles. The amount of calcified material removed is directly related to the intensity, PRF and DF. It was found that the presence of bubbles accelerates the removal of calcified material. In order to ensure that pure mechanical mode ultrasound was used, the protocols were designed so that the temperature does not exceed 1 °C.

  18. Theory and operation of 2-D array piezoelectric micromachined ultrasound transducers.

    Science.gov (United States)

    Dausch, David E; Castellucci, John B; Chou, Derrick R; von Ramm, Olaf T

    2008-11-01

    Piezoelectric micromachined ultrasound transducers (pMUTs) are a new approach for the construction of 2-D arrays for forward-looking 3-D intravascular (IVUS) and intracardiac (ICE) imaging. Two-dimensional pMUT test arrays containing 25 elements (5 x 5 arrays) were bulk micromachined in silicon substrates. The devices consisted of lead zirconate titanate (PZT) thin film membranes formed by deep reactive ion etching of the silicon substrate. Element widths ranged from 50 to 200 microm with pitch from 100 to 300 mum. Acoustic transmit properties were measured in de-ionized water with a calibrated hydrophone placed at a range of 20 mm. Measured transmit frequencies for the pMUT elements ranged from 4 to 13 MHz, and mode of vibration differed for the various element sizes. Element capacitance varied from 30 to over 400 pF depending on element size and PZT thickness. Smaller element sizes generally produced higher acoustic transmit output as well as higher frequency than larger elements. Thicker PZT layers also produced higher transmit output per unit electric field applied. Due to flexure mode operation above the PZT coercive voltage, transmit output increased nonlinearly with increased drive voltage. The pMUT arrays were attached directly to the Duke University T5 Phased Array Scanner to produce real-time pulse-echo B-mode images with the 2-D pMUT arrays.

  19. Focused ultrasound facilitated thermo-chemotherapy for targeted retinoblastoma treatment: a modeling study.

    Science.gov (United States)

    Wang, Shutao; Mahesh, Sankaranarayana P; Liu, Ji; Geist, Craig; Zderic, Vesna

    2012-07-01

    Retinoblastoma is the most common type of intraocular tumors in children. Currently, with early detection and improved systemic chemo-adjuvant therapies, treatment paradigm has shifted from survival to globe salvation/vision preservation. The objective of our work has been to explore the possible application of focused ultrasound (FUS) for targeted drug delivery in the posterior pole retinoblastoma. Specifically, theoretical models were implemented to evaluate the feasibility of using FUS to generate localized hyperthermia in retinal tumor areas, for potential triggering the chemotherapeutic agent deployment from heat-sensitive drug carriers. In-vitro experiments were conducted in tissue-mimicking phantoms with embedded excised rabbit eyes to validate the reliability of the modeling results. After confirming the reliability of our model, various FUS transducer parameters were investigated to induce maximal hyperthermia coverage in the tumor, while sparing adjacent eye structures (e.g. the lens). The evaluated FUS parameters included operating frequency, total acoustic power, geometric dimensions, transducer f-number, standoff distance, as well as different pulsing scenarios. Our modeling results suggest that the most suitable ultrasound frequency for this type of treatments was in the range of 2-3.5 MHz depending on the size of retinoblastoma. Appropriate transducer f-number (close to 1) and standoff distance could be selected to minimize the risks of over-heating undesired regions. With the total acoustic power of 0.4 W, 56.3% of the tumor was heated to hyperthermic temperature range (39-44 °C) while the temperature in lens was maintained below 41 °C. In conclusion, FUS-induced hyperthermia for targeted drug delivery may be a viable option in treatments of juxta-foveal or posterior pole retinoblastomas. Future in-vivo studies will allow us to determine the effectiveness and safety of the proposed approach. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Nonlinear Effect on Focusing Gain of a Focusing Transducer with a Wide Aperture Angle

    Institute of Scientific and Technical Information of China (English)

    LIU Ming-He; ZHANG Dong; GONG Xiu-Fen

    2007-01-01

    @@ Nonlinear effect on focusing gain of acoustic field radiated from a 1-MHz focusing transmitter with a wide aperture angle of 35° is theoretically and experimentally investigated. With the enhancement of nonlinearity, the focusing gains of both intensity and peak positive pressure show non-monotonic behaviour. There exist the same saturated levels at which the maximum outputs are reached and their spatial distributions are more localized. In contrast,the peak negative pressure always decreases monotonically and its spatial distribution is less localized.

  1. Improved heating efficiency with High-Intensity Focused Ultrasound using a new ultrasound source excitation.

    Science.gov (United States)

    Bigelow, Timothy A

    2009-01-01

    High-Intensity Focused Ultrasound (HIFU) is quickly becoming one of the best methods to thermally ablate tissue noninvasively. Unlike RF or Laser ablation, the tissue can be destroyed without inserting any probes into the body minimizing the risk of secondary complications such as infections. In this study, the heating efficiency of HIFU sources is improved by altering the excitation of the ultrasound source to take advantage of nonlinear propagation. For ultrasound, the phase velocity of the ultrasound wave depends on the amplitude of the wave resulting in the generation of higher harmonics. These higher harmonics are more efficiently converted into heat in the body due to the frequency dependence of the ultrasound absorption in tissue. In our study, the generation of the higher harmonics by nonlinear propagation is enhanced by transmitting an ultrasound wave with both the fundamental and a higher harmonic component included. Computer simulations demonstrated up to a 300% increase in temperature increase compared to transmitting at only the fundamental for the same acoustic power transmitted by the source.

  2. Targeted and reversible blood-retinal barrier disruption via focused ultrasound and microbubbles.

    Directory of Open Access Journals (Sweden)

    Juyoung Park

    Full Text Available The blood-retinal barrier (BRB prevents most systemically-administered drugs from reaching the retina. This study investigated whether burst ultrasound applied with a circulating microbubble agent can disrupt the BRB, providing a noninvasive method for the targeted delivery of systemically administered drugs to the retina. To demonstrate the efficacy and reversibility of such a procedure, five overlapping targets around the optic nerve head were sonicated through the cornea and lens in 20 healthy male Sprague-Dawley rats using a 690 kHz focused ultrasound transducer. For BRB disruption, 10 ms bursts were applied at 1 Hz for 60 s with different peak rarefactional pressure amplitudes (0.81, 0.88 and 1.1 MPa. Each sonication was combined with an IV injection of a microbubble ultrasound contrast agent (Definity. To evaluate BRB disruption, an MRI contrast agent (Magnevist was injected IV immediately after the last sonication, and serial T1-weighted MR images were acquired up to 30 minutes. MRI contrast enhancement into the vitreous humor near targeted area was observed for all tested pressure amplitudes, with more signal enhancement evident at the highest pressure amplitude. At 0.81 MPa, BRB disruption was not detected 3 h post sonication, after an additional MRI contrast injection. A day after sonication, the eyes were processed for histology of the retina. At the two lower exposure levels (0.81 and 0.88 MPa, most of the sonicated regions were indistinguishable from the control eyes, although a few tiny clusters of extravasated erythrocytes (petechaie were observed. More severe retinal damage was observed at 1.1 MPa. These results demonstrate that focused ultrasound and microbubbles can offer a noninvasive and targeted means to transiently disrupt the BRB for ocular drug delivery.

  3. Photoacoustic-guided focused ultrasound for accurate visualization of brachytherapy seeds with the photoacoustic needle

    Science.gov (United States)

    Singh, Mithun Kuniyil Ajith; Parameshwarappa, Vinay; Hendriksen, Ellen; Steenbergen, Wiendelt; Manohar, Srirang

    2016-12-01

    An important problem in minimally invasive photoacoustic (PA) imaging of brachytherapy seeds is reflection artifacts caused by the high signal from the optical fiber/needle tip reflecting off the seed. The presence of these artifacts confounds interpretation of images. In this letter, we demonstrate a recently developed concept called photoacoustic-guided focused ultrasound (PAFUSion) for the first time in the context of interstitial illumination PA imaging to identify and remove reflection artifacts. In this method, ultrasound (US) from the transducer is focused on the region of the optical fiber/needle tip identified in a first step using PA imaging. The image developed from the US diverging from the focus zone at the tip region visualizes only the reflections from seeds and other acoustic inhomogeneities, allowing identification of the reflection artifacts of the first step. These artifacts can then be removed from the PA image. Using PAFUSion, we demonstrate reduction of reflection artifacts and thereby improved interstitial PA visualization of brachytherapy seeds in phantom and ex vivo measurements on porcine tissue.

  4. Functional Assay of Cancer Cell Invasion Potential Based on Mechanotransduction of Focused Ultrasound

    Directory of Open Access Journals (Sweden)

    Andrew C. Weitz

    2017-08-01

    Full Text Available Cancer cells undergo a number of biophysical changes as they transform from an indolent to an aggressive state. These changes, which include altered mechanical and electrical properties, can reveal important diagnostic information about disease status. Here, we introduce a high-throughput, functional technique for assessing cancer cell invasion potential, which works by probing for the mechanically excitable phenotype exhibited by invasive cancer cells. Cells are labeled with fluorescent calcium dye and imaged during stimulation with low-intensity focused ultrasound, a non-contact mechanical stimulus. We show that cells located at the focus of the stimulus exhibit calcium elevation for invasive prostate (PC-3 and DU-145 and bladder (T24/83 cancer cell lines, but not for non-invasive cell lines (BPH-1, PNT1A, and RT112/84. In invasive cells, ultrasound stimulation initiates a calcium wave that propagates from the cells at the transducer focus to other cells, over distances greater than 1 mm. We demonstrate that this wave is mediated by extracellular signaling molecules and can be abolished through inhibition of transient receptor potential channels and inositol trisphosphate receptors, implicating these proteins in the mechanotransduction process. If validated clinically, our technology could provide a means to assess tumor invasion potential in cytology specimens, which is not currently possible. It may therefore have applications in diseases such as bladder cancer, where cytologic diagnosis of tumor invasion could improve clinical decision-making.

  5. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Modeling of Nonlinear Propagation in Multi-layer Biological Tissues for Strong Focused Ultrasound

    Science.gov (United States)

    Fan, Ting-Bo; Liu, Zhen-Bo; Zhang, Zhe; Zhang, Dong; Gong, Xiu-Fen

    2009-08-01

    A theoretical model of the nonlinear propagation in multi-layered tissues for strong focused ultrasound is proposed. In this model, the spheroidal beam equation (SBE) is utilized to describe the nonlinear sound propagation in each layer tissue, and generalized oblique incidence theory is used to deal with the sound transmission between two layer tissues. Computer simulation is performed on a fat-muscle-liver tissue model under the irradiation of a 1 MHz focused transducer with a large aperture angle of 35°. The results demonstrate that the tissue layer would change the amplitude of sound pressure at the focal region and cause the increase of side petals.

  6. Intracranial treatment envelope mapping of transcranial focused ultrasound

    Science.gov (United States)

    Eames, Matthew D. C.; Hananel, Arik; Kassell, Neal F.; Snell, John W.

    2012-11-01

    Presented here are the results of a volumetric, thermal treatment envelope map for transcranial focused ultrasound. The aim was to determine the treatable volume of the intracranial cavity in order to identify potential clinical applications and direct future research efforts. It was determined that thalamic targets are optimal for both transcranical MRg-FUS systems used in this work, which operate at 220 kHz and 650 kHz, respectively. It is hoped that future research efforts will focus on expanding these treatment envelopes in order to expand the possible neurosurgical applications for this technology.

  7. Design, simulation and testing of capacitive micromachined ultrasound transducer-based phospholipidic biosensor elements

    Science.gov (United States)

    Sapeliauskas, E.; Vanagas, G.; Barauskas, D.; Mikolajunas, M.; Pakenas, E.; Pelenis, D.; Sergalis, G.; Jukna, T.; Virzonis, D.

    2015-07-01

    In this study we present theoretical proof of the principle of using interdigital capacitive micromachined ultrasound transducers (CMUT IDTs) for the detection of phospholipid membrane elasticity. Proof of principle was needed to find out whether the new type of microelectromechanical sensors of the toxins incorporated with the lipid membranes was feasible. CMUT IDTs for 10 MHz operation in water, with 146 µm spaced double fingers were designed and fabricated using the surface micromachining technique. Fabricated CMUTs were tested for their resonance in air and for Scholte-type wave transmission in deionized water and isopropanol solutions containing 0%, 10% and 20% water. The amplitude and phase velocity of the excited and received Scholte waves were measured in a 200 µm height microchannel, capped with a thick layer of soft polymer, which suppressed the production of non-informative guided waves. It was determined that the average sensitivity of Scholte wave phase velocity within the given range of solution concentrations is 2.9 m s-1 per one percent. Experimental data were also used to verify the adequacy of the finite element model, which was found to be suitable for reliable prediction of the phospholipid membrane elasticity impact on the Scholte wave phase velocity or the resonance frequency in the present IDT structure. It was determined that for the analyzed conditions (the elasticity of simulated phospholipid membrane changed from 1 to 5 GPa) the sensitivity of the measurement channel is expected to be no worse than 2 kHz GPa-1 in terms of the Scholte wave and CMUT IDT resonance frequency. This leads to a positive conclusion on the feasibility of the new sensor type.

  8. Development of a spherically focused phased array transducer for ultrasonic image-guided hyperthermia

    Science.gov (United States)

    Liu, Jingfei; Foiret, Josquin; Stephens, Douglas N.; Le Baron, Olivier; Ferrara, Katherine W.

    2016-07-01

    A 1.5 MHz prolate spheroidal therapeutic array with 128 circular elements was designed to accommodate standard imaging arrays for ultrasonic image-guided hyperthermia. The implementation of this dual-array system integrates real-time therapeutic and imaging functions with a single ultrasound system (Vantage 256, Verasonics). To facilitate applications involving small animal imaging and therapy the array was designed to have a beam depth of field smaller than 3.5 mm and to electronically steer over distances greater than 1 cm in both the axial and lateral directions. In order to achieve the required f number of 0.69, 1-3 piezocomposite modules were mated within the transducer housing. The performance of the prototype array was experimentally evaluated with excellent agreement with numerical simulation. A focal volume (2.70 mm (axial)  ×  0.65 mm (transverse)  ×  0.35 mm (transverse)) defined by the  -6 dB focal intensity was obtained to address the dimensions needed for small animal therapy. An electronic beam steering range defined by the  -3 dB focal peak intensity (17 mm (axial)  ×  14 mm (transverse)  ×  12 mm (transverse)) and  -8 dB lateral grating lobes (24 mm (axial)  ×  18 mm (transverse)  ×  16 mm (transverse)) was achieved. The combined testing of imaging and therapeutic functions confirmed well-controlled local heating generation and imaging in a tissue mimicking phantom. This dual-array implementation offers a practical means to achieve hyperthermia and ablation in small animal models and can be incorporated within protocols for ultrasound-mediated drug delivery.

  9. Investigations on the heating effect of PE-LD induced by high-intensity focused ultrasound.

    Science.gov (United States)

    Oehm, Lukas; Bach, Sascha; Majschak, Jens-Peter

    2016-08-01

    High-intensity focused ultrasound is widely applied in tissue treatment as well as for heating of solid polymer materials. Previous studies investigating the heating effect in polymer materials utilized sound transmission through water or other fluids at low HIFU power. In this study, the ultrasonic transducer possesses a solid sound conductor made of aluminum and a high HIFU power of above 100W was applied to heat solid PE-LD samples. Temperature measurements were performed by calibrated non-invasive infrared thermal imaging. A strong heating effect with heating above melting temperature and evaporation temperature within less than 1s of irradiation was observed. Furthermore, the acoustic coupling defined by the force applied by the ultrasonic applicator to the polymer material was found to be fundamental to induce the heating effect. This investigation reveals HIFU for new applications in the field of polymer processing.

  10. Erythrocytes and microbubble contrast agents, improve the therapeutic efficiency of high intensity focused ultrasound

    Science.gov (United States)

    Takegami, Kenji; Kaneko, Yukio; Watanabe, Toshiaki; Maruyama, Toshiyuki; Matsumoto, Yoichiro; Nagawa, Hirokazu

    2005-03-01

    Erythrocytes, an well as Levovist microbubble contrast agent, enhance the heating effect of high intensity focused ultrasound (HIFU) and increase the coagulation volume produced by HIFU irradiation. In vitro experiments used human plasma with various concentrations of human erythrocytes in combination with or without Levovist. In vivo experiments used eight Japan white rabbits with three levels of anaemia. Using a 2.17 MHz transducer, HIFU was applied for 60 seconds, and the temperature rise and the volume of coagulation necrosis was evaluated. There was a significant correlation between the HIFU-induced temperature rise and hematocrit, with a correlation coefficient of 0.998 (p=0.0001). Although the temperature rise was smaller at low hematocrit, it was significantly increased by adding Levovist to the suspension (panaemia group was significantly increased by using Levovist (p<0.01).

  11. High-intensity focused ultrasound monitoring using harmonic motion imaging for focused ultrasound (HMIFU) under boiling or slow denaturation conditions.

    Science.gov (United States)

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Apostolakis, Iason-Zacharias; Konofagou, Elisa E

    2015-07-01

    Harmonic motion imaging for focused ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method that utilizes an amplitude-modulated therapeutic ultrasound beam to induce an oscillatory radiation force at the HIFU focus and estimates the focal tissue displacement to monitor the HIFU thermal treatment. In this study, the performance of HMIFU under acoustic, thermal, and mechanical effects was investigated. The performance of HMIFU was assessed in ex vivo canine liver specimens (n = 13) under slow denaturation or boiling regimes. A passive cavitation detector (PCD) was used to assess the acoustic cavitation activity, and a bare-wire thermocouple was used to monitor the focal temperature change. During lesioning with slow denaturation, high quality displacements (correlation coefficient above 0.97) were observed under minimum cavitation noise, indicating the tissue initial-softening-then- stiffening property change. During HIFU with boiling, HMIFU monitored a consistent change in lesion-to-background displacement contrast (0.46 ± 0.37) despite the presence of strong cavitation noise due to boiling during lesion formation. Therefore, HMIFU effectively monitored softening-then-stiffening during lesioning under slow denaturation, and detected lesioning under boiling with a distinct change in displacement contrast under boiling in the presence of cavitation. In conclusion, HMIFU was shown under both boiling and slow denaturation regimes to be effective in HIFU monitoring and lesioning identification without being significantly affected by cavitation noise.

  12. High Intensity Focused Ultrasound Monitoring using Harmonic Motion Imaging for Focused Ultrasound (HMIFU) under boiling or slow denaturation conditions

    Science.gov (United States)

    Hou, Gary Y.; Marquet, Fabrice; Wang, Shutao; Apostolakis, Iason-Zacharias; Konofagou, Elisa E.

    2015-01-01

    Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a recently developed High-Intensity Focused Ultrasound (HIFU) treatment monitoring method that utilizes an amplitude-modulated therapeutic ultrasound beam to induce an oscillatory radiation force at the HIFU focus and estimates the focal tissue displacement to monitor the HIFU thermal treatment. In this study, the performance of HMIFU under acoustic, thermal and mechanical effects were investigated. The performance of HMIFU was assessed in ex vivo canine liver specimens (n=13) under slow denaturation or boiling regimes. Passive Cavitation Detector (PCD) was used to assess the acoustic cavitation activity while a bare-wire thermocouple was used to monitor the focal temperature change. During lesioning with slow denaturation, high quality displacements (correlation coefficient above 0.97) were observed under minimum cavitation noise, indicating tissue the initial-softening-then-stiffening property change. During HIFU with boiling, HMIFU monitored a consistent change in lesion-to-background displacement contrast (0.46±0.37) despite the presence of strong cavitation noise due to boiling during lesion formation. Therefore, HMIFU effectively monitored softening-then-stiffening during lesioning under slow denaturation, and detected lesioning under boiling with a distinct change in displacement contrast under boiling in the presence of cavitation. In conclusion, HMIFU was shown effective in HIFU monitoring and lesioning identification without being significantly affected by cavitation noise. PMID:26168177

  13. Validity and reliability of rectus femoris ultrasound measurements: Comparison of curved-array and linear-array transducers

    Directory of Open Access Journals (Sweden)

    Kendra Hammond, MD

    2014-11-01

    Full Text Available Muscle-mass loss augers increased morbidity and mortality in critically ill patients. Muscle-mass loss can be assessed by wide linear-array ultrasound transducers connected to cumbersome, expensive console units. Whether cheaper, hand-carried units equipped with curved-array transducers can be used as alternatives is unknown. Accordingly, our primary aim was to investigate in 15 nondisabled subjects the validity of measurements of rectus femoris cross-sectional area by using a curved-array transducer against a linear-array transducer—the reference-standard technique. In these subjects, we also determined the reliability of measurements obtained by a novice operator versus measurements obtained by an experienced operator. Lastly, the relationship between quadriceps strength and rectus area recorded by two experienced operators with a curved-array transducer was assessed in 17 patients with chronic obstructive pulmonary disease (COPD. In nondisabled subjects, the rectus cross-sectional area measured with the curved-array transducer by the novice and experienced operators was valid (intraclass correlation coefficient [ICC]: 0.98, typical percentage error [%TE]: 3.7% and reliable (ICC: 0.79, %TE: 9.7%. In the subjects with COPD, both reliability (ICC: 0.99 and repeatability (%TE: 7.6% and 9.8% were high. Rectus area was related to quadriceps strength in COPD for both experienced operators (coefficient of determination: 0.67 and 0.70. In conclusion, measurements of rectus femoris cross-sectional area recorded with a curved-array transducer connected to a hand-carried unit are valid, reliable, and reproducible, leading us to contend that this technique is suitable for cross-sectional and longitudinal studies.

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

    Science.gov (United States)

    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.

  15. Particle image velocimetry on simulated 3D ultrafast ultrasound from pediatric matrix TEE transducers

    Science.gov (United States)

    Voorneveld, J. D.; Bera, D.; van der Steen, A. F. W.; de Jong, N.; Bosch, J. G.

    2017-03-01

    Ultrafast 3D transesophageal echocardiographic (TEE) imaging, combined with 3D echo particle image velocimetry (ePIV), would be ideal for tracking the complex blood flow patterns in the heart. We are developing a miniature pediatric matrix TEE transducer that employs micro-beamforming (μBF) and allows high framerate in 3D. In this paper, we assess the feasibility of 3D ePIV with a high frame rate, small aperture transducer and the influence of the micro-beamforming technique. We compare the results of 3D ePIV on simulated images using the μBF transducer and an idealized, fully sampled (FS) matrix transducer. For the two transducers, we have simulated high-framerate imaging of an 8.4mm diameter artery having a known 4D velocity field. The simulations were performed in FieldII. 1000 3D volumes, at a rate of 1000 volumes/sec, were created using a single diverging transmission per volume. The error in the 3D velocity estimation was measured by comparing the ePIV results of both transducers to the ground truth. The results on the simulated volumes show that ePIV can estimate the 4D velocity field of the arterial phantom using these small-aperture transducers suitable for pediatric 3D TEE. The μBF transducer (RMSE 44.0%) achieved comparable ePIV accuracy to that of the FS transducer (RMSE 42.6%).

  16. Optimizing sonication protocols for transthoracic focused ultrasound surgery

    Science.gov (United States)

    Gao, J.; Volovick, A.; Cao, R.; Nabi, G.; Cochran, S.; Melzer, A.; Huang, Z.

    2012-11-01

    During transthoracic focused ultrasound surgery (TFUS), the intervening ribs absorb and reflect the majority of the ultrasound energy excited by an acoustic source, resulting in pain, bone injuries and insufficient energy delivered to the target organs of liver, kidney, and pancreas. Localized hot spots may also exist at the interfaces between the ribs and soft tissue and in the highly absorptive regions such as the skin and connective tissue. The aims of this study were to clarify the effects of focal beam distortion and frequency-dependent rib heating in TFUS and to propose possible techniques to reduce the side-effects of rib heating and increase ultrasound efficacy. Frequency-dependent heating at the target and the ribs were estimated using finite element analysis (PZFlex, Weidlinger Associates Inc, USA) along with experimental verification on a range of different phantoms. The ratio of ultrasonic power density at the target and the ribs, the time-varying spatial distribution of temperature, and the ablated focus of each sonication were taken as key indicators to determine the optimal operating frequency. Comparison with a patient specific model was also made. TFUS seems to be useful to treat tumours that are small and near the surface of the abdominal organs. For targets deep inside these organs, severe attenuation of energy occurs, suggesting that purely ultrasound thermal ablation with advanced heating patterns will have limited effects in improving the treatment efficacy. Results demonstrate that the optimal ultrasound frequency is around 0.8 MHz for the configurations considered, but this may shift to higher frequencies with changes in the axial and lateral positions of the tumours relative to the ribs. To date, we have elucidated the most important effects and correlated these with idealised anatomical geometry. The changes in frequency and other techniques such as selection of excited element patterns in FUS arrays had some effect. However, more advanced

  17. Focused ultrasound surgery-induced vascular occlusion in fetal medicine

    Science.gov (United States)

    Rivens, Ian H.; Rowland, Ian; Denbow, Mark; Fisk, Nicholas M.; Leach, Martin O.; ter Haar, Gail R.

    1998-04-01

    Aim: This study investigates whether it is possible to occlude blood flow in vivo using high intensity focused ultrasound surgery (FUS). Such an effect could be used in the non-invasive treatment of fetal dysfunctions. Conclusion: Our ability to curtail blood flow using FUS allows the possibility of non-invasively treating feto-fetal transfusion syndrome by occluding the placental shunt vessels responsible for the vascular imbalance in twins sharing a placenta. This would have advantages over currently available interventional treatments (surgery or intrauterine lasers), which have significant related mortality and morbidity.

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

    Science.gov (United States)

    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.

  19. Modeling transducer impulse responses for predicting calibrated pressure pulses with the ultrasound simulation program Field II

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2010-01-01

    FIELD II is a simulation software capable of predicting the field pressure in front of transducers having any complicated geometry. A calibrated prediction with this program is, however, dependent on an exact voltage-to-surface acceleration impulse response of the transducer. Such impulse response...... is not calculated by FIELD II. This work investigates the usability of combining a one-dimensional multilayer transducer modeling principle with the FIELD II software. Multilayer here refers to a transducer composed of several material layers. Measurements of pressure and current from Pz27 piezoceramic disks...... as well as pressure and intensity measurements in front of a 128 element commercial convex medical transducer are compared to the simulations. Results show that the models can predict the pressure from the piezoceramic disks with a root mean square (rms) error of 11.2% to 36.2% with a 2 dB amplitude...

  20. Impact of microbubble enhanced, pulsed, focused ultrasound on tumor circulation of subcutaneous VX2 cancer

    Institute of Scientific and Technical Information of China (English)

    Li Peijing; Zhu Mei; Xu Yali; Zhao Yang; Gao Shunji; Liu Zheng; Gao Yun-hua

    2014-01-01

    Background Intravascular microbubble-enhanced acoustic cavitation is capable of disrupting the vascular walls of capillaries and small vessels.This study was designed to investigate the impact of microbubble-enhanced,pulsed and focused ultrasound (MEUS) on the blood perfusion of subcutaneous VX2 tumors in rabbits.Methods Subcutaneous VX2 cancers in twenty New Zealand rabbits were treated by combining high-pressure amplitude,pulsed and focused therapeutic ultrasound (TUS) and intravenous microbubble injections.The TUS transducer was operated with a peak negative pressure of 4.6 MPa and a duty cycle of 0.41%.Controls were subcutaneous VX2 cancers treated with TUS or microbubbles only.Contrast-enhanced ultrasound (CEUS) and intravenous Evans Blue (EB) perfusion were performed to assess the tumor circulation.The tumor microvascular disruption was assessed by histological examination.Results CEUS showed that the tumor circulation almost vanished after MEUS treatment.The average peak grayscale value (GSV) of tumor CEUS dropped significantly from 84.1±22.4 to 15.8±10.8 in the MEUS-treated tumors but no significant GSV changes were found in tumors in the two control groups.The mean tumor EB content of the MEUS-treated tumors was significantly lower than that of the controls.Histological examination found scattered tumor microvascular disruption with intercellular edema after MEUS treatment.Conclusion The tumor circulation of VX2 cancers can be arrested or significantly reduced by MEUS due to microvascular disruption.

  1. Miniaturized Cell Lysis Device Using Spherically Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    李刚; 肖宏; 郭旻; 程京

    2003-01-01

    A prototype of a miniaturized cell lysis device developed using a concave spherical transducer is capable of lysing bacteria without added chemical denaturants, enzymes or microparticles and is capable of efficiently lysing yeast without any mechanical or enzymatic pretreatment.The device is designed for miniature bio-analysis systems where cell lysing is needed to obtain intracellular materials for further analysis such as DNA identification.The device lysis efficiency was evaluated using viable cell counts and microscopy.Additionally, the device efficiency was compared with that of traditional chemical cell lysis methods using standard molecular biological techniques such as agarose gels and ultraviolet (UV) spectroscopy.The results indicate that efficient bacteria and cell disruption can be achieved through a low-voltage-driven and spherically focused high-frequency ultrasonic device.

  2. Use of High Intensity Focused Ultrasound for Treating Malignant Tumors

    Institute of Scientific and Technical Information of China (English)

    WenzhiChen; ZhibiaoWang; FengWu; JinBai; HuiZhu; JianzhongZou; KequanLi; FanglinXie; ZhilongWang

    2004-01-01

    OBJECTIVE To investigate the efficacy and side effects of high intensity focused ultrasound(HIFU) in the treatment of malignant solid tumors. METHODS Thirty patients who refused surgery and/or were refractory to chemotherapy were treated by HIFU alone, with the efficacy and side effects monitored as follows: observation of vital organ signs; functional assay of important organs; imaging examinations including: digital subtraction angiography (DSA), CT, MRI, single photon emission computed tomography (SPECT), large core needle biopsy, complications and metastasis. RESULTS After HIFU therapy, the vital signs remained stable and the functions of the heart, lung, kidney and liver were also normal. DSA images showed that small or larger arteries were not damaged. After a follow-up of 10-38 months(mean 23.1 months), 26 patients(87%) were alive. The volume of the tumor underwent complete regression in 10 patients. Shrinkage of the tumor volume ≥50% was observed in 13 patients. Eight of 13 patients were examined by large core needle biopsy, all showing necrosis and/or fibrosis though 3 patients(10%) had local recurrence. Two of these were retreated again by HIFU and the locally recurrent tumors were controlled. New metastases developed in 5 patients after H IFU. Two patients suffered from peripheral nerve injuriy and they have recovered during the follow-up. One patient developed skin injury. CONCLUSION High intensity focused ultrasound is effective and safe in the treatment of malignant solid tumors.

  3. Blood coagulation using High Intensity Focused Ultrasound (HIFU)

    Science.gov (United States)

    Nguyen, Phuc V.; Oh, Junghwan; Kang, Hyun Wook

    2014-03-01

    High Intensity Focused Ultrasound (HIFU) technology provides a feasible method of achieving thermal coagulation during surgical procedures. One of the potential clinical benefits of HIFU can induce immediate hemostasis without suturing. The objective of this study was to investigate the efficiency of a HIFU system for blood coagulation on severe vascular injury. ngHIFU treatment was implemented immediately after bleeding in artery. The ultrasound probe was made of piezoelectric material, generating a central frequency of 2.0 MHz as well as an ellipsoidal focal spot of 2 mm in lateral dimension and 10 mm in axial dimension. Acoustic coagulation was employed on a perfused chicken artery model in vitro. A surgical incision (1 to 2 mm long) was made with a scapel on the arterial wall, and heparinized autologous blood was made to leak out from the incision with a syringe pump. A total of 5 femoral artery incisions was treated with the HIFU beam. The intensity of 4500 W/cm2 at the focus was applied for all treatments. Complete hemostasis was achieved in all treatments, along with the treatment times of 25 to 50 seconds. The estimated intraoperative blood loss was from 2 to 5 mL. The proposed HIFU system may provide an effective method for immediate blood coagulation for arteries and veins in clinical applications.

  4. Optimal design of a piezoelectric transducer for exciting guided wave ultrasound in rails

    Science.gov (United States)

    Ramatlo, Dineo A.; Wilke, Daniel N.; Loveday, Philip W.

    2017-02-01

    An existing Ultrasonic Broken Rail Detection System installed in South Africa on a heavy duty railway line is currently being upgraded to include defect detection and location. To accomplish this, an ultrasonic piezoelectric transducer to strongly excite a guided wave mode with energy concentrated in the web (web mode) of a rail is required. A previous study demonstrated that the recently developed SAFE-3D (Semi-Analytical Finite Element - 3 Dimensional) method can effectively predict the guided waves excited by a resonant piezoelectric transducer. In this study, the SAFE-3D model is used in the design optimization of a rail web transducer. A bound-constrained optimization problem was formulated to maximize the energy transmitted by the transducer in the web mode when driven by a pre-defined excitation signal. Dimensions of the transducer components were selected as the three design variables. A Latin hypercube sampled design of experiments that required a total of 500 SAFE-3D analyses in the design space was employed in a response surface-based optimization approach. The Nelder-Mead optimization algorithm was then used to find an optimal transducer design on the constructed response surface. The radial basis function response surface was first verified by comparing a number of predicted responses against the computed SAFE-3D responses. The performance of the optimal transducer predicted by the optimization algorithm on the response surface was also verified to be sufficiently accurate using SAFE-3D. The computational advantages of SAFE-3D in optimal transducer design are noteworthy as more than 500 analyses were performed. The optimal design was then manufactured and experimental measurements were used to validate the predicted performance. The adopted design method has demonstrated the capability to automate the design of transducers for a particular rail cross-section and frequency range.

  5. Focused ultrasound-modulated glomerular ultrafiltration assessed by functional changes in renal arteries.

    Directory of Open Access Journals (Sweden)

    Feng-Yi Yang

    Full Text Available This study demonstrates the feasibility of using focused ultrasound (FUS to modulate glomerular ultrafiltration by renal artery sonication and determine if protein-creatinine ratios are estimated through vascular parameters. All animal experiments were approved by our Animal Care and Use Committee. The renal arteries of Sprague-Dawley rats were surgically exposed and sonicated at various acoustic power levels using a FUS transducer with a resonant frequency of 1 MHz. The mean peak systolic velocity (PSV of the blood flow was measured by Doppler ultrasound imaging. Urinary protein-creatinine ratios were calculated during the experiments. Histological examination of renal arteries and whole kidneys was performed. The PSV, pulsatility index, and resistance index of blood flow significantly increased in the arteries after FUS sonication without microbubbles (p<0.05. The change in normalized protein-creatinine ratios significantly increased with increasing acoustic power, but such was not observed when microbubbles were administered. Furthermore, no histological changes were observed in the hematoxylin- and eosin-stained sections. Glomerular ultrafiltration is regulated temporarily by renal artery sonication without microbubbles. Monitoring vascular parameters are useful in estimating the normalized change in protein-creatinine ratios.

  6. A Pilot Study Investigating the Potential of High-Intensity Focused Ultrasound to Treat Tumours Rapidly

    Science.gov (United States)

    Cranston, Jonathan M.; Rivens, Ian; ter Haar, Gail; Kennedy, James

    2007-05-01

    The aim of this project was to investigate the possibility of rapid tumour destruction by a novel method of treating the periphery of a tumour and inducing ischemia by impeding the blood supply. Ex vivo experiments were initially carried out in bovine liver to determine the optimum conditions for focal depth, gantry transducer speed circle diameter and intensity of the ultrasound beam. In vivo experiments were then performed in PGV rat livers implanted with a HSN fibrosarcoma cell line. The tumours were treated by novel technique of creating an annular lesion around the perimeter of the tumour. Macroscopic and microscopic examination of the lesion at post mortem was performed. In addition histological examination of the untreated tumour which was within the annular circle of treatment was examined. This showed evidence of karyolytic nuclei a week after treatment suggesting death by infarction within this area. There was also some evidence of endothelial damage in the blood vessels with fragmented nuclei visible in the lumen. The work presented here adds to our understanding of how high intensity focused ultrasound may be used to treat tumours in as faster and more efficient way. Further work in this area will facilitate the design of future therapeutic interventions in the medical and veterinary world.

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

    Science.gov (United States)

    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.

  8. Nonlinear 3-D simulation of high-intensity focused ultrasound therapy in the kidney

    CERN Document Server

    Suomi, Visa; Treeby, Bradley; Cleveland, Robin

    2016-01-01

    Kidney cancer is a severe disease which can be treated non-invasively using high-intensity focused ultrasound (HIFU) therapy. However, tissue in front of the transducer and the deep location of kidney can cause significant losses to the efficiency of the treatment. The effect of attenuation, refraction and reflection due to different tissue types on HIFU therapy of the kidney was studied using a nonlinear ultrasound simulation model. The geometry of the tissue was derived from a computed tomography (CT) dataset of a patient which had been segmented for water, bone, soft tissue, fat and kidney. The combined effect of inhomogeneous attenuation and sound-speed was found to result in an 11.0 dB drop in spatial peak-temporal average (SPTA) intensity in the kidney compared to pure water. The simulation without refraction effects showed a 6.3 dB decrease indicating that both attenuation and refraction contribute to the loss in focal intensity. The losses due to reflections at soft tissue interfaces were less than 0....

  9. Phase Relation of Harmonics in Nonlinear Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    Zhe-Fan Peng; Wei-Jun Lin; Shi-Lei Liu; Chang Su; Hai-Lan Zhang; Xiu-Ming Wang

    2016-01-01

    The phase relation of harmonics in high-intensity focused ultrasound is investigated numerically and experimentally.The nonlinear Westervelt equation is solved to model nonlinear focused sound field by using the finite difference time domain method.Experimental waveforms are measured by a robust needle hydrophone.Then the relative phase quantity is introduced and obtained by using the zero-phase filter.The results show that the nth harmonic relative phase quantity is approximately (n-1)π/3 at geometric center and increases along the axial direction.Moreover,the relative phase quantity decreases with the increase of source amplitude.This phase relation gives an explanation of some nonlinear phenomena such as the discrepancy of positive and negative pressure.

  10. MR guided focused ultrasound: technical acceptance measures for a clinical system

    Energy Technology Data Exchange (ETDEWEB)

    Gorny, K R; Hangiandreou, N J; Hesley, G K; Gostout, B S; McGee, K P; Felmlee, J P [Department of Radiology, Mayo Clinic, Rochester, MN 55905 (United States)

    2006-06-21

    Magnetic resonance (MR) guided focused ultrasound (MRgFUS) is a hybrid technique which offers efficient and safe focused ultrasound (FUS) treatments of uterine fibroids under MR guidance and monitoring. As a therapy device, MRgFUS requires systematic testing over a wide range of operational parameters prior to use in the clinical environment. We present technical acceptance tests and data for the first clinical MRgFUS system, ExAblate (registered) 2000 (InSightec Inc., Haifa, Israel), that has been FDA approved for treating uterine fibroids. These tests characterize MRgFUS by employing MR temperature measurements in tissue mimicking phantoms. The coronal scan plane is empirically demonstrated to be most reliable for measuring temperature elevations resulting from high intensity ultrasound (US) pulses ('sonications') and shows high sensitivity to changes in sonication parameters. Temperatures measured in the coronal plane were used as a measure of US energy deposited within the focal spot for a range of sonication parameters used in clinical treatments: spot type, spot length, output power, sonication duration, US frequency, and depth of sonication. In addition, MR images acquired during sonications were used to measure effective diameters and lengths of available sonication spot types and lengths. At a constant 60 W output power, the effective spot type diameters were measured to vary between 4.7 {+-} 0.3 mm and 6.6 {+-} 0.4 mm; treatment temperatures were found to decrease with increasing spot diameter. Prescribing different spot lengths was found to have no effect on the measured length or on measured temperatures. Tests of MRgFUS positioning accuracy determined errors in the direction parallel to the propagation of the US beam to be significantly greater than those in the perpendicular direction; most sonication spots were erroneously positioned towards the FUS transducer. The tests reported here have been demonstrated to be sufficiently sensitive to

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

    Science.gov (United States)

    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

  12. Focused ultrasound-mediated suppression of chemically-induced acute epileptic EEG activity

    Directory of Open Access Journals (Sweden)

    Chung Yong-An

    2011-03-01

    Full Text Available Abstract Background Epilepsy is a common neurological disorder, which is attributed to uncontrollable abnormal hyper-excitability of neurons. We investigated the feasibility of using low-intensity, pulsed radiation of focused ultrasound (FUS to non-invasively suppress epileptic activity in an animal model (rat, which was induced by the intraperitonial injection of pentylenetetrazol (PTZ. Results After the onset of induced seizures, FUS was transcranially administered to the brain twice for three minutes each while undergoing electroencephalographic (EEG monitoring. An air-backed, spherical segment ultrasound transducer (diameter: 6 cm; radius-of-curvature: 7 cm operating at a fundamental frequency of 690 KHz was used to deliver a train of 0.5 msec-long pulses of sonication at a repetitive rate of 100 Hz to the thalamic areas of the brain. The acoustic intensity (130 mW/cm2 used in the experiment was sufficiently within the range of safety guidelines for the clinical ultrasound imaging. The occurrence of epileptic EEG bursts from epilepsy-induced rats significantly decreased after sonication when it was compared to the pre-sonication epileptic state. The PTZ-induced control group that did not receive any sonication showed a sustained number of epileptic EEG signal bursts. The animals that underwent sonication also showed less severe epileptic behavior, as assessed by the Racine score. Histological analysis confirmed that the sonication did not cause any damage to the brain tissue. Conclusions These results revealed that low-intensity, pulsed FUS sonication suppressed the number of epileptic signal bursts using acute epilepsy model in animal. Due to its non-invasiveness and spatial selectivity, FUS may offer new perspectives for a possible non-invasive treatment of epilepsy.

  13. 开口柱面换能器声场分析%Study of Focused Ultrasonic Field of Cylindrical Transducer with a Hole

    Institute of Scientific and Technical Information of China (English)

    赵泉洲; 惠春; 余立立; 胡振林

    2011-01-01

    Objective: Focused ultrasound treatment of superficial tissue disease, gynecological there focused transducer placed at the same time and location of the probe problems in the actual design of the treatment must be considered in the first place the B-probe the impact of the sound field of focus, This relates to a cylindrical opening focused ultrasound transducer sound field of numerical calculation and simulation, calculated by three-dimensional sound field distribution, while the self-focusing of cylindrical transducer in different opening shapes, location, size of the sound field impact, to guide the opening of the actual transducer design. Methods: hi this paper, three-dimensional Cartesian coordinate system, the application of variable-step method of Simpson double integral focused ultrasound on the open cylinder transducer sound field for a numerical calculation and simulation, draw three-dimensional sound field distribution. Results: Openings of different shapes, sizes, location of the sound field distribution simulation results show that: different shape of the opening pressure will cause the amplitude of the focus area decreased, opening the radius increases, the pressure showed a downward trend, Z axis of the sound pressure in the exchange can control the edge of the large middle small. With the open center of the greater distance from the origin, Z axis of the sound pressure distribution more uneven, but has little effect on the focus position.Conclusions: We can see from the effects on the distribution of the three-dimensional sound field of different parameters: cylindrical ultrasound transducer opening shape,location, size of the focus areas of sound pressure are significantly affected. Compared with the given conditions, selected centrally located, smaller, transducers, focusing performance can be improved, and the opening shape of the transducer little effect on the focus.%目的:聚焦超声治疗妇科浅表组织疾病中存在聚焦换能器和

  14. Intense focused ultrasound stimulation of the rotator cuff: evaluation of the source of pain in rotator cuff tears and tendinopathy.

    Science.gov (United States)

    Gellhorn, Alfred C; Gillenwater, Cody; Mourad, Pierre D

    2015-09-01

    The objective of this preliminary study was to evaluate the ability of individual 0.1-s long pulses of intense focused ultrasound (iFU) emitted with a carrier frequency of 2 MHz to evoke diagnostic sensations when applied to patients whose shoulders have rotator cuff tears or tendinopathy. Patients were adults with painful shoulders and clinical and imaging findings consistent with rotator cuff disease. iFU stimulation of the shoulder was performed using B-mode ultrasound coupled with a focused ultrasound transducer that allowed image-guided delivery of precisely localized pulses of energy to different anatomic areas around the rotator cuff. The main outcome measure was iFU spatial average-temporal average intensity (I_SATA), and location required to elicit sensation. In control patients, iFU produced no sensation throughout the range of stimulation intensities (≤2000 W/cm(2) I_SATA). In patients with rotator cuff disease, iFU was able to induce sensation in the tendons of the rotator cuff, the subacromial bursa, and the subchondral bone in patients with chronic shoulder pain and rotator cuff disease, with an average ± standard deviation intensity equaling 680 ± 281 W/cm(2) I_SATA. This result suggests a primary role for these tissues in the pathogenesis of shoulder pain related to rotator cuff tendinopathy. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  15. Effect of Transducer Orientation on Errors in Ultrasound Image-Based Measurements of Human Medial Gastrocnemius Muscle Fascicle Length and Pennation.

    Science.gov (United States)

    Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

    2016-01-01

    Ultrasound imaging is often used to measure muscle fascicle lengths and pennation angles in human muscles in vivo. Theoretically the most accurate measurements are made when the transducer is oriented so that the image plane aligns with muscle fascicles and, for measurements of pennation, when the image plane also intersects the aponeuroses perpendicularly. However this orientation is difficult to achieve and usually there is some degree of misalignment. Here, we used simulated ultrasound images based on three-dimensional models of the human medial gastrocnemius, derived from magnetic resonance and diffusion tensor images, to describe the relationship between transducer orientation and measurement errors. With the transducer oriented perpendicular to the surface of the leg, the error in measurement of fascicle lengths was about 0.4 mm per degree of misalignment of the ultrasound image with the muscle fascicles. If the transducer is then tipped by 20°, the error increases to 1.1 mm per degree of misalignment. For a given degree of misalignment of muscle fascicles with the image plane, the smallest absolute error in fascicle length measurements occurs when the transducer is held perpendicular to the surface of the leg. Misalignment of the transducer with the fascicles may cause fascicle length measurements to be underestimated or overestimated. Contrary to widely held beliefs, it is shown that pennation angles are always overestimated if the image is not perpendicular to the aponeurosis, even when the image is perfectly aligned with the fascicles. An analytical explanation is provided for this finding.

  16. An integrated ultrasound-guided high intensity focused ultrasound system for in-vivo experiment

    Science.gov (United States)

    Liu, Dalong; Ebbini, Emad S.

    2017-03-01

    We present the system architecture of an integrated Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) system for image-guided surgery and temperature tracking in vivo. The system is capable of operating with multiple frontends. Current implementation has a SonixRP for imaging and a custom designed dual mode ultrasound array (DMUA) system (32Tx/32Rx) for imaging/therapy. The highlights of the system include a fully-programmable, multiple data stream capable data processing engine, and an arbitrarily programmable high power array driver that is able to synthesize complex beam patterns in space and time. The data processing engine features a pipeline-style design that can be programmed on-the-fly by re-arranging the pre-verified GPU-accelerated high performance pipeline blocks, which cover an extensive range from basic functions such as filtering to specialized processing like speckle tracking. Furthermore, the pipeline design also has the option of bringing in MATLAB (Mathworks, Natick, MA, US) as part of the processing chain, thus vastly increase the capability of the system. By properly balancing the processing load between GPU-enabled routine and MATLAB script. This allows one to achieve a high degree of flexibility while meeting real-time constraints. Results are presented from in vivo rat experiment. Where low dose of therapeutic ultrasound was delivered into the hind limb of the Copenhagen rats using DMUA and temperature was tracked using a linear probe (HST, Ultrasonix). The data is processed in realtime with MATLAB in the loop to perform temperature regularization. Results show that we can reliably track the low temperature heating in the presence of motion artifacts (respiration and pulsation).

  17. Controlled Hyperthermia with MRI-guided Focused Ultrasound

    DEFF Research Database (Denmark)

    Hokland, Steffen; Salomir, Rares; Pedersen, Michael

    within the plane ROI with steep temperature gradients at its boundaries. Covering the ROI by several consecutive spirals individually modified with respect to applied FUS power and local speed of the focal point based on the MRI temperature maps, the thermal profile may be controlled towards a pre......Introduction: Hyperthermia is an appealing oncological treatment since the significant regions of hypoxia contained in most solid tumours are known to be sensitive to the cytotoxic effect of heat. However, due to the seemingly insurmountable technical difficulties associated with delivering thermal...... doses sufficient to induce cellular deactivation thermotherapy is still regarded as an experimental treatment. In contrast to other thermo-therapeutic modalities Focused Ultrasound (FUS) may be employed non-invasively to deliver a highly localized thermal build-up in deep seated regions of the body...

  18. 80-MHz intravascular ultrasound transducer using PMN-PT free-standing film.

    Science.gov (United States)

    Li, Xiang; Wu, Wei; Chung, Youngsoo; Shih, Wan Y; Shih, Wei-Heng; Zhou, Qifa; Shung, K Kirk

    2011-11-01

    [Pb(Mg(1/3)Nb(2/3))O(3)](0.63)[PbTiO(3)](0.37) (PMN-PT) free-standing film of comparable piezoelectric properties to bulk material with thickness of 30 μm has been fabricated using a modified precursor coating approach. At 1 kHz, the dielectric permittivity and loss were 4364 and 0.033, respectively. The remnant polarization and coercive field were 28 μC/cm(2) and 18.43 kV/cm. The electromechanical coupling coefficient k(t) was measured to be 0.55, which was close to that of bulk PMN-PT single-crystal material. Based on this film, high-frequency (82 MHz) miniature ultrasonic transducers were fabricated with 65% bandwidth and 23 dB insertion loss. Axial and lateral resolutions were determined to be as high as 35 and 176 μm. In vitro intravascular imaging on healthy rabbit aorta was performed using the thin film transducers. In comparison with a 35-MHz IVUS transducer, the 80-MHz transducer showed superior resolution and contrast with satisfactory penetration depth. The imaging results suggest that PMN-PT free-standing thin film technology is a feasible and efficient way to fabricate very-high-frequency ultrasonic transducers.

  19. Ultrasound imaging and evaluation of lesion induced by High Intensity Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    ZHONG Hui; WAN Mingxi; JIANG Yifeng; WANG Supin

    2006-01-01

    The present study was to investigate the differential imaging method for detecting HIFU (High Intensity Focused Ultrasound)-induced lesions and the estimation of variation of attenuation for lesion evaluation with log spectral difference algorithm. Experiment results of bovine muscle and liver in vitro were acquired. Several algorithms for lesion detection - Absolute Difference (AD), Sum Absolute Differences (SAD) and Sum Squared Differences (SSD) - were analyzed with several window sizes and threshold values. Then three attenuation parameters were compared to evaluate the degree of tissue damage. It was found that variation of the mean attenuation △(α) was an effective parameter to evaluate lesions.

  20. Linear array transducer for high-power airborne ultrasound using flextensional structure

    Science.gov (United States)

    Yamamoto, Jun; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2015-07-01

    To change the direction of ultrasonic irradiation without moving a transducer, a high-power airborne ultrasonic transducer for a one-dimensional phased array system was designed and tested. A flextensional element transducer with higher-mode bending vibration was fabricated to obtain a high vibration amplitude over a wide aperture, where a phase-compensating stepped structure was employed. The width of the main lobe at half maximum and the sidelobe level were measured to be 14.3 deg and 0.78, respectively. The maximal sound pressure of 132 dB (0 dB re. 0.02 mPa) was obtained under the applied voltage of 4.0 V. The beam steering characteristics of a phased array using eight elements were compared with the simple theory.

  1. Prostate Ultrasound

    Medline Plus

    Full Text Available ... chest. To obtain high-quality images, an ultrasound transducer – a plastic cylinder about the size of a ... or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the ...

  2. Pulsed application of focused ultrasound to the LI4 elicits deqi sensations: pilot study.

    Science.gov (United States)

    Yoo, Seung-Schik; Lee, Wonhye; Kim, Hyungmin

    2014-08-01

    Focused ultrasound (FUS) techniques enable the delivery of acoustic pressure waves to a localized, specific region of anatomy, and mechanically stimulate the sonicated region when given in a train of pulses. The present pilot study examines if the pulsed application of acoustic waves focused to an acupuncture point (LI4, Hegu), i.e. FUS acupuncture, can elicit deqi sensations. The FUS was generated by a single-element ultrasound transducer, and delivered to the LI4 of acupuncture-naïve participants (n=10) for a duration of 1s using 2 ms tone-burst-duration and 50 Hz pulse repetition frequency. The subjective ratings of deqi descriptors were obtained across different conditions, i.e. FUS acupuncture using acoustic intensities of 1 and 3 W/cm(2) (spatial-peak temporal-averaged intensity, Ispta), sham sonication condition, tactile stimulation using a von Frey monofilament, and needle-based real and sham acupuncture. We also measured the presence of sharp pain, unpleasantness, and anxiety level during each condition. The FUS acupuncture given at 3 W/cm(2) elicited deqi sensation ratings similar to those acquired during the needle-based acupuncture condition across the subjects, with significantly reduced levels of non-deqi related sensations, such as sharp pain, anxiety and unpleasantness. The lower acoustic intensity also generated deqi sensations, but at a lesser degree than the ones acquired using the higher acoustic intensity. Neither the sham conditions nor the tactile stimulation elicited deqi sensations. The present data on acoustic acupuncture, with its exquisite spatial and depth control, along with the ability to electronically adjust its intensity, may suggest its potential utilization as an alternative mode of acupuncture, although further study is needed to probe its clinical efficacy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Focused ultrasound induces apoptosis in pancreatic cancer cells

    Institute of Scientific and Technical Information of China (English)

    GUO Qian; JIANG Li-xin; HU Bing

    2012-01-01

    Background The incidence and mortality rate of pancreatic cancer have increased dramatically in China over recent decades.Focused ultrasound (FU) has been somewhat successful in treating pancreatic cancer.The purpose of this study was to investigate apoptosis in pancreatic cancer cells induced by FU.Methods Suspension of human pancreatic carcinoma cell line PaTu 8988t was radiated by FU,using five doses with different radiation parameters and patterns,including one blank control.Temperature increase of the cell suspension was monitored.Cell apoptosis and death after FU radiation was observed using fluorescence microscopy and was tested by flow cytometer at 3,6,12,24,and 48 hours after ultrasound radiation.Results The maximum cell suspension temperatures following five radiation doses were 28°C,(42.20±2.17)°C,(50.80±0.84)°C,(55.80±2.17)°C,and (65.20±3.11)°C; differences between the doses were statistically significant (P <0.05).The apoptosis rate peaked at 24 hours after radiation,at (0.56±0.15)%,(1.28±0.16)%,(1.84±0.29)%,(5.74±1.15)%,and (2.00±0.84)% for the five doses; differences between the doses were statistically significant (P <0.05).Between doses 1-4,cell apoptosis rates increased as the Tmax increased.In dose 5,as the Tmax was above 60°C,the apoptosis rate decreased.Conclusion Sub-threshold thermal exposures of FU radiation with a continuous radiation pattern could result in higher oercentage of apoptosed cells.

  4. Ultrasound pulse-echo measurements on rough surfaces with linear array transducers

    DEFF Research Database (Denmark)

    Sjøj, Sidsel M. N.; Blanco, Esther N.; Wilhjelm, Jens E.

    2012-01-01

    The echo from planar surfaces with rms roughness, Rq, in the range from 0-155 μm was measured with a clinical linear array transducer at different angles of incidence at 6 MHz and 12 MHz. The echo-pulse from the surfaces was isolated with an equal sized window and the power of the echo-pulse was ...

  5. A Novel Method to Measure Acoustic Power of Focusing Transducer with Spherical Surface Based on Self-Reciprocity Theorem

    Institute of Scientific and Technical Information of China (English)

    DUAN Shi-Mei; SHOU Wen-De; HE Pei-Zhong; QIAN De-Chu; XIA Rong-Min

    2005-01-01

    @@ A novel method to measure acoustic power of focusing transducer based on the self-reciprocity theorem of con vergent spherical acoustic wave is proposed. The performance of this reciprocity method is compared with that of the radiation force balance (RFB) method and the admittance circle method. The average deviations of the reciprocity method from RFB in measurements of the acoustic power and the radiation conductance for a focusing transducer of 1.525 MHz are 7.5% and 3.6% respectively, and for another focusing transducer of 5.27MHz,they are 1.7% and 1.1%. The measured radiation conductance deviation by the reciprocity method from the admittance circle method for the focusing transducer of 1.525 MHz is 7.9%. It presents encouraging results even in measuring low acoustic power level. The overall uncertainty of acoustic power measurement using the method is evaluated below 10%, and it has many advantages such as high signal-to-noise ratio, good stability and less interference of bubbles and environment.

  6. Echinococcus granulosus: protoscolicidal effect of high intensity focused ultrasound.

    Science.gov (United States)

    Zou, Xiaoyi; Wang, Junan; Zhao, Hailong; Zhang, Jing; Wu, Weihua; Ye, Bin

    2009-04-01

    High intensity focused ultrasound (HIFU) is a new non-invasive technique which can cause cell death and tissue necrosis by focusing high-energy ultrasonic waves on a single location. The aim of our work is to investigate the damaging effect of HIFU on Echinococcus granulosus protoscolices, as well as its inhibitory effect on growth of hydatid cysts derived from protoscolices. The damaging effect of HIFU on protoscolices was investigated by following parasite mortality after irradiation, while the inhibitory effect was investigated by infection experiments in vivo. The results demonstrated that HIFU was able to damage protoscolices and the protoscolicidal effect was dose-dependent and showed late-onset. The growth of protoscolices that survived the exposure to HIFU was obviously suppressed in vitro, and the mean weight of hydatid cysts resulting from such protoscolices in the experimental group was less than that in controls. Evidences including the protoscolicidal effect, fragmentized protoscolices and low post exposure temperatures, suggest that cavitation may contribute to the protoscolicidal effect of HIFU. In addition, the structure of the germinal membrane in cysts developing from the irradiated protoscolices was not as normal or intact as that from non-irradiated ones, and morphological changes related to degeneration were observed, suggesting that HIFU could prevent protoscolices from developing normal germinal membrane and consequently stop the proliferation of secondary hydatid cysts. HIFU demonstrated damaging effect on protoscolices, inhibited the growth of protoscolices in vitro and in vivo, and could be a possible therapeutic option for cystic echinococcosis.

  7. MR-guided focused ultrasound surgery, present and future

    Energy Technology Data Exchange (ETDEWEB)

    Schlesinger, David, E-mail: djs9c@virginia.edu [Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia 22908 and Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia 22908 (United States); Benedict, Stanley [Department of Radiation Oncology, University of California Davis, Davis, California 95817 (United States); Diederich, Chris [Department of Radiation Oncology, University of California San Francisco, San Francisco, California 94115 (United States); Gedroyc, Wladyslaw [Department of Medicine, Imperial College, London SW7 2AZ (United Kingdom); Klibanov, Alexander [Departments of Medicine, Cardiovascular Medicine, and Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908 (United States); Larner, James [Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia 22908 (United States)

    2013-08-01

    MR-guided focused ultrasound surgery (MRgFUS) is a quickly developing technology with potential applications across a spectrum of indications traditionally within the domain of radiation oncology. Especially for applications where focal treatment is the preferred technique (for example, radiosurgery), MRgFUS has the potential to be a disruptive technology that could shift traditional patterns of care. While currently cleared in the United States for the noninvasive treatment of uterine fibroids and bone metastases, a wide range of clinical trials are currently underway, and the number of publications describing advances in MRgFUS is increasing. However, for MRgFUS to make the transition from a research curiosity to a clinical standard of care, a variety of challenges, technical, financial, clinical, and practical, must be overcome. This installment of the Vision 20/20 series examines the current status of MRgFUS, focusing on the hurdles the technology faces before it can cross over from a research technique to a standard fixture in the clinic. It then reviews current and near-term technical developments which may overcome these hurdles and allow MRgFUS to break through into clinical practice.

  8. Transcranial focused ultrasound stimulation of human primary visual cortex

    Science.gov (United States)

    Lee, Wonhye; Kim, Hyun-Chul; Jung, Yujin; Chung, Yong An; Song, In-Uk; Lee, Jong-Hwan; Yoo, Seung-Schik

    2016-09-01

    Transcranial focused ultrasound (FUS) is making progress as a new non-invasive mode of regional brain stimulation. Current evidence of FUS-mediated neurostimulation for humans has been limited to the observation of subjective sensory manifestations and electrophysiological responses, thus warranting the identification of stimulated brain regions. Here, we report FUS sonication of the primary visual cortex (V1) in humans, resulting in elicited activation not only from the sonicated brain area, but also from the network of regions involved in visual and higher-order cognitive processes (as revealed by simultaneous acquisition of blood-oxygenation-level-dependent functional magnetic resonance imaging). Accompanying phosphene perception was also reported. The electroencephalo graphic (EEG) responses showed distinct peaks associated with the stimulation. None of the participants showed any adverse effects from the sonication based on neuroimaging and neurological examinations. Retrospective numerical simulation of the acoustic profile showed the presence of individual variability in terms of the location and intensity of the acoustic focus. With exquisite spatial selectivity and capability for depth penetration, FUS may confer a unique utility in providing non-invasive stimulation of region-specific brain circuits for neuroscientific and therapeutic applications.

  9. Design of a Broadband Electrical Impedance Matching Network for Piezoelectric Ultrasound Transducers Based on a Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Jianfei An

    2014-04-01

    Full Text Available An improved method based on a genetic algorithm (GA is developed to design a broadband electrical impedance matching network for piezoelectric ultrasound transducer. A key feature of the new method is that it can optimize both the topology of the matching network and perform optimization on the components. The main idea of this method is to find the optimal matching network in a set of candidate topologies. Some successful experiences of classical algorithms are absorbed to limit the size of the set of candidate topologies and greatly simplify the calculation process. Both binary-coded GA and real-coded GA are used for topology optimization and components optimization, respectively. Some calculation strategies, such as elitist strategy and clearing niche method, are adopted to make sure that the algorithm can converge to the global optimal result. Simulation and experimental results prove that matching networks with better performance might be achieved by this improved method.

  10. Design of a broadband electrical impedance matching network for piezoelectric ultrasound transducers based on a genetic algorithm.

    Science.gov (United States)

    An, Jianfei; Song, Kezhu; Zhang, Shuangxi; Yang, Junfeng; Cao, Ping

    2014-04-16

    An improved method based on a genetic algorithm (GA) is developed to design a broadband electrical impedance matching network for piezoelectric ultrasound transducer. A key feature of the new method is that it can optimize both the topology of the matching network and perform optimization on the components. The main idea of this method is to find the optimal matching network in a set of candidate topologies. Some successful experiences of classical algorithms are absorbed to limit the size of the set of candidate topologies and greatly simplify the calculation process. Both binary-coded GA and real-coded GA are used for topology optimization and components optimization, respectively. Some calculation strategies, such as elitist strategy and clearing niche method, are adopted to make sure that the algorithm can converge to the global optimal result. Simulation and experimental results prove that matching networks with better performance might be achieved by this improved method.

  11. Use of nakagami statistics and empirical mode decomposition for ultrasound tissue characterization by a nonfocused transducer.

    Science.gov (United States)

    Tsui, Po-Hsiang; Chang, Chien-Cheng; Ho, Ming-Chih; Lee, Yu-Hsin; Chen, Yung-Sheng; Chang, Chien-Chung; Huang, Norden E; Wu, Zhao-Hua; Chang, King-Jen

    2009-12-01

    The Nakagami parameter associated with the Nakagami distribution estimated from ultrasonic backscattered signals reflects the scatterer concentration in a tissue. A nonfocused transducer does not allow tissue characterization based on the Nakagami parameter. This paper proposes a new method called the noise-assisted Nakagami parameter based on empirical mode decomposition of noisy backscattered echoes to allow quantification of the scatterer concentration based on data obtained using a nonfocused transducer. To explore the practical feasibility of the proposed method, the current study performed experiments on phantoms and measurements on rat livers in vitro with and without fibrosis induction. The results show that using a nonfocused transducer makes it possible to use the noise-assisted Nakagami parameter to classify phantoms with different scatterer concentrations and different stages of liver fibrosis in rats more accurately than when using techniques based on the echo intensity and the conventional Nakagami parameter. However, the conventional Nakagami parameter and the noise-assisted Nakagami parameter have different meanings: the former represents the statistics of signals backscattered from unresolvable scatterers, whereas the latter is associated with stronger resolvable scatterers or local inhomogeneity caused by scatterer aggregation.

  12. Modelling the temperature evolution of bone under high intensity focused ultrasound.

    Science.gov (United States)

    ten Eikelder, H M M; Bošnački, D; Elevelt, A; Donato, K; Di Tullio, A; Breuer, B J T; van Wijk, J H; van Dijk, E V M; Modena, D; Yeo, S Y; Grüll, H

    2016-02-21

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  13. Modelling the temperature evolution of bone under high intensity focused ultrasound

    Science.gov (United States)

    ten Eikelder, H. M. M.; Bošnački, D.; Elevelt, A.; Donato, K.; Di Tullio, A.; Breuer, B. J. T.; van Wijk, J. H.; van Dijk, E. V. M.; Modena, D.; Yeo, S. Y.; Grüll, H.

    2016-02-01

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  14. Nanobiotechnology promotes noninvasive high-intensity focused ultrasound cancer surgery.

    Science.gov (United States)

    Chen, Yu; Chen, Hangrong; Shi, Jianlin

    2015-01-07

    The successful cancer eradication in a noninvasive manner is the ultimate objective in the fight against cancer. As a "bloodless scalpel," high-intensity focused ultrasound (HIFU) is regarded as one of the most promising and representative noninvasive therapeutic modalities for cancer surgery. However, large-scale clinical applications of HIFU are still in their infancy because of critical efficiency and safety issues which remain to be solved. Fortunately, recently developed nanobiotechnology provides an alternative efficient approach to improve such important issues in HIFU, especially for cancer therapy. This Research News presents the very recent exciting progresses on the elaborate design and fabrication of organic, inorganic, and organic/inorganic hybrid nanoparticles for enhancing the HIFU ablation efficiency against tumor tissues. It is highly expected that this Research News can arouse more extensive research enthusiasm on the development of functional nanomaterials for highly efficient HIFU-based synergistic therapy, which will give a promising noninvasive therapeutic modality for the successful cancer therapy with minimal damage to surrounding normal tissues, due to the noninvasive and site-specific therapeutic features of HIFU.

  15. Extracorporeal High-Intensity Focused Ultrasound Treatment for Breast Cancer

    Institute of Scientific and Technical Information of China (English)

    HuiZhu; FengWu; WenzhiChen; YoudeCao; JinBai; ZhibiaoWang

    2004-01-01

    OBJECTIVE To evaluate the clinical safety and efficacy of using highintensity focused ultrasound (HIFU) therapy, for breast cancer, and to select the appropriate methods in evaluating the therapeutic effects.METHODS A total of 24 patients with breast cancer underwent HIFU treatment 1-2 weeks before receiving modified radical mastectomy. During and after HIFU therapy, changes in blood pressure, breath, pulse and peripheral blood oxygen saturation were monitored. At the same time, the damage of the skin and tissue produced by HIFU at the target region was evaluated as well. Surgically excised samples were used for pathological examinations to evaluate the HIFU-induced destruction of the targeted tissue. Three patients received Tc-ECT and 1 MRI examinations before and after HIFU.RESULTS HIFU treatment had no apparent influence on either the tissue nearby the target or on vital signs of the patients. Pathological, tc-ECT and MRI examinations demonstrated that targeted tissue showed complete coagulative necrosis.CONCLUSION Under the guidance of real-time ultrasonic imaging, HIFU can effectively and safely destroy the breast cancer mass and 99MTc-ECT and MRI examination can be utilized to evaluate the therapeutic effects.HIFU may become one of the options for breast cancer therapy in the future.

  16. Therapeutic Potential of Transcranial Focused Ultrasound for Rett Syndrome

    Science.gov (United States)

    Tsai, Shih-Jen

    2016-01-01

    Rett syndrome (RTT) is a severe neurodevelopmental disorder occurring almost exclusively in females and is caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2) in the majority of cases. MeCP2 is essential for the normal function of nerve cells, including neuronal development, maturation, and synaptic activity. RTT is characterized by normal early development followed by autistic-like features, slowed brain and head growth, gait abnormalities, seizures, breathing irregularities, and cognitive disabilities. Medical management in RTT remains supportive and symptomatic. Brain-derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of RTT. Recent studies have shown a phenotypic reversal by increasing BDNF expression in a RTT mouse model. Thus, manipulation of BDNF expression/signaling in the brain could be therapeutic for this disease. Transcranial focused ultrasound for (tFUS) can noninvasively focally modulate human cortical function, stimulate neurogenesis, and increase BDNF in animal studies. Consequently, tFUS may be of therapeutic potential for Rett syndrome. Further evaluation of the therapeutic effects of tFUS in Mecp2 deficient animal models is needed before clinical trials can begin. PMID:27786169

  17. Robotic Assisted Laparoscopic Prostatectomy after High Intensity Focused Ultrasound Failure

    Directory of Open Access Journals (Sweden)

    Leon Telis

    2017-01-01

    Full Text Available Background. Prostate cancer is the most common cancer diagnosed in men. As new focal therapies become more popular in treatment of prostate cancer, failure cases requiring salvage therapy with either surgical or other techniques are being reported. Objective. To report the options in treatment of prostate cancer after recurrence or failure of the primary treatment modality. Methods. We report a salvage robotic assisted laparoscopic radical prostatectomy (RALP for prostate cancer recurrence following high intensity focused ultrasound treatment (HIFU in the United States. Results. A 67-year-old man who underwent HIFU treatment for prostate adenocarcinoma 2 years prior was presented with a rising prostate specific antigen of 6.1 ng/mL to our clinic. A biopsy proven recurrent disease in the area of previous treatment documented the failure of treatment. The patient elected to undergo a salvage RALP. The operation time was 159 minutes. The patient was discharged from the hospital on postoperative day 1 with no complications. The catheter was removed on post-op day 10. The patient reserved sexual function and urinary continence. The PSA levels on 6 months’ follow-up are undetectable. Conclusions. Salvage RALP is an effective and safe treatment choice for recurrent prostate adenocarcinoma following failed HIFU treatment if operated by an experienced surgeon.

  18. Effects of Dynamic Changes in Ultrasound Attenuation and Blood Perfusion on Lesion Formation of Multiple focus Pattern during Ultrasound Surgery

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chen-xi; BAI Jing-feng; CHEN Ya-zhu

    2007-01-01

    A nonlinear finite-element program was developed to simulate the dynamic evolution of coagulation in tissue considering temperature and thermal-dose dependence of the ultrasound attenuation and blood perfusion rate.The effects of these dynamic parameters on the lesion formation were investigated in the particular case of ultrasound hepatic ablation with bi-focus intensity pattern.The results of simulations were compared that incorporate dynamic changes of ultrasound attenuation and perfusion and results that neglect these effects.The result shows that thermal-dose-dependent ultrasound attenuation is the dominating factor in the full dynamic model.If the dynamic ultrasound attenuation is ignored, a relatively significant underestimation of the temperature rise appears in the focal plane and the region next to the focal plane, resulting in an underestimation in predicting diameter of coagulation.Higher heating intensity leads to greater underestimation.

  19. Quantitative ultrasound imaging for monitoring in situ high-intensity focused ultrasound exposure.

    Science.gov (United States)

    Ghoshal, Goutam; Kemmerer, Jeremy P; Karunakaran, Chandra; Abuhabsah, Rami; Miller, Rita J; Sarwate, Sandhya; Oelze, Michael L

    2014-10-01

    Quantitative ultrasound (QUS) imaging is hypothesized to map temperature elevations induced in tissue with high spatial and temporal resolution. To test this hypothesis, QUS techniques were examined to monitor high-intensity focused ultrasound (HIFU) exposure of tissue. In situ experiments were conducted on mammary adenocarcinoma tumors grown in rats and lesions were formed using a HIFU system. A thermocouple was inserted into the tumor to provide estimates of temperature at one location. Backscattered time-domain waveforms from the tissue during exposure were recorded using a clinical ultrasonic imaging system. Backscatter coefficients were estimated using a reference phantom technique. Two parameters were estimated from the backscatter coefficient (effective scatterer diameter (ESD) and effective acoustic concentration (EAC). The changes in the average parameters in the regions corresponding to the HIFU focus over time were correlated to the temperature readings from the thermocouple. The changes in the EAC parameter were consistently correlated to temperature during both heating and cooling of the tumors. The changes in the ESD did not have a consistent trend with temperature. The mean ESD and EAC before exposure were 120 ± 16 μm and 32 ± 3 dB/cm3, respectively, and changed to 144 ± 9 μm and 51 ± 7 dB/cm3, respectively, just before the last HIFU pulse was delivered to the tissue. After the tissue cooled down to 37 °C, the mean ESD and EAC were 126 ± 8 μm and 35 ± 4 dB/cm3, respectively. Peak temperature in the range of 50-60 °C was recorded by a thermocouple placed just behind the tumor. These results suggest that QUS techniques have the potential to be used for non-invasive monitoring of HIFU exposure.

  20. Feasibility study on photoacoustic guidance for high-intensity focused ultrasound-induced hemostasis

    Science.gov (United States)

    Nguyen, Van Phuc; Kim, Jeehyun; Ha, Kang-lyeol; Oh, Junghwan; Kang, Hyun Wook

    2014-10-01

    The feasibility of photoacoustic imaging (PAI) application was evaluated to map punctured blood vessels thermally treated by high-intensity focused ultrasound (HIFU) for hemostasis. A single-element HIFU transducer with a central frequency of 2.0 MHz, was used to induce thermal hemostasis on the punctured arteries. The HIFU-treated lesion was imaged and localized by high-contrast PAI guidance. The results showed that complete hemostasis was achieved after treatment of the damaged blood vessels within 25 to 52 s at the acoustic intensity of 3600 W/cm2. The coagulation time for the animal artery was ˜20% longer than that of the phantom possibly due to a lower Young's modulus. The reconstructed PA images were able to distinguish the treated area from the surrounding tissue in terms of augmented signal amplitudes (up to three times). Spectroscopic studies demonstrated that the optimal imaging wavelength was found to be 700 nm in order to reconstruct high-contrast photoacoustic images on HIFU-treated lesions. The proposed PAI integrated with HIFU treatment can be a feasible application to obtain safe and rapid hemostasis for acute arterial bleeding.

  1. High-Intensity Focused Ultrasound (Hifu) Treatment For Thyroid Nodules: Experimental And First Clinical Studies

    Science.gov (United States)

    Esnault, Olivier; Franc, Brigitte; Leenhardt, Laurence; Rouxel, Agnès; Ménégaux, Fabrice; Lacoste, François

    2007-05-01

    OBJECTIVE: Thyroid nodules are common and can only be removed by surgery. High-intensity focused ultrasound (HIFU) could be a possible minimally invasive alternative treatment. The aim of this study was to assess the feasibility of using HIFU to precisely ablate thyroid nodules without affecting neighbouring structures. METHODS: HIFU was generated by a 3-MHz spherical piezocomposite transducer moved across the target in a stepwise fashion. In a first clinical study 25 patients had their nodules treated with HIFU 2 weeks prior to planned thyroidectomy, using increasing energy. The last patients received a local anesthesia. The lesions were assessed by the pathologist. RESULTS: The histological lesions were clearly visible in most of the fully treated patients, particularly those who received higher energy. Superficial and reversible skin blisters were observed in 7 patients. The design of the treatment head was subsequently modified to eliminate such risk. CONCLUSION: The patient trials confirmed the precision of the targeting and set the energy levels for safe thyroid nodule ablation with HIFU. Further study is needed to assess nodule's changes at longer follow-up.

  2. Focused-ultrasound termination of an early pregnancy in rhesus macaques (Macaca mulatta): a pilot study.

    Science.gov (United States)

    Du, Yong-Hong; Zou, Jian-Zhong; Bai, Jin; Zhan, Yang; Wu, Feng; Wang, Zhi-Biao

    2012-12-01

    We explored the effectiveness, safety, and feasibility of focused ultrasound in terminating undesired pregnancy. A high-intensity focused ultrasound therapeutic unit was employed to terminate early pregnancies in rhesus macaques. B-mode ultrasound incorporated within the system was used to locate and study the gestational sacs of 6 rhesus macaques with gestation ages of 37 to 66 days, and varying modes of ultrasound exposure were adopted in the termination of the early pregnancies of the rhesus macaques. After focused ultrasound exposure, B-mode ultrasound of the gestational sacs showed significant lethal changes. Of the 6 rhesus macaques, 5 underwent complete abortions whereas 1 rhesus macaque underwent an incomplete abortion. The rhesus macaques resumed their menstrual cycles 50 days after focused-ultrasound treatment. The results suggested that focused ultrasound could be safe, feasible, and effective in terminating early pregnancies in rhesus macaques. As a novel physical method, it may be a promising ablation for a potentially clinical application. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  3. First in vivo use of a capacitive micromachined ultrasound transducer array-based imaging and ablation catheter.

    Science.gov (United States)

    Stephens, Douglas N; Truong, Uyen T; Nikoozadeh, Amin; Oralkan, Omer; Seo, Chi Hyung; Cannata, Jonathan; Dentinger, Aaron; Thomenius, Kai; de la Rama, Alan; Nguyen, Tho; Lin, Feng; Khuri-Yakub, Pierre; Mahajan, Aman; Shivkumar, Kalyanam; O'Donnell, Matt; Sahn, David J

    2012-02-01

    The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures. The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed. The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites. Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures.

  4. First In Vivo Use of a Capacitive Micromachined Ultrasound Transducer Array–Based Imaging and Ablation Catheter

    Science.gov (United States)

    Stephens, Douglas N.; Truong, Uyen T.; Nikoozadeh, Amin; Oralkan, Ömer; Seo, Chi Hyung; Cannata, Jonathan; Dentinger, Aaron; Thomenius, Kai; de la Rama, Alan; Nguyen, Tho; Lin, Feng; Khuri-Yakub, Pierre; Mahajan, Aman; Shivkumar, Kalyanam; O’Donnell, Matt; Sahn, David J.

    2012-01-01

    Objectives The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures. Methods The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed. Results The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites. Conclusions Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures. PMID:22298868

  5. The use of two-photon microscopy to study the biological effects of focused ultrasound on the brain

    Science.gov (United States)

    Burgess, Alison; Cho, Eunice E.; Shaffaf, Leila; Nhan, Tam; Poon, Charissa; Hynynen, Kullervo

    2012-03-01

    Focused ultrasound (FUS) has been used to successfully disrupt the blood-brain barrier (BBB), aiding in the delivery of therapeutic agents to the brain and leading to improvements in disease pathology. Although significant progress has been made in the development of FUS technology, there is still a lack of understanding of the biophysical mechanisms of the BBB disruption and the microscopic effects of this disruption on brain cells. In this study, we combine a custom built ultrasound transducer with two-photon microscopy to conduct real time monitoring of BBB disruption in vivo. We have manufactured and tested a single element piezoelectric transducer with frequencies ranging from 1.15 to 1.30 MHz. Sonications were performed using 0.07-0.25 MPa estimated in situ pressure, 10 ms pulses, 1 Hz pulse repetition frequency for a total duration of 120 s in the presence of microbubbles. BBB disruption was observed through a cranial window created in the rat skull after intravenous injection of dextran conjugated- Texas Red (MW: 10,000 - 70,000 Da). Using this experimental setup, we have observed and characterized 3 different leakage patterns following BBB disruption. Our results indicate that varying the acoustic power leading to in situ pressure changes, may allow us to control the mechanism of BBB disruption. Furthermore, we have labelled astrocytes in vivo in order to visualize the effects of FUS on this cell population. Combination of our custom transducers with two-photon microscopy will allow significant advancement in allow significant advancement in the understanding of the mechanisms and cellular effects of FUS-induced BBB disruption.

  6. Displacement analysis of diagnostic ultrasound backscatter: A methodology for characterizing, modeling, and monitoring high intensity focused ultrasound therapy

    OpenAIRE

    2010-01-01

    Accurate monitoring of high intensity focused ultrasound (HIFU) therapy is critical for widespread clinical use. Pulse-echo diagnostic ultrasound (DU) is known to exhibit temperature sensitivity through relative changes in time-of-flight between two sets of radio frequency (RF) backscatter measurements, one acquired before and one after therapy. These relative displacements, combined with knowledge of the exposure protocol, material properties, heat transfer, and measurement noise statistics,...

  7. Theoretical Calculation of a Focused Acoustic Field from a Linear Phased Array on a Concave Cylindrical Transducer

    Institute of Scientific and Technical Information of China (English)

    YU Li-Li; SHOU Wen-De; HUI Chun

    2011-01-01

    A new linear phased array on a concave cylindrical transducer is designed for meeting the specific requirements of applications for interstitial thermal ablation. Using the array, a focal line can be generated rapidly and the focal position can be adjusted in the proper range without the use of complex mechanical structures. The focused acoustic Reid distributions in the axial, radial and azimuthal directions of the transducer are investigated theoretically by numerical simulation. Effects of the focal distance, steering angle, element arc-width, arc-space between adjacent elements and number of elements on the acoustic field are also thoroughly studied. Many important results are obtained.%A new linear phased array on a concave cylindrical transducer is designed for meeting the specific requirements of applications for interstitial thermal ablation.Using the array,a focal line can be generated rapidly and the focal position can be adjusted in the proper range without the use of complex mechanical structures.The focused acoustic field distributions in the axial,radial and azimuthal directions of the transducer are investigated theoretically by numerical simulation.Effects of the focai distance,steering angle,element arc-width,arc-space between adjacent elements and number of elements on the acoustic field are also thoroughly studied.Many important results are obtained.Interstitial thermal ablation is a promising technique for treating tumors that are both nonresectable and difficult to reach with extracorporeal therapy.[1,2] In this method,a small transducer is brought into contact with the targeted region and emits a highintensity acoustic wave;the interaction between the wave and the tissues causes a strong heating effect that induces the thermal coagulation and necrosis of the target.[3

  8. HIGH-INTENSITY FOCUSED ULTRASOUND CASTRATION FOR BREAST CANCER PATIENTS

    Institute of Scientific and Technical Information of China (English)

    王书文; 和新盈; 石景森; 赵东利; 李明众; 王诚; 薛文华

    2003-01-01

    Objective: To evaluate the safety and efficacy of external high-intensity focused ultrasound(HIFU) castration for breast cancerous patients after mastectomy if they are at a high risk of recurrence. Methods: We recruited 52 consecutive patients with primary operable breast cancer who were treated with mastectomy with excision of regional lymph nodes. Patients were positive for ER and PR immuno- cytochemical staining, node-positive, un-menopause, over 40 years old and were divided into two groups randomly. For castration, 26 patients received one or two times of HIFU treatment within five days, and the other patients received radiotherapy with DT 18Gy/9 f/11days. During and after the treatment, local changes and systemic response of the patients were observed. Results: After 1 month treatment, levels of serum E1 and E2 were significantly decreased compared to before treatment in HIFU groups (P<0.01 and P<0.001). The same changes were occurred in radiotherapy(RT) groups (P<0.05 and P<0.01). The levels of serum E1 or E2 in RT groups were higher than in HIFU groups (P<0.05). The symptom distribution of 'climacteric syndrome' of HIFU groups were significantly different from RT groups (P<0.01). The follow-up time was 4 months. The incidence of amenorrhea was 100% in all patients. No serious complications were seen. The temperature, pulse, blood pressure, and respiratory rate of the patients were almost normal. Conclusion: We have shown that the use of HIFU in the castrating of patients with breast cancer is feasible, safe and effective. This technology may provide a rapid noninvasive alterative to conventional bilateral oophorectomy or RT castration.

  9. Optical focusing inside scattering media with time-reversed ultrasound microbubble encoded (TRUME) light

    CERN Document Server

    Ruan, Haowen; Yang, Changhuei

    2015-01-01

    Focusing light inside scattering media in a freely addressable fashion is challenging, as the wavefront of the scattered light is highly disordered. Recently developed ultrasound-guided wavefront shaping methods are addressing this challenge, albeit with relatively low modulation efficiency and resolution limitations. In this paper, we present a new technique, time-reversed ultrasound microbubble encoded (TRUME) optical focusing, which is able to focus light with improved efficiency and sub-ultrasound wavelength resolution. This method ultrasonically destructs microbubbles, and measures the wavefront change to compute and render a suitable time-reversed wavefront solution for focusing. We demonstrate that the TRUME technique can create an optical focus at the site of bubble destruction with a size of ~2 microns. Due to the nonlinear pressure-to-destruction response, the TRUME technique can break the addressable focus resolution barrier imposed by the ultrasound focus. We experimentally demonstrate a 2-fold ad...

  10. Prostate Ultrasound

    Medline Plus

    Full Text Available ... are the limitations of Prostate Ultrasound Imaging? What is Ultrasound Imaging of the Prostate? Ultrasound is safe ... transducer into the body. top of page How is the procedure performed? In men, the prostate gland ...

  11. Local piezoelectric behavior in PZT-based thin films for ultrasound transducers

    Science.gov (United States)

    Griggio, Flavio

    Piezoelectric microelectromechanical systems (MEMS) are currently used in inkjet printers and precision resonators; numerous additional applications are being investigated for sensors, low-voltage actuators, and transducers. This work was aimed at improving piezoelectric MEMS by taking two approaches: 1) identifying factors affecting the piezoelectric response of ferroelectric thin films and 2) demonstrating integration of these films into a high frequency array transducer. It was found that there are several key factors influencing the piezoelectric response of thin films for a given material composition. First, large grain size improves the piezoelectric response. This was demonstrated using chemical solution deposited lead nickel niobate -- lead zirconate titanate (0.3)Pb(Ni 0.33Nb0.67)O3 - (0.7)Pb(Zr0.45Ti 0.55O3), (PNN-PZT) ferroelectric thin films. It was shown that this composition allows greater microstructural control than does PZT. Dielectric permittivities ranging from 1350 to 1520 and a transverse piezoelectric coefficient e31,f as high as -- 9.7 C/m 2 were observed for films of about 0.25 mum in thickness. The permittivity and piezoelectric response as well as extrinsic contributions to the dielectric constant increased by 14 and 12 % respectively for samples with grain sizes ranging from 110 to 270 nm. A second factor influencing the piezoelectric response is film composition with respect to the morphotropic phase boundary (MPB). The composition dependence of the dielectric and piezoelectric nonlinearities was characterized in epitaxially grown (0.3)Pb(Ni0.33Nb0.67)O3-(0.7)Pb(Zr xTi1-xO3) thin films deposited on SrTiO 3 to minimize the influence of large-angle grain boundaries. Tetragonal, MPB and rhombohedral films were prepared by changing the Zr/Ti ratio. The largest dielectric and piezoelectric nonlinearities were observed for the rhombohedral sample; this resulted from a higher domain wall mobility due to a smaller ferroelectric distortion and

  12. Harmonic motion imaging for abdominal tumor detection and high-intensity focused ultrasound ablation monitoring: an in vivo feasibility study in a transgenic mouse model of pancreatic cancer.

    Science.gov (United States)

    Chen, Hong; Hou, Gary Y; Han, Yang; Payen, Thomas; Palermo, Carmine F; Olive, Kenneth P; Konofagou, Elisa E

    2015-09-01

    Harmonic motion imaging (HMI) is a radiationforce- based elasticity imaging technique that tracks oscillatory tissue displacements induced by sinusoidal ultrasonic radiation force to assess the resulting oscillatory displacement denoting the underlying tissue stiffness. The objective of this study was to evaluate the feasibility of HMI in pancreatic tumor detection and high-intensity focused ultrasound (HIFU) treatment monitoring. The HMI system consisted of a focused ultrasound transducer, which generated sinusoidal radiation force to induce oscillatory tissue motion at 50 Hz, and a diagnostic ultrasound transducer, which detected the axial tissue displacements based on acquired radio-frequency signals using a 1-D cross-correlation algorithm. For pancreatic tumor detection, HMI images were generated for pancreatic tumors in transgenic mice and normal pancreases in wild-type mice. The obtained HMI images showed a high contrast between normal and malignant pancreases with an average peak-to-peak HMI displacement ratio of 3.2. Histological analysis showed that no tissue damage was associated with HMI when it was used for the sole purpose of elasticity imaging. For pancreatic tumor ablation monitoring, the focused ultrasound transducer was operated at a higher acoustic power and longer pulse length than that used in tumor detection to simultaneously induce HIFU thermal ablation and oscillatory tissue displacements, allowing HMI monitoring without interrupting tumor ablation. HMI monitoring of HIFU ablation found significant decreases in the peak-to-peak HMI displacements before and after HIFU ablation with a reduction rate ranging from 15.8% to 57.0%. The formation of thermal lesions after HIFU exposure was confirmed by histological analysis. This study demonstrated the feasibility of HMI in abdominal tumor detection and HIFU ablation monitoring.

  13. Feasibility of laser-integrated high intensity focused ultrasound (HIFU) treatment for bladder tumors: in vitro study (Conference Presentation)

    Science.gov (United States)

    Nguyen, Van Phuc; Park, Suhyun; Oh, Junghwan; Kang, Hyun Wook

    2016-02-01

    Previous studies have shown that photothemal therapy combined with high intensity focused ultrasound (HIFU) can provide a promising method to achieve rapid thermal coagulation during surgical procedures. The current study investigated the feasibility of the laser-integrated high intensity focused ultrasound (HIFU) application to treat bladder tumors by enhancing thermal effects and therapeutic depth in vitro. To generate thermal coagulation, a single element HIFU transducer with a central frequency of 2.0 MHz was used to transmit acoustic energy to 15 fresh porcine bladders injected with an artificial tumor (100 µl gelatin and hemoglobin solution) in vitro. Simultaneously, an 80-W 532-nm laser system was also implemented to induce thermal necrosis in the targeted tissue. The intensity of 570 W/cm2 at the focus of HIFU and laser energy of 0.9 W were applied to all the samples for 40 s. The temperature rise increased up to about 1.6 or 3 folds (i.e., ΔT=32±3.8 K for laser-integrated HIFU, ΔT=20±6.5 K for HIFU only, and ΔT=11±5.6 K for laser only). The estimated lesion depth also increased by 1.3 and 2 folds during the dual-thermal treatment, in comparison with the treatment by either HIFU or laser. The results indicated that the laser-integrated HIFU treatment can be an efficient hyperthermic method for tumor coagulation.

  14. Triggered Drug Release from Superhydrophobic Meshes using High-Intensity Focused Ultrasound

    OpenAIRE

    Yohe, Stefan T.; Kopechek, Jonathan A.; Porter, Tyrone M; Colson, Yolonda L.; Grinstaff, Mark W.

    2013-01-01

    Application of high-intensity focused ultrasound to drug-loaded superhydrophobic meshes affords triggered drug release by displacing an entrapped air layer. The air layer within the superhydrophobic meshes is characterized using direct visualization and B-mode imaging. Drug-loaded superhydrophobic meshes are cytotoxic in an in vitro assay after ultrasound treatment.

  15. Towards MR-guided high intensity focused ultrasound ablation of liver tumors

    NARCIS (Netherlands)

    Wijlemans, J.W.

    2015-01-01

    Magnetic Resonance-guided High Intensity Focused Ultrasound (MR-HIFU) is a promising technique which can be used for completely non-invasive tissue ablation. The converging ultrasound beam penetrates the skin and subcutaneous tissues with damage, while heating the tissue only in the focal point. The

  16. Evaluate thermal lesion using Nakagami imaging for monitoring of high-intensity focused ultrasound

    Science.gov (United States)

    Zhang, Siyuan; Li, Chong; Zhou, Fanyu; Wang, Supin; Wan, Mingxi

    2017-03-01

    High-intensity focused ultrasound (HIFU) is currently being developed as a noninvasive technique for the treatment of cancer located in various tissues. Cavitation microbubbles (MBs) have been potential to aid treatment while the acoustic posterior shadowing effects of MBs influence the accuracy for defining the location and range of ablated thermal lesions during focused ultrasound surgery when using ultrasonic monitoring imaging. This work explored the feasibility of using ultrasonic Nakagami imaging to evaluate the ablated region induced by focused ultrasound exposures at different acoustic power levels in transparent tissue-mimicking phantoms.

  17. Effects of human hair on trans-cranial focused ultrasound efficacy in an ex-vivo cadaver model

    Science.gov (United States)

    Hananel, Arik; Snell, John W.; Kassell, Neal F.; Eames, Matthew D. C.

    2012-11-01

    Current practice before a trans-cranial MR guided Focused ultrasound procedure is shaving the patient head on treatment day. Here we present an initial attempt to evaluate the feasibility of trans-cranial FUS, in an unshaved, ex-vivo cadaver skull. We have sonicated using 220kHz and 710kHz head transducers, a cadaver skull filled with tissue mimicking phantom and covered with a wig made of human hair to evaluate feasibility of acoustic energy transfer in a full size model. Heating at focal point was measured using MR proton resonance shift thermometry. Results showed negligible effect of hair in 220kHz, and an 18% drop in temperature elevation when using 710kHz.

  18. A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Bao-Yu; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning, E-mail: xjiang5@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhu, Jiadeng; Zhang, Xiangwu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-01-12

    The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10{sup −3 }Pa/(W/m{sup 2}), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

  19. [Genetic algorithm application to multi-focus patterns of 256-element phased array for focused ultrasound surgery].

    Science.gov (United States)

    Xu, Feng; Wan, Mingxi; Lu, Mingzhu

    2008-10-01

    The genetic optimal algorithm and sound field calculation approach for the spherical-section phased array are presented in this paper. The in-house manufactured 256-element phased array focused ultrasound surgery system is briefly described. The on-axis single focus and off-axis single focus are simulated along with the axis-symmetric six-focus patter and the axis-asymmetric four-focus pattern using a 256-element phased array and the genetic optimal algorithm and sound field calculation approach. The experimental results of the described 256-element phased array focused ultrasound surgery system acting on organic glass and phantom are also analyzed. The results of the simulations and experiments confirm the applicability of the genetic algorithm and field calculation approaches in accurately steering three dimensional foci and focus.

  20. High-intensity focused ultrasound treatment of abnormal vaginal bleeding secondary to uterine myoma.

    Science.gov (United States)

    Lim, Jung Hyun; Chung, Dong Jin; Lim, Young Tec; Cho, Sae Hyun; Lee, Jae Mun; Hahn, Seong-Tae

    2011-03-01

    We describe the use of high-intensity focused ultrasound for acute vaginal bleeding secondary to uterine myoma in 2 young female patients. Both patients had episodes of abnormal vaginal bleeding with severe dysmenorrhea that was not efficiently controlled by medical treatment. After high-intensity focused ultrasound ablation, both vaginal bleeding control and symptom relief were achieved without postinterventional complications. The patients remained free of symptoms during 2 months of follow-up and regained normal menstruation after high-intensity focused ultrasound therapy. High-intensity focused ultrasound treatment is one of the least invasive options for dysfunctional vaginal bleeding and may be an effective and safe alternative to other procedures in women of reproductive age with abnormal vaginal bleeding secondary to uterine myoma.

  1. Focused cardiac ultrasound in the emergency department for patients admitted with respiratory symptoms

    DEFF Research Database (Denmark)

    Laursen, C. B.

    2015-01-01

    triage, patients with cardiac arrest, patients with undifferentiated shock, patients with cardiopulmonary instability, patients with respiratory symptoms, trauma patients with suspected cardiac injuries, and assessment of the fluid status before fluid loading. When using focused cardiac ultrasound (US...

  2. In vivo demonstration of reflection artifact reduction in photoacoustic imaging using synthetic aperture photoacoustic-guided focused ultrasound (PAFUSion).

    Science.gov (United States)

    Singh, Mithun Kuniyil Ajith; Jaeger, Michael; Frenz, Martin; Steenbergen, Wiendelt

    2016-08-01

    Reflection artifacts caused by acoustic inhomogeneities are a critical problem in epi-mode biomedical photoacoustic imaging. High light fluence beneath the probe results in photoacoustic transients, which propagate into the tissue and reflect back from echogenic structures. These reflection artifacts cause problems in image interpretation and significantly impact the contrast and imaging depth. We recently proposed a method called PAFUSion (Photoacoustic-guided focused ultrasound) to identify such reflection artifacts in photoacoustic imaging. In its initial version, PAFUSion mimics the inward-travelling wavefield from small blood vessel-like PA sources by applying ultrasound pulses focused towards these sources, and thus provides a way to identify the resulting reflection artifacts. In this work, we demonstrate reduction of reflection artifacts in phantoms and in vivo measurements on human volunteers. In view of the spatially distributed PA sources that are found in clinical applications, we implemented an improved version of PAFUSion where photoacoustic signals are backpropagated to imitate the inward travelling wavefield and thus the reflection artifacts. The backpropagation is performed in a synthetic way based on the pulse-echo acquisitions after transmission on each single element of the transducer array. The results provide a direct confirmation that reflection artifacts are prominent in clinical epi-photoacoustic imaging, and that PAFUSion can strongly reduce these artifacts to improve deep-tissue photoacoustic imaging.

  3. SU-E-J-04: Integration of Interstitial High Intensity Therapeutic Ultrasound Applicators On a Clinical MRI-Guided High Intensity Focused Ultrasound Treatment Planning Software Platform

    Energy Technology Data Exchange (ETDEWEB)

    Ellens, N [Johns Hopkins University, Baltimore, Maryland (United States); Partanen, A [Philips Healthcare, Andover, Massachusetts (United States); Ghoshal, G; Burdette, E [Acoustic MedSystems Inc., Savoy, IL (United States); Farahani, K [National Cancer Institute, Bethesda, MD (United States)

    2015-06-15

    Purpose: Interstitial high intensity therapeutic ultrasound (HITU) applicators can be used to ablate tissue percutaneously, allowing for minimally-invasive treatment without ionizing radiation [1,2]. The purpose of this study was to evaluate the feasibility and usability of combining multielement interstitial HITU applicators with a clinical magnetic resonance imaging (MRI)-guided focused ultrasound software platform. Methods: The Sonalleve software platform (Philips Healthcare, Vantaa, Finland) combines anatomical MRI for target selection and multi-planar MRI thermometry to provide real-time temperature information. The MRI-compatible interstitial US applicators (Acoustic MedSystems, Savoy, IL, USA) had 1–4 cylindrical US elements, each 1 cm long with either 180° or 360° of active surface. Each applicator (4 Fr diameter, enclosed within a 13 Fr flexible catheter) was inserted into a tissue-mimicking agar-silica phantom. Degassed water was circulated around the transducers for cooling and coupling. Based on the location of the applicator, a virtual transducer overlay was added to the software to assist targeting and to allow automatic thermometry slice placement. The phantom was sonicated at 7 MHz for 5 minutes with 6–8 W of acoustic power for each element. MR thermometry data were collected during and after sonication. Results: Preliminary testing indicated that the applicator location could be identified in the planning images and the transducer locations predicted within 1 mm accuracy using the overlay. Ablation zones (thermal dose ≥ 240 CEM43) for 2 active, adjacent US elements ranged from 18 mm × 24 mm (width × length) to 25 mm × 25 mm for the 6 W and 8 W sonications, respectively. Conclusion: The combination of interstitial HITU applicators and this software platform holds promise for novel approaches in minimally-invasive MRI-guided therapy, especially when bony structures or air-filled cavities may preclude extracorporeal HIFU.[1] Diederich et al

  4. Morphometric analysis of high-intensity focused ultrasound-induced lipolysis on cadaveric abdominal and thigh skin.

    Science.gov (United States)

    Lee, Sugun; Kim, Hee-Jin; Park, Hyun Jun; Kim, Hyoung Moon; Lee, So Hyun; Cho, Sung Bin

    2017-07-01

    Non-focused ultrasound and high-intensity focused ultrasound (HIFU) devices induce lipolysis by generating acoustic cavitation and coagulation necrosis in targeted tissues. We aimed to investigate the morphometric characteristics of immediate tissue reactions induced by 2 MHz, 13-mm focused HIFU via two-dimensional ultrasound images and histologic evaluation of cadaveric skin from the abdomen and thigh. Acoustic fields of a 2 MHz, 38-mm HIFU transducer were characterized by reconstruction of the fields using acoustic intensity measurement. Additionally, abdominal and thigh tissues from a fresh cadaver were treated with a HIFU device for a single, two, and three pulses at the pulse energy of 130 J/cm(2) and a penetration depth of 13 mm. Acoustic intensity measurement revealed characteristic focal zones of significant thermal injury at the depth of 38 mm. In both the abdomen and thigh tissue, round to oval ablative thermal injury zones (TIZs) were visualized in subcutaneous fat layers upon treatment with a single pulse of HIFU treatment. Two to three HIFU pulses generated larger and more remarkable ablative zones throughout subcutaneous fat layers. Finally, experimental treatment in a tumescent infiltration-like setting induced larger HIFU-induced TIZs of an oval or columnar shape, compared to non-tumescent settings. Although neither acoustic intensity measurement nor cadaveric tissue exactly reflects in vivo HIFU-induced reactions in human tissue, we believe that our data will help guide further in vivo studies in investigating the therapeutic efficacy and safety of HIFU-induced lipolysis.

  5. MR-guided high-intensity focused ultrasound treatment of uterine fibroids

    OpenAIRE

    2016-01-01

    Antonia Wiggermann,1 Michael Beldoch,1 Friederike Hoellen,2 Peter Hunold1 1Clinic for Radiology and Nuclear Medicine, 2Department of Obstetrics and Gynecology, University Hospital Schleswig-Holstein, Lübeck, Germany Abstract: Uterine fibroids are benign, encapsulated uterine tumors, representing the most common reason for hysterectomy in premenopausal women. High-intensity focused ultrasound (HIFU; also known as focused ultrasound surgery) is a noninvasive technique leading to tissu...

  6. Microinterferometer transducer

    Science.gov (United States)

    Corey, III, Harry S.

    1979-01-01

    An air-bearing microinterferometer transducer is provided for increased accuracy, range and linearity over conventional displacement transducers. A microinterferometer system is housed within a small compartment of an air-bearing displacement transducer housing. A movable cube corner reflector of the interferometer is mounted to move with the displacement gauging probe of the transducer. The probe is disposed for axial displacement by means of an air-bearing. Light from a single frequency laser is directed into an interferometer system within the transducer housing by means of a self-focusing fiber optic cable to maintain light coherency. Separate fringe patterns are monitored by a pair of fiber optic cables which transmit the patterns to a detecting system. The detecting system includes a bidirectional counter which counts the light pattern fringes according to the direction of movement of the probe during a displacement gauging operation.

  7. Modeling of high-intensity focused ultrasound-induced lesions in the presence of cavitation bubbles

    Science.gov (United States)

    Chavrier; Chapelon; Gelet; Cathignol

    2000-07-01

    The classical "Bio Heat Transfer Equation (BHTE)" model is adapted to take into account the effects of oscillating microbubbles that occur naturally in the tissue during high-intensity focused ultrasound (HIFU) treatment. First, the Gilmore-Akulichev model is used to quantify the acoustic pressure scattered by microbubbles submitted to HIFU. Because this scattered pressure is not monochromatic, the concept of harmonic attenuation is introduced and a global attenuation coefficient is estimated for bubble-filled tissues. The first results show that this global attenuation coefficient varies significantly with respect to several parameters such as the frequency and the density of microbubbles in the medium, but also with respect to the incident acoustic pressure which thus becomes a transcendental function. Under these conditions, a layer-by-layer modeling, in the direction of propagation, is proposed to calculate the ultrasonic beam. Finally, the BHTE is solved and the HIFU-induced lesions are estimated by the calculation of the thermal dose. Using this model, it can be observed first that, when the firing power increases, the lesion develops clearly in the direction of the transducer, with a shape agreeing with in vivo experimentation. Next, it is observed that the lesion can be significantly modified in size and position, if an interface (skin or inner wall) is simulated as a zone with multiple cavitation nuclei. With a firing power increase, it is also shown how a secondary lesion can appear at the interface and how, beyond a certain threshold, this lesion develops at the main lesion expense. Finally, a better in-depth homogeneity of lesions is observed when the acoustic frequency of HIFU is increased.

  8. WE-G-12A-01: High Intensity Focused Ultrasound Surgery and Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Farahani, K [National Cancer Institute, Rockville, MD (United States); O' Neill, B [The Methodist Hospital Research Institute, Houston, TX (United States)

    2014-06-15

    More and more emphasis is being made on alternatives to invasive surgery and the use of ionizing radiation to treat various diseases including cancer. Novel screening, diagnosis, treatment and monitoring of response to treatment are also hot areas of research and new clinical technologies. Ultrasound(US) has gained traction in all of the aforementioned areas of focus. Especially with recent advances in the use of ultrasound to noninvasively treat various diseases/organ systems. This session will focus on covering MR-guided focused ultrasound and the state of the art clinical applications, and the second speaker will survey the more cutting edge technologies e.g. Focused Ultrasound (FUS) mediated drug delivery, principles of cavitation and US guided FUS. Learning Objectives: Fundamental physics and physical limitations of US interaction with tissue and nanoparticles The alteration of tissue transport using focused ultrasound US control of nanoparticle drug carriers for targeted release The basic principles of MRI-guided focused ultrasound (MRgFUS) surgery and therapy the current state of the art clinical applications of MRgFUS requirements for quality assurance and treatment planning.

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

    Science.gov (United States)

    Khokhlova, Tatiana D; Wang, Yak-Nam; Simon, Julianna C; Cunitz, Bryan W; Starr, Frank; Paun, Marla; Crum, Lawrence A; Bailey, Michael R; Khokhlova, Vera A

    2014-06-03

    The clinical use of high intensity focused ultrasound (HIFU) therapy for noninvasive tissue ablation has been recently gaining momentum. In HIFU, ultrasound energy from an extracorporeal source is focused within the body to ablate tissue at the focus while leaving the surrounding organs and tissues unaffected. Most HIFU therapies are designed to use heating effects resulting from the absorption of ultrasound by tissue to create a thermally coagulated treatment volume. Although this approach is often successful, it has its limitations, such as the heat sink effect caused by the presence of a large blood vessel near the treatment area or heating of the ribs in the transcostal applications. HIFU-induced bubbles provide an alternative means to destroy the target tissue by mechanical disruption or, at its extreme, local fractionation of tissue within the focal region. Here, we demonstrate the feasibility of a recently developed approach to HIFU-induced ultrasound-guided tissue fractionation in an in vivo pig model. In this approach, termed boiling histotripsy, a millimeter-sized boiling bubble is generated by ultrasound and further interacts with the ultrasound field to fractionate porcine liver tissue into subcellular debris without inducing further thermal effects. Tissue selectivity, demonstrated by boiling histotripsy, allows for the treatment of tissue immediately adjacent to major blood vessels and other connective tissue structures. Furthermore, boiling histotripsy would benefit the clinical applications, in which it is important to accelerate resorption or passage of the ablated tissue volume, diminish pressure on the surrounding organs that causes discomfort, or insert openings between tissues.

  10. The utility of sparse 2D fully electronically steerable focused ultrasound phased arrays for thermal surgery: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Ellens, Nicholas; Pulkkinen, Aki; Song Junho; Hynynen, Kullervo, E-mail: nicholas.ellens@utoronto.ca [Department of Imaging Research, Sunnybrook Research Institute, Toronto (Canada)

    2011-08-07

    Sparse arrays are widely used in diagnostic ultrasound for their strong performance and relative technical simplicity. This simulation study assessed the efficacy of phased arrays of varied sparseness for thermal surgery, especially with regard to power consumption and near-field heating. It employs a linear ultrasound propagation model and a semi-analytical solution to the Pennes' bioheat transfer equation. The basic design had 4912 cylindrical transducers (500 kHz) arranged on a flat 12 cm disk (1.5 mm spacing). This array was compared to randomly-thinned sparse arrays with 75%, 50% and 25% populations. Temperature elevations of 60 and 70 deg. C were induced in sonication times of 5-20 s, at foci spanning depths of 50-150 mm and radii of 0-60 mm. The sparse arrays produced nearly indistinguishable focal patterns but, averaged across the foci, required 132%, 200% and 393% of the power of the full array, respectively, applied through fewer transducer elements. Comparable results were found at 1 MHz from equivalent arrays. Simulated lesions were formed (thermal dose {>=} 240 equivalent minutes at 43 deg. C (T{sub 43})) and 'transition' and 'unsafe' regions (both defined as 5 min < T{sub 43} < 240 min) were identified, the former immediately surrounding the lesion and the latter anywhere else. At a depth of 100 mm, sparse arrays were found to produce comparable lesions to the full array at the focus, but 'unsafe', over-heated near-field regions after some ablated lesion volume: about 12 mL for the 25% array, around 100 mL for the 50% array, while the 75% and full arrays produced 150 mL lesions safely.

  11. Controlled Hyperthermia with MRI-guided Focused Ultrasound

    DEFF Research Database (Denmark)

    Hokland, Steffen; Salomir, Rares; Pedersen, Michael

    -based temperature maps. Discussion MRI-thermometry: Of the various MRI-based thermometers the temperature dependent chemical shift of the proton resonance frequency (PRF) is the most widely used providing accurate and high resolution temperature maps. The primary weaknesses of PRF-based thermometry...... is the vulnerability to motion-artifacts, baseline drift and the fact that the PRF in lipids is independent of temperature. FUS-technology: At moderate intensities absorption of ultrasound (US) in tissue results in a local increase in temperature. As in other wave phenomena the extent of the focal point...

  12. Basics of biomedical ultrasound for engineers

    CERN Document Server

    Azhari, Haim

    2010-01-01

    "Basics of Biomedical Ultrasound for Engineers is a structured textbook for university engineering courses in biomedical ultrasound and for researchers in the field. This book offers a tool for building a solid understanding of biomedical ultrasound, and leads the novice through the field in a step-by-step manner. The book begins with the most basic definitions of waves, proceeds to ultrasounds in fluids, and then delves into solid ultrasounds, the most complicated kind of ultrasound. It encompasses a wide range of topics within biomedical ultrasound, from conceptual definitions of waves to the intricacies of focusing devices, transducers, and acoustic fields"--Provided by publisher.

  13. Full-wave nonlinear ultrasound simulation on distributed clusters with applications in high-intensity focused ultrasound

    CERN Document Server

    Jaros, Jiri; Treeby, Bradley E

    2014-01-01

    Model-based treatment planning and exposimetry for high-intensity focused ultrasound (HIFU) requires the numerical simulation of nonlinear ultrasound propagation through heterogeneous and absorbing media. This is a computationally demanding problem due to the large distances travelled by the ultrasound waves relative to the wavelength of the highest frequency harmonic. Here, the k-space pseudospectral method is used to solve a set of coupled partial differential equations equivalent to a generalised Westervelt equation. The model is implemented in C++ and parallelised using the message passing interface (MPI) for solving large-scale problems on distributed clusters. The domain is partitioned using a 1D slab decomposition, and global communication is performed using a sparse communication pattern. Operations in the spatial frequency domain are performed in transposed space to reduce the communication burden imposed by the 3D fast Fourier transform. The performance of the model is evaluated using grid sizes up ...

  14. Nonlinear propagation of focused ultrasound in layered biological tissues based on angular spectrum approach

    Institute of Scientific and Technical Information of China (English)

    Zhu Xiao-Feng; Zhou Lin; Zhang Dong; Gong Xiu-Fen

    2005-01-01

    Nonlinear propagation of focused ultrasound in layered biological tissues is theoretically studied by using the angular spectrum approach (ASA), in which an acoustic wave is decomposed into its angular spectrum, and the distribution of nonlinear acoustic fields is calculated in arbitrary planes normal to the acoustic axis. Several biological tissues are used as specimens inserted into the focusing region illuminated by a focused piston source. The second harmonic components within or beyond the biological specimens are numerically calculated. Validity of the theoretical model is examined by measurements. This approach employing the fast Fourier transformation gives a clear visualization of the focused ultrasound, which is helpful for nonlinear ultrasonic imaging.

  15. [Focused surgical bedside ultrasound: E-FAST (focused assessment with sonography in trauma) - abdominal aortic aneurysm - cholecystolithiasis - acute appendicitis].

    Science.gov (United States)

    Studer, Maria; Studer, Peter

    2014-06-04

    Ultrasound is an easy to learn and highly efficient diagnostic tool to complete the clinical examination and improve bedside decision-making. In the trauma room, surgeons are often required to make a quick decision as to whether or not a patient needs an emergency intervention or whether further diagnostics are required. For this reason, education of surgeons in performing focused emergency ultrasound is pivotal. The goal of ICAN is to improve and expand the education of surgeons in Switzerland. This article provides a short review of the most frequent surgical pathologies encountered in the emergency room.

  16. Study of the temperature rise induced by a focusing transducer with a wide aperture angle on biological tissue containing ribs

    Science.gov (United States)

    Xin, Wang; Jiexing, Lin; Xiaozhou, Liu; Jiehui, Liu; Xiufen, Gong

    2016-04-01

    We used the spheroidal beam equation to calculate the sound field created by focusing a transducer with a wide aperture angle to obtain the heat deposition, and then we used the Pennes bioheat equation to calculate the temperature field in biological tissue with ribs and to ascertain the effects of rib parameters on the temperature field. The results show that the location and the gap width between the ribs have a great influence on the axial and radial temperature rise of multilayer biological tissue. With a decreasing gap width, the location of the maximum temperature rise moves forward; as the ribs are closer to the transducer surface, the sound energy that passes through the gap between the ribs at the focus decreases, the maximum temperature rise decreases, and the location of the maximum temperature rise moves forward with the ribs. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB921504 and 2011CB707902), the National Natural Science Foundation of China (Grant No. 11274166), the Fundamental Research Funds for the Central Universities, China (Grant No. 020414380001), the Fund from State Key Laboratory of Acoustics, Chinese Academy of Sciences (Grant No. SKLA201401), China Postdoctoral Science Foundation (Grant No. 2013M531313), and the Priority Academic Program Development of Jiangsu Higher Education Institutions and SRF for ROCS, SEM.

  17. A new sensitizer DVDMS combined with multiple focused ultrasound treatments: an effective antitumor strategy

    Science.gov (United States)

    Xiong, Wenli; Wang, Pan; Hu, Jianmin; Jia, Yali; Wu, Lijie; Chen, Xiyang; Liu, Quanhong; Wang, Xiaobing

    2015-12-01

    Sonodynamic therapy (SDT) was developed as a promising noninvasive approach. The present study investigated the antitumor effect of a new sensitizer (sinoporphyrin sodium, referred to as DVDMS) combined with multiple ultrasound treatments on sarcoma 180 both in vitro and in vivo. The combined treatment significantly suppressed cell viability, potentiated apoptosis, and markedly inhibited angiogenesis in vivo. In vivo, the tumor weight inhibition ratio reached 89.82% fifteen days after three sonication treatments plus DVDMS. This effect was stronger than one ultrasound alone (32.56%) and than one round of sonication plus DVDMS (59.33%). DVDMS combined with multiple focused ultrasound treatments initiated tumor tissue destruction, induced cancer cell apoptosis, inhibited tumor angiogenesis, suppressed cancer cell proliferation, and decreased VEGF and PCNA expression levels. Moreover, the treatment did not show obvious signs of side effects or induce a drop in body weight. These results indicated that DVDMS combined with multiple focused ultrasounds may be a promising strategy against solid tumor.

  18. Study of focusing characteristics of ultrasound for designing acoustic lens in ultrasonic moxibustion device

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Hyun; Song, Sung Jin; Kim, Hak Joon [School of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2015-04-15

    Traditional moxibustion therapy can cause severe pain and leave scarring burns at the moxibustion site as it relies on the practitioner's subjective and qualitative treatment. Recently, ultrasound therapy has received attention as an alternative to moxibustion therapy owing to its objectiveness and quantitative nature. However, in order to convert ultrasound energy into heat energy, there is a need to precisely understand the ultrasound-focusing characteristics of the acoustic lens. Therefore, in this study, an FEM simulation was performed for acoustic lenses with different geometries a concave lens and zone lens as the geometry critically influences ultrasound focusing. The acoustic pressure field, amplitude, and focal point were also calculated. Furthermore, the performance of the fabricated acoustic lens was verified by a sound pressure measurement experiment.

  19. Sub-array patterns of spherical-section phased array for high intensity focused ultrasound surgery

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaodong; WANG Xufei; LU Mingzhu; WAN Mingxi

    2005-01-01

    The sub-array field patterns of spherical-section phased array were implemented for noninvasive ultrasound surgery of liver-tumor. The sub-array approach included field calculation, pseudo-inverse method and genetic algorithm. The sub-arrays uncovered by ribs according to scanned images normally emitted ultrasound. The results from different sub-arrays demonstrated quite satisfied acoustic performances, which included qualified focus size and intensity level for ultrasound surgery with single-focus and multi-foci patterns. Moreover, the patterns could decrease power accumulation on the ribs, and avoid damaging normal tissues. Thus the sub-array method provides a promising tool for phased array ultrasound propagating through strong obstacles like human rib cage, and it may broaden the therapeutic area, make the surgery safer and more flexible.

  20. Evaluation of frequency-dependent ultrasound attenuation in transparent medium using focused shadowgraph technique

    Science.gov (United States)

    Iijima, Yukina; Kudo, Nobuki

    2017-07-01

    Acoustic fields of a short-pulsed ultrasound propagating through a transparent medium with ultrasound attenuation were visualized by the focused shadowgraph technique. A brightness waveform and its spatial integrations were derived from a visualized field image and compared with a pressure waveform measured by a membrane hydrophone. The experimental results showed that first-order integration of the brightness wave has good agreement with the pressure waveforms. Frequency-dependent attenuation of the pulse propagating through castor oil was derived from brightness and pressure waveforms, and attenuation coefficients determined from focused shadowgraphy and hydrophone techniques showed good agreement. The results suggest the usefulness of the shadowgraph technique not only for the visualization of ultrasound fields but also for noncontact estimation of rough pressure waveforms and correct ultrasound attenuation.

  1. Thermal effects generated by high-intensity focused ultrasound beams at normal incidence to a bone surface.

    Science.gov (United States)

    Nell, Diane M; Myers, Matthew R

    2010-01-01

    Experiments and computations were performed to study factors affecting thermal safety when high-intensity focused ultrasound (HIFU) beams are normally incident (i.e., beam axis normal to the interface) upon a bone/soft-tissue interface. In particular, the temperature rise and thermal dose were determined as a function of separation between the beam focus and the interface. Under conditions representative of clinical HIFU procedures, it was found that the thermal dose at the bone surface can exceed the threshold for necrosis even when the beam focus is more than 4 cm from the bone. Experiments showed that reflection of the HIFU beam from the bone back into the transducer introduced temperature fluctuations of as much as +/-15% and may be an important consideration for safety analyses at sufficiently high acoustic power. The applicability of linear propagation models in predicting thermal dose near the interface was also addressed. Linear models, while underpredicting thermal dose at the focus, provided a conservative (slight overprediction) estimate of thermal dose at the bone surface. Finally, temperature rise due to absorption of shear waves generated by the HIFU beam in the bone was computed. Modeling shear-wave propagation in the thermal analysis showed that the predicted temperature rise off axis was as much as 30% higher when absorption of shear waves is included, indicating that enhanced heating due to shear-wave absorption is potentially important, even for normally incident HIFU beams.

  2. Prostate Ultrasound

    Medline Plus

    Full Text Available ... use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds ...

  3. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds ...

  4. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the ... probe through the gel into the body. The transducer collects the sounds that bounce back and a ...

  5. MO-AB-210-00: Diagnostic Ultrasound Imaging Quality Control and High Intensity Focused Ultrasound Therapy Hands-On Workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-06-15

    The goal of this ultrasound hands-on workshop is to demonstrate advancements in high intensity focused ultrasound (HIFU) and to demonstrate quality control (QC) testing in diagnostic ultrasound. HIFU is a therapeutic modality that uses ultrasound waves as carriers of energy. HIFU is used to focus a beam of ultrasound energy into a small volume at specific target locations within the body. The focused beam causes localized high temperatures and produces a well-defined regions of necrosis. This completely non-invasive technology has great potential for tumor ablation and targeted drug delivery. At the workshop, attendees will see configurations, applications, and hands-on demonstrations with on-site instructors at separate stations. The involvement of medical physicists in diagnostic ultrasound imaging service is increasing due to QC and accreditation requirements. At the workshop, an array of ultrasound testing phantoms and ultrasound scanners will be provided for attendees to learn diagnostic ultrasound QC in a hands-on environment with live demonstrations of the techniques. Target audience: Medical physicists and other medical professionals in diagnostic imaging and radiation oncology with interest in high-intensity focused ultrasound and in diagnostic ultrasound QC. Learning Objectives: Learn ultrasound physics and safety for HIFU applications through live demonstrations Get an overview of the state-of-the art in HIFU technologies and equipment Gain familiarity with common elements of a quality control program for diagnostic ultrasound imaging Identify QC tools available for testing diagnostic ultrasound systems and learn how to use these tools List of supporting vendors for HIFU and diagnostic ultrasound QC hands-on workshop: Philips Healthcare Alpinion Medical Systems Verasonics, Inc Zonare Medical Systems, Inc Computerized Imaging Reference Systems (CIRS), Inc. GAMMEX, Inc., Cablon Medical BV Steffen Sammet: NIH/NCI grant 5R25CA132822, NIH/NINDS grant 5R25NS

  6. Design and fabrication of a low-frequency (1-3 MHz) ultrasound transducer for accurate placement of screw implants in the spine

    Science.gov (United States)

    Manbachi, Amir; Lee, Mike; Foster, F. Stuart; Ginsberg, Howard J.; Cobbold, Richard S. C.

    2014-03-01

    In 2012 approximately 800,000 spinal fusion surgeries were performed in the United States, requiring the insertion of screws into the pedicles. Their exact placement is critical and made complex due to limited visibility of the spine, continuous bleeding in the exposed regions, and variability in morphologies. The alarmingly high rate of screw misplacements (up to 20%) reported in the literature is of major concern since such misplacements can place the surrounding vital structures at risk. A potential guidance method for determining the best screw trajectory is by the use of real-time ultrasound imaging similar to that used for intravascular imaging. An endovascular transducer could be inserted into the pedicle to image the anatomy from within and identify bone boundaries. A major challenge of imaging within bone is high signal attenuation. The rapid increase of attenuation with frequency requires much lower frequencies (1-3 MHz) than those used in intravascular imaging. This study describes the custom design and fabrication of 2 MHz ultrasound probes (3.5 mm diameter/ 11 Fr) for pedicle screw guidance. Three transducer designs are explored to provide improved sensitivity and signal to noise ratio, compared to the previously tested transducer within the pedicle. Experimental measurements are compared with the results obtained using various simulation tools. The work reported in this paper represents the first stage in our ultimate goal of developing a 32- element phased array that is capable of generating a radial B-mode image.

  7. Impact of Focused Ultrasound-enhanced Drug Delivery on Survival in Rats with Glioma

    Science.gov (United States)

    Treat, Lisa Hsu; Zhang, Yongzhi; McDannold, Nathan; Hynynen, Kullervo

    2009-04-01

    Malignancies of the brain remain difficult to treat with chemotherapy because the selective permeability of the blood-brain barrier (BBB) blocks many potent agents from reaching their target. Previous studies have illustrated the feasibility of drug and antibody delivery across the BBB using MRI-guided focused ultrasound. In this study, we investigated the impact of focused ultrasound-enhanced delivery of doxorubicin on survival in rats with aggressive glioma. Sprague-Dawley rats were implanted with 9 L gliosarcoma cells in the brain. Eight days after implantation, each rat received one of the following: (1) no treatment (control), (2) a single treatment with microbubble-enhanced MRI-guided focused ultrasound (FUS only), (3) a single treatment with i.v. liposomal doxorubicin (DOX only), or (4) a single treatment with microbubble-enhanced MRI-guided focused ultrasound and concurrent i.v. injections of liposomal doxorubicin (FUS+DOX). The survival time from implantation to death or euthanasia was recorded. We observed a modest but significant increase in median survival time in rats treated with combined MRI-guided focused ultrasound chemotherapy, compared to chemotherapy alone (p0.10). Our study demonstrates for the first time a therapeutic benefit achieved with ultrasound-enhanced drug delivery across the blood-brain barrier. This confirmation of efficacy in an in vivo tumor model indicates that targeted drug delivery using MRI-guided focused ultrasound has the potential to have a major impact on the treatment of patients with brain tumors and other neurological disorders.

  8. Focused Ultrasound-Induced Neurogenesis Requires an Increase in Blood-Brain Barrier Permeability

    Science.gov (United States)

    Mooney, Skyler J.; Shah, Kairavi; Yeung, Sharon; Burgess, Alison; Aubert, Isabelle; Hynynen, Kullervo

    2016-01-01

    Transcranial focused ultrasound technology used to transiently open the blood-brain barrier, is capable of stimulating hippocampal neurogenesis; however, it is not yet known what aspects of the treatment are necessary for enhanced neurogenesis to occur. The present study set out to determine whether the opening of blood-brain barrier, the specific pressure amplitudes of focused ultrasound, and/or the intravenous administration of microbubbles (phospholipid microspheres) are necessary for the enhancement of neurogenesis. Specifically, mice were exposed to burst (10ms, 1Hz burst repetition frequency) focused ultrasound at the frequency of 1.68MHz and with 0.39, 0.78, 1.56 and 3.0MPa pressure amplitudes. These treatments were also conducted with or without microbubbles, at 0.39 + 0.78MPa or 1.56 + 3.0MPa, respectively. Only focused ultrasound at the ~0.78 MPa pressure amplitude with microbubbles promoted hippocampal neurogenesis and was associated with an increase in blood-brain barrier permeability. These results suggest that focused ultrasound -mediated neurogenesis is dependent upon the opening of the blood-brain barrier. PMID:27459643

  9. Synthetic Aperture Focusing Applied to Imaging Using a Rotating Single Element Transducer

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2007-01-01

    This paper applies the concept of virtual sources and mono-static synthetic aperture focusing (SAF) to 2-dimensional imaging with a single rotating mechanically focused concave element with the objective of improving lateral resolution and signal-to-noise ratio (SNR). The geometrical focal point ...

  10. MRI-guided High-Intensity Focused Ultrasound of Breast Cancer

    NARCIS (Netherlands)

    Merckel, L.G.

    2014-01-01

    Magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) is a promising technique for completely noninvasive tumor ablation. This thesis focuses on its application for the treatment of patients with breast cancer. The first part of the thesis describes the role of breast MRI for

  11. MRI-guided High-Intensity Focused Ultrasound of Breast Cancer

    NARCIS (Netherlands)

    Merckel, L.G.

    2014-01-01

    Magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) is a promising technique for completely noninvasive tumor ablation. This thesis focuses on its application for the treatment of patients with breast cancer. The first part of the thesis describes the role of breast MRI for

  12. High intensity focused ultrasound technology, its scope and applications in therapy and drug delivery.

    Science.gov (United States)

    Phenix, Christopher Peter; Togtema, Melissa; Pichardo, Samuel; Zehbe, Ingeborg; Curiel, Laura

    2014-01-01

    Ultrasonography is a safe, inexpensive and wide-spread diagnostic tool capable of producing real-time non-invasive images without significant biological effects. However, the propagation of higher energy, intensity and frequency ultrasound waves through living tissues can induce thermal, mechanical and chemical effects useful for a variety of therapeutic applications. With the recent development of clinically approved High Intensity Focused Ultrasound (HIFU) systems, therapeutic ultrasound is now a medical reality. Indeed, HIFU has been used for the thermal ablation of pathological lesions; localized, minimally invasive ultrasound-mediated drug delivery through the transient formation of pores on cell membranes; the temporary disruption of skin and the blood brain barrier; the ultrasound induced break-down of blood clots; and the targeted release of drugs using ultrasound and temperature sensitive drug carriers. This review seeks to engage the pharmaceutical research community by providing an overview on the biological effects of ultrasound as well as highlighting important therapeutic applications, current deficiencies and future directions.

  13. Combined passive acoustic mapping and magnetic resonance thermometry for monitoring phase-shift nanoemulsion enhanced focused ultrasound therapy

    Science.gov (United States)

    Crake, Calum; Meral, F. Can; Burgess, Mark T.; Papademetriou, Iason T.; McDannold, Nathan J.; Porter, Tyrone M.

    2017-08-01

    Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure. Here, we employed phase-shift nanoemulsions (PSNE) embedded in tissue phantoms to promote cavitation and hence temperature rise induced by FUS. In addition, we incorporated passive acoustic mapping (PAM) alongside simultaneous MR thermometry in order to visualize both acoustic emissions and temperature rise, within the bore of a full scale clinical MRI scanner. Focal cavitation of PSNE could be resolved using PAM and resulted in accelerated heating and increased the maximum elevated temperature measured via MR thermometry compared to experiments without nanoemulsions. Over time, the simultaneously acquired acoustic and temperature maps show translation of the focus of activity towards the FUS transducer, and the magnitude of the increase in cavitation and focal shift both increased with nanoemulsion concentration. PAM results were well correlated with MRI thermometry and demonstrated greater sensitivity, with the ability to detect cavitation before enhanced heating was observed. The results suggest that PSNE could be beneficial for enhancement of thermal focused ultrasound therapies and that PAM could be a critical tool for monitoring this process.

  14. Microbubble mediated dual-frequency high intensity focused ultrasound thrombolysis: An In vitro study

    Science.gov (United States)

    Suo, Dingjie; Jin, Zhiyang; Jiang, Xiaoning; Dayton, Paul A.; Jing, Yun

    2017-01-01

    High intensity focused ultrasound (HIFU) has recently emerged as a promising alternative approach for thrombolysis. However, the high acoustic energy required by HIFU could elicit thermal damage bioeffects, impeding the clinical translation of this technique. This paper investigates the use of dual-frequency focused ultrasound (DFFU) mediated by microbubbles (MBs) to minimize the acoustic power required for thrombolysis in vitro. It was found that MBs, with sufficient concentration, could significantly lower the power threshold for thrombolysis for both DFFU and single-frequency focused ultrasound (SFFU). In addition, SFFU needs about 96%-156% higher energy to achieve the same thrombolysis efficiency as that of DFFU. The thrombolysis efficiency is also found to increase with the duty cycle. The measured cavitation signals reveal that the enhanced inertial cavitation is likely responsible for the improved thrombolysis under DFFU and MBs.

  15. Feasibility of a focused ultrasound training programme for medical undergraduate students.

    Science.gov (United States)

    Wong, Ivan; Jayatilleke, Thilina; Kendall, Richard; Atkinson, Paul

    2011-03-01

    Although ultrasound is a core skill for many clinical specialties, UK medical schools are not currently required to teach this skill. The College of Emergency Medicine (CEM) has championed the use of ultrasound to answer focused clinical questions in emergency settings. We have designed and piloted an ultrasound training course for undergraduate medical students addressing one important indication: ultrasound assessment of the abdominal aorta. Fourteen clinical students, who had no prior experience of using ultrasound, received focused ultrasound training in the form of didactic instruction, a short bedside practical workshop and self-directed learning over a 20-day period. At the end of this period, the students were assessed by a structured viva and an observed structured clinical examination (OSCE) used for accreditation by the CEM. The primary endpoint was the number of students who passed the assessment. The secondary endpoint was the accuracy of the students' anatomical measurements. Thirteen of the 14 (93%) students completed the training and assessment. Eight of the 13 (62%) students passed both the viva and OSCE, and were deemed to have achieved the CEM standard. The measurements by the competent students were not statistically different from those of experienced practitioners. We have shown for the first time that it is feasible to train inexperienced undergraduate students to scan the abdominal aorta to a professional standard using a focused training course. It is time for the medical education community to address whether focused ultrasound training should accompany traditional clinical skills, such as using a stethoscope, in UK medical school curricula. © Blackwell Publishing Ltd 2011.

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

    Science.gov (United States)

    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.

  17. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... transducer into the body. Doppler ultrasound, a special application of ultrasound, measures the direction and speed of ... understanding of the possible charges you will incur. Web page review process: This Web page is reviewed ...

  18. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... 3-D ultrasound or sonohysterography for patients with infertility. In this setting, three-dimensional ultrasound provides information ... the transducer is pressed against the skin, it directs small pulses of inaudible, high-frequency sound waves ...

  19. Prostate Ultrasound

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    Full Text Available ... of page What will I experience during and after the procedure? Ultrasound exams in which the transducer ... a regular ultrasound imaging probe on the perineal skin of the patient, between the legs and behind ...

  20. Processing ultrasound backscatter to monitor high-intensity focused ultrasound (HIFU) therapy

    Science.gov (United States)

    Kaczkowski, Peter J.; Anand, Ajay; Bailey, Michael R.

    2005-09-01

    The development of new noninvasive surgical methods such as HIFU for the treatment of cancer and internal bleeding requires simultaneous development of new sensing approaches to guide, monitor, and assess the therapy. Ultrasound imaging using echo amplitude has long been used to map tissue morphology for diagnostic interpretation by the clinician. New quantitative ultrasonic methods that rely on amplitude and phase processing for tissue characterization are being developed for monitoring of ablative therapy. We have been developing the use of full wave ultrasound backscattering for real-time temperature estimation, and to image changes in tissue backscatter spectrum as therapy progresses. Both approaches rely on differential processing of the backscatter signal in time, and precise measurement of phase differences. Noise and artifacts from motion and nonstationary speckle statistics are addressed by constraining inversions for tissue parameters with physical models. We present results of HIFU experiments with static point and scanned HIFU exposures in which temperature rise can be accurately mapped using a new heat transfer equation (HTE) model-constrained inverse approach. We also present results of a recently developed spectral imaging method that elucidates microbubble-mediated nonlinearity not visible as a change in backscatter amplitude. [Work supported by Army MRMC.

  1. Use of stationary focused ultrasound fields for characterization of tissue and localized tissue ablation

    Science.gov (United States)

    Winey, Brian Andrew

    Ultrasound-induced blood stasis has been observed for more than 30 years. The physical understanding of the phenomenon has not been fully explored. Analytical descriptions of the acoustic interaction with spheres in suspension have been derived but the physical implications and limitations have not been demonstrated. The analytical expressions will be tested against physical observations using numerical simulations. The simulations will begin with stationary spheres and continue with the inclusion of moving spheres and a moving suspending fluid. To date, experimental observations of acoustically induced blood stasis have been either in vitro or invasive. We demonstrate ultrasound-induced blood stasis in murine normal leg muscle versus tumor-bearing legs, observed through noninvasive measurements of optical spectroscopy, and discuss possible diagnostic uses for this effect of ultrasound. We derive the optimal optical wavelengths for measuring the effects of the ultrasound at small source detector separations. Using optical oximetry performed at the optimal wavelengths, we demonstrate that effects of ultrasound can be used to differentiate tumor from normal leg muscle tissue in mice. To provide a statistical analysis of the experiments, we propose a novel diagnostic algorithm that quantitatively differentiates tumor from nontumor with maximum specificity 0.83, maximum sensitivity 0.79, and area under receiver-operating-characteristics curve 0.90. Ultrasound has long been known to cause tissue heating when applied in high intensities. More recently, interest has arisen in the area of High Intensity Focused Ultrasound (HIFU) for localized tissue heating effects, specifically thermal ablation. All present techniques employ focused traveling high intensity acoustic waves to create a region of elevated temperature. Such high intensity traveling waves can be damaging to normal tissue in the vicinity of the focal region, and have demonstrated surface burns and caused

  2. Focused ultrasound: concept for automated transcutaneous control of hemorrhage in austere settings.

    Science.gov (United States)

    Kucewicz, John C; Bailey, Michael R; Kaczkowski, Peter J; Carter, Stephen J

    2009-04-01

    High intensity focused ultrasound (HIFU) is being developed for a range of clinical applications. Of particular interest to NASA and the military is the use of HIFU for traumatic injuries because HIFU has the unique ability to transcutaneously stop bleeding. Automation of this technology would make possible its use in remote, austere settings by personnel not specialized in medical ultrasound. Here a system to automatically detect and target bleeding is tested and reported. The system uses Doppler ultrasound images from a clinical ultrasound scanner for bleeding detection and hardware for HIFU therapy. The system was tested using a moving string to simulate blood flow and targeting was visualized by Schlieren imaging to show the focusing of the HIFU acoustic waves. When instructed by the operator, a Doppler ultrasound image is acquired and processed to detect and localize the moving string, and the focus of the HIFU array is electronically adjusted to target the string. Precise and accurate targeting was verified in the Schlieren images. An automated system to detect and target simulated bleeding has been built and tested. The system could be combined with existing algorithms to detect, target, and treat clinical bleeding.

  3. Use of high-intensity focused ultrasound in the treatment of both benign and malignant prostatic disease

    Science.gov (United States)

    Kernen, Kenneth M.; Miles, Brian J.

    2000-05-01

    , investigators found rectal injuries in up to 15%, anastomotic strictures in 27% and urinary incontinence in approximately 58%, as well as an overall higher estimated blood loss, transfusions, and hospital stay greater than that of a standard radical retropubic prostatectomy. Cryotherapy also has a significant complication rate with incontinence (73%), impotence (72%), and prolonged dysuria in 67%. In this report, biopsies were negative in 77% but biochemical failure occurred in 58% of patients. High intensity focused ultrasound (HIFU) therapy is a relatively new treatment modality and is being applied transrectally for the treatment of both benign prostatic hyperplasia and adenocarcinoma of the prostate. The therapy is also under evaluation at multiple centers in the United States for the treatment of radiorecurrent prostate cancer. In Europe, it not only being evaluated as treatment for radiorecurrent prostate cancer, but is also being evaluated and offered as a minimally invasive primary therapy for prostate cancers localized to the gland. The technique of HIFU generation has been previously described in detail. The ablation device is comprised of a patient treatment table, main computer, an oscillator, power amplifier, power measurement system, probe movement system, endorectal probe with built-in ultrasound scanner and treatment transducer, and reprography equipment. The patient is administered either a spinal or general anesthesia, positioned on the treatment table on his side with the legs flexed, the endorectal probe is then inserted. The ultrasound imaging is used to detect the contours of the prostate and the target volume to be treated is then calculated. Under computer control, the HIFU device position and then successively repositions the endorectal probe, delivering the high intensity focused ultrasound according to the treatment blocks defined by the surgeon. This sequence then repeats until all sectors of the prostate have been treated. HIFU is generated by high

  4. Simulation study of a chaotic cavity transducer based virtual phased array used for focusing in the bulk of a solid material.

    Science.gov (United States)

    Delrue, Steven; Van Den Abeele, Koen; Matar, Olivier Bou

    2016-04-01

    In acoustic and ultrasonic non-destructive testing techniques, it is sometimes beneficial to concentrate sound energy at a chosen location in space and at a specific instance in time, for example to improve the signal-to-noise ratio or activate the nonlinearity of damage features. Time Reversal (TR) techniques, taking advantage of the reversible character of the wave equation, are particularly suited to focus ultrasonic waves in time and space. The characteristics of the energy focusing in solid media using principles of time reversed acoustics are highly influenced by the nature and dimensions of the medium, the number of transducers and the length of the received signals. Usually, a large number of transducers enclosing the domain of interest is needed to improve the quality of the focusing. However, in the case of highly reverberant media, the number of transducers can be reduced to only one (single-channel TR). For focusing in a non-reverberant medium, which is impossible when using only one source, an adaptation of the single-channel reciprocal TR procedure has been recently suggested by means of a Chaotic Cavity Transducer (CCT), a single element transducer glued on a cavity of chaotic shape. In this paper, a CCT is used to focus elastic energy, at different times, in different points along a predefined line on the upper surface of a thick solid sample. Doing so, all focusing points can act as a virtual phased array transducer, allowing to focus in any point along the depth direction of the sample. This is impossible using conventional reciprocal TR, as you need to have access to all points in the bulk of the material for detecting signals to be used in the TR process. To asses and provide a better understanding of this concept, a numerical study has been developed, allowing to verify the basic concepts of the virtual phased array and to illustrate multi-component time reversal focusing in the bulk of a solid material.

  5. Histological and biochemical analysis of mechanical and thermal bioeffects in boiling histotripsy lesions induced by high intensity focused ultrasound.

    Science.gov (United States)

    Wang, Yak-Nam; Khokhlova, Tatiana; Bailey, Michael; Hwang, Joo Ha; Khokhlova, Vera

    2013-03-01

    Recent studies have shown that shockwave heating and millisecond boiling in high-intensity focused ultrasound fields can result in mechanical fractionation or emulsification of tissue, termed boiling histotripsy. Visual observations of the change in color and contents indicated that the degree of thermal damage in the emulsified lesions can be controlled by varying the parameters of the exposure. The goal of this work was to examine thermal and mechanical effects in boiling histotripsy lesions using histologic and biochemical analysis. The lesions were induced in ex vivo bovine heart and liver using a 2-MHz single-element transducer operating at duty factors of 0.005-0.01, pulse durations of 5-500 ms and in situ shock amplitude of 73 MPa. Mechanical and thermal damage to tissue was evaluated histologically using conventional staining techniques (hematoxylin and eosin, and nicotinamide adenine dinucleotide-diaphorase). Thermal effects were quantified by measuring denaturation of salt soluble proteins in the treated region. According to histologic analysis, the lesions that visually appeared as a liquid contained no cellular structures larger than a cell nucleus and had a sharp border of one to two cells. Both histologic and protein analysis showed that lesions obtained with short pulses (thermal damage. Increasing the pulse duration resulted in an increase in thermal damage. However, both protein analysis and nicotinamide adenine dinucleotide-diaphorase staining showed less denaturation than visually observed as whitening of tissue. The number of high-intensity focused ultrasound pulses delivered per exposure did not change the lesion shape or the degree of thermal denaturation, whereas the size of the lesion showed a saturating behavior suggesting optimal exposure duration. This study confirmed that boiling histotripsy offers an effective, predictable way to non-invasively fractionate tissue into sub-cellular fragments with or without inducing thermal damage.

  6. Acute Cholecystitis Detected by Serial Emergency Department Focused Right Upper Quadrant Ultrasound

    Directory of Open Access Journals (Sweden)

    David Bosch

    2016-06-01

    Full Text Available Acute cholecystitis is a common etiology of acute right upper quadrant pain in patients presenting to the emergency department (ED. The use of ED-focused right upper quadrant ultrasound (RUQ US is becoming more widely utilized to evaluate abdominal pain thought to be hepatobiliary in nature. We describe a case series of two patients with acute cholecystitis detected by serial ED-focused RUQ US. Case 1: A woman presented to the ED with epigastric pain of acute onset. She was initially found to have a mild leukocytosis and cholelithiasis detected by ED-focused RUQ US. Seventy-five minutes later, the patient had a repeat bedside ultrasound by the same sonographer that showed visual evidence of acute cholecystitis that was later confirmed by surgical pathology. She was treated operatively. Case 2: A man with known cholelithiasis presents to the ED with acute-onset RUQ pain. Initial RUQ ultrasound performed by the Department of Radiology (University of Colorado Hospital was equivocal, showing cholelithiasis with a mildly thickened wall and no pericholecystic fluid. A repeat ED-focused RUQ ultrasound 5 hours later showed increased wall thickness and pericholecystic fluid. The patient was subsequently taken for same-day cholecystectomy. This case series demonstrates the dynamic and progressive nature of acute cholecystitis detected by ED-focused RUQ US. It also highlights how serial bedside ultrasonography can reduce harm, appropriately triage patients with hepatobiliary disease and lead to reductions in overall morbidity.

  7. Targeted Drug Delivery to the Brain by MRI-guided Focused Ultrasound

    Science.gov (United States)

    Treat, Lisa Hsu; McDannold, Nathan; Vykhodtseva, Natalia; Zhang, Yongzhi; Tam, Karen; Hynynen, Kullervo

    2006-05-01

    The effect of focused ultrasound on the absorption of liposome-encapsulated doxorubicin in the brain was investigated. By applying focused ultrasound in the presence of microbubble ultrasound contrast agent, we achieved targeted drug delivery to the brain in vivo. Tissue drug concentrations in sonicated brain corresponded with cytotoxic levels measured in various human tumors and were significantly different from those measured in unexposed contralateral control samples (p ⩽ 0.02). In addition, increased MR signal enhancement at the focal location on contrast-enhanced T1-weighted fast spin echo images correlated with increased penetration of doxorubicin into brain tissue (r = 0.85), indicating the potential of MRI to be used as an indicator of blood-brain barrier permeability during treatment. Further investigation is required to evaluate the efficacy of this technique and to optimize its parameters for clinical application.

  8. Photoacoustic-guided focused ultrasound (PAFUSion for identifying reflection artifacts in photoacoustic imaging

    Directory of Open Access Journals (Sweden)

    Mithun Kuniyil Ajith Singh

    2015-12-01

    Full Text Available Influence of acoustic inhomogeneities and resulting reflection artifacts is an important problem in reflection-mode photoacoustic imaging. Absorption of light by skin and superficial optical absorbers will generate photoacoustic transients, which traverse into the tissue and get reflected from structures having different acoustic impedance. These reflected photoacoustic signals, when reconstructed, may appear in the region of interest, which causes difficulties in image interpretation. We propose a novel method to identify and potentially eliminate reflection artifacts in photoacoustic images using photoacoustic-guided focused ultrasound [PAFUSion]. Our method uses focused ultrasound pulses to mimic the wave field produced by photoacoustic sources and thus provides a way to identify reflection artifacts in clinical combined photoacoustic and pulse-echo ultrasound. Simulation and phantom results are presented to demonstrate the validity and impact of this method. Results show that PAFUSion can identify reflections in photoacoustic images and thus envisages potential for improving photoacoustic imaging of acoustically inhomogeneous tissue.

  9. Feasibility study of a single-element transcranial focused ultrasound system for blood-brain barrier opening

    Science.gov (United States)

    Marquet, Fabrice; Tung, Yao-Sheng; Teichert, Tobias; Ferrera, Vincent P.; Konofagou, Elisa E.

    2012-10-01

    The blood-brain barrier (BBB) is a specialized vascular system that impedes entry of all large and the vast majority of small molecules including the most potent CNS disease therapeutic agents from entering from the lumen into the brain parenchyma. Microbubble-enhanced, focused ultrasound (ME-FUS) has been previously shown to disrupt noninvasively, selectively, and transiently the BBB in small animals in vivo. The study addresses the focusing properties of single-element transducers at intermediate frequencies (500 kHz) through primate and human skulls, targeting clinically relevant targets extracted from 3D brain atlases such as the hippocampus and the basal ganglia, which are typically affected by early Alzheimer's and Parkinson's disease, respectively. A preliminary in vivo study was performed to study the frequency dependence of BBB opening parameters in mice. Then, feasibility of transcranial ME-FUS BBB opening in non-human primates was demonstrated with subsequent BBB recovery. Sonications were combined with two different types of microbubbles (custom made 4-5 μm and Definity®). 3T MRI was used to confirm the BBB disruption and to assess brain damage.

  10. Targeting accuracy and closing timeline of the microbubble-enhanced focused ultrasound blood-brain barrier opening in non-human primates

    Science.gov (United States)

    Marquet, Fabrice; Tung, Yao-Sheng; Teichert, Tobias; Wu, Shih-Ying; Wang, Shutao; Downs, Matthew; Ferrera, Vincent P.; Konofagou, Elisa E.

    2012-11-01

    The delivery of drugs to specific neural targets faces two fundamental problems: Most drugs do not cross the blood-brain barrier and those that do spread to all parts of the brain. To date there exists only one non-invasive methodology with the potential to solve these problems: selective blood-brain barrier disruption using micro-bubble enhanced focused ultrasound. We have recently developed a single-element 500 kHz spherical transducer ultrasound setup for use in the non-human primate. Using this system for selective blood-brain barrier disruption is technically no more challenging than positioning a TMS coil, and does not rely on MRI-guided targeting or expensive phased array ultrasound systems. So far, however, the targeting accuracy that can be achieved with this system has not been quantified systematically. Here we tested the accuracy of the system by targeting the caudate nucleus of the basal ganglia in two macaque monkeys. Our results show that average in-plane error of the system is on the order of 2 mm and targeting error in depth, i.e., along the ultrasound path, is even smaller and averaged 1.2 mm. In summary, targeting accuracy of our system is good enough to enable the selective delivery of drugs to specific sub-structures of the basal ganglia.

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

    Science.gov (United States)

    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

  12. A novel sound-blocking structure based on the muffler principle for rib-sparing transcostal high-intensity focused ultrasound treatment.

    Science.gov (United States)

    Chao, Yu-Tin; Hsu, Che-Jung; Yu, Ya-Lin; Yen, Jia-Yush; Ho, Ming-Chih; Chen, Yung-Yaw; Chang, Hung-Cheng; Lian, Feng-Li

    2015-01-01

    The main challenge in transcostal high-intensity focused ultrasound therapy is minimising heat deposition in the ribs while ensuring that a sufficient dose is delivered to the target region. Current approaches rely on expensive multichannel phased-array systems to turn the individual transducer on and off according to either geometrical arrangements or complicated wave calculations. To protect the ribs from heating, the ultrasound energy must not only not reach the ribs, but must also not accumulate in front of the ribs. The research in this paper proposes a different approach, of attaching a sound-blocking structure in front of the rib cage with similar effects to those of an engine exhaust muffler. The sound-blocking structure is based on the muffler principle to prevent ultrasound energy from reaching the ribs and reduce the amount of energy reflected back to the applicator. Finite element simulations with a 0.5-MHz transducer of the overall sound fields and temperature distribution showed that the ultrasound pressure and energy level would decrease behind the novel sound-blocking structures, thereby resulting in a lower temperature at the ribs than at the tumour. Without the protecting structure, the rib temperature reached 104.19 °C whereas with the structure it reached only 37.86 °C. An experimental set-up using porcine ribs with a phantom was also developed to validate the concept, which showed that the rib temperature reached 73 °C without protection within 1 min of ablation time whereas it reached 36.5 °C with the device. The tumour region in the tests reached 51 °C and 49 °C with and without protection, respectively.

  13. Focused, phased-array plane piston and spherically-shaped concave piston transducers: comparison for the same aperture and focal point.

    Science.gov (United States)

    Warriner, Renée K; Cobbold, Richard S C

    2012-04-01

    It has sometimes been assumed that the phased-array plane piston transducer and the spherically-shaped concave piston transducer are equivalent structures when both have the same aperture and focal point. This assumption has not been previously examined, nor has an expression for the on-axis impulse response of the focused, phased-array plane piston transducer been derived. It is shown in this paper how such an expression can be obtained. Comparisons of the impulse response for both structures show similarities, as well as some differences that could be significant as the observation point approaches the focal point. Comparisons are also performed for wide-band pulses close to the focus as well as for sinusoidal excitation. A physical explanation for the cause of the impulse response discrepancy is shown to be due to the nature of the piston focusing delay and its effect on the Rayleigh integral.

  14. Piezoelectric Composite Micromachined Multifrequency Transducers for High-Resolution, High-Contrast Ultrasound Imaging for Improved Prostate Cancer Assessment

    Science.gov (United States)

    2016-10-01

    MHz) transducer was developed for demonstrating the feasibility of transrectal acoustic angiography. This was the first dual mode 3/15 MHz array... acoustic angiography imaging in intracavity applications. A single element dual-frequency IVUS transducer was developed for concept validation, which...the backside of the transmitter is close to the free boundary, which cannot absorb backward travelling waves, the low acoustic impedance (19.8 MRayl

  15. A prototype stimulator system for noninvasive Low Intensity Focused Ultrasound delivery.

    Science.gov (United States)

    Mulgaonkar, Amit P; Singh, Rahul S; Babakhanian, Meghedi; Culjat, Martin O; Grundfest, Warren S; Gorgulho, Alessandra; Lacan, Goran; De Salles, Antonio A F; Bystritsky, Alexander; Melega, William P

    2012-01-01

    A prototype Low Intensity Focused Ultrasound (LIFU) stimulator system was developed to evaluate non-invasive neuromodulation in a large animal model. We conducted a feasibility study on a Göttingen minipig, demonstrating reversible, targeted transcranial neuromodulation. The hypothalamus of the minipig was repeatedly stimulated with LIFU which evoked temporally correlated increases in both heart rate and blood pressure.

  16. 76 FR 43119 - Medical Devices; General and Plastic Surgery Devices; Classification of the Focused Ultrasound...

    Science.gov (United States)

    2011-07-20

    ... focused ultrasound exposure (thermal damage), such as erythema, edema, pigmentary changes, and pain. These... risk is addressed by recommended treatment parameters that have been shown to be safe with little or no... risk is addressed by recommended treatment parameters that have been shown to be safe with little or no...

  17. Simulation Based Investigation of Focusing Phased Array Ultrasound in Dissimilar Metal Welds

    Directory of Open Access Journals (Sweden)

    Hun-Hee Kim

    2016-02-01

    Full Text Available Flaws at dissimilar metal welds (DMWs, such as reactor coolant systems components, Control Rod Drive Mechanism (CRDM, Bottom Mounted Instrumentation (BMI etc., in nuclear power plants have been found. Notably, primary water stress corrosion cracking (PWSCC in the DMWs could cause significant reliability problems at nuclear power plants. Therefore, phased array ultrasound is widely used for inspecting surface break cracks and stress corrosion cracks in DMWs. However, inspection of DMWs using phased array ultrasound has a relatively low probability of detection of cracks, because the crystalline structure of welds causes distortion and splitting of the ultrasonic beams which propagates anisotropic medium. Therefore, advanced evaluation techniques of phased array ultrasound are needed for improvement in the probability of detection of flaws in DMWs. Thus, in this study, an investigation of focusing and steering phased array ultrasound in DMWs was carried out using a time reversal technique, and an adaptive focusing technique based on finite element method (FEM simulation. Also, evaluation of focusing performance of three different focusing techniques was performed by comparing amplitude of phased array ultrasonic signals scattered from the targeted flaw with three different time delays.

  18. Focused ultrasound for treatment of uterine myoma: From experimental model to clinical practice

    Directory of Open Access Journals (Sweden)

    Terzić Milan

    2008-01-01

    Full Text Available It is well known that focused ultrasound has a biologic effect on tissue. High intensity focused ultrasound (HIFU on a small target area raises the temperature of the tissue enough to denaturate proteins and cause irreversible cell damage. The tight focus of the ultrasound energy allows delivery of the intended dose to a very precise location. The resulting coagulation necrosis is relatively painless. The application of this method in the human clinical setting has required pilot studies on an animal model. Although the treatment had a high success rate, there was a significant percentage of complications, mainly attributed to the technical drawbacks of the procedure. Therefore, this method has been modified for use in humans, and the HIFU is now guided, monitored and controlled by magnetic resonance imaging (MRI. In October 2004, Food and Drug Adiministration (FDA approved MRI guided focused ultrasound treatment of uterine fibroids in humans. Since then, successful treatment of uterine myomas by HIFU has been performed in thousands of women.

  19. International consensus on use of focused ultrasound for painful bone metastases : Current status and future directions

    NARCIS (Netherlands)

    Huisman, Merel; ter Haar, Gail; Napoli, Alessandro; Hananel, Arik; Ghanouni, Pejman; Lövey, György; Nijenhuis, Robbert J; van den Bosch, Maurice A A J; Rieke, Viola; Majumdar, Sharmila; Marchetti, Luca; Pfeffer, Raphael M; Hurwitz, Mark D

    2015-01-01

    Focused ultrasound surgery (FUS), in particular magnetic resonance guided FUS (MRgFUS), is an emerging non-invasive thermal treatment modality in oncology that has recently proven to be effective for the palliation of metastatic bone pain. A consensus panel of internationally recognised experts in

  20. Bone metastasis treatment using magnetic resonance-guided high intensity focused ultrasound

    NARCIS (Netherlands)

    Yeo, Sin Yuin; Elevelt, Aaldert; Donato, Katia; van Rietbergen, Bert; ter Hoeve, Natalie D.; van Diest, Paul J.; Grüll, Holger

    2015-01-01

    Objectives: Bone pain resulting from cancer metastases reduces a patient's quality of life. Magnetic Resonance-guided High Intensity Focused Ultrasound (MR-HIFU) is a promising alternative palliative thermal treatment technique for bone metastases that has been tested in a few clinical studies. Here

  1. International consensus on use of focused ultrasound for painful bone metastases : Current status and future directions

    NARCIS (Netherlands)

    Huisman, Merel; ter Haar, Gail; Napoli, Alessandro; Hananel, Arik; Ghanouni, Pejman; Lövey, György; Nijenhuis, Robbert J; van den Bosch, Maurice A A J; Rieke, Viola; Majumdar, Sharmila; Marchetti, Luca; Pfeffer, Raphael M; Hurwitz, Mark D

    2015-01-01

    Focused ultrasound surgery (FUS), in particular magnetic resonance guided FUS (MRgFUS), is an emerging non-invasive thermal treatment modality in oncology that has recently proven to be effective for the palliation of metastatic bone pain. A consensus panel of internationally recognised experts in f

  2. International consensus on use of focused ultrasound for painful bone metastases : Current status and future directions

    NARCIS (Netherlands)

    Huisman, Merel; ter Haar, Gail; Napoli, Alessandro; Hananel, Arik; Ghanouni, Pejman; Lövey, György; Nijenhuis, Robbert J; van den Bosch, Maurice A A J|info:eu-repo/dai/nl/182981630; Rieke, Viola; Majumdar, Sharmila; Marchetti, Luca; Pfeffer, Raphael M; Hurwitz, Mark D

    2015-01-01

    Focused ultrasound surgery (FUS), in particular magnetic resonance guided FUS (MRgFUS), is an emerging non-invasive thermal treatment modality in oncology that has recently proven to be effective for the palliation of metastatic bone pain. A consensus panel of internationally recognised experts in f

  3. Analytical estimation of ultrasound properties, thermal diffusivity, and perfusion using magnetic resonance-guided focused ultrasound temperature data

    Science.gov (United States)

    Dillon, C. R.; Borasi, G.; Payne, A.

    2016-01-01

    For thermal modeling to play a significant role in treatment planning, monitoring, and control of magnetic resonance-guided focused ultrasound (MRgFUS) thermal therapies, accurate knowledge of ultrasound and thermal properties is essential. This study develops a new analytical solution for the temperature change observed in MRgFUS which can be used with experimental MR temperature data to provide estimates of the ultrasound initial heating rate, Gaussian beam variance, tissue thermal diffusivity, and Pennes perfusion parameter. Simulations demonstrate that this technique provides accurate and robust property estimates that are independent of the beam size, thermal diffusivity, and perfusion levels in the presence of realistic MR noise. The technique is also demonstrated in vivo using MRgFUS heating data in rabbit back muscle. Errors in property estimates are kept less than 5% by applying a third order Taylor series approximation of the perfusion term and ensuring the ratio of the fitting time (the duration of experimental data utilized for optimization) to the perfusion time constant remains less than one.

  4. Ultrasonic transducer

    Science.gov (United States)

    Taylor, Steven C.; Kraft, Nancy C.

    2007-03-13

    An ultrasonic transducer having an effective center frequency of about 42 MHz; a bandwidth of greater than 85% at 6 dB; a spherical focus of at least 0.5 inches in water; an F4 lens; a resolution sufficient to be able to detect and separate a 0.005 inch flat-bottomed hole at 0.005 inches below surface; and a beam size of approximately 0.006–0.008 inches measured off a 11/2 mm ball in water at the transducer's focal point.

  5. Numerical study of a simple transcranial focused ultrasound system applied to blood-brain barrier opening.

    Science.gov (United States)

    Deffieux, Thomas; Konofagou, Elisa E

    2010-12-01

    In this paper, we investigate the focalization properties of single-element transducers at low frequencies (300 to 1000 kHz) through primate and human skulls. The study addresses the transcranial targeting involved in ultrasound- induced blood-brain barrier (BBB) opening with clinically relevant targets such as the hippocampus and the basal ganglia, which are typically affected by early Alzheimer's and Parkinson's disease, respectively. A finite-difference, timedomain simulation platform is used to solve the 3-D linear acoustic wave equation with CT-based acoustic maps of the skulls. The targeted brain structures were extracted from 3-D brain atlases registered with the skulls and used to virtually position and orient the transducers. The effect of frequency is first investigated and the targeting of the different structures is then tested. The frequency of 500 kHz provided the best tradeoff between phase aberrations and standing wave effects in the human case, whereas the frequency of 800 kHz was most suitable in the case of the primate skull. A fast periodic linear chirp method was developed and found capable of reducing the standing wave effects. Such a simple, affordable, and convenient system is concluded to be feasible for BBB opening in primates and humans and could thus allow for its broader impact and applications.

  6. Enhancement of antitumor vaccine in ablated hepatocellular carcinoma by high-intensity focused ultrasound

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    AIM:To investigate whether tumor debris created by high-intensity focused ultrasound(HIFU)could trigger antitumor immunity in a mouse hepatocellular carcinoma model. METHODS:Twenty C57BL/6J mice bearing H22 hepatocellular carcinoma were used to generate antitumor vaccines.Ten mice underwent HIFU ablation,and the remaining 10 mice received a sham-HIFU procedure with no ultrasound irradiation.Sixty normal mice were randomly divided into HIFU vaccine,tumor vaccine and control groups.These mice were immunized w...

  7. Method and system to synchronize acoustic therapy with ultrasound imaging

    Science.gov (United States)

    Owen, Neil (Inventor); Bailey, Michael R. (Inventor); Hossack, James (Inventor)

    2009-01-01

    Interference in ultrasound imaging when used in connection with high intensity focused ultrasound (HIFU) is avoided by employing a synchronization signal to control the HIFU signal. Unless the timing of the HIFU transducer is controlled, its output will substantially overwhelm the signal produced by ultrasound imaging system and obscure the image it produces. The synchronization signal employed to control the HIFU transducer is obtained without requiring modification of the ultrasound imaging system. Signals corresponding to scattered ultrasound imaging waves are collected using either the HIFU transducer or a dedicated receiver. A synchronization processor manipulates the scattered ultrasound imaging signals to achieve the synchronization signal, which is then used to control the HIFU bursts so as to substantially reduce or eliminate HIFU interference in the ultrasound image. The synchronization processor can alternatively be implemented using a computing device or an application-specific circuit.

  8. Microelectronics mounted on a piezoelectric transducer: method, simulations, and measurements.

    Science.gov (United States)

    Johansson, Jonny; Delsing, Jerker

    2006-01-01

    This paper describes the design of a highly integrated ultrasound sensor where the piezoelectric ceramic transducer is used as the carrier for the driver electronics. Intended as one part in a complete portable, battery operated ultrasound sensor system, focus has been to achieve small size and low power consumption. An optimized ASIC driver stage is mounted directly on the piezoelectric transducer and connected using wire bond technology. The absence of wiring between driver and transducer provides excellent pulse control possibilities and eliminates the need for broad band matching networks. Estimates of the sensor power consumption are made based on the capacitive behavior of the piezoelectric transducer. System behavior and power consumption are simulated using SPICE models of the ultrasound transducer together with transistor level modelling of the driver stage. Measurements and simulations are presented of system power consumption and echo energy in a pulse echo setup. It is shown that the power consumption varies with the excitation pulse width, which also affects the received ultrasound energy in a pulse echo setup. The measured power consumption for a 16 mm diameter 4.4 MHz piezoelectric transducer varies between 95 microW and 130 microW at a repetition frequency of 1 kHz. As a lower repetition frequency gives a linearly lower power consumption, very long battery operating times can be achieved. The measured results come very close to simulations as well as estimated ideal minimum power consumption.

  9. Estimation of blood velocity vectors using transverse ultrasound beam focusing and cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Lacasa, Isabel Rodriguez

    1999-01-01

    Modern ultrasound scanners estimate the blood velocity by tracking the movement of the blood scatterers along the ultrasound beam. This is done by emitting pulsed ultrasound fields and finding the shift in position from pulse to pulse by correlating the received signals. Only the velocity component...... along the beam direction is found, and this is a serious limitation in the current scanners, since most blood vessels are parallel to the skin surface. A method to find the velocity across the vessel has been suggested by Bonnefous (1988). Here a number of parallel receive beams are measured and used...... or across it or in any direction to the beam. The focused lines, thus, follow the flow and a cross-correlation of lines from different pulses can find the movement of the blood particles between pulse emissions and, thus, the blood velocity. The new approach is investigated using the Field II simulation...

  10. Physician-performed Focused Ultrasound: An Update on Its Role and Performance

    Directory of Open Access Journals (Sweden)

    Sornsupha Limchareon

    2015-06-01

    Full Text Available There is an increase in the use of focused ultrasound (US by physicians because it offers the major benefit of reduction in time to diagnosis. Some of these physicians have received formal training on focused US, others have not received any such training. However, among the formal training given on focused US, there is inconsistency across the teaching protocols. This review presents performances of focused US commonly performed by physicians, compared with radiology US. The various teaching protocols are also discussed.

  11. Elucidation of the role of biological factors and device design in cerebral NIRS using an in vivo hematoma model based on high-intensity focused ultrasound

    Science.gov (United States)

    Wang, Jianting; Huang, Stanley; Myers, Matthew; Chen, Yu; Welle, Cristin; Pfefer, Joshua

    2016-03-01

    Near-Infrared Spectroscopy (NIRS) is an emerging medical countermeasure for rapid, field detection of hematomas caused by traumatic brain injury (TBI). Bench and animal tests to determine NIRS sensitivity and specificity are needed. However, current animal models involving non-invasively induced, localized neural damage are limited. We investigated an in vivo murine hematoma model in which cerebral hemorrhage was induced noninvasively by high-intensity focused ultrasound (HIFU) with calibrated positioning and parameters. To characterize the morphology of induced hematomas, we used skull-intact histological evaluation. A multi-wavelength fiber-optic NIRS system with three source-detector separation distances was used to detect hematoma A 1.1 MHz transducer produced consistent small-to-medium hematoma localized to a single hemisphere, along with bruising of the scalp, with a low mortality rate. A 220 kHz transducer produced larger, more diffuse hematomas, with higher variability in size and a correspondingly higher mortality rate. No skin bruising or blood accumulation between the skin and skull was observed following injury application with the 220 kHz transducer. Histological analysis showed higher sensitivity for larger hematomas (>4x4 mm2). NIRS optical density change after HIFU was able to detect all hematomas, with sensitivity dependent on wavelength and separation distance. While improvements in methods for validating cerebral blood distribution are needed, the HIFU hematoma model provided useful insights that will inform development of biologically relevant, performance test methods for cerebral NIRS systems.

  12. Computational exploration of wave propagation and heating from transcranial focused ultrasound for neuromodulation

    Science.gov (United States)

    Mueller, Jerel K.; Ai, Leo; Bansal, Priya; Legon, Wynn

    2016-10-01

    Objective. While ultrasound is largely established for use in diagnostic imaging, its application for neuromodulation is relatively new and crudely understood. The objective of the present study was to investigate the effects of tissue properties and geometry on the wave propagation and heating in the context of transcranial neuromodulation. Approach. A computational model of transcranial-focused ultrasound was constructed and validated against empirical data. The models were then incrementally extended to investigate a number of issues related to the use of ultrasound for neuromodulation, including the effect on wave propagation of variations in geometry of skull and gyral anatomy as well as the effect of multiple tissue and media layers, including scalp, skull, CSF, and gray/white matter. In addition, a sensitivity analysis was run to characterize the influence of acoustic properties of intracranial tissues. Finally, the heating associated with ultrasonic stimulation waveforms designed for neuromodulation was modeled. Main results. The wave propagation of a transcranially focused ultrasound beam is significantly influenced by the cranial domain. The half maximum acoustic beam intensity profiles are insensitive overall to small changes in material properties, though the inclusion of sulci in models results in greater peak intensity values compared to a model without sulci (1%-30% greater). Finally, heating using currently employed stimulation parameters in humans is highest in bone (0.16 °C) and is negligible in brain (4.27 × 10-3 °C) for a 0.5 s exposure. Significance. Ultrasound for noninvasive neuromodulation holds great promise and appeal for its non-invasiveness, high spatial resolution and deep focal lengths. Here we show gross brain anatomy and biological material properties to have limited effect on ultrasound wave propagation and to result in safe heating levels in the skull and brain.

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

    Science.gov (United States)

    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.

  14. Ultrasound

    Science.gov (United States)

    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 ...

  15. Review on triggered liposomal drug delivery with a focus on ultrasound.

    Science.gov (United States)

    Moussa, Hesham G; Martins, Ana M; Husseini, Ghaleb A

    2015-01-01

    Chemotherapy is widely used for cancer treatment; however, it causes unwanted side effects in patients. To avoid these adverse effects, nanocarriers have been developed, which can be loaded with the chemotherapeutic agents, directed to the cancer site and, once there, are exposed to stimuli that will trigger the drug release. Liposomes can be chemically modified to increase their circulation time, their stability, and their sensitivity to specific stimulus. Additionally, ligands can be conjugated to their surface, allowing for their specific binding to receptors overexpressed on the surface of cancer cells and the subsequent internalization via endocytosis. Using a triggering mechanism, including temperature, ultrasound, enzymes or a change in pH, the release of the drug is controlled and induced inside the cells, hence avoiding drug release in systemic circulation, which in turn reduces the undesired side effects of conventional chemotherapy. Ultrasound has been widely studied as a drug release trigger from liposomes, due to its well-known physics and previous uses in medicine. This review focuses on liposome-based drug delivery systems, using different trigger mechanisms, with a focus on ultrasound. The physical mechanisms of ultrasound release are also investigated and the results of in vitro and in vivo studies are summarized.

  16. Simulation study of the effects of near- and far-field heating during focused ultrasound uterine fibroid ablation using an electronically focused phased array: A theoretical analysis of patient safety

    Energy Technology Data Exchange (ETDEWEB)

    Ellens, Nicholas, E-mail: nicholas.ellens@utoronto.ca; Hynynen, Kullervo [Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada)

    2014-07-15

    Purpose: Assess the feasibility of using large-aperture, flat ultrasonic transducer arrays with 6500 small elements operating at 500 kHz without the use of any mechanical components for the thermal coagulation of uterine fibroids. This study examines the benefits and detriments of using a frequency that is significantly lower than that used in clinical systems (1–1.5 MHz). Methods: Ultrasound simulations were performed using the anatomies of five fibroid patients derived from 3D MRI. Using electronic steering solely, the ultrasound focus from a flat, 6500-element phased array was translated around the volume of the fibroids in various patterns to assess the feasibility of completing full treatments from fixed physical locations. Successive temperature maps were generated by numerically solving the bioheat equation. Using a thermal dose model, the bioeffects of these simulations were quantified and analyzed. Results: The simulations indicate that such an array could be used to perform fibroid treatments to 18 EM{sub 43} at an average rate of 90 ± 20 cm{sup 3}/h without physically moving the transducer array. On average, the maximum near-field thermal dose for each patient was below 4 EM{sub 43}. Fibroid tissue could be treated as close as 40 mm to the spine without reaching temperatures expected to cause pain or damage. Conclusions: Fibroids were successfully targeted and treated from a single transducer position to acceptable extents and without causing damage in the near- or far-field. Compared to clinical systems, treatment rates were good. The proposed treatment paradigm is a promising alternative to existing systems and warrants further investigation.

  17. Imaging of implant needles for real-time HDR-brachytherapy prostate treatment using biplane ultrasound transducers.

    Science.gov (United States)

    Siebert, Frank-André; Hirt, Markus; Niehoff, Peter; Kovács, György

    2009-08-01

    Ultrasound imaging is becoming increasingly important in prostate brachytherapy. In high-dose-rate (HDR) real-time planning procedures the definition of the implant needles is often performed by transrectal ultrasound. This article describes absolute measurements of the visibility and accuracy of manual detection of implant needle tips and compares measurement results of different biplane ultrasound systems in transversal and longitudinal (i.e., sagittal) ultrasound modes. To obtain a fixed coordinate system and stable conditions the measurements were carried out in a water tank using a dedicated marker system. Needles were manually placed in the phantom until the observer decided by the real-time ultrasound image that the zero position was reached. A comparison of three different ultrasound systems yielded an offset between 0.8 and 3.1 mm for manual detection of the needle tip in ultrasound images by one observer. The direction of the offset was discovered to be in the proximal direction, i.e., the actual needle position was located more distally compared to the ultrasound-based definition. In the second part of the study, the ultrasound anisotropy of trocar implant needles is reported. It was shown that the integrated optical density in a region of interest around the needle tip changes with needle rotation. Three peaks were observed with a phase angle of 120 degrees. Peaks appear not only in transversal but also in longitudinal ultrasound images, with a phase shift of 60 degrees. The third section of this study shows results of observer dependent influences on needle tip detection in sagittal ultrasound images considering needle rotation. These experiments were carried out using the marker system in a water tank. The needle tip was placed exactly at the position z=0 mm. It was found that different users tend to differently interpret the same ultrasound images. The needle tip was manually detected five times in the ultrasound images by three experienced observers

  18. Localization of focused-ultrasound beams in a tissue phantom, using remote thermocouple arrays.

    Science.gov (United States)

    Hariharan, Prasanna; Dibaji, Seyed Ahmad Reza; Banerjee, Rupak K; Nagaraja, Srinidhi; Myers, Matthew R

    2014-12-01

    In focused-ultrasound procedures such as vessel cauterization or clot lysis, targeting accuracy is critical. To investigate the targeting accuracy of the focused-ultrasound systems, tissue phantoms embedded with thermocouples can be employed. This paper describes a method that utilizes an array of thermocouples to localize the focused ultrasound beam. All of the thermocouples are located away from the beam, so that thermocouple artifacts and sensor interference are minimized. Beam propagation and temperature rise in the phantom are simulated numerically, and an optimization routine calculates the beam location that produces the best agreement between the numerical temperature values and those measured with thermocouples. The accuracy of the method was examined as a function of the array characteristics, including the number of thermocouples in the array and their orientation. For exposures with a 3.3-MHz source, the remote-thermocouple technique was able to predict the focal position to within 0.06 mm. Once the focal location is determined using the localization method, temperatures at desired locations (including the focus) can be estimated from remote thermocouple measurements by curve fitting an analytical solution to the heat equation. Temperature increases in the focal plane were predicted to within 5% agreement with measured values using this method.

  19. Frequency dependence of backscatter from thin, oblique, finite-length cylinders measured with a focused transducer-with applications in cancellous bone.

    Science.gov (United States)

    Wear, Keith A; Harris, Gerald R

    2008-11-01

    A model is presented for the echo from a thin, oblique, finite-length cylinder. The echo is calculated from the line integral of the transducer directivity pattern along the cylinder axis. The model was validated with broadband pulse-echo measurements from (1) a perpendicular (to the ultrasound beam) nylon wire as a function of lateral displacement from the beam center, (2) a tilted nylon wire as a function of the angle of inclination relative to the ultrasound beam, and (3) a quasi-parallel-nylon-wire phantom, which mimicked the scattering properties of cancellous bone. The transducer directivity pattern (as a function of position and frequency) was measured with a membrane hydrophone. The model predicts an approximately cubic frequency dependence of backscatter coefficient from the phantom, as has been observed experimentally in cancellous bone. The model also predicts the relationship between the cylinder length and the exponent of a power law fit to backscatter coefficient versus frequency, which is 4 for very short (compared to a wavelength) cylinders and asymptotically approaches 3 for very long cylinders.

  20. Portable high-intensity focused ultrasound system with 3D electronic steering, real-time cavitation monitoring, and 3D image reconstruction algorithms: a preclinical study in pigs

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin Woo; Lee, Jae Young; Hwang, Eui Jin; Hwang, In Pyeong; Woo, Sung Min; Lee, Chang Joo; Park, Eun Joo; Choi, Byung Ihn [Dept. of Radiology and Institute of Radiation Medicine, Seoul National University Hospital, Seoul (Korea, Republic of)

    2014-10-15

    The aim of this study was to evaluate the safety and accuracy of a new portable ultrasonography-guided high-intensity focused ultrasound (USg-HIFU) system with a 3-dimensional (3D) electronic steering transducer, a simultaneous ablation and imaging module, real-time cavitation monitoring, and 3D image reconstruction algorithms. To address the accuracy of the transducer, hydrophones in a water chamber were used to assess the generation of sonic fields. An animal study was also performed in five pigs by ablating in vivo thighs by single-point sonication (n=10) or volume sonication (n=10) and ex vivo kidneys by single-point sonication (n=10). Histological and statistical analyses were performed. In the hydrophone study, peak voltages were detected within 1.0 mm from the targets on the y- and z-axes and within 2.0-mm intervals along the x-axis (z-axis, direction of ultrasound propagation; y- and x-axes, perpendicular to the direction of ultrasound propagation). Twenty-nine of 30 HIFU sessions successfully created ablations at the target. The in vivo porcine thigh study showed only a small discrepancy (width, 0.5-1.1 mm; length, 3.0 mm) between the planning ultrasonograms and the pathological specimens. Inordinate thermal damage was not observed in the adjacent tissues or sonic pathways in the in vivo thigh and ex vivo kidney studies. Our study suggests that this new USg-HIFU system may be a safe and accurate technique for ablating soft tissues and encapsulated organs.

  1. Laser-enhanced thermal effect of moderate intensity focused ultrasound on bio-tissues

    Science.gov (United States)

    Zhao, JinYu; Zhang, ShuYi; Shui, XiuJi; Fan, Li

    2017-09-01

    For avoiding extra-damage to healthy tissues surrounding the focal point during high intensity focused ultrasound (HIFU) treatment in medical therapy, to reduce the ultrasonic intensity outside the focal point is expected. Thus, the heating processes induced by moderate intensity focused ultrasound (MIFU) and enhanced by combined irradiation of laser pulses for bio-tissues are studied in details. For fresh bio-tissues, the enhanced thermal effects by pulsed laser combined with MIFU irradiation are observed experimentally. To explore the mechanisms of these effects, several tissue-mimicking materials composed of agar mixed with graphite powders are prepared and studied for comparison, but the laser-enhanced thermal effects in these mimicking materials are much less than that in the fresh bio-tissues. Therefore, it is suggested that the laser-enhanced thermal effects may be mainly attributed to bio-activities and related photo-bio-chemical effects of fresh tissues.

  2. Driving Circuitry for Focused Ultrasound Noninvasive Surgery and Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Kullervo Hynynen

    2011-01-01

    Full Text Available Recent works on focused ultrasound (FUS have shown great promise for cancer therapy. Researchers are continuously trying to improve system performance, which is resulting in an increased complexity that is more apparent when using multi-element phased array systems. This has led to significant efforts to reduce system size and cost by relying on system integration. Although ideas from other fields such as microwave antenna phased arrays can be adopted in FUS, the application requirements differ significantly since the frequency range used in FUS is much lower. In this paper, we review recent efforts to design efficient power monitoring, phase shifting and output driving techniques used specifically for high intensity focused ultrasound (HIFU.

  3. Current status of high-intensity focused ultrasound for the management of uterine adenomyosis

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Vincent Y. T. [Dept. of Obstetrics and Gynaecology, Queen Mary Hospital, The University of Hong Kong, Hong Kong (China)

    2017-04-15

    While high-intensity focused ultrasound has been used for some time in the management of uterine fibroids, its effectiveness and safety in managing adenomyosis is less well established. A literature review was performed of all eligible reports using this modality as a treatment for adenomyosis. Relevant publications were obtained from the PubMed electronic database from inception through March 2016. Eleven articles, including information from 1,150 treatments and follow-up data from 990 patients, were reviewed. High-intensity focused ultrasound appears to be effective and safe in the management of symptomatic adenomyosis, and can be considered as an alternative uterine-sparing option for women with this condition.

  4. Outcome of unintended pregnancy after ultrasound-guided high-intensity focused ultrasound ablation of uterine fibroids.

    Science.gov (United States)

    Qin, Juan; Chen, Jin-Yun; Zhao, Wen-Peng; Hu, Liang; Chen, Wen-Zhi; Wang, Zhi-Biao

    2012-06-01

    To evaluate the safety of ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation of uterine fibroids among women with unintentional pregnancy within 1 year of therapy. A retrospective analysis was conducted of 435 women who underwent USgHIFU therapy at Chongqing Medical University, China, between October 1, 2006, and October 1, 2009. Unplanned pregnancy was reported by 24 women within 1 year of USgHIFU ablation; 8 of these women had desired pregnancy before undergoing treatment. A total of 27 fibroids were detected, 24 of which were treated (mean volume 65.9±58.8 cm(3)). Pregnancy was continued by 7 women without any complications. One pregnant woman who had desired pregnancy before therapy underwent an induced abortion owing to concerns about the effects of USgHIFU on the fetus. Fourteen women without pregnancy intention before USgHIFU therapy chose to undergo induced abortion; 2 women experienced spontaneous abortion. No adhesion occurred after USgHIFU therapy. Furthermore, USgHIFU, labor, and abortion had no effect on subsequent menstruation or sexual activities. Pregnancy within 1 year after USgHIFU ablation of uterine fibroids appears safe; however, large scale studies are required to confirm these data. Copyright © 2012 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  5. Displacement analysis of diagnostic ultrasound backscatter: a methodology for characterizing, modeling, and monitoring high intensity focused ultrasound therapy.

    Science.gov (United States)

    Speyer, Gavriel; Kaczkowski, Peter J; Brayman, Andrew A; Crum, Lawrence A

    2010-07-01

    Accurate monitoring of high intensity focused ultrasound (HIFU) therapy is critical for widespread clinical use. Pulse-echo diagnostic ultrasound (DU) is known to exhibit temperature sensitivity through relative changes in time-of-flight between two sets of radio frequency (RF) backscatter measurements, one acquired before and one after therapy. These relative displacements, combined with knowledge of the exposure protocol, material properties, heat transfer, and measurement noise statistics, provide a natural framework for estimating the administered heating, and thereby therapy. The proposed method, termed displacement analysis, identifies the relative displacements using linearly independent displacement patterns, or modes, each induced by a particular time-varying heating applied during the exposure interval. These heating modes are themselves linearly independent. This relationship implies that a linear combination of displacement modes aligning the DU measurements is the response to an identical linear combination of heating modes, providing the heating estimate. Furthermore, the accuracy of coefficient estimates in this approximation is determined a priori, characterizing heating, thermal dose, and temperature estimates for any given protocol. Predicted performance is validated using simulations and experiments in alginate gel phantoms. Evidence for a spatially distributed interaction between temperature and time-of-flight changes is presented.

  6. General Ultrasound Imaging

    Medline Plus

    Full Text Available ... of page How is the procedure performed? For most ultrasound exams, you will be positioned lying face- ... Ultrasound examinations are painless and easily tolerated by most patients. Ultrasound exams in which the transducer is ...

  7. General Ultrasound Imaging

    Medline Plus

    Full Text Available ... data into 3-D images. A Doppler ultrasound study may be part of an ultrasound examination. Doppler ... usually stain or discolor clothing. In some ultrasound studies, the transducer is attached to a probe and ...

  8. General Ultrasound Imaging

    Medline Plus

    Full Text Available ... ultrasound. top of page How does the procedure work? Ultrasound imaging is based on the same principles ... not stain or discolor clothing. In some ultrasound studies, the transducer is attached to a probe and ...

  9. High-intensity focused ultrasound to treat primary hyperparathyroidism: a feasibility study in four patients

    DEFF Research Database (Denmark)

    Kovatcheva, Roussanka D; Vlahov, Jordan D; Shinkov, Alexander D;

    2010-01-01

    Many patients with primary hyperparathyroidism either decline or are not candidates for surgical parathyroidectomy. There are drawbacks to medical therapy as well as percutaneous ethanol injection as alternative therapies for primary hyperparathyroidism. Therefore, in this pilot study, our aim...... was to test the feasibility, safety, and efficacy of a newly developed noninvasive high-intensity focused ultrasound (HIFU) technique for the nonsurgical management of primary hyperparathyroidism....

  10. A Rectourethral Fistula due to Transrectal High-Intensity Focused Ultrasound Treatment: Diagnosis and Management

    OpenAIRE

    2012-01-01

    Colovesical fistula (CVF) is an abnormal connection between the enteric and the urinary systems. The rectourethral fistula (RUF) is a possible but extremely rare complication of treatment of prostate cancer with “transrectal High-Intensity Focused Ultrasound (HIFU) treatment.” We present a case of CVF due to HIFU treatment of recurrent prostate cancer. The case was assessed with cystography completed with a pelvic CT scan—with MPR, MIP, and VR reconstruction—before emptying the bladder. Since...

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

    OpenAIRE

    Cui, Huizhong; Zhang, Ti; Yang, Xinmai

    2013-01-01

    Laser-enhanced cavitation during high intensity focused ultrasound (HIFU) was studied in vivo using a small animal model. Laser light was employed to illuminate the sample concurrently with HIFU radiation. The resulting cavitation was detected with a passive cavitation detector. The in vivo measurements were made under different combinations of HIFU treatment depths, laser wavelengths, and HIFU durations. The results demonstrated that concurrent light illumination during HIFU has the potentia...

  12. TU-B-210-00: MR-Guided Focused Ultrasound Therapy in Oncology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-06-15

    MR guided focused ultrasound (MRgFUS), or alternatively high-intensity focused ultrasound (MRgHIFU), is approved for thermal ablative treatment of uterine fibroids and pain palliation in bone metastases. Ablation of malignant tumors is under active investigation in sites such as breast, prostate, brain, liver, kidney, pancreas, and soft tissue. Hyperthermia therapy with MRgFUS is also feasible, and may be used in conjunction with radiotherapy and for local targeted drug delivery. MRI allows in situ target definition and provides continuous temperature monitoring and subsequent thermal dose mapping during HIFU. Although MRgHIFU can be very precise, treatment of mobile organs is challenging and advanced techniques are required because of artifacts in MR temperature mapping, the need for intercostal firing, and need for gated HIFU or tracking of the lesion in real time. The first invited talk, “MR guided Focused Ultrasound Treatment of Tumors in Bone and Soft Tissue”, will summarize the treatment protocol and review results from treatment of bone tumors. In addition, efforts to extend this technology to treat both benign and malignant soft tissue tumors of the extremities will be presented. The second invited talk, “MRI guided High Intensity Focused Ultrasound – Advanced Approaches for Ablation and Hyperthermia”, will provide an overview of techniques that are in or near clinical trials for thermal ablation and hyperthermia, with an emphasis of applications in abdominal organs and breast, including methods for MRTI and tracking targets in moving organs. Learning Objectives: Learn background on devices and techniques for MR guided HIFU for cancer therapy Understand issues and current status of clinical MRg HIFU Understand strategies for compensating for organ movement during MRgHIFU Understand strategies for strategies for delivering hyperthermia with MRgHIFU CM - research collaboration with Philips.

  13. Osteoid osteoma: MR-guided focused ultrasound for entirely noninvasive treatment.

    Science.gov (United States)

    Napoli, Alessandro; Mastantuono, Marco; Cavallo Marincola, Beatrice; Anzidei, Michele; Zaccagna, Fulvio; Moreschini, Oreste; Passariello, Roberto; Catalano, Carlo

    2013-05-01

    To determine the preliminary feasibility, safety, and clinical efficacy of magnetic resonance (MR)-guided focused ultrasound for the treatment of painful osteoid osteoma. This prospective institutional review board-approved study involved six consecutive patients (five males and one female; mean age, 21 years) with a diagnosis of osteoid osteoma based on clinical and imaging findings. All patients underwent MR-guided focused ultrasound ablation after providing informed consent. Lesions located in the vertebral body were excluded. The number of sonications and the energy deposition were recorded. Treatment success was determined at 1, 3, and 6 months after treatment. A visual analog scale (VAS) score for pain was used to assess changes in symptoms. MR imaging features of osteoid osteoma (edema, hyperemia, and nidus vascularization) were considered at baseline and at imaging follow-up. Treatment was performed with a mean of 4 sonications ± 1.8 (standard deviation), with a mean energy deposition of 866 J ± 211. No treatment- or anesthesia-related complications occurred. The pre- and posttreatment mean VAS scores significantly differed (7.9 ± 1.4 and 0.0 ± 0.0, respectively). At imaging, the edema and hyperemia associated with osteoid osteoma gradually disappeared in all lesions. However, nidus vascularization still persisted after treatment in four of six patients. This limited series demonstrated that MR-guided focused ultrasound treatment of osteoid osteoma can be performed safely with a high rate of success and without apparent treatment-related morbidity.

  14. [Effects of high intensity focused ultrasound with SonoVue on blood vessels pathological examinations].

    Science.gov (United States)

    Qin, Yan; Bai, Jin; Li, Faqi; Wang, Zhibiao

    2010-12-01

    The injury of tumor blood vessels will break up the nutrition supply for the tumor. In this paper, we investigated the effects exerted by high intensity focused ultrasound (HIFU) combined with ultrasound microbubble agent on blood vessels. Ultrasound diagnosis was used to find the goat hepatic blood vessels each being approximately 3mm in diameter. HIFU was focused on the blood vessels. The acoustic power was 250W; HIFU irradiating Mode was line scan (the length of the line: 10 mm; speed: 3 mm/s; irradiating time: 30s). In the experimental group, 0.03 ml/kg SonoVue was injected into the goat before HIFU irradiation,while normal saline was given to the control group. The goats were killed at 24h after HIFU irradiation, then goat liver tissues and blood vessels of target area were taken out. HE staining and Victoria's blue and Ponceau's staining of tissue section showed that the endothelial cells of blood vessels dropped off and became necrosed, and the continuity of blood vessels was interrupted. HIFU combined with SonoVue will damage large blood vessels on HIFU focus, but there is no evident discrepancy between the group with SonoVue and the group without SonoVue.

  15. Measurement of temperature decrease caused by blood flow in focused ultrasound irradiation by thermal imaging method

    Science.gov (United States)

    Tsuchiya, Takenobu; Hatano, Yuichi; Mori, Yashunori; Shen, Rakushin; Endoh, Nobuyuki

    2016-07-01

    In this study, to estimate the local temperature changes caused by a thick blood vessel, the temperature distribution in a tissue phantom with a thick blood vessel during focused ultrasound irradiation was measured by a thermal imaging method. The blood flow rate in the simulated blood vessel was varied and the relationship between flow rate and temperature decrease was examined. The phantom using the thermal imaging method is divided into two parts, and the increases in temperature distribution as a function of blood flow rate are measured using a thermocamera under constant ultrasound irradiation. The irradiation conditions of ultrasound waves were a central frequency of 1 MHz, a wave number length of 200 cycles, and a duty ratio of 0.2. The irradiation duration was 5 min, and the ultrasound intensity I SPTA was 36 W/cm2. The amount of temperature decrease caused by the cooling effect of blood flow increased with the blood flow rate and it became constant at a certain threshold of blood flow rate. The threshold of blood flow rate is about 250 ml/min.

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

    Science.gov (United States)

    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.

  17. 3-D Ultrasound Imaging Performance of a Row-Column Addressed 2-D Array Transducer: A Measurement Study

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2013-01-01

    A real-time 3-D ultrasound measurement using only 32 elements and 32 emissions is presented. The imaging quality is compared to a conventionally fully addressed array using 1024 elements and 256 emissions. The main-lobe of the measured line spread function is almost identical, but the side-lobe l...... ultrasound probe made by Vermon S.A....... is 510% larger than when row-column addressing the array. The cyst radius needed to achieve -20 dB intensity in the cyst is 396% larger for the fully addressed array compared to the row-column addressed array. The measurements were made using the experimental ultrasound scanner SARUS and a 32x32 element...

  18. Magnetic resonance image-guided versus ultrasound-guided high-intensity focused ultrasound in the treatment of breast cancer

    Institute of Scientific and Technical Information of China (English)

    Sheng Li; Pei-Hong Wu

    2013-01-01

    Image-guided high-intensity focused ultrasound (HIFU) has been used for more than ten years,primarily in the treatment of liver and prostate cancers.HIFU has the advantages of precise cancer ablation and excellent protection of healthy tissue.Breast cancer is a common cancer in women.HIFU therapy,in combination with other therapies,has the potential to improve both oncologic and cosmetic outcomes for breast cancer patients by providing a curative therapy that conserves mammary shape.Currently,HIFU therapy is not commonly used in breast cancer treatment,and efforts to promote the application of HIFU is expected.In this article,we compare different image-guided models for HIFU and reviewed the status,drawbacks,and potential of HIFU therapy for breast cancer.

  19. Piezoelectric Composite Micromachined Multifrequency Transducers for High-Resolution, High-Contrast Ultrasound Imaging for Improved Prostate Cancer Assessment

    Science.gov (United States)

    2014-08-01

    Industries Inc., Rochester, NY). The hydrophone was moved laterally and axially and the measured pressure values were processed to obtain the pressure...transmission condition was same as pressure mapping condition (2 MHz, cycles, 300 mVpp, and 55dB gain). The cellulose tube was filled with water, air, and...bubbles & water) Outlet Function generator Power amplifier Computer/LabVIEW Transducer Cellulose tubeWater tank z y x Figure 18. Bubble signal

  20. Determination of tissue thermal conductivity by measuring and modeling temperature rise induced in tissue by pulsed focused ultrasound.

    Directory of Open Access Journals (Sweden)

    Tamara Kujawska

    Full Text Available A tissue thermal conductivity (Ks is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of temperature-time T(t rises induced in a tested tissue sample by a pulsed focused ultrasound with measured acoustic properties using thermocouples located on the acoustic beam axis. Measurements were performed for 20-cycle tone bursts with a 2 MHz frequency, 0.2 duty-cycle and 3 different initial pressures corresponding to average acoustic powers equal to 0.7 W, 1.4 W and 2.1 W generated from a circular focused transducer with a diameter of 15 mm and f-number of 1.7 in a two-layer system of media: water/beef liver. Measurement results allowed to determine position of maximum heating located inside the beef liver. It was found that this position is at the same axial distance from the source as the maximum peak-peak pressure calculated for each nonlinear beam produced in the two-layer system of media. Then, the method involves modeling of T(t at the point of maximum heating and fitting it to the experimental data by adjusting Ks. The averaged value of Ks determined by the proposed method was found to be 0.5±0.02 W/(m·°C being in good agreement with values determined by other methods. The proposed method is suitable for determining Ks of some animal tissues in vivo (for example a rat liver.

  1. An intelligent nanotheranostic agent for targeting, redox-responsive ultrasound imaging, and imaging-guided high-intensity focused ultrasound synergistic therapy.

    Science.gov (United States)

    Wang, Xia; Chen, Hangrong; Zhang, Kun; Ma, Ming; Li, Faqi; Zeng, Deping; Zheng, Shuguang; Chen, Yu; Jiang, Lixin; Xu, Huixiong; Shi, Jianlin

    2014-04-09

    A novel multifunctional nanotheranostic agent with targeting, redox-responsive ultrasound imaging and ultrasound imaging-guided high-intensity focused ultrasound (HIFU) therapy (MSNC-PEG-HA(SS)-PFH, abbreviated as MPH(SS)-PFH) capabilities is developed. The redox-responsive guest molecule release and ultrasound imaging functions can be both integrated in such a "smart" theranostic agent, which is accomplished by the redox-triggered transition from the crosslinking state to retrocrosslinking state of the grafted polyethylene glycol-disulfide hyaluronic acid molecules on the particle surface when reaching a reducing environment in vitro. More importantly, under the tailored ultrasound imaging guiding, in vivo Hela tumor-bearing nude mice can be thoroughly and spatial-accurately ablated during HIFU therapy, due to the targeted accumulation, responsive ultrasound imaging guidance and the synergistic ablation functions of nanotheranostic agent MPH(SS)-PFH in the tumors. This novel multifunctional nano-platform can serve as a promising candidate for further studies on oncology therapy, due to its high stability, responsive and indicative ultrasound imaging of tumors, and enhanced HIFU therapeutic efficiency and spatial accuracy under ultrasound-guidance.

  2. Focused ultrasound treatment of abscesses induced by methicillin resistant Staphylococcus aureus: Feasibility study in a mouse model

    Energy Technology Data Exchange (ETDEWEB)

    Rieck, Birgit [Thunder Bay Regional Research Institute, Thunder Bay, Ontario P7B6V4 (Canada); Bates, David; Pichardo, Samuel, E-mail: spichard@lakeheadu.ca, E-mail: lcuriel@lakeheadu.ca; Curiel, Laura, E-mail: spichard@lakeheadu.ca, E-mail: lcuriel@lakeheadu.ca [Thunder Bay Regional Research Institute, Thunder Bay, Ontario P7B6V4, Canada and Lakehead University, Thunder Bay, Ontario P7B6V4 (Canada); Zhang, Kunyan [Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Escott, Nicholas [Department of Pathology, Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario P7B 6V4 (Canada); Mougenot, Charles [Philips Healthcare, Ontario L6C 2S3 (Canada)

    2014-06-15

    Purpose: To study the therapeutic effect of focused ultrasound on abscesses induced by methicillin-resistantStaphylococcus aureus (MRSA). MRSA is a major nosocomial pathogen where immunocompromised patients are prone to develop infections that are less and less responsive to regular treatments. Because of its capability to induce a rise of temperature at a very precise location, the use of focused ultrasound represents a considerable opportunity for therapy of localized MRSA-related infections. Methods: 50μl of MRSA strain USA400 bacteria suspension at a concentration of 1.32 ± 0.5 × 10{sup 5} colony forming units (cfu)/μl was injected subcutaneously in the left flank of BALB/c mice. An abscess of 6 ± 2 mm in diameter formed after 48 h. A transducer operating at 3 MHz with a focal length of 50 mm and diameter of 32 mm was used to treat the abscess. The focal point was positioned 2 mm under the skin at the abscess center. Forty-eight hours after injection four ultrasound exposures of 9 s each were applied to each abscess under magnetic resonance imaging guidance. Each exposure was followed by a 1 min pause. These parameters were based on preliminary experiments to ensure repetitive accurate heating of the abscess. Real-time estimation of change of temperature was done using water-proton resonance frequency and a communication toolbox (matMRI) developed inhouse. Three experimental groups of animals each were tested: control, moderate temperature (MT), and high temperature (HT). MT and HT groups reached, respectively, 52.3 ± 5.1 and 63.8 ± 7.5 °C at the end of exposure. Effectiveness of the treatment was assessed by evaluating the bacteria amount of the treated abscess 1 and 4 days after treatment. Myeloperoxidase (MPO) assay evaluating the neutrophil amount was performed to assess the local neutrophil recruitment and the white blood cell count was used to evaluate the systemic inflammatory response after focused ultrasound treatment. Results: Macroscopic

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

    Science.gov (United States)

    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. Modeling and Predicting Tissue Movement and Deformation for High Intensity Focused Ultrasound Therapy

    Science.gov (United States)

    Liao, Xiangyun; Yuan, Zhiyong; Lai, Qianfeng; Guo, Jiaxiang; Zheng, Qi; Yu, Sijiao; Tong, Qianqian; Si, Weixin; Sun, Mingui

    2015-01-01

    Purpose In ultrasound-guided High Intensity Focused Ultrasound (HIFU) therapy, the target tissue (such as a tumor) often moves and/or deforms in response to an external force. This problem creates difficulties in treating patients and can lead to the destruction of normal tissue. In order to solve this problem, we present a novel method to model and predict the movement and deformation of the target tissue during ultrasound-guided HIFU therapy. Methods Our method computationally predicts the position of the target tissue under external force. This prediction allows appropriate adjustments in the focal region during the application of HIFU so that the treatment head is kept aligned with the diseased tissue through the course of therapy. To accomplish this goal, we utilize the cow tissue as the experimental target tissue to collect spatial sequences of ultrasound images using the HIFU equipment. A Geodesic Localized Chan-Vese (GLCV) model is developed to segment the target tissue images. A 3D target tissue model is built based on the segmented results. A versatile particle framework is constructed based on Smoothed Particle Hydrodynamics (SPH) to model the movement and deformation of the target tissue. Further, an iterative parameter estimation algorithm is utilized to determine the essential parameters of the versatile particle framework. Finally, the versatile particle framework with the determined parameters is used to estimate the movement and deformation of the target tissue. Results To validate our method, we compare the predicted contours with the ground truth contours. We found that the lowest, highest and average Dice Similarity Coefficient (DSC) values between predicted and ground truth contours were, respectively, 0.9615, 0.9770 and 0.9697. Conclusion Our experimental result indicates that the proposed method can effectively predict the dynamic contours of the moving and deforming tissue during ultrasound-guided HIFU therapy. PMID:25993644

  5. MRI-Guided Focused Ultrasound as a New Method of Drug Delivery

    Directory of Open Access Journals (Sweden)

    M. Thanou

    2013-01-01

    Full Text Available Ultrasound-mediated drug delivery under the guidance of an imaging modality can improve drug disposition and achieve site-specific drug delivery. The term focal drug delivery has been introduced to describe the focal targeting of drugs in tissues with the help of imaging and focused ultrasound. Focal drug delivery aims to improve the therapeutic profile of drugs by improving their specificity and their permeation in defined areas. Focused-ultrasound- (FUS- mediated drug delivery has been applied with various molecules to improve their local distribution in tissues. FUS is applied with the aid of microbubbles to enhance the permeability of bioactive molecules across BBB and improve drug distribution in the brain. Recently, FUS has been utilised in combination with MRI-labelled liposomes that respond to temperature increase. This strategy aims to “activate” nanoparticles to release their cargo locally when triggered by hyperthermia induced by FUS. MRI-guided FUS drug delivery provides the opportunity to improve drug bioavailability locally and therefore improve the therapeutic profiles of drugs. This drug delivery strategy can be directly translated to clinic as MRg FUS is a promising clinically therapeutic approach. However, more basic research is required to understand the physiological mechanism of FUS-enhanced drug delivery.

  6. Characterization of Different Microbubbles in Assisting Focused Ultrasound-Induced Blood-Brain Barrier Opening

    Science.gov (United States)

    Wu, Sheng-Kai; Chu, Po-Chun; Chai, Wen-Yen; Kang, Shih-Tsung; Tsai, Chih-Hung; Fan, Ching-Hsiang; Yeh, Chih-Kuang; Liu, Hao-Li

    2017-04-01

    Microbubbles (MBs) serve as a critical catalyst to amplify local cavitation in CNS capillary lumen to facilitate focused ultrasound (FUS) to transiently open the blood-brain barrier (BBB). However, limited understanding is available regarding the effect of different microbubbles to induce BBB opening. The aim of this study is to characterize different MBs on their effect in FUS-induced BBB opening. Three MBs, SonoVue, Definity, and USphere, were tested, with 0.4-MHz FUS exposure at 0.62-1.38 of mechanical index (MI) on rats. Evans blue, dynamic contrast-enhanced (DCE) MRI and small-animal ultrasound imaging were used as surrogates to allow molecule-penetrated quantification, BBB-opened observation, and MBs circulation/persistence. Cavitation activity was measured via the passive cavitation detection (PCD) setup to correlate with the exposure level and the histological effect. Under given and identical MB concentrations, the three MBs induced similar and equivalent BBB-opening effects and persistence. In addition, a treatment paradigm by adapting exposure time is proposed to compensate MB decay to retain the persistence of BBB-opening efficiency in multiple FUS exposures. The results potentially improve understanding of the equivalence among MBs in focused ultrasound CNS drug delivery, and provide an effective strategy for securing persistence in this treatment modality.

  7. High-intensity focused ultrasound for thyroid nodule ablation: the evidence to date

    Directory of Open Access Journals (Sweden)

    Kovatcheva RD

    2017-01-01

    Full Text Available Roussanka D Kovatcheva,1 Katja Zaletel,2 1Department of Thyroid and Metabolic Bone Disorders, Clinical Center of Endocrinology, Medical University, Sofia, Bulgaria; 2Department of Nuclear Medicine, University Medical Centre Ljubljana, Ljubljana, Slovenia Abstract: Thyroid nodules are common in occurrence and most of them are benign in nature. Some of these nodules are to be treated as they continue to grow or cause undesirable symptoms. Recently, several minimally invasive thermal ablation techniques have been introduced to overcome the complications of traditional methods such as surgery. High-intensity focused ultrasound (HIFU is the latest advance in treatment modalities, which is a noninvasive procedure that permits localized target destruction without affecting the surrounding tissues. HIFU is currently used in the treatment of various solid malignant and benign tumors. The purpose of this review is to provide an introduction to the literature, principles, and advances of HIFU therapy of benign thyroid nodules, as well as to provide a discussion on its efficacy, complications, and future. Keywords: thyroid nodule, high-intensity focused ultrasound, ultrasound guidance, ablation techniques

  8. Feasibility of vibro-acoustography with a quasi-2D ultrasound array transducer for detection and localizing of permanent prostate brachytherapy seeds: A pilot ex vivo study

    Energy Technology Data Exchange (ETDEWEB)

    Mehrmohammadi, Mohammad; Kinnick, Randall R.; Fatemi, Mostafa, E-mail: fatemi.mostafa@mayo.edu [Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota 55905 (United States); Alizad, Azra [Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota 55905 and Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905 (United States); Davis, Brian J. [Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2014-09-15

    Purpose: Effective permanent prostate brachytherapy (PPB) requires precise placement of radioactive seeds in and around the prostate. The impetus for this research is to examine a new ultrasound-based imaging modality, vibro-acoustography (VA), which may serve to provide a high rate of PPB seed detection while also effecting enhanced prostate imaging. The authors investigate the ability of VA, implemented on a clinical ultrasound (US) scanner and equipped with a quasi-2D (Q2D) array US transducer, to detect and localize PPB seeds in excised prostate specimens. Methods: Nonradioactive brachytherapy seeds were implanted into four excised cadaver prostates. A clinical US scanner equipped with a Q2D array US transducer was customized to acquire both US and C-scan VA images at various depths. The VA images were then used to detect and localize the implanted seeds in prostate tissue. To validate the VA results, computed tomography (CT) images of the same tissue samples were obtained to serve as the reference by which to evaluate the performance of VA in PPB seed detection. Results: The results indicate that VA is capable of accurately identifying the presence and distribution of PPB seeds with a high imaging contrast. Moreover, a large ratio of the PPB seeds implanted into prostate tissue samples could be detected through acquired VA images. Using CT-based seed identification as the standard, VA was capable of detecting 74%–92% of the implanted seeds. Additionally, the angular independency of VA in detecting PPB seeds was demonstrated through a well-controlled phantom experiment. Conclusions: Q2DVA detected a substantial portion of the seeds by using a 2D array US transducer in excised prostate tissue specimens. While VA has inherent advantages associated with conventional US imaging, it has the additional advantage of permitting detection of PPB seeds independent of their orientation. These results suggest the potential of VA as a method for PPB imaging that

  9. Three-dimensional electrode displacement elastography using the Siemens C7F2 fourSight four-dimensional ultrasound transducer.

    Science.gov (United States)

    Bharat, Shyam; Fisher, Ted G; Varghese, Tomy; Hall, Timothy J; Jiang, Jingfeng; Madsen, Ernest L; Zagzebski, James A; Lee, Fred T

    2008-08-01

    Because ablation therapy alters the elastic modulus of tissues, emerging strain imaging methods may enable clinicians for the first time to have readily available, cost-effective, real-time guidance to identify the location and boundaries of thermal lesions. Electrode displacement elastography is a method of strain imaging tailored specifically to ultrasound-guided electrode-based ablative therapies (e.g., radio-frequency ablation). Here tissue deformation is achieved by applying minute perturbations to the unconstrained end of the treatment electrode, resulting in localized motion around the end of the electrode embedded in tissue. In this article, we present a method for three-dimensional (3D) elastographic reconstruction from volumetric data acquired using the C7F2 fourSight four-dimensional ultrasound transducer, provided by Siemens Medical Solutions USA, Inc. (Issaquah, WA, USA). Lesion reconstruction is demonstrated for a spherical inclusion centered in a tissue-mimicking phantom, which simulates a thermal lesion embedded in a normal tissue background. Elastographic reconstruction is also performed for a thermal lesion created in vitro in canine liver using radio-frequency ablation. Postprocessing is done on the acquired raw radio-frequency data to form surface-rendered 3D elastograms of the inclusion. Elastographic volume estimates of the inclusion compare reasonably well with the actual known inclusion volume, with 3D electrode displacement elastography slightly underestimating the true inclusion volume.

  10. An optimized ultrasound digital beamformer with dynamic focusing implemented on FPGA.

    Science.gov (United States)

    Almekkawy, Mohamed; Xu, Jingwei; Chirala, Mohan

    2014-01-01

    We present a resource-optimized dynamic digital beamformer for an ultrasound system based on a field-programmable gate array (FPGA). A comprehensive 64-channel receive beamformer with full dynamic focusing is embedded in the Altera Arria V FPGA chip. To improve spatial and contrast resolution, full dynamic beamforming is implemented by a novel method with resource optimization. This was conceived using the implementation of the delay summation through a bulk (coarse) delay and fractional (fine) delay. The sampling frequency is 40 MHz and the beamformer includes a 240 MHz polyphase filter that enhances the temporal resolution of the system while relaxing the Analog-to-Digital converter (ADC) bandwidth requirement. The results indicate that our 64-channel dynamic beamformer architecture is amenable for a low power FPGA-based implementation in a portable ultrasound system.

  11. Real-time feedback control for high-intensity focused ultrasound system using localized motion imaging

    Science.gov (United States)

    Sugiyama, Ryusuke; Kanazawa, Kengo; Seki, Mika; Azuma, Takashi; Sasaki, Akira; Takeuchi, Hideki; Fujiwara, Keisuke; Itani, Kazunori; Tamano, Satoshi; Yoshinaka, Kiyoshi; Takagi, Shu; Matsumoto, Yoichiro

    2015-07-01

    High-intensity focused ultrasound (HIFU) is one of the noninvasive treatment for tumors. Visualizing the treated area inside the human body is necessary to control the HIFU exposure. Localized motion imaging (LMI) using ultrasound to induce and detect tissue deformation is one technique to detect a change in tissue stiffness caused by thermal coagulation. In experiments with porcine liver, LMI has shown to detect deformation with less than 20% accuracy. We have developed a prototype feedback control system using real-time LMI. In this system, coagulation size was measured every 1 s and controlled to correspond to a targeted size. The typical size error was reduced to 14% from 35%. LMI displacements in normal and coagulated tissues were sufficiently different to discriminate between coagulated areas and noncoagulated ones after HIFU sonication and to visualize treated areas after HIFU treatment.

  12. A radiation emission shielding method for high intensity focus ultrasound probes.

    Science.gov (United States)

    Wu, Hao; Shen, Guofeng; Chen, Yazhu

    2015-01-01

    Electromagnetic compatibility (EMC) is a key issue in the design and development of safe and effective medical instruments. The treatment probes of high intensity focused ultrasound (HIFU) systems not only receive and transmit electromagnetic waves, but also radiate ultrasound waves, resulting in electromagnetic coupling. In this paper, an electromagnetic shielding method involving the enclosure of the probe in a copper wire mesh was introduced. First, sound pressure distribution simulations and measurements were performed using a hydrophone in order to evaluate the effects of the wire mesh on the acoustic performance of the HIFU system. The results indicated that the wire mesh did not disturb the normalized sound pressure field. In addition, the attenuation of the maximum pressure in the focal plane was equal to 6.2%. Then, the electronic emission level was tested in a chamber. After the implementation of the wire mesh, the 10-100 MHz frequency band radiation was suppressed, and the HIFU system satisfied the national EMC standards.

  13. Curvelet based automatic segmentation of supraspinatus tendon from ultrasound image: a focused assistive diagnostic method.

    Science.gov (United States)

    Gupta, Rishu; Elamvazuthi, Irraivan; Dass, Sarat Chandra; Faye, Ibrahima; Vasant, Pandian; George, John; Izza, Faizatul

    2014-12-04

    Disorders of rotator cuff tendons results in acute pain limiting the normal range of motion for shoulder. Of all the tendons in rotator cuff, supraspinatus (SSP) tendon is affected first of any pathological changes. Diagnosis of SSP tendon using ultrasound is considered to be operator dependent with its accuracy being related to operator's level of experience. The automatic segmentation of SSP tendon ultrasound image was performed to provide focused and more accurate diagnosis. The image processing techniques were employed for automatic segmentation of SSP tendon. The image processing techniques combines curvelet transform and mathematical concepts of logical and morphological operators along with area filtering. The segmentation assessment was performed using true positives rate, false positives rate and also accuracy of segmentation. The specificity and sensitivity of the algorithm was tested for diagnosis of partial thickness tears (PTTs) and full thickness tears (FTTs). The ultrasound images of SSP tendon were taken from medical center with the help of experienced radiologists. The algorithm was tested on 116 images taken from 51 different patients. The accuracy of segmentation of SSP tendon was calculated to be 95.61% in accordance with the segmentation performed by radiologists, with true positives rate of 91.37% and false positives rate of 8.62%. The specificity and sensitivity was found to be 93.6%, 94% and 95%, 95.6% for partial thickness tears and full thickness tears respectively. The proposed methodology was successfully tested over a database of more than 116 US images, for which radiologist assessment and validation was performed. The segmentation of SSP tendon from ultrasound images helps in focused, accurate and more reliable diagnosis which has been verified with the help of two experienced radiologists. The specificity and sensitivity for accurate detection of partial and full thickness tears has been considerably increased after segmentation when

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

    Science.gov (United States)

    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.

  15. Numerical simulation of high intensity focused ultrasound temperature distribution for transcranial brain therapy

    Science.gov (United States)

    Zhang, Qian; Wang, Yizhe; Zhou, Wenzheng; Zhang, Ji; Jian, Xiqi

    2017-03-01

    To provide a reference for the HIFU clinical therapeutic planning, the temperature distribution and lesion volume are analyzed by the numerical simulation. The adopted numerical simulation is based on a transcranial ultrasound therapy model, including an 8 annular-element curved phased array transducer. The acoustic pressure and temperature elevation are calculated by using the approximation of Westervelt Formula and the Pennes Heat Transfer Equation. In addition, the Time Reversal theory and eliminating hot spot technique are combined to optimize the temperature distribution. With different input powers and exposure times, the lesion volume is evaluated based on temperature threshold theory. The lesion region could be restored at the expected location by the time reversal theory. Although the lesion volume reduces after eliminating the peak temperature in the skull and more input power and exposure time is required, the injury of normal tissue around skull could be reduced during the HIFU therapy. The prediction of thermal deposition in the skull and the lesion region could provide a reference for clinical therapeutic dose.

  16. Realtime control of multiple-focus phased array heating patterns based on noninvasive ultrasound thermography.

    Science.gov (United States)

    Casper, Andrew; Liu, Dalong; Ebbini, Emad S

    2012-01-01

    A system for the realtime generation and control of multiple-focus ultrasound phased-array heating patterns is presented. The system employs a 1-MHz, 64-element array and driving electronics capable of fine spatial and temporal control of the heating pattern. The driver is integrated with a realtime 2-D temperature imaging system implemented on a commercial scanner. The coordinates of the temperature control points are defined on B-mode guidance images from the scanner, together with the temperature set points and controller parameters. The temperature at each point is controlled by an independent proportional, integral, and derivative controller that determines the focal intensity at that point. Optimal multiple-focus synthesis is applied to generate the desired heating pattern at the control points. The controller dynamically reallocates the power available among the foci from the shared power supply upon reaching the desired temperature at each control point. Furthermore, anti-windup compensation is implemented at each control point to improve the system dynamics. In vitro experiments in tissue-mimicking phantom demonstrate the robustness of the controllers for short (2-5 s) and longer multiple-focus high-intensity focused ultrasound exposures. Thermocouple measurements in the vicinity of the control points confirm the dynamics of the temperature variations obtained through noninvasive feedback.

  17. Piezoelectric Composite Micromachined Multifrequency Transducers for High-Resolution, High-Contrast Ultrasound Imaging for Improved Prostate Cancer Assessment

    Science.gov (United States)

    2015-08-01

    Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT: Approved for Public Release; Distribution Unlimited...SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) U.S. Army Medical Research and Materiel Command Fort Detrick...a Siemens EV- 8C4 transrectal ultrasound probe. In the in-vivo study, molecular imaging and microvascular mapping will both be performed to assess

  18. Development and characterization of a blood mimicking fluid for high intensity focused ultrasound.

    Science.gov (United States)

    Liu, Yunbo; Maruvada, Subha; King, Randy L; Herman, Bruce A; Wear, Keith A

    2008-09-01

    A blood mimicking fluid (BMF) has been developed for the acoustic and thermal characterizations of high intensity focused ultrasound (HIFU) ablation devices. The BMF is based on a degassed and de-ionized water solution dispersed with low density polyethylene microspheres, nylon particles, gellan gum, and glycerol. A broad range of physical parameters, including attenuation coefficient, speed of sound, viscosity, thermal conductivity, and diffusivity, were characterized as a function of temperature (20-70 degrees C). The nonlinear parameter B/A and backscatter coefficient were also measured at room temperature. Importantly, the attenuation coefficient is linearly proportional to the frequency (2-8 MHz) with a slope of about 0.2 dB cm(-1) MHz(-1) in the 20-70 degrees C range as in the case of human blood. Furthermore, sound speed and bloodlike backscattering indicate the usefulness of the BMF for ultrasound flow imaging and ultrasound-guided HIFU applications. Most of the other temperature-dependent physical parameters are also close to the reported values in human blood. These properties make it a unique HIFU research tool for developing standardized exposimetry techniques, validating numerical models, and determining the safety and efficacy of HIFU ablation devices.

  19. SU-E-J-162: Quality Assurance Procedures for MR Guided Focused Ultrasound Treatment of Bone Metastasis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L; Chen, X; Wang, B; Gupta, R; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

    2014-06-01

    Purpose: The purpose of this work is to develop and verify our quality assurance (QA) procedures to ensure the safety and efficacy of MR-guided focused ultrasound (MRgFUS) treatment of bone metastases. Methods: A practical QA program was developed. Monthly and daily QA (DQA) procedures were performed. The major QA items included the checks of the machine hardware, software and patient safety features. Briefly, these checks/tests include: 1) the cooling system reservoir and treatment table; 2) power to the treatment table; 3) the MR coil; 4) the transducer position with MRI; 5) image display on the treatment work station; 6) the effective focal spot in 3 directions using MR thermometry; and 7) all the safety devices including a sonication lamp, and the emergency stop-sonication switches. In order to avoid patient skin burn, it is important to remove gas bubbles in the interfaces between the treatment table and the gel pad, and the gel pad and patients skin during the patient setup. Our QA procedures have been verified and evaluated through patient treatments. Seven patients with scapula, humeral head, sacrum, ilium, pubic ramus and acetabular bone metastases were treated using MRgFUS. Results: Our study showed that all seven patients tolerated the MRgFUS treatment well. No skin toxicity or other complications were observed. The pain score (0–10) using the visual analog scale (VAS) was significantly reduced from 8.0 ± 1.1 before treatment to 4.7 ± 3.0, 3.0 ± 1.5, 3.2 ± 2.8 and 3.4 ± 1.5 at one day, one month, two months and three months after the MRgFUS treatment, respectively. Conclusion: We demonstrated that with the appropriate QA procedures, MRgFUS is a safe, effective and noninvasive treatment modality for palliation of bone metastases.

  20. Multi-parametric monitoring and assessment of high-intensity focused ultrasound (HIFU) boiling by harmonic motion imaging for focused ultrasound (HMIFU): an ex vivo feasibility study.

    Science.gov (United States)

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E

    2014-03-07

    Harmonic motion imaging for focused ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in vitro and in vivo. Here, a multi-parametric study is performed to investigate both elastic and acoustics-independent viscoelastic tissue changes using the Harmonic Motion Imaging (HMI) displacement, axial compressive strain and change in relative phase shift during high energy HIFU treatment with tissue boiling. Forty three (n = 43) thermal lesions were formed in ex vivo canine liver specimens (n = 28). Two-dimensional (2D) transverse HMI displacement maps were also obtained before and after lesion formation. The same method was repeated in 10 s, 20 s and 30 s HIFU durations at three different acoustic powers of 8, 10, and 11 W, which were selected and verified as treatment parameters capable of inducing boiling using both thermocouple and passive cavitation detection (PCD) measurements. Although a steady decrease in the displacement, compressive strain, and relative change in the focal phase shift (Δϕ) were obtained in numerous cases, indicating an overall increase in relative stiffness, the study outcomes also showed that during boiling, a reverse lesion-to-background displacement contrast was detected, indicating potential change in tissue absorption, geometrical change and/or, mechanical gelatification or pulverization. Following treatment, corresponding 2D HMI displacement images of the thermal lesions also mapped consistent discrepancy in the lesion-to-background displacement contrast. Despite the expectedly chaotic changes in acoustic properties with boiling, the relative change in phase shift showed a consistent decrease, indicating its robustness to monitor biomechanical properties independent of the acoustic property changes throughout the HIFU treatment. In addition, the 2D HMI displacement images confirmed and indicated the increase in the thermal lesion size with

  1. Multi-parametric monitoring and assessment of High Intensity Focused Ultrasound (HIFU) boiling by Harmonic Motion Imaging for Focused Ultrasound (HMIFU): An ex vivo feasibility study

    Science.gov (United States)

    Hou, Gary Y.; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E.

    2014-01-01

    Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in vitro and in vivo. Here, a multi-parametric study is performed to investigate both elastic and acoustics-independent viscoelastic tissue changes using the Harmonic Motion Imaging (HMI) displacement, axial compressive strain and change in relative phase-shift during high energy HIFU treatment with tissue boiling. Forty three (n=43) thermal lesions were formed in ex vivo canine liver specimens (n=28). Two dimensional (2D) transverse HMI displacement maps were also obtained before and after lesion formation. The same method was repeated in 10-s, 20-s and 30-s HIFU durations at three different acoustic powers of 8, 10, and 11W, which were selected and verified as treatment parameters capable of inducing boiling using both thermocouple and Passive Cavitation Detection (PCD) measurements. Although a steady decrease in the displacement, compressive strain, and relative change in the focal phase shift (Δφ) were obtained in numerous cases, indicating an overall increase in relative stiffness, the study outcomes also showed that during boiling, a reverse lesion-to-background displacement contrast was detected, indicating potential change in tissue absorption, geometrical change and/or, mechanical gelatification or pulverization. Following treatment, corresponding 2D HMI displacement images of the thermal lesions also mapped consistent discrepancy in the lesion-to-background displacement contrast. Despite unpredictable changes in acoustic properties with boiling, the relative change in phase shift showed a consistent decrease, indicating its robustness to monitor biomechanical properties independent of the acoustic property change throughout the HIFU treatment. In addition, the 2D HMI displacement images confirmed and indicated the increase in the thermal lesion size with treatment duration

  2. HIGH INTENSITY FOCUSED ULTRASOUND FOR TREATMENT UNRESECTABLE MALIGNANT TUMORS IN 75 PATIENTS

    Institute of Scientific and Technical Information of China (English)

    郑国强

    2004-01-01

    Objective: To study preliminary experience of high intensity focused ultrasound (HIFU) for unresectable malignant tumors in 75 patients. Methods: The clinical data of 75 patients with unresectable tumor was analyzed retrospectively. Results: Among 75 patients, ten out of 57 cases achieved good local control in short-term, 5 patients liver tumor, 4 patients with tumor in the chest wall and one patient with bone matestics. Seven patients had skin burn and 2 patients developed intestinal perforations. Conclusion: HIFU is a novel tool for local tumor treatment. HIFU treatment for patients with unresectable tumor in the chest wall is effective.

  3. Magnetic resonance-guided focused ultrasound: a new technology for clinical neurosciences.

    Science.gov (United States)

    Jolesz, Ferenc A; McDannold, Nathan J

    2014-02-01

    Transcranial MRI-guided focused ultrasound (TcMRgFUS) is an old idea but a new technology that may change the entire clinical field of the neurosciences. TcMRgFUS has no cumulative effect, and it is applicable for repeatable treatments, controlled by real-time dosimetry, and capable of immediate tissue destruction. Most importantly, it has extremely accurate targeting and constant monitoring. It is potentially more precise than proton beam therapy and definitely more cost effective. Neuro-oncology may be the most promising area of future TcMRgFUS applications.

  4. Systematic evaluation of a secondary method for measuring diagnostic-level medical ultrasound transducer output power based on a large-area pyroelectric sensor

    Science.gov (United States)

    Zeqiri, B.; Žauhar, G.; Rajagopal, S.; Pounder, A.

    2012-06-01

    A systematic study of the application of a novel pyroelectric technique to the measurement of diagnostic-level medical ultrasound output power is described. The method exploits the pyroelectric properties of a 0.028 mm thick membrane of polyvinylidene fluoride (PVDF), backed by an acoustic absorber whose ultrasonic absorption coefficient approaches 1000 dB cm-1 at 3 MHz. When exposed to an ultrasonic field, absorption of ultrasound adjacent to the PVDF-absorber interface results in heating and the generation of a pyroelectric output voltage across gold electrodes deposited on the membrane. For a sensor large enough to intercept the whole of the acoustic beam, the output voltage can be calibrated for the measurement of acoustic output power. A number of key performance properties of the method have been investigated. The technique is very sensitive, with a power to voltage conversion factor of typically 0.23 V W-1. The frequency response of a particular embodiment of the sensor in which acoustic power reflected at the absorber-PVDF interface is subsequently returned to the pyroelectric membrane to be absorbed, has been evaluated over the frequency range 1.5 MHz to 10 MHz. This has shown the frequency response to be flat to within ±4%, above 2.5 MHz. Below this frequency, the sensitivity falls by 20% at 1.5 MHz. Linearity of the technique has been demonstrated to within ±1.6% for applied acoustic power levels from 1 mW up to 120 mW. A number of other studies targeted at assessing the achievable measurement uncertainties are presented. These involve: the effects of soaking, the influence of the angle of incidence of the acoustic beam, measurement repeatability and sensitivity to transducer positioning. Additionally, over the range 20 °C to 30 °C, the rate of change in sensitivity with ambient temperature has been shown to be +0.5% °C-1. Implications of the work for the development of a sensitive, traceable, portable, secondary method of ultrasound output power

  5. Model of a Piezoelectric Transducer

    Science.gov (United States)

    Goodenow, Debra

    2004-01-01

    It's difficult to control liquid and gas in propellant tanks in zero gravity. A possible a design would utilize acoustic liquid manipulation (ALM) technology which uses ultrasonic beams conducted through a liquid and solid media, to push gas bubbles in the liquid to desirable locations. We can propel and control the bubble with acoustic radiation pressure by aiming the acoustic waves on the bubble s surface. This allows us to design a so called smart tank in which the ALM devices transfer the gas to the outer wall of the tank and isolating the liquid in the center. Because the heat transfer rate of a gas is lower of that of the liquid it would substantially decrease boil off and provide of for a longer storage life. The ALM beam is composed of little wavelets which are individual waves that constructively interfere with each other to produce a single, combined acoustic wave front. This is accomplished by using a set of synchronized ultrasound transducers arranged in an array. A slight phase offset of these elements allows us to focus and steer the beam. The device that we are using to produce the acoustic beam is called the piezoelectric transducer. This device converts electrical energy to mechanical energy, which appears in the form of acoustic energy. Therefore the behavior of the device is dependent on both the mechanical characteristics, such as its density, cross-sectional area, and its electrical characteristics, such as, electric flux permittivity and coupling factor. These devices can also be set up in a number of modes which are determined by the way the piezoelectric device is arranged, and the shape of the transducer. For this application we are using the longitudinal or thickness mode for our operation. The transducer also vibrates in the lateral mode, and one of the goals of my project is to decrease the amount of energy lost to the lateral mode. To model the behavior of the transducers I will be using Pspice, electric circuit modeling tool, to

  6. Focused ultrasound examination of the chest on patients admitted with acute signs of respiratory problems

    DEFF Research Database (Denmark)

    Riishede, M; Laursen, C B; Teglbjærg, L S

    2016-01-01

    INTRODUCTION: Patients with acute respiratory problems poses a diagnostic challenge because similar symptoms can be caused by various pathological conditions. Focused ultrasound examination (f-US) of the heart and lungs has proven to increase the diagnostic accuracy in these patients. In this pro......INTRODUCTION: Patients with acute respiratory problems poses a diagnostic challenge because similar symptoms can be caused by various pathological conditions. Focused ultrasound examination (f-US) of the heart and lungs has proven to increase the diagnostic accuracy in these patients...... presumptive diagnosis at 4 hours from admission. METHODS AND ANALYSIS: This is a semiblinded randomised prospective study. 288 patients will be included and randomised into the control or intervention group. All patients receive a standard diagnostic evaluation by the EP to assess the primary presumptive....... As standard for correct diagnosis, we perform a blinded journal audit after discharge. As primary analysis, we use the intention-to-treat analysis. CONCLUSIONS: This study is the first multicentre trial in EDs to investigate whether f-US, in the hands of the EP, increases the proportion of correct diagnosis...

  7. Effect of acoustic streaming on tissue heating due to high-intensity focused ultrasound

    CERN Document Server

    Solovchuk, Maxim A; Thiriet, Marc; Lin, Win-Li

    2011-01-01

    The influences of blood vessels and focused location on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors is studied. A three-dimensional acoustics-thermal-fluid coupling model is employed to compute the temperature field in the hepatic cancerous region. The model is based on the linear Westervelt and bioheat equations as well as the nonlinear Navier-Stokes equations for the liver parenchyma and blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. Different blood vessel diameters and focal point locations were investigated. We found from this three-dimensional numerical study that in large blood vessels both the convective cooling and acoustic streaming can change considerably the temperature field and the thermal lesion near blood vessels. If the blood vessel is located within the beam width, both acoustic streaming and blood flow cooling effects should be taken into account. The predicted temperature ...

  8. Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

    Directory of Open Access Journals (Sweden)

    Shin Yoshizawa

    2017-03-01

    Full Text Available A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the ultrasonic heating, resulting in the significant reduction of the treatment time. In this paper, a method named “trigger HIFU exposure” which employs cavitation microbubbles is introduced and its results are reviewed. A trigger HIFU sequence consists of high-intensity short pulses followed by moderate-intensity long bursts. Cavitation bubbles induced in a multiple focal regions by rapidly scanning the focus of high-intensity pulses enhanced the temperature increase significantly and produced a large coagulation region with high efficiency.

  9. Prostate Ultrasound

    Medline Plus

    Full Text Available ... physician during a routine physical exam or prostate cancer screening exam. an elevated blood test result. difficulty ... vessels or to detect abnormal masses, such as tumors. In an ultrasound examination, a transducer both sends ...

  10. Prostate Ultrasound

    Science.gov (United States)

    ... prostate. help diagnose the cause of a man's infertility. A transrectal ultrasound of the prostate gland is ... the transducer is pressed against the skin, it directs small pulses of inaudible, high-frequency sound waves ...

  11. Prostate Ultrasound

    Medline Plus

    Full Text Available ... prostate. help diagnose the cause of a man's infertility. A transrectal ultrasound of the prostate gland is ... the transducer is pressed against the skin, it directs small pulses of inaudible, high-frequency sound waves ...

  12. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... areas of the body while other areas, especially air-filled lungs, are poorly suited for ultrasound. For ... make secure contact with the body and eliminate air pockets between the transducer and the skin that ...

  13. Prostate Ultrasound

    Medline Plus

    Full Text Available ... an ultrasound transducer – a plastic cylinder about the size of a finger – is inserted short distance into ... the object is as well as the object's size, shape and consistency (whether the object is solid ...

  14. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ... the transducer (the device placed on the patient's skin to send and receive the returning sound waves), ...

  15. Prostate Ultrasound

    Medline Plus

    Full Text Available ... probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ... the transducer (the device placed on the patient's skin to send and receive the returning sound waves), ...

  16. Ultrasound -- Pelvis

    Medline Plus

    Full Text Available ... extract a sample of cells from organs for laboratory testing. Doppler ultrasound images can help the physician ... The transducer sends out inaudible, high—frequency sound waves into the body and then listens for the ...

  17. Focused Vascular Ultrasound for the Assessment of Atherosclerosis: A Proof-of-Concept Study.

    Science.gov (United States)

    Johri, Amer M; Calnan, Catherine M; Matangi, Murray F; MacHaalany, Jimmy; Hétu, Marie-France

    2016-09-01

    Current decisions to refer for angiographic coronary assessment are based on pain character, risk scores, stress testing, and occasionally calcium scoring. Carotid plaque has emerged as an effective vascular biomarker, but the cost and time of a full carotid ultrasound examination are disadvantageous. Focused vascular ultrasound (FOVUS) is a rapid limited assessment of carotid plaque that can be conducted by non-vascular-trained operators. The objective of the study was to determine the test characteristics of FOVUS for the assessment of significant coronary atherosclerosis in symptomatic patients referred for cardiac assessment. In this prospective study, FOVUS was performed in 208 outpatients at low to intermediate risk undergoing same-day angiography. Carotid artery maximal plaque height was measured in each participant. A previously established receiver operating characteristic curve determined that a value of ≥1.5 mm was the threshold for significant angiographic coronary artery disease. FOVUS scan results, alone or combined with stress testing, were analyzed for the prediction of significant coronary artery disease. The negative predictive value and sensitivity of plaque height alone by FOVUS were found to be 77% and 93%, respectively. Adding the FOVUS scan result to stress testing significantly increased the negative predictive value and sensitivity of these traditional risk stratification tools. Rapid carotid plaque height measurement by FOVUS enhanced atherosclerosis risk prediction in patients referred for cardiac assessment. Rapid plaque quantification had good negative predictive value and high sensitivity alone or in combination with stress testing. FOVUS may serve as a potential point-of-care ultrasound tool in the integrated assessment of cardiac pain. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  18. Safety Issues for HIFU Transducer Design

    Science.gov (United States)

    Fleury, Gérard; Berriet, Rémi; Chapelon, Jean Yves; ter Haar, Gail; Lafon, Cyril; Le Baron, Olivier; Chupin, Laurent; Pichonnat, Fabrice; Lenormand, Jérôme

    2005-03-01

    In contrast with most ultrasound modalities for medical applications, (especially ultrasound imaging), High Intensity Focused Ultrasound (HIFU) involves technologies and procedures which may present risk to the patient. These risks, resulting from the high power levels required for effective therapy, should be taken into account at the earliest stages in the design of a system dedicated to HIFU treatment. An understanding of these risks must thus be shared amongst the many players in the field of therapy using high power ultrasound. Moreover, since the number of applications of HIFU has increased appreciably over recent years and the technology is ready to move from the research to the industrial level, it is worth now considering solutions that should be put in place to guarantee the safety of the patient during HIFU treatment. This paper reports thoughts on this, identifies some risks to the patient that must be taken into consideration in the design of HIFU transducers, and proposes some solutions that could prevent the deleterious consequences of transducer misuse or failure. For the main risks identified, such as exceeding the desired acoustic power or poor control of tissue targeting, a description of transducer performance that could potentially result in problems is systematically sought. This allows proposals for precautions to be taken during operation to be made. Parameters which should be monitored to ensure safe use are also suggested. This type of approach, which should be undertaken for the different components of a therapeutic system, highlights the challenges that must be faced in the immediate future for the development and safe exploitation of HIFU systems. The necessity for standard definitions of the parameters to be checked or monitored during HIFU treatments is crucial in this approach, as is the availability of reliable dedicated measurement devices. Co-ordinated action on these topics in the HIFU community would contribute to the

  19. General Ultrasound Imaging

    Medline Plus

    Full Text Available ... use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds ...

  20. General Ultrasound Imaging

    Medline Plus

    Full Text Available ... or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the ... probe through the gel into the body. The transducer collects the sounds that bounce back and a ...

  1. Segmentation Method for Magnetic Resonance-Guided High-Intensity Focused Ultrasound Therapy Planning

    Directory of Open Access Journals (Sweden)

    A. Vargas-Olivares

    2017-01-01

    Full Text Available High-intensity focused ultrasound (HIFU is a minimally invasive therapy modality in which ultrasound beams are concentrated at a focal region, producing a rise of temperature and selective ablation within the focal volume and leaving surrounding tissues intact. HIFU has been proposed for the safe ablation of both malignant and benign tissues and as an agent for drug delivery. Magnetic resonance imaging (MRI has been proposed as guidance and monitoring method for the therapy. The identification of regions of interest is a crucial procedure in HIFU therapy planning. This procedure is performed in the MR images. The purpose of the present research work is to implement a time-efficient and functional segmentation scheme, based on the watershed segmentation algorithm, for the MR images used for the HIFU therapy planning. The achievement of a segmentation process with functional results is feasible, but preliminary image processing steps are required in order to define the markers for the segmentation algorithm. Moreover, the segmentation scheme is applied in parallel to an MR image data set through the use of a thread pool, achieving a near real-time execution and making a contribution to solve the time-consuming problem of the HIFU therapy planning.

  2. Induction of apoptosis in vivo in the rabbit brain with focused ultrasound and Optison.

    Science.gov (United States)

    Vykhodtseva, Natalia; McDannold, Nathan; Hynynen, Kullervo

    2006-12-01

    Histologic effects of focused ultrasound (FUS) exposures combined with an ultrasound contrast agent (Optison) were investigated to examine whether the lesions were dominated by apoptosis or necrosis. The rabbit brains (n = 17) were sonicated (1.5 MHz, peak rarefactional pressure amplitude: 1.4 to 8.8 MPa) after Optison was injected intravenously (IV). MRI and light microscopy were used to examine tissue effects. To detect apoptosis, TUNEL staining based on labeling of DNA strand breaks was used. The average number of apoptotic and necrotic cells in 300 x 220 microm microscopic fields were counted in 18 representative lesions. Lesions in the rabbit brains were created at lowered acoustic power levels when FUS was combined with Optison. In histology, the lesions exhibited red blood cell extravasations and destruction of blood vessels. At 4 h after sonication, the lesions lost many cells, and the remaining cells exhibited both necrotic and apoptotic features. Overall, apoptosis dominated; there were, on average, 32.3 +/- 13.2 apoptotic cells per microscopic field compared with only 5.1 +/- 3.4 necrotic cells per field. In conclusion, FUS combined with Optison could produce lesions that are dominated by apoptosis, presumably induced primarily via ischemia after cavitation-produced damage to the brain vasculature.

  3. In vitro cell system for studying molecular mechanisms of action associated with low intensity focused ultrasound

    Science.gov (United States)

    Babakhanian, Meghedi; Fan, Richard E.; Mulgaonkar, Amit P.; Singh, Rahul; Culjat, Martin O.; Danesh, Shahab M.; Toro, Ligia; Grundfest, Warren; Melega, William P.

    2012-03-01

    Low intensity focused ultrasound (LIFU) is now being considered as a noninvasive brain therapy for clinical applications. We maintain that LIFU can efficiently deliver energy from outside the skull to target specific brain regions, effecting localized neuromodulation. However, the underlying molecular mechanisms that drive this LIFU-induced neuromodulation are not well-defined due, in part, to our lack of understanding of how particular sets of LIFU delivery parameters affect the outcome. To efficiently conduct multiple sweeps of different parameters and determine their effects, we have developed an in-vitro system to study the effects of LIFU on different types of cells grown in culture. Presently, we are evaluating how LIFU affects the ionic flux that may underlie neuronal excitation and inhibition observed in-vivo. The results of our in-vitro studies will provide a rationale for selection of optimal LIFU parameter to be used in subsequent in-vivo applications. Thus, a prototype ultrasound cell assay system has been developed to conduct these studies, and is described in this work.

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

    Science.gov (United States)

    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).

  5. Physiological Motion and Registration of Abnormalities in Liver During Focused Ultrasound Surgery

    Science.gov (United States)

    Chauhan, Sunita; Rh, Abhilash

    Continuous deformation and dislocation of soft tissues in the abdominal and thoracic region presents a major issue for effective targeting of all non-invasive ablative modalities such as radiotherapy/surgery and Focused Ultrasound Surgery. Most significant among these is the movement of the target organs due to physiological processes such as respiration. The movement is found to be most significant for liver and kidneys. We studied movement and compensation strategies with the aim to implement them during ultrasound ablation using our robotic system for targeted FUS dose delivery. The motion pattern of the liver can be assumed to be in a single plane as it closely follows the movement of the diaphragm. However, the movement of kidneys is three dimensional and follows complicated patterns. Kidney motion is highly subject specific and has poor repeatability. In our research, we quantify the relation of liver movement and the breathing pattern so as to achieve real-time movement compensation using a prediction-correlation approach.

  6. Sonablate-500TM Transrectal High-intensity Focused Ultrasound (HIFU) for Benign Prostatic Hyperplasia Patients

    Institute of Scientific and Technical Information of China (English)

    L(U) Jun; HU Weilie; WANG Wei; ZHANG Yuanfeng; CHEN Zhaoyang; YE Zhangqun

    2007-01-01

    To evaluate the safety and efficacy of transrectal high-intensity focused ultrasound (HIFU) in the treatment of benign prostatic hyperplasia (BPH), serial studies were conducted in 150 BPH pa- tients before and 30 min, 1, 2, 6 and 12 month(s) after Sonablate-500TM HIFU treatment. A sili- con-coated indwelling 16F latex catheter was placed during the determination of the therapy zone. Preoperative and postoperative evaluations were made by using the international prostate symptom score (IPSS), quality of life (QOL), uroflowmetric findings and transrectal ultrasound, and incidence of complications. The cystourethrography was done in 23 patients within 1 year postoperatively. The results showed that after HIFU treatment, IPSS and QOL scores were significantly decreased at 1, 2, 6 and 12 month(s) (P<0.01). Maximum urine flow rate (6.0 to 17.2 mL/s, P<0.01), PVR (75.0 to 30.3,P<0.01) and prostatic volume (65.0 to 38.1 mL, P<0.05) were significantly improved 12 months after the operation. Recurrent urinary retention (n=2) and urethrorectal fistula (n=1) occurred at the 15th postoperative day. The duration of the HIFU prostate ablation was 25-90 rain. The mean time for an indwelling catheter was 3-19 days. These data demonstrate that treatment of BPH with Sonab- late-500TM HIFU is safe and effective.

  7. Treating glioblastoma multiforme with selective high-dose liposomal doxorubicin chemotherapy induced by repeated focused ultrasound

    Directory of Open Access Journals (Sweden)

    Yang FY

    2012-02-01

    Full Text Available Feng-Yi Yang1, Ming-Che Teng1, Maggie Lu2, Hsiang-Fa Liang2, Yan-Ru Lee1, Chueh-Chuan Yen3, Muh-Lii Liang4,5, Tai-Tong Wong51Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, 2Drug Delivery Laboratory, Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, 3Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital and National Yang-Ming University School of Medicine, Taipei, 4Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, 5Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, TaiwanBackground: High-dose tissue-specific delivery of therapeutic agents would be a valuable clinical strategy. We have previously shown that repeated transcranial focused ultrasound is able to increase the delivery of Evans blue significantly into brain tissue. The present study shows that repeated pulsed high-intensity focused ultrasound (HIFU can be used to deliver high-dose atherosclerotic plaque-specific peptide-1 (AP-1-conjugated liposomes selectively to brain tumors.Methods: Firefly luciferase (Fluc-labeled human GBM8401 glioma cells were implanted into NOD-scid mice. AP-1-conjugated liposomal doxorubicin or liposomal doxorubicin alone was administered followed by pulsed HIFU and the doxorubicin concentration in the treated brains quantified by fluorometer. Growth of the labeled glioma cells was monitored through noninvasive bioluminescence imaging and finally the brain tissue was histologically examined after sacrifice.Results: Compared with the control group, the animals treated with 5 mg/kg injections of AP-1 liposomal doxorubicin or untargeted liposomal doxorubicin followed by repeated pulsed HIFU not only showed significantly enhanced accumulation of drug at the sonicated tumor site but also a significantly elevated tumor-to-normal brain drug

  8. Heating in vascular tissue and flow-through tissue phantoms induced by focused ultrasound

    Science.gov (United States)

    Huang, Jinlan

    High intensity focused ultrasound (HIFU) can be used to control bleeding, both from individual blood vessels as well as from gross damage to the capillary bed. This process, called acoustic hemostasis, is being studied in the hope that such a method would ultimately provide a lifesaving treatment during the so-called "golden hour", a brief grace period after a severe trauma in which prompt therapy can save the life of an injured person. Thermal effects play a major role in occlusion of small vessels and also appear to contribute to the sealing of punctures in major blood vessels. However, aggressive ultrasound-induced tissue heating can also impact healthy tissue and can lead to deleterious mechanical bioeffects. Moreover, the presence of vascularity can limit one's ability to elevate the temperature of blood vessel walls owing to convective heat transport. In an effort to better understand the heating process in tissues with vascular structure we have developed a numerical simulation that couples models for ultrasound propagation, acoustic streaming, ultrasound heating and blood cooling in Newtonian viscous media. The 3-D simulation allows for the study of complicated biological structures and insonation geometries. We have also undertaken a series of in vitro experiments, in non-uniform flow-through tissue phantoms, designed to provide a ground truth verification of the model predictions. The calculated and measured results were compared over a range of values for insonation pressure, insonation time, and flow rate; we show good agreement between predictions and measurements. We then conducted a series of simulations that address two limiting problems of interest: hemostasis in small and large vessels. We employed realistic human tissue properties and considered more complex geometries. Results show that the heating pattern in and around a blood vessel is different for different vessel sizes, flow rates and for varying beam orientations relative to the flow axis

  9. Design of patient-specific focused ultrasound arrays for non-invasive brain therapy with increased trans-skull transmission and steering range

    Science.gov (United States)

    Hughes, Alec; Hynynen, Kullervo

    2017-09-01

    The use of a phased array of ultrasound transducer elements to sonicate through the skull has opened the way for new treatments and the delivery of therapeutics beyond the blood-brain barrier. The limited steering range of current clinical devices, particularly at higher frequencies, limits the regions of the brain that are considered treatable by ultrasound. A new array design is introduced that allows for high levels of beam steering and increased transmission throughout the brain. These improvements are achieved using concave transducers normal to the outer-skull surface in a patient-specific configuration to target within the skull, so that the far-field of each beam is within the brain. It is shown that by using pulsed ultrasound waves timed to arrive in-phase at the desired target, sufficient levels of acoustic energy are delivered for blood-brain barrier opening throughout the brain.

  10. Curved PVDF airborne transducer.

    Science.gov (United States)

    Wang, H; Toda, M

    1999-01-01

    In the application of airborne ultrasonic ranging measurement, a partially cylindrical (curved) PVDF transducer can effectively couple ultrasound into the air and generate strong sound pressure. Because of its geometrical features, the ultrasound beam angles of a curved PVDF transducer can be unsymmetrical (i.e., broad horizontally and narrow vertically). This feature is desired in some applications. In this work, a curved PVDF air transducer is investigated both theoretically and experimentally. Two resonances were observed in this transducer. They are length extensional mode and flexural bending mode. Surface vibration profiles of these two modes were measured by a laser vibrometer. It was found from the experiment that the surface vibration was not uniform along the curvature direction for both vibration modes. Theoretical calculations based on a model developed in this work confirmed the experimental results. Two displacement peaks were found in the piezoelectric active direction of PVDF film for the length extensional mode; three peaks were found for the flexural bending mode. The observed peak positions were in good agreement with the calculation results. Transient surface displacement measurements revealed that vibration peaks were in phase for the length extensional mode and out of phase for the flexural bending mode. Therefore, the length extensional mode can generate a stronger ultrasound wave than the flexural bending mode. The resonance frequencies and vibration amplitudes of the two modes strongly depend on the structure parameters as well as the material properties. For the transducer design, the theoretical model developed in this work can be used to optimize the ultrasound performance.

  11. The Efficacy of High-Intensity Focused Ultrasound (HIFU) in Advanced Pancreatic Cancer

    Institute of Scientific and Technical Information of China (English)

    Bo Xie; Jiajun Ling; Weiming Zhang; Xueqin Huang; Jihua Zhen; Yanzhe Huang

    2008-01-01

    OBJECTIVE To observe the efficacy of high-intensity focused ultrasound (HIFU)in the treatment of late-stage pancreatic cancer.METHODS Sixteen patients with advanced pancreatic cancer received HIFU therapy.Evaluation of efficacy was made on the basis of changes in clinical symptoms and variations in the tumor echo and size.RESULTS Clinical symptoms such as pain were significantly alleviated,echo of the tumor was enhanced with B-US and the quality of life such as eating,sleeping and mental status was markedly improved;no serious complications were observed.CONCLUSION The use of HIFU in the treatment of advanced pancreatic cancer is feasible and safe.It is effective in killing the carcinoma cells and alleviaring pain.This technique may offer non-invasive therapy for the treatment of patients with late-stage pancreatic cancer.

  12. Improved highly accurate localized motion imaging for monitoring high-intensity focused ultrasound therapy

    Science.gov (United States)

    Qu, Xiaolei; Azuma, Takashi; Sugiyama, Ryusuke; Kanazawa, Kengo; Seki, Mika; Sasaki, Akira; Takeuchi, Hideki; Fujiwara, Keisuke; Itani, Kazunori; Tamano, Satoshi; Takagi, Shu; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-07-01

    Visualizing an area subjected to high-intensity focused ultrasound (HIFU) therapy is necessary for controlling the amount of HIFU exposure. One of the promising monitoring methods is localized motion imaging (LMI), which estimates coagulation length by detecting the change in stiffness. In this study, we improved the accuracy of our previous LMI by dynamic cross-correlation window (DCCW) and maximum vibration amount (MVA) methods. The DCCW method was used to increase the accuracy of estimating vibration amplitude, and the MVA method was employed to increase signal-noise ratio of the decrease ratio at the coagulated area. The qualitative comparison of results indicated that the two proposed methods could suppress the effect of noise. Regarding the results of the quantitative comparison, coagulation length was estimated with higher accuracy by the improved LMI method, and the root-mean-square error (RMSE) was reduced from 2.51 to 1.69 mm.

  13. Grains unchained: local fluidization of a granular packing by focused ultrasound.

    Science.gov (United States)

    Lidon, Pierre; Taberlet, Nicolas; Manneville, Sébastien

    2016-02-28

    We report experimental results on the dynamics of a granular packing submitted to high-intensity focused ultrasound. Acoustic radiation pressure is shown to remotely induce local rearrangements within a pile as well as global motion around the focal spot in an initially jammed system. We demonstrate that this fluidization process is intermittent for a range of acoustic pressures and hysteretic when the pressure is cycled. Such a first-order-like unjamming transition is reproduced in numerical simulations in which the acoustic pressure field is modeled by a localized external force. Further analysis of the simulated packings suggests that in the intermittent regime unjamming is not associated with any noticeable prior structural signature. A simple two-state model based on effective temperatures is proposed to account for these findings.

  14. A Rectourethral Fistula due to Transrectal High-Intensity Focused Ultrasound Treatment: Diagnosis and Management.

    Science.gov (United States)

    Fiaschetti, Valeria; Manenti, Guglielmo; Di Poce, Isabelle; Fornari, Maria; Ricci, Aurora; Finazzi Agrò, Enrico; Simonetti, Giovanni

    2012-01-01

    Colovesical fistula (CVF) is an abnormal connection between the enteric and the urinary systems. The rectourethral fistula (RUF) is a possible but extremely rare complication of treatment of prostate cancer with "transrectal High-Intensity Focused Ultrasound (HIFU) treatment." We present a case of CVF due to HIFU treatment of recurrent prostate cancer. The case was assessed with cystography completed with a pelvic CT scan-with MPR, MIP, and VR reconstruction-before emptying the bladder. Since the CT scan confirmed that the fistula involved solely the urethra and excluded even a minimal involvement of the bladder, it was possible to employ a conservative treatment by positioning a Foley catheter of monthly duration, in order to allow the urethra to rest. Still today, after 6 months, the patient is in a good clinical condition and has not shown yet signs of a recurrence of the fistula.

  15. Magnetic resonance-guided focused ultrasound surgery for leiomyoma-associated infertility

    Science.gov (United States)

    Bouwsma, Esther V. A.; Gorny, Krzysztof R.; Hesley, Gina K.; Jensen, Jani R.; Peterson, Lisa G; Stewart, Elizabeth A.

    2017-01-01

    Objective To describe magnetic resonance-guided focused ultrasound surgery (FUS) as a treatment for a case of leiomyoma-associated infertility. Design Case report from a randomized clinical trial. Setting Academic medical center. Patient(s) A 37-year-old woman with known leiomyomas and a history of 18 months of home-inseminations from a known donor. Intervention(s) Magnetic resonance-guided FUS treatment of uterine fibroids, where the dominant fibroid distorted the uterine cavity. Main Outcome Measure(s) Pregnancy. Result(s) A viable intrauterine pregnancy, with a full-term vaginal delivery, was conceived after a single clomiphene citrate and intrauterine insemination cycle. Conclusion(s) The role of FUS for enhancement of fertility in women with nonhysteroscopically resectable uterine fibroids distorting the uterine cavity should be investigated further. PMID:21570071

  16. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) treatment for uterine fibroids

    Science.gov (United States)

    Abdullah, BJJ; Subramaniam, RV; Omar, SS; Wragg, P; Ramli, N; Wui, AL; Lee, CC; Yusof, Y

    2010-01-01

    Magnetic Resonance-guided focused Ultrasound Surgery (MRgFUS) is gaining popularity as an alternative to medical and surgical interventions in the management of symptomatic uterine fibroids. Studies have shown that it is an effective non-invasive treatment with minimal associated risks as compared to myomectomy and hysterectomy. MRgFUS can be offered to a majority of patients suffering from symptomatic uterine fibroids. It has been suggested that the use of broader inclusion criteria as well as the mitigation techniques makes it possible to offer MRgFUS to a much larger subset of patients than previously believed. This paper will describe how MRgFUS treatment for uterine fibroids is performed at the University of Malaya Medical Centre, Kuala Lumpur, Malaysia. PMID:21611036

  17. Focused ultrasound-mediated drug delivery through the blood-brain barrier.

    Science.gov (United States)

    Burgess, Alison; Shah, Kairavi; Hough, Olivia; Hynynen, Kullervo

    2015-05-01

    Despite recent advances in blood-brain barrier (BBB) research, it remains a significant hurdle for the pharmaceutical treatment of brain diseases. Focused ultrasound (FUS) is one method to transiently increase permeability of the BBB to promote drug delivery to specific brain regions. An introduction to the BBB and a brief overview of the methods, which can be used to circumvent the BBB to promote drug delivery, is provided. In particular, we discuss the advantages and limitations of FUS technology and the efficacy of FUS-mediated drug delivery in models of disease. MRI for targeting and evaluating FUS treatments, combined with administration of microbubbles, allows for transient, reproducible BBB opening. The integration of a real-time acoustic feedback controller has improved treatment safety. Successful clinical translation of FUS has the potential to transform the treatment of brain disease worldwide without requiring the development of new pharmaceutical agents.

  18. Influence of the abdominal wall on the nonlinear propagation of focused therapeutic ultrasound

    Institute of Scientific and Technical Information of China (English)

    Liu Zhen-Bo; Fan Ting-Bo; Zhang Dong; Gong Xiu-Fen

    2009-01-01

    y This article theoretically studies the influence of inhomogeneous abdominal walls on focused therapeutic ultrasound based on the phase screen model. An inhomogeneous tissue is considered as a combination of a homogeneous medium and a phase aberration screen. Variations of acoustic parameters such as peak positive pressure, peak negative pressure, and acoustic intensity are discussed with respect to the phase screen statistics of human abdominal walls. Results indicate that the abdominal wall can result in energy loss of the sound in the focal plane. For a typical human abdominal wall with correlation length of 7.9 mm and variance of 0.36, the peak acoustic intensity radiated from a 1 MHz transmitter with a radius of 30 mm can be reduced by about 14% at the focal plane.

  19. Laser-enhanced high-intensity focused ultrasound heating in an in vivo small animal model

    Science.gov (United States)

    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.

  20. Influence of Early Pregnancy Termination by Focused Ultrasound Beams on Menstrual Recovery of Macaques

    Institute of Scientific and Technical Information of China (English)

    Yong-hong DU; Zheng-ai XIONG; Jian-zhong ZOU; Yi TAN; Jin BAI; Zhi-biao WANG

    2004-01-01

    Objective To explore the effects on macaques' menstrual recovery after terminating early pregnancy by focused ultrasound beams (FUB)Methods FUB was used to terminate early pregnancy in 5 macaques with gestation duration ranging from 37-66 d. Two circles after the recovery of menstruation, color Doppler flow imaging (CDFI) and magnetic resonance imaging (MRI) were used to estimate the shape, size and blood flow of uterus, and pathological examinations were performed to check against any lesions to uterine endometrium and ovary.Results Forty days after FUB abortion, menstruation recovered and the volume and duration of each macaque's menstruation were not changed compared with those before gestation. CDFI and MRI suggested that the siz.e and shape of uterus were normal.The endometrial line was clear and no lesions were found in adjacent organs.Conclusion FUB termination of early pregnancy in macaques did not damage their ovarian tissue and had no influence on subsequent menstrual recovery.

  1. [High-intensity focused ultrasound and prostate cancer: technology, state of the art and future].

    Science.gov (United States)

    Vespasiani, G; Asimakopoulos, A D; Finazzi Agrò, E; Virgili, G

    2008-01-01

    BACKGROUND. The potential applications of the high-intensity focused ultrasound (HIFU) as a minimally invasive therapy of the localized prostate cancer explain the growing interest of the urologic community towards this technique. HIFU has been assessed for its role in the treatment of localized prostate cancer in patients who otherwise would not have benefited from surgery, and in local recurrences after radiation failure. Methods. Relevant information on HIFU treatment was identified through a literature search of published studies. RESULTS. High biochemical efficacy, excellent tumor local control and favorable mid- and long-term oncological data with a low morbidity rate have been shown in many series of patients. CONCLUSIONS. Although HIFU is a recent and emerging technology, it has been well studied and developed to a point that HIFU will undoubtedly be an effective alternative to radiation therapy.

  2. A Rectourethral Fistula due to Transrectal High-Intensity Focused Ultrasound Treatment: Diagnosis and Management

    Directory of Open Access Journals (Sweden)

    Valeria Fiaschetti

    2012-01-01

    Full Text Available Colovesical fistula (CVF is an abnormal connection between the enteric and the urinary systems. The rectourethral fistula (RUF is a possible but extremely rare complication of treatment of prostate cancer with “transrectal High-Intensity Focused Ultrasound (HIFU treatment.” We present a case of CVF due to HIFU treatment of recurrent prostate cancer. The case was assessed with cystography completed with a pelvic CT scan—with MPR, MIP, and VR reconstruction—before emptying the bladder. Since the CT scan confirmed that the fistula involved solely the urethra and excluded even a minimal involvement of the bladder, it was possible to employ a conservative treatment by positioning a Foley catheter of monthly duration, in order to allow the urethra to rest. Still today, after 6 months, the patient is in a good clinical condition and has not shown yet signs of a recurrence of the fistula.

  3. Preliminary assessment of one-dimensional MR elastography for use in monitoring focused ultrasound therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Le [Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55905 (United States); Glaser, Kevin J [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States); Rouviere, Olivier [Department of GenitoUrinary Radiology, Hopital E Herriot, 5, place d' Arsonval, 69003 Lyon (France); Gorny, Krzysztof R [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States); Chen, Shigao [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States); Manduca, Armando [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States); Ehman, Richard L [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States); Felmlee, Joel P [Department of Radiology, Mayo Clinic College of Medicine, Mayo Clinic Foundation, 200 1st St. SW, Rochester, MN 55905, Rochester, MN 55905 (United States)

    2007-09-21

    The purpose of this work is to assess a fast technique that measures tissue stiffness and temperature during focused ultrasound thermal therapy (FUS). A one-dimensional (1D) MR elastography (MRE) pulse sequence was evaluated for the purpose of obtaining rapid measurements of thermally induced changes in tissue stiffness and temperature for monitoring FUS treatments. The accuracy of the 1D measurement was studied by comparing tissue displacements measured by 1D MRE with those measured by the well-established 2D MRE pulse sequence. The reproducibility of the 1D MRE measurement was assessed, in gel phantoms and ex vivo porcine tissue, for varied FUS intensity levels (31.5-199.9 W cm{sup -2}) and over a range of displacements at the focus (0.1-1 {mu}m). Temperature elevations in agarose gel phantoms were measured using 1D MRE and calibrated using fiberoptic-thermometer-based measurements. The 1D MRE displacement measurements are highly correlated with those obtained with the 2D technique (R{sup 2} = 0.88-0.93), indicating that 1D MRE can successfully measure tissue displacement. Ten repeated trials at each FUS power level yielded a minimum detectable displacement change of 0.2 {mu}m in phantoms and 0.4 {mu}m in tissue (at 95% confidence level). The 1D MRE temperature measurements correlated well with temperature changes measured simultaneously with fiberoptic thermometers (R{sup 2} = 0.97). The 1D MRE technique is capable of detecting tissue displacements as low as 0.4 {mu}m, which is an order of magnitude smaller than 5 {mu}m displacements expected during FUS therapy (Le et al 2005 AIP Conf. Proc.: Ther. Ultrasound 829 186-90). Additionally, 1D MRE was shown to provide adequate measurements of temperature elevations in tissue. These findings indicate that 1D MRE may be an effective tool for monitoring FUS treatments.

  4. Focused ultrasound solid-liquid extraction for the determination of organic biomarkers in beachrocks.

    Science.gov (United States)

    Blanco-Zubiaguirre, L; Arrieta, N; Iturregui, A; Martinez-Arkarazo, I; Olivares, M; Castro, K; Olazabal, M A; Madariaga, J M

    2015-11-01

    Beachrocks are consolidated coastal sedimentary formations resulting mainly from the relative rapid cementation of beach sediments by different calcium carbonate polymorphs. Although previous works have already studied the elemental composition and the mineral phases composing these cements, few of them have focused their attention on the organic matter present therein. This work describes an extraction methodology based on focused ultrasound solid-liquid extraction (FUSLE), followed by analysis using large volume injection (LVI) in a programmable temperature vaporizer (PTV) combined with gas chromatography-mass spectrometry (GC-MS) in order to determine organics such as polycyclic aromatic hydrocarbons (PAHs) and biomarkers (hopanes), which can increase and confirm the information obtained so far. This goal has been achieved after the optimization of the main parameters affecting the extraction procedure, such as, extraction solvent, FUSLE variables (amplitude, extraction time and pulse time) and also variables affecting the LVI-PTV (vent time, injection speed and cryo-focusing temperature). The developed method rendered results comparable to traditional extraction methods in terms of accuracy (77-109%) and repeatability (RSD<23%). Finally, the analyses performed over real beachrock samples from the Bay of Biscay (Northern Spain) revealed the presence of the 16 EPA priority PAHs, as well as some organic biomarkers which could increase the knowledge about such beachrock formation.

  5. Focused ultrasound of the pleural cavities and the pericardium by nurses after cardiac surgery.

    Science.gov (United States)

    Graven, Torbjørn; Wahba, Alexander; Hammer, Anne Marie; Sagen, Ove; Olsen, Øystein; Skjetne, Kyrre; Kleinau, Jens Olaf; Dalen, Havard

    2015-02-01

    We aimed to study the feasibility and reliability of focused ultrasound (US) examinations to quantify pericardial (PE)- and pleural effusion (PLE) by a pocket-size imaging device (PSID) performed by nurses in patients early after cardiac surgery. After a 3-month training period, with cardiologists as supervisors, two nurses examined 59 patients (20 women) with US using a PSID at a median of 5 days after cardiac surgery. The amount of PE and PLE was classified in four categories by US (both) and chest x-ray (PLE only). Echocardiography, including US of the pleural cavities, by experienced cardiologists was used as reference. Focused US by the nurses was more sensitive than x-ray to detect PLE. The correlations of the quantification of PE and PLE by the nurses and reference was r (95% confidence interval) 0.76 (0.46-0.89) and 0.81 (0.73-0.89), both p nurses. Cardiac nurses were able to obtain reliable measurements and quantification of both PE and PLE bedside by focused US and outperform the commonly used chest x-ray regarding PLE after cardiac surgery.

  6. Ultrasound

    Science.gov (United States)

    ... Saunders; 2014:chap 66. Cosgrove DO, Eckersley RJ, Harvey CJ, Lim A. Ultrasound. In: Adam A, Dixon AK, Gillard ... Northside Radiology Associates, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the ...

  7. A beamforming study for implementation of vibro-acoustography with a 1.75-D array transducer.

    Science.gov (United States)

    Urban, Matthew W; Chalek, Carl; Haider, Bruno; Thomenius, Kai E; Fatemi, Mostafa; Alizad, Azra

    2013-03-01

    Vibro-acoustography (VA) is an ultrasound-based imaging modality that uses radiation force produced by two cofocused ultrasound beams separated by a small frequency difference, Δf, to vibrate tissue at Δf. An acoustic field is created by the object vibration and measured with a nearby hydrophone. This method has recently been implemented on a clinical ultrasound system using 1-D linear-array transducers. In this article, we discuss VA beamforming and image formation using a 1.75-D array transducer. A 1.75-D array transducer has several rows of elements in the elevation direction which can be controlled independently for focusing. The advantage of the 1.75-D array over a 1-D linear-array transducer is that multiple rows of elements can be used for improving elevation focus for imaging formation. Six configurations for subaperture design for the two ultrasound beams necessary for VA imaging were analyzed. The point-spread functions for these different configurations were evaluated using a numerical simulation model. Four of these configurations were then chosen for experimental evaluation with a needle hydrophone as well as for scanning two phantoms. Images were formed by scanning a urethane breast phantom and an ex vivo human prostate. VA imaging using a 1.75-D array transducer offers several advantages over scanning with a linear-array transducer, including improved image resolution and contrast resulting from better elevation focusing of the imaging point-spread function.

  8. A Beamforming Study for Implementation of Vibro-acoustography with a 1.75D Array Transducer

    Science.gov (United States)

    Urban, Matthew W.; Chalek, Carl; Haider, Bruno; Thomenius, Kai E.; Fatemi, Mostafa; Alizad, Azra

    2013-01-01

    Vibro-acoustography (VA) is an ultrasound-based imaging modality that uses radiation force produced by two cofocused ultrasound beams separated by a small frequency difference, Δf, to vibrate tissue at Δf. An acoustic field is created by the object vibration and measured with a nearby hydrophone. This method has recently been implemented on a clinical ultrasound system using one-dimensional (1D) linear array transducers. In this article, we discuss VA beamforming and image formation using a 1.75D array transducer. A 1.75D array transducer has several rows of elements in the elevation direction which can be controlled independently for focusing. The advantage of the 1.75D array over a 1D linear array transducer is that multiple rows of elements can be used for improving elevation focus for imaging formation. Six configurations for subaperture design for the two ultrasound beams necessary for VA imaging were analyzed. The point-spread functions for these different configurations were evaluated using a numerical simulation model. Four of these configurations were then chosen for experimental evaluation with a needle hydrophone as well as for scanning two phantoms. Images were formed by scanning a urethane breast phantom and an ex vivo human prostate. VA imaging using a 1.75D array transducer offers several advantages over scanning with a linear array transducer including improved image resolution and contrast due to better elevation focusing of the imaging point-spread function. PMID:23475919

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

    Science.gov (United States)

    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

  10. Computation of acoustic ressure fields produced in feline brain by high-intensity focused ultrasound

    Science.gov (United States)

    Omidi, Nazanin

    In 1975, Dunn et al. (JASA 58:512-514) showed that a simple relation describes the ultrasonic threshold for cavitation-induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during those experimental exposures by estimating them using nonlinear rather than linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted, with the compressional amplitude of the wave becoming greater, and the rarefactional amplitude becoming lower than the values calculated using linear theory. The implications of these results for clinical exposures are discussed.

  11. Focused ultrasound simultaneous irradiation/MRI imaging, and two-stage general kinetic model.

    Directory of Open Access Journals (Sweden)

    Sheng-Yao Huang

    Full Text Available Many studies have investigated how to use focused ultrasound (FUS to temporarily disrupt the blood-brain barrier (BBB in order to facilitate the delivery of medication into lesion sites in the brain. In this study, through the setup of a real-time system, FUS irradiation and injections of ultrasound contrast agent (UCA and Gadodiamide (Gd, an MRI contrast agent can be conducted simultaneously during MRI scanning. By using this real-time system, we were able to investigate in detail how the general kinetic model (GKM is used to estimate Gd penetration in the FUS irradiated area in a rat's brain resulting from UCA concentration changes after single FUS irradiation. Two-stage GKM was proposed to estimate the Gd penetration in the FUS irradiated area in a rat's brain under experimental conditions with repeated FUS irradiation combined with different UCA concentrations. The results showed that the focal increase in the transfer rate constant of Ktrans caused by BBB disruption was dependent on the doses of UCA. Moreover, the amount of in vivo penetration of Evans blue in the FUS irradiated area in a rat's brain under various FUS irradiation experimental conditions was assessed to show the positive correlation with the transfer rate constants. Compared to the GKM method, the Two-stage GKM is more suitable for estimating the transfer rate constants of the brain treated with repeated FUS irradiations. This study demonstrated that the entire process of BBB disrupted by FUS could be quantitatively monitored by real-time dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI.

  12. Short-duration-focused ultrasound stimulation of Hsp70 expression in vivo

    Science.gov (United States)

    Kruse, D. E.; Mackanos, M. A.; O'Connell-Rodwell, C. E.; Contag, C. H.; Ferrara, K. W.

    2008-07-01

    The development of transgenic reporter mice and advances in in vivo optical imaging have created unique opportunities to assess and analyze biological responses to thermal therapy directly in living tissues. Reporter mice incorporating the regulatory regions from the genes encoding the 70 kDa heat-shock proteins (Hsp70) and firefly luciferase (luc) as reporter genes can be used to non-invasively reveal gene activation in living tissues in response to thermal stress. High-intensity-focused ultrasound (HIFU) can deliver measured doses of acoustic energy to highly localized regions of tissue at intensities that are sufficient to stimulate Hsp70 expression. We report activation of Hsp70-luc expression using 1 s duration HIFU heating to stimulate gene expression in the skin of the transgenic reporter mouse. Hsp70 expression was tracked for 96 h following the application of 1.5 MHz continuous-wave ultrasound with spatial peak intensities ranging from 53 W cm-2 up to 352 W cm-2. The results indicated that peak Hsp70 expression is observed 6-48 h post-heating, with significant activity remaining at 96 h. Exposure durations were simulated using a finite-element model, and the predicted temperatures were found to be consistent with the observed Hsp70 expression patterns. Histological evaluation revealed that the thermal damage starts at the stratum corneum and extends deeper with increasing intensity. These results indicated that short-duration HIFU may be useful for inducing heat-shock expression, and that the period between treatments needs to be greater than 96 h due to the protective properties of Hsp70.

  13. Short-duration-focused ultrasound stimulation of Hsp70 expression in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Kruse, D E; Ferrara, K W [Department of Biomedical Engineering, University of California, Davis, CA 95616 (United States); Mackanos, M A; O' Connell-Rodwell, C E; Contag, C H [Stanford University School of Medicine, Stanford, CA 94305 (United States)], E-mail: dekruse@ucdavis.edu, E-mail: kwferrara@ucdavis.edu, E-mail: mackanos@stanford.edu, E-mail: ceoconnell@stanford.edu, E-mail: ccontag@stanford.edu

    2008-07-07

    The development of transgenic reporter mice and advances in in vivo optical imaging have created unique opportunities to assess and analyze biological responses to thermal therapy directly in living tissues. Reporter mice incorporating the regulatory regions from the genes encoding the 70 kDa heat-shock proteins (Hsp70) and firefly luciferase (luc) as reporter genes can be used to non-invasively reveal gene activation in living tissues in response to thermal stress. High-intensity-focused ultrasound (HIFU) can deliver measured doses of acoustic energy to highly localized regions of tissue at intensities that are sufficient to stimulate Hsp70 expression. We report activation of Hsp70-luc expression using 1 s duration HIFU heating to stimulate gene expression in the skin of the transgenic reporter mouse. Hsp70 expression was tracked for 96 h following the application of 1.5 MHz continuous-wave ultrasound with spatial peak intensities ranging from 53 W cm{sup -2} up to 352 W cm{sup -2}. The results indicated that peak Hsp70 expression is observed 6-48 h post-heating, with significant activity remaining at 96 h. Exposure durations were simulated using a finite-element model, and the predicted temperatures were found to be consistent with the observed Hsp70 expression patterns. Histological evaluation revealed that the thermal damage starts at the stratum corneum and extends deeper with increasing intensity. These results indicated that short-duration HIFU may be useful for inducing heat-shock expression, and that the period between treatments needs to be greater than 96 h due to the protective properties of Hsp70.

  14. High-intensity focused ultrasound sonothrombolysis: the use of perfluorocarbon droplets to achieve clot lysis at reduced acoustic power.

    Science.gov (United States)

    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.

  15. Ultrasound physics.

    Science.gov (United States)

    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.

  16. Simulation of high-intensity focused ultrasound lesions in presence of boiling.

    Science.gov (United States)

    Grisey, Anthony; Yon, Sylvain; Letort, Véronique; Lafitte, Pauline

    2016-01-01

    The lesions induced by high-intensity focused ultrasound (HIFU) thermal ablations are particularly difficult to simulate due to the complexity of the involved phenomena. In particular, boiling has a strong influence on the lesion shape. Thus, it must be accounted for if it happens during the pulses to be modeled. However, no acoustic model enables the simulation of the resulting wave scattering. Therefore, we propose an equivalent model for the heat deposition pattern in the presence of boiling. Firstly, the acoustic field is simulated with k-Wave and the heat source term is calculated. Then, a thermal model is designed, including the equivalent model for boiling. It is rigorously calibrated and validated through the use of diversified ex vivo and in vivo data, including usually unexploited data types related to the bubble clouds. The proposed model enabled to efficiently simulate unitary pulses properties, including the sizes of the lesions, their morphology, the boiling onset time, and the influence of the boiling onset time on the lesions sizes. In this article, the whole procedure of model design, calibration, and validation is discussed. In addition to depicting the creative use of data, our modeling approach focuses on the understanding of the mechanisms influencing the shape of the lesion. Further work is required to study the influence of the remaining bubble clouds in the context of pulse groups.

  17. Focused cardiac ultrasound is feasible in the general practice setting and alters diagnosis and management of cardiac disease

    Directory of Open Access Journals (Sweden)

    James Yates

    2016-08-01

    Full Text Available Background: Ultrasound-assisted examination of the cardiovascular system with focused cardiac ultrasound by the treating physician is non-invasive and changes diagnosis and management of patient’s with suspected cardiac disease. This has not been reported in a general practice setting. Aim: To determine whether focused cardiac ultrasound performed on patients aged over 50 years changes the diagnosis and management of cardiac disease by a general practitioner. Design and setting: A prospective observational study of 80 patients aged over 50 years and who had not received echocardiography or chest CT within 12 months presenting to a general practice. Method: Clinical assessment and management of significant cardiac disorders in patients presenting to general practitioners were recorded before and after focused cardiac ultrasound. Echocardiography was performed by a medical student with sufficient training, which was verified by an expert. Differences in diagnosis and management between conventional and ultrasound-assisted assessment were recorded. Results and conclusion: Echocardiography and interpretation were acceptable in all patients. Significant cardiac disease was detected in 16 (20% patients, including aortic stenosis in 9 (11% and cardiac failure in 7 (9%, which were missed by clinical examination in 10 (62.5% of these patients. Changes in management occurred in 12 patients (15% overall and 75% of those found to have significant cardiac disease including referral for diagnostic echocardiography in 8 (10%, commencement of heart failure treatment in 3 (4% and referral to a cardiologist in 1 patient (1%. Routine focused cardiac ultrasound is feasible and frequently alters the diagnosis and management of cardiac disease in patients aged over 50 years presenting to a general practice.

  18. Low-intensity focused ultrasound (LIFU-induced acoustic droplet vaporization in phase-transition perfluoropentane nanodroplets modified by folate for ultrasound molecular imaging

    Directory of Open Access Journals (Sweden)

    Liu J

    2017-01-01

    Full Text Available Jianxin Liu,1,* Tingting Shang,1,* Fengjuan Wang,1 Yang Cao,1 Lan Hao,1 JianLi Ren,1,2 Haitao Ran,1,2 Zhigang Wang,1,2 Pan Li,1,2 Zhiyu Du3 1Chongqing Key Laboratory of Ultrasound Molecular Imaging, 2Department of Ultrasound, 3Postgraduate Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China *These authors contributed equally to this work Abstract: The commonly used ultrasound (US molecular probes, such as targeted microbubbles and perfluorocarbon emulsions, present a number of inherent problems including the conflict between US visualization and particle penetration. This study describes the successful fabrication of phase changeable folate-targeted perfluoropentane nanodroplets (termed FA-NDs, a novel US molecular probe for tumor molecular imaging with US. Notably, these FA-NDs can be triggered by low-intensity focused US (LIFU sonication, providing excellent US enhancement in B-mode and contrast-enhanced US mode in vitro. After intravenous administration into nude mice bearing SKOV3 ovarian carcinomas, 1,1'-dioctadecyl-3,3,3',3' -tetramethylindotricarbocyanine iodide-labeled FA-NDs were found to accumulate in the tumor region. FA-NDs injection followed by LIFU sonication exhibited remarkable US contrast enhancement in the tumor region. In conclusion, combining our elaborately developed FA-NDs with LIFU sonication provides a potential protocol for US molecular imaging in folate receptor-overexpressing tumors. Keywords: low-intensity focused ultrasound, perfluoropentane nanodroplets, acoustic droplet vaporization, ultrasound molecular imaging, targeting

  19. Frequency dependence of the acoustic field generated from a spherical cavity transducer with open ends

    Energy Technology Data Exchange (ETDEWEB)

    Li, Faqi; Zeng, Deping; He, Min; Wang, Zhibiao, E-mail: dzhang@nju.edu.cn, E-mail: wangzhibiao@haifu.com.cn [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, Chongqing 401121 (China); Song, Dan; Lei, Guangrong [National Engineering Research Center of Ultrasound Medicine, Chongqing 401121 (China); Lin, Zhou; Zhang, Dong, E-mail: dzhang@nju.edu.cn, E-mail: wangzhibiao@haifu.com.cn [Institute of Acoustics, Key Laboratory of Modern Acoustics, MOE, Nanjing University, Nanjing 210093 (China); Wu, Junru [Department of Physics, University of Vermont, Burlington, VT 05405 (United States)

    2015-12-15

    Resolution of high intensity focused ultrasound (HIFU) focusing is limited by the wave diffraction. We have developed a spherical cavity transducer with two open ends to improve the focusing precision without sacrificing the acoustic intensity (App Phys Lett 2013; 102: 204102). This work aims to theoretically and experimentally investigate the frequency dependence of the acoustic field generated from the spherical cavity transducer with two open ends. The device emits high intensity ultrasound at the frequency ranging from 420 to 470 kHz, and the acoustic field is measured by a fiber optic probe hydrophone. The measured results shows that the spherical cavity transducer provides high acoustic intensity for HIFU treatment only in its resonant modes, and a series of resonant frequencies can be choosen. Furthermore, a finite element model is developed to discuss the frequency dependence of the acoustic field. The numerical simulations coincide well with the measured results.

  20. Histopathology of breast cancer after magnetic resonance-guided high-intensity focused ultrasound and radiofrequency ablation

    NARCIS (Netherlands)

    Knuttel, Floor; Waaijer, Laurien; Merckel, LG; van den Bosch, Maurice A A J; Witkamp, Arjen J.; Deckers, Roel; van Diest, Paul J.

    AIMS: Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation and radiofrequency ablation (RFA) are being researched as possible substitutes for surgery in breast cancer patients. The histopathological appearance of ablated tissue has not been studied in great detail. This

  1. MRI methods for the evaluation of high intensity focused ultrasound tumor treatment : Current status and future needs

    NARCIS (Netherlands)

    Hectors, Stefanie J C G; Jacobs, Igor; Moonen, Chrit T W; Strijkers, Gustav J; Nicolay, Klaas

    2016-01-01

    Thermal ablation with high intensity focused ultrasound (HIFU) is an emerging noninvasive technique for the treatment of solid tumors. HIFU treatment of malignant tumors requires accurate treatment planning, monitoring and evaluation, which can be facilitated by performing the procedure in an MR-gui

  2. Magnetic resonance-guided focused ultrasound surgery for the noninvasive curative ablation of tumors and palliative treatments: a review.

    Science.gov (United States)

    Kopelman, Doron; Papa, Moshe

    2007-05-01

    This article reviews and discusses the up-to-date data on and feasibility of focused ultrasound surgery. This technique uses high-energy ultrasound beams that can be directed to penetrate through the skin and various soft tissues, focus on the target, and destroy tumors by increasing the temperature at the targeted tissue volume. The boundaries of the treatment area are sharply demarcated (focused) without causing damage to the surrounding organs. Although the idea of using sound waves to ablate tumors was first demonstrated in the 1940 s, only recent developments have enabled this technology to become more controlled and, hence, more feasible. The major breakthrough toward its clinical use came with coupling the thermal ablative process to advanced imaging. The development of magnetic resonance as the foundation to guide and evaluate the end results of focused ultrasound surgery treatment, the image guidance of the ultrasound beam, and the development of a reliable method for tissue temperature measurement and real-time feedback of the extent of tissue destruction have pushed this novel technology forward in oncological practice.

  3. Efficacy of Magnetic Resonance-guided Focused Ultrasound Surgery for Bone Metastases Pain Palliation

    Science.gov (United States)

    Kawasaki, Motohiro; Nanba, Hirofumi; Kato, Tomonari; Tani, Toshikazu; Ushida, Takahiro

    2011-09-01

    Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is a novel treatment method that achieves non-invasive thermal ablation by focusing many ultrasound waves on a target tissue with real-time monitoring of the location and temperature of the target during the procedure. We investigated the palliative effect on pain and safety of MRgFUS in painful bone metastases. Six patients (mean age, 65.8 years) who met eligibility criteria for the clinical study approved by our Institutional Ethics Committee based on the cooperative protocol were treated with MRgFUS. Targeted sites included the sacrum (n = 1), ilium (n = 2), scapula (n = 2), and femur (n = 1). The mean follow-up period was 9.2 months. All procedures were performed as a single-session treatment using the treatment system that is integrated into the patient table of a magnetic resonance image (MRI) scanner. Endpoints were change in the intensity of pain due to bone metastases from before to after the treatment, as measured on a numerical rating scale, pain interference with daily activities as determined by the Brief pain inventory (BPI), change in images, and safety. Pain relief was obtained in all patients early after treatment, with a reduction in the mean pain score from 6.0±1.3 at baseline to 1.2±1.0 at the end of follow-up as well as in pain interference with daily activities. The mean time required for a single-session treatment was 83.7±37.0 min, with a mean number of sonications required of 13.3±3.7 and mean energy applied of 846.4±273.5 J. No significant growth of tumors was observed, nor were there treatment-related adverse events. These results suggest that MRgFUS has a non-invasive palliative effect on the localized pain in patients with bone metastasis. MRgFUS could become an option in treatment strategies for painful bone metastases in the future.

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

    Science.gov (United States)

    2012-09-01

    the observed enhancement are not well understood. It is thought mainly due to the nonthermal effects of ultrasound —mechanical streaming and cavitation ...AD ________________ Award Number: W81XWH-08-1-0469 TITLE: MR Guided Pulsed High Intensity Focused Ultrasound Enhancement of (Enter title of award...Intensity Focused Ultrasound Enhancement of 5b. GRANT NUMBER Gene Therapy Combined with Androgen Deprivation and Radiotherapy W81XWH-08-1-0469 for Prostate

  5. Non-thermal ablation of rabbit liver VX2 tumor by pulsed high intensity focused ultrasound with ultrasound contrast agent: Pathological characteristics

    Institute of Scientific and Technical Information of China (English)

    Cheng-Wen Zhou; Fa-Qi Li; Yan Qin; Chun-Mei Liu; Xiao-Lin Zheng; Zhi-Biao Wang

    2008-01-01

    AIM:To investigate the pathological characteristics of non-thermal damage induced by pulsed high intensity focused ultrasound (PHIFU) combined with ultrasound contrast agent (UCA),SonoVue (Bracco SpA,Milan,Italy) in rabbit liver VX2 tumor.METHODS:Liver VX2 tumor models were established in 20 rabbits,which were divided randomly into PHIFU combined with ultrasound contrast agent group (PHIFU + UCA group) and sham group.In the PHIFU + UCA group,0.2 mL of SonoVue was injected intravenously into the tumor,followed by ultrasound exposure of Isp 5900 W/cm2.The rabbits were sacrificed one day after ultrasound exposure.Specimens of the exposed tumor tissues were obtained and observed pathologically under light microscope and transmission electron microscope.The remaining tumor tissues were sent for 2,3,5-Triphenyltetrazolium chloride (TTC) staining.RESULTS:Before TTC staining,tumor tissues in both the sham and the PHIFU + UCA groups resembled gray fish meat.After TTC staining,the tumor tissues were uniformly stained red,with a clear boundary between tumor tissue and normal tissue.Histological examination showed signs of tumor cell injury in PHIFU + UCA group,with cytoplasmic vacuoles of various sizes,chromatin margination and karyopyknosis.Electron microscopic examination revealed tumor cell volume reduction,karyopyknosis,chromatin margination,intercellular space widening,the presence of high electron-density apoptotic bodies and vacuoles in cytoplasm.CONCLUSION:The non-thermal effects of PHIFU combined with UCA can be used to ablate rabbit liver VX2 tumors.

  6. Magnetic resonance imaging for the exploitation of bubble-enhanced heating by high-intensity focused ultrasound: a feasibility study in ex vivo liver.

    Science.gov (United States)

    Elbes, Delphine; Denost, Quentin; Robert, Benjamin; Köhler, Max O; Tanter, Mickaël; Bruno, Quesson

    2014-05-01

    Bubble-enhanced heating (BEH) may be exploited to improve the heating efficiency of high-intensity focused ultrasound in liver and to protect tissues located beyond the focal point. The objectives of this study, performed in ex vivo pig liver, were (i) to develop a method to determine the acoustic power threshold for induction of BEH from displacement images measured by magnetic resonance acoustic radiation force imaging (MR-ARFI), and (ii) to compare temperature distribution with MR thermometry for HIFU protocols with and without BEH. The acoustic threshold for generation of BEH was determined in ex vivo pig liver from MR-ARFI calibration curves of local tissue displacement resulting from sonication at different powers. Temperature distributions (MR thermometry) resulting from "conventional" sonications (20 W, 30 s) were compared with those from "composite" sonications performed at identical parameters, but after a HIFU burst pulse (0.5 s, acoustic power over the threshold for induction of BEH). Displacement images (MR-ARFI) were acquired between sonications to measure potential modifications of local tissue displacement associated with modifications of tissue acoustic characteristics induced by the burst HIFU pulse. The acoustic threshold for induction of BEH corresponded to a displacement amplitude of approximately 50 μm in ex vivo liver. The displacement and temperature images of the composite group exhibited a nearly spherical pattern, shifted approximately 4 mm toward the transducer, in contrast to elliptical shapes centered on the natural focal position for the conventional group. The gains in maximum temperature and displacement values were 1.5 and 2, and the full widths at half-maximum of the displacement data were 1.7 and 2.2 times larger than in the conventional group in directions perpendicular to ultrasound propagation axes. Combination of MR-ARFI and MR thermometry for calibration and exploitation of BEH appears to increase the efficiency and safety

  7. Complications of high intensity focused ultrasound in patients with recurrent and metastatic abdominal tumors

    Institute of Scientific and Technical Information of China (English)

    Jian-Jun Li; Guo-Liang Xu; Mo-Fa Gu; Guang-Yu Luo; Zhang Rong; Pei-Hong Wu; Jian-Chuan Xia

    2007-01-01

    AIM: To analyze the local and systemic complications of high intensity focused ultrasound (HIFU) for patients with recurrent and metastatic abdominal tumors.METHODS: From Aug 2001 to Aug 2004, 17 patients with recurrent and metastatic abdominal tumors were enrolled in this study. Real-time sonography was taken, and vital signs, liver and kidney function, skin burns, local reactions, and systemic effects were observed and recored before, during, and after HIFU. CT and MRI were also taken before and after HIFU.RESULTS: All 17 patients had skin burns and pAln in the treatment region; the next common complication was neurapraxia of the stomach and intestines to variable degrees. The other local and systemic complications were relatively rare. Severe complications were present in two patients; one developed a superior mesenteric artery infarction resulting in necrosis of the entire small intestines, and the other one suffered from a perforation in terminal ileum due to HIFU treatment.CONCLUSION: Although HIFU is a one of noninvasive treatments for the recurrent and metastatic abdominal tumors, there are still some common and severe complications which need serious consideration.

  8. PATHOMORPHISM OF PROSTATE CANCER DURING HIGH-INTENSITY FOCUSED ULTRASOUND TREATMENT

    Directory of Open Access Journals (Sweden)

    R. N. Fomkin

    2014-07-01

    Full Text Available The purpose of the study was to evaluate the efficiency of prostate cancer (PC treatment using high-intensity focused ultrasound (HIFU on the basis of morphometric and immunohistochemical (IHC analyses of postoperative prostate biopsy specimens. The study subjects were 40 patients with localized and locally advanced PC. The postoperative morphological analysis was made on the basis of standard hematoxylineosin staining and morphometric and IHC studies using the following antibodies: PCNA, Bcl-2, AMACR, Е-cadherin, and ANDR (Dako. Pre- and post-HIFU therapy histological examination of the routinely hematoxylin-eosin-stained specimens showed that the therapeutic pathomorphism of the tumor corresponded to grades III and IV. It was established that the IHC study should be used as an additional crite-rion for the efficiency of PC therapy after HIFU ablation. In spite of positive clinical, laboratory, instrumental, and objective changes, the patients with high AMACR and Bcl-2 levels and decreased Е-cadherin expression may be considered as a group at risk for prolonged malignant growth or recurrent PC.

  9. Focused ultrasound-mediated sonochemical internalization: an alternative to light-based therapies

    Science.gov (United States)

    Gonzales, Jonathan; Nair, Rohit Kumar; Madsen, Steen J.; Krasieva, Tatiana; Hirschberg, Henry

    2016-07-01

    Activation of sonosensitizers via focused ultrasound (FUS), i.e., sonodynamic therapy has been proposed as an extension to light-activated photodynamic therapy for the treatment of brain as well as other tumors. The use of FUS, as opposed to light, allows treatment to tumor sites buried deep within tissues as well as through the intact skull. We have examined ultrasonic activation of sonosensitizers together with the anticancer agent bleomycin (BLM), i.e., sonochemical internalization (SCI). SCI is a technique that utilizes FUS for the enhanced delivery of endo-lysosomal trapped macromolecules into the cell cytoplasm in a similar manner to light-based photochemical internalization. The released agent can, therefore, exert its full biological activity, in contrast to being degraded by lysosomal hydrolases. Our results indicate that, compared to drug or FUS treatment alone, FUS activation of the sonosensitizer AlPcS2a together with BLM significantly inhibits the ability of treated glioma cells to grow as three-dimensional tumor spheroids in vitro.

  10. Focused ultrasound-enhanced intranasal brain delivery of brain-derived neurotrophic factor

    Science.gov (United States)

    Chen, Hong; Yang, Georgiana Zong Xin; Getachew, Hoheteberhan; Acosta, Camilo; Sierra Sánchez, Carlos; Konofagou, Elisa E.

    2016-06-01

    The objective of this study was to unveil the potential mechanism of focused ultrasound (FUS)-enhanced intranasal (IN) brain drug delivery and assess its feasibility in the delivery of therapeutic molecules. Delivery outcomes of fluorescently-labeled dextrans to mouse brains by IN administration either before or after FUS sonication were compared to evaluate whether FUS enhances IN delivery by active pumping or passive diffusion. Fluorescence imaging of brain slices found that IN administration followed by FUS sonication achieved significantly higher delivery than IN administration only, while pre-treatment by FUS sonication followed by IN administration was not significantly different from IN administration only. Brain-derived neurotrophic factor (BDNF), a promising neurotrophic factor for the treatment of many central nervous system diseases, was delivered by IN followed by FUS to demonstrate the feasibility of this technique and compared with the established FUS technique where drugs are injected intravenously. Immunohistochemistry staining of BDNF revealed that FUS-enhanced IN delivery achieved similar locally enhanced delivery as the established FUS technique. This study suggested that FUS enhances IN brain drug delivery by FUS-induced active pumping of the drug and demonstrated that FUS-enhanced IN delivery is a promising technique for noninvasive and localized delivery of therapeutic molecules to the brain.

  11. Electrophysiological Changes Correlated with Temperature Increases Induced by High-Intensity Focused Ultrasound Ablation

    Science.gov (United States)

    Wu, Z.; Kumon, R. E.; Laughner, J. I.; Efimov, I. R.; Deng, C. X.

    2014-01-01

    To gain better understanding of the detailed mechanisms of high-intensity focused ultrasound (HIFU) ablation for cardiac arrhythmias, we investigated how the cellular electrophysiological (EP) changes were correlated with temperature increases and thermal dose (cumulative equivalent minutes [CEM43]) during HIFU application using Langendorff-perfused rabbit hearts. Employing voltage-sensitive dye di-4-ANEPPS, we measured the EP and temperature during HIFU using simultaneous optical mapping and infrared imaging. Both action potential amplitude (APA) and AP duration at 50% repolarization (APD50) decreased with temperature increases, and APD50 was more thermally sensitive than APA. EP and tissue changes were irreversible when HIFU-induced temperature increased above 52.3 ± 1.4 °C and log10(CEM43) above 2.16 ± 0.51 (n = 5), but were reversible when temperature was below 50.1 ± 0.8 °C and log10(CEM43) below −0.9 ± 0.3 (n = 9). EP and temperature/thermal dose changes were spatially correlated with HIFU induced tissue necrosis surrounded by a transition zone. PMID:25516446

  12. Analgesic effect of high intensity focused ultrasound in patients with advanced pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    Xinjin Tan; Jian Chen; Li Ren; Ruilu Lin; Zailian Chen

    2013-01-01

    Objective:The aim of this study was to evaluate the analgesic ef ect of high intensity focused ultrasound (HIFU) in patients with advanced pancreatic cancer. Methods:A total of 106 patients with advanced pancreatic cancer accompanied by abdominal pain were treated by HIFU. Pain intensities and quantities of morphine consumption before and after treatment were observed and compared. Results:The average pain intensities before treatment, and at d3, d7 after treatment were 5.80 ± 2.14, 2.73 ± 2.68, 2.45 ± 2.43 respectively (P<0.01). Fifty-nine cases (55.7%) got to extremely ef ective, and 29 cases (27.4%) ef ective. Total ef icient rate was 83.0%. The average quantities of morphine consumption before and after treatment in the patients with grade III pain were 114.9 ± 132.5 mg, 16.8 ± 39.7 mg each person everyday respectively (P<0.01). Conclusion:HIFU can relieve pain suf ered by patients with pancreatic cancer ef ectively. It is a new adjuvant treatment for pancreatic cancer pain.

  13. High-Intensity Focused Ultrasound for Prostate Cancer: Long-Term Followup and Complications Rate

    Directory of Open Access Journals (Sweden)

    Umberto Maestroni

    2012-01-01

    Full Text Available Introduction. As it is well known, High Intensity Focused Ultrasound (HIFU is a minimally invasive procedure for prostate cancer. Many investigators reported their series of patients, demonstrating the effectiveness of the treatment. The most majority of Authors, however, do not report the side effects and the complications of the procedure, which is the aim of our study. The diagnosis and management of complications is discussed, and the oncologic outcome is reported in terms of quality of life. Materials and Methods. We report our experience in 89 patients, low-, intermediate-, and high-risk patients according with D’Amico classification. All data collected along the study were analyzed, including side effects and complications of the procedure. Results. Our series demonstrates the effectiveness of the procedure, in line with larger series reported in literature by other investigators. The most important side effects are sexual function impairment and transient incontinence in a minority of cases. Minor complications are reported as well as rare cases of major complications, which can require surgical treatment.

  14. Non-invasive cardiac pacing with image-guided focused ultrasound

    Science.gov (United States)

    Marquet, Fabrice; Bour, Pierre; Vaillant, Fanny; Amraoui, Sana; Dubois, Rémi; Ritter, Philippe; Haïssaguerre, Michel; Hocini, Mélèze; Bernus, Olivier; Quesson, Bruno

    2016-11-01

    Currently, no non-invasive cardiac pacing device acceptable for prolonged use in conscious patients exists. High Intensity Focused Ultrasound (HIFU) can be used to perform remote pacing using reversibility of electromechanical coupling of cardiomyocytes. Here we described an extracorporeal cardiac stimulation device and study its efficacy and safety. We conducted experiments ex vivo and in vivo in a large animal model (pig) to evaluate clinical potential of such a technique. The stimulation threshold was determined in 10 different ex vivo hearts and different clinically relevant electrical effects such as consecutive stimulations of different heart chambers with a single ultrasonic probe, continuous pacing or the inducibility of ventricular tachycardia were shown. Using ultrasonic contrast agent, consistent cardiac stimulation was achievable in vivo for up to 1 hour sessions in 4 different animals. No damage was observed in inversion-recovery MR sequences performed in vivo in the 4 animals. Histological analysis revealed no differences between stimulated and control regions, for all ex vivo and in vivo cases.

  15. Tracking Perfluorocarbon Nanoemulsion Delivery by 19F MRI for Precise High Intensity Focused Ultrasound Tumor Ablation

    Science.gov (United States)

    Shin, Soo Hyun; Park, Eun-Joo; Min, Changki; Choi, Sun Il; Jeon, Soyeon; Kim, Yun-Hee; Kim, Daehong

    2017-01-01

    Perfluorocarbon nanoemulsions (PFCNEs) have recently been undergoing rigorous study to investigate their ability to improve the therapeutic efficacy of tumor ablation by high intensity focused ultrasound (HIFU). For precise control of PFCNE delivery and thermal ablation, their accumulation and distribution in a tumor should be quantitatively analyzed. Here, we used fluorine-19 (19F) magnetic resonance imaging (MRI) to quantitatively track PFCNE accumulation in a tumor, and analyzed how intra-tumoral PFCNE quantities affect the therapeutic efficacy of HIFU treatment. Ablation outcomes were assessed by intra-voxel incoherent motion analysis and bioluminescent imaging up to 14 days after the procedure. Assessment of PFCNE delivery and treatment outcomes showed that 2-3 mg/mL of PFCNE in a tumor produces the largest ablation volume under the same HIFU insonation conditions. Histology showed varying degrees of necrosis depending on the amount of PFCNE delivered. 19F MRI promises to be a valuable platform for precisely guiding PFCNE-enhanced HIFU ablation of tumors. PMID:28255351

  16. Magnetic resonance imaging of boiling induced by high intensity focused ultrasound.

    Science.gov (United States)

    Khokhlova, Tatiana D; Canney, Michael S; Lee, Donghoon; Marro, Kenneth I; Crum, Lawrence A; Khokhlova, Vera A; Bailey, Michael R

    2009-04-01

    Both mechanically induced acoustic cavitation and thermally induced boiling can occur during high intensity focused ultrasound (HIFU) medical therapy. The goal was to monitor the temperature as boiling was approached using magnetic resonance imaging (MRI). Tissue phantoms were heated for 20 s in a 4.7-T magnet using a 2-MHz HIFU source with an aperture and radius of curvature of 44 mm. The peak focal pressure was 27.5 MPa with corresponding beam width of 0.5 mm. The temperature measured in a single MRI voxel by water proton resonance frequency shift attained a maximum value of only 73 degrees C after 7 s of continuous HIFU exposure when boiling started. Boiling was detected by visual observation, by appearance on the MR images, and by a marked change in the HIFU source power. Nonlinear modeling of the acoustic field combined with a heat transfer equation predicted 100 degrees C after 7 s of exposure. Averaging of the calculated temperature field over the volume of the MRI voxel (0.3 x 0.5 x 2 mm(3)) yielded a maximum of 73 degrees C that agreed with the MR thermometry measurement. These results have implications for the use of MRI-determined temperature values to guide treatments with clinical HIFU systems.

  17. Does the phase of menstrual cycle affect MR-guided focused ultrasound surgery of uterine leiomyomas?

    Energy Technology Data Exchange (ETDEWEB)

    So, Minna J. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Fennessy, Fiona M. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Zou, Kelly H. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); McDannold, Nathan [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Hynynen, Kullervo [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Jolesz, Ferenc A. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Stewart, Elizabeth A. [Department of Obstetrics and Gynecology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Rybicki, Frank J. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States); Tempany, Clare M. [Department of Radiology, Brigham and Women' s Hospital/Harvard Medical School, Boston, MA (United States)]. E-mail: ctempanyafdhal@partners.org

    2006-08-15

    Purpose: To determine whether the phase of menstrual cycle at the time of MR-guided focused ultrasound surgery (MRgFUS) treatment for uterine leiomyomas affects treatment outcome. Methods: We enrolled all patients participating in a prospective phase III clinical trial from our center who completed 6 months of clinical and imaging follow-up. Patients with irregular cycles and those on oral contraceptives were excluded. Data prospectively documenting the date of the last menstrual period (LMP) at the time of treatment, length and duration of cycle, and raw symptom severity score (SSS) from the Uterine Fibroid Symptom and Quality of Life questionnaire, at baseline and 6 months were collected. Proliferative phase patients were determined retrospectively as those who were treated within less than 14 days from LMP; secretory phase patients were classified as those who were treated greater than 14 days from LMP. Results: A total of 58 patients were enrolled. There was no significant difference in the mean SSS at baseline and mean SSS at 6 months between patients treated in the proliferative versus secretory phase of the cycle. No significant difference in the SSS change from baseline to 6 months was seen between the two groups. Conclusions: Menstrual cycle phase does not influence MRgFUS treatment outcome. Symptomatic improvement occurs with treatment during either phase of the menstrual cycle. Thus, the scheduling of MRgFUS treatment need not be based upon the phase of the menstrual cycle.

  18. MRI Guided Focused Ultrasound Thalamotomy for Moderate-to-Severe Tremor in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Ilana Schlesinger

    2015-01-01

    Full Text Available Background. Thalamotomy is effective in alleviating tremor in Parkinson’s disease (PD. Methods. Seven PD patients, mean age 59.4 ± 9.8 years (range, 46–74 with a mean disease duration of 5.4 ± 2.8 years (range, 2–10 suffering from severe refractory tremor, underwent ventral intermediate nucleus thalamotomy using MRI guided focused ultrasound (MRgFUS, an innovative technology that enables noninvasive surgery. Results. Tremor stopped in the contralateral upper extremity in all patients immediately following treatment. Total UPDRS decreased from 37.4 ± 12.2 to 18.8 ± 11.1 (p=0.007 and PDQ-39 decreased from 42.3 ± 16.4 to 21.6 ± 10.8 (p=0.008 following MRgFUS. These effects were sustained (mean follow-up 7.3 months. Adverse events during MRgFUS included headache (n=3, dizziness (n=2, vertigo (n=4, and lip paresthesia (n=1 and following MRgFUS were hypogeusia (n=1, unsteady feeling when walking (n=1, resolved, and disturbance when walking tandem (n=1, resolved. Conclusions. Thalamotomy using MRgFUS is safe and effective in PD patients. Large randomized studies are needed to assess prolonged efficacy and safety.

  19. Role of acoustic interface layer during high intensity focused ultrasound therapeutics

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    After interface layer was simulated by the magnetic nano-particles in the egg white phantom, high intensity focused ultrasound (HIFU) at the same dosage was introduced to radiate the phantom in different depths to blow the acoustic interface layer to mimic "point" exposure. The results showed that the volumes of biological focal region (BFR) were enlarged when the acoustic focal region (AFR) is close with interface layer. This meant that the magnetic nano-particles enhanced the therapeutic efficiency of HIFU. When the distance of the AFR from the interface layer was 10 mm, the size and shape of the BFR were similar with those of the control group, but a larger lesion at the interface, which was harmful for treatment, was observed. When the distance of the AFR to the interface layer increased to 30 mm, the size and shape of the BFR were also similar to those of the control group. When the thickness of the interface layer diminished, the utility of enhancement decreased. Continuous increase of the safe area for treatment and decrease of the utility of enhancement were observed along with the abatement of the thickness of the interface layer

  20. Image-based control of the magnetic resonance imaging-guided focused ultrasound thermotherapy.

    Science.gov (United States)

    Salomir, Rares; Delemazure, Anne-Sophie; Palussière, Jean; Rouvière, Olivier; Cotton, François; Chapelon, Jean-Yves

    2006-06-01

    Magnetic resonance imaging (MRI)-guided focused ultrasound surgery (FUS) is a full noninvasive approach for localized thermal ablation of deep tissues, coupling the following: (1) a versatile, nonionizing physical agent for therapy and (2) a state-of-the art diagnosis and on-line monitoring tool. A commercially available, Food and Drug Administration-approved device using the MRI-guided FUS exists since 2004 for the ablation of benign tumors (uterine fibroids); however, the ultimate goal of the technological, methodological, and medical research in this field is to provide a clinical-routine tool for fighting localized cancer. When addressing cancer applications, the accurate spatial control of the delivered thermal dose is mandatory. Contiguous destruction of the target volume must be achieved in a minimum time, whereas sparing as much as possible the neighboring healthy tissues and especially when some adjacent regions are critical. This paper reviews some significant developments reported in the literature related to the image-based control of the FUS therapy for kidney, breast, prostate, and brain, including the own experience of the authors on the active feedback control of the temperature during FUS ablation. In addition, preliminary results of an original study of MRI-guided FUS ablation of VX2 carcinoma in kidney, under active temperature control, are described here.

  1. Image-Guided Transcranial Focused Ultrasound Stimulates Human Primary Somatosensory Cortex

    Science.gov (United States)

    Lee, Wonhye; Kim, Hyungmin; Jung, Yujin; Song, In-Uk; Chung, Yong An; Yoo, Seung-Schik

    2015-03-01

    Focused ultrasound (FUS) has recently been investigated as a new mode of non-invasive brain stimulation, which offers exquisite spatial resolution and depth control. We report on the elicitation of explicit somatosensory sensations as well as accompanying evoked electroencephalographic (EEG) potentials induced by FUS stimulation of the human somatosensory cortex. As guided by individual-specific neuroimage data, FUS was transcranially delivered to the hand somatosensory cortex among healthy volunteers. The sonication elicited transient tactile sensations on the hand area contralateral to the sonicated hemisphere, with anatomical specificity of up to a finger, while EEG recordings revealed the elicitation of sonication-specific evoked potentials. Retrospective numerical simulation of the acoustic propagation through the skull showed that a threshold of acoustic intensity may exist for successful cortical stimulation. The neurological and neuroradiological assessment before and after the sonication, along with strict safety considerations through the individual-specific estimation of effective acoustic intensity in situ and thermal effects, showed promising initial safety profile; however, equal/more rigorous precautionary procedures are advised for future studies. The transient and localized stimulation of the brain using image-guided transcranial FUS may serve as a novel tool for the non-invasive assessment and modification of region-specific brain function.

  2. Keratorefractive Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Eyes

    Directory of Open Access Journals (Sweden)

    Zhiyu Du

    2016-01-01

    Full Text Available Purpose. To evaluate high intensity focused ultrasound (HIFU as an innovation and noninvasive technique to correct presbyopia by altering corneal curvature in the rabbit eye. Methods. Eighteen enucleated rabbit eyes were treated with a prototype HIFU keratoplasty. According to the therapy power, these eyes were divided three groups: group 1 (1 W, group 2 (2 W, and group 3 (3 W. The change in corneal power was quantified by a Sirius Scheimpflug camera. Light microscopy (LM and transmission electron microscopy (TEM were performed to determine the effect on the corneal stroma. Results. In the treated eyes, the corneal curvature increases from 49.42 ± 0.30 diopters (D and 48.00 ± 1.95 D before procedure to 51.37 ± 1.11 D and 57.00 ± 1.84 D after HIFU keratoplasty application in groups 1 and 3, respectively. The major axis and minor axis of the focal region got longer when the powers of the HIFU got increased; the difference was statistically significant (p<0.05. LM and TEM showed HIFU-induced shrinkage of corneal stromal collagen with little disturbance to the underlying epithelium. Conclusions. We have preliminarily exploited HIFU to establish a new technique for correcting presbyopia. HIFU keratoplasty will be a good application prospect for treating presbyopia.

  3. Safety Validation of Repeated Blood-Brain Barrier Disruption Using Focused Ultrasound.

    Science.gov (United States)

    Kobus, Thiele; Vykhodtseva, Natalia; Pilatou, Magdalini; Zhang, Yongzhi; McDannold, Nathan

    2016-02-01

    The purpose of this study was to investigate the effects on the brain of multiple sessions of blood-brain barrier (BBB) disruption using focused ultrasound (FUS) in combination with micro-bubbles over a range of acoustic exposure levels. Six weekly sessions of FUS, using acoustical pressures between 0.66 and 0.80 MPa, were performed under magnetic resonance guidance. The success and degree of BBB disruption was estimated by signal enhancement of post-contrast T1-weighted imaging of the treated area. Histopathological analysis was performed after the last treatment. The consequences of repeated BBB disruption varied from no indications of vascular damage to signs of micro-hemorrhages, macrophage infiltration, micro-scar formations and cystic cavities. The signal enhancement on the contrast-enhanced T1-weighted imaging had limited value for predicting small-vessel damage. T2-weighted imaging corresponded well with the effects on histopathology and could be used to study treatment effects over time. This study demonstrates that repeated BBB disruption by FUS can be performed with no or limited damage to the brain tissue.

  4. Chemotherapy of glioblastoma by targeted liposomal platinum compounds with focused ultrasound.

    Science.gov (United States)

    Yang, Feng-Yi; Horng, Shih-Cheng

    2013-01-01

    Giloblastoma multiforme (GBM) is the most aggressive brain neoplasm, and patients have a poor prognosis after radiation and chemotherapy. The chemotherapy protocols still marginally improve the anti-tumor effect of patients with glioblastoma because the therapeutic dosage of many drugs is impeded by the blood-brain barrier (BBB). The use of liposomal drugs to GBM treatment might benefit from a more crossing of the BBB due to the lipid nature achieving higher doses of drug at the tumor sites. Human GBM-bearing mice were injected intravenously with cisplatin encapsulated in atherosclerotic plaque-specific peptide-1 (AP-1)-conjugated liposomes or unconjugated liposome. Moreover, the administration of AP-1 liposomal cisplatin (lipoplatin) followed by focused ultrasound (FUS)-induced BBB disruption. Tumor progression was monitored by biophotonic imaging. The preliminary data demonstrated that the GBM chemotherapy with AP-1 lipoplatin followed by pulsed FUS showed a modest improvement of tumor growth in the brain compared to the group treated with lipoplatin alone. Further investigations are needed to use this new targeted lipoplatin in treatment of malignancies.

  5. Modeling of phased array transducers.

    Science.gov (United States)

    Ahmad, Rais; Kundu, Tribikram; Placko, Dominique

    2005-04-01

    Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM (distributed point source method) is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.

  6. A retrospective comparison of microwave ablation and high intensity focused ultrasound for treating symptomatic uterine fibroids

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wen-Peng, E-mail: zwp215@163.com; Han, Zhi-Yu, E-mail: hanzhiyu301@hotmail.com; Zhang, Jing, E-mail: zjbch@sina.com; Liang, Ping, E-mail: liangping301@hotmail.com

    2015-03-15

    Highlights: •Both HIFU and PMWA are thermal ablation techniques and they all provide safe and reliable alternative treatment methods for uterine fibroids. •However, whether there are obvious difference between these two kinds of approaches in improving symptom, treatment time, ablation rate, regression rate and adverse events, until now, there are no clinical trials which have been performed to compare the therapeutic effects of HIFU and PMWA. •In this research, we retrospectively compare the results of these two treatment methods. •To our knowledge, our study is the first directly comparing long-term outcome after PMWA and HIFU in patients with uterine fibroids. -- Abstract: Objectives: To retrospectively compare the effectiveness and safety of percutaneous microwave ablation (PMWA) and ultrasound-guided high-intensity focused ultrasound (USgHIFU) for treating symptomatic uterine fibroids. Methods: Seventy-three women with symptomatic uterine fibroids who met the inclusion criteria were enrolled in our study from September 2012 to December 2013. Thirty-one patients with forty uterine fibroids underwent PMWA, and forty-two patients with fifty-one uterine fibroids underwent USgHIFU. A contrast-enhanced MRI was performed before and after treatment, and all patients were followed up for 6 months. Assessment endpoints included symptom severity scores (SSS), treatment time, ablation rate, fibroid regression rate and adverse events. Results: The mean age of the patients in our study was 35.4 ± 6.2 years (range, 21–49 years), and the median volume of uterine fibroids was 95.7 cm{sup 3} (60.3–131.5 cm{sup 3}). The ablation rate of uterine fibroids was 79.8 ± 18.2% and 77.1 ± 14.9% in the PMWA group and the USgHIFU group, respectively, and showed no significant difference between the groups. Changes in SSS after PMWA were similar in the PMWA group (47.7 pre-treatment vs. 29.9 post-treatment) and USgHIFU group (42.1 pre-treatment vs. 24.6 post-treatment). The

  7. Enhanced high intensity focused ultrasound heat deposition for more efficient hemostasis

    Science.gov (United States)

    Labuda, Cecille Pemberton

    High intensity focused ultrasound (HIFU) is currently being developed for hemorrhage control since it provides rapid energy deposition in the form of heat in the HIFU focal region. When the HIFU focus is targeted on soft tissue wounds, the resulting elevation of tissue temperature cauterizes the tissues thus stopping the bleeding. If HIFU is targeted near blood vessels with millimeter-range diameter, the rate of heat deposition is limited by loss of heat to the blood flow. Maximizing the local heat deposition is important for the achievement of HIFU-induced hemorrhage control, or "hemostasis", near large vessels. In this study, the effect of a fiber device on the heat deposition in the HIFU focal region is investigated in tissue-mimicking flow phantoms with liquid albumen as the heat-sensitive denaturing flow fluid. The effect of the embedded fiber on albumen coagulation in the flow phantom is compared to the degree and rate of albumen coagulation when no fiber is present. The effect of the fiber device on the size of lesions formed in a heat-sensitive tissue-mimicking phantom is also investigated. Finally, finite difference time domain simulations are performed to determine the heat deposition in a tissue-mimicking phantom with a nylon disc embedded and a phantom with the nylon disc removed. The results of this study are quite promising for the possibility of increased efficacy of hemostasis for such a device in concert with HIFU in vessel-containing tissue volumes where HIFU alone is not completely effective.

  8. Computational Complexity Reduction of Synthetic-aperture Focus in Ultrasound Imaging Using Frequency-domain Reconstruction.

    Science.gov (United States)

    Moghimirad, Elahe; Mahloojifar, Ali; Mohammadzadeh Asl, Babak

    2016-05-01

    A new frequency-domain implementation of a synthetic aperture focusing technique is presented in the paper. The concept is based on synthetic aperture radar (SAR) and sonar that is a developed version of the convolution model in the frequency domain. Compared with conventional line-by-line imaging, synthetic aperture imaging has a better resolution and contrast at the cost of more computational load. To overcome this problem, point-by-point reconstruction methods have been replaced by block-processing algorithms in radar and sonar; however, these techniques are relatively unknown in medical imaging. In this paper, we extended one of these methods called wavenumber to medical ultrasound imaging using a simple model of synthetic aperture focus. The model, derived here for monostatic mode, can be generalized to multistatic as well. The method consists of 4 steps: a 2D fast Fourier transform of the data, frequency shift of the data to baseband, interpolation to convert polar coordinates to rectangular ones, and returning the data to the spatial-domain using a 2D inverse Fourier transform. We have also used chirp pulse excitation followed by matched filtering and spotlighting algorithm to compensate the effect of differences in parameters between radar and medical imaging. Computational complexities of the two methods, wavenumber and delay-and-sum (DAS), have been calculated. Field II simulated point data have been used to evaluate the results in terms of resolution and contrast. Evaluations with simulated data show that for typical phantoms, reconstruction by the wavenumber algorithm is almost 20 times faster than classical DAS while retaining the resolution. © The Author(s) 2015.

  9. Improved survival in rats with glioma using MRI-guided focused ultrasound and microbubbles to disrupt the blood-brain barrier and deliver Doxil

    Science.gov (United States)

    Aryal, Muna; Zhi Zhang, Yong; Vykhodtseva, Natalia; Park, Juyoung; Power, Chanikarn; McDannold, Nathan

    2012-02-01

    Blood-brain-barrier (BBB) limits the transportation of most neuropeptides, proteins (enzymes, antibodies), chemotherapeutic agents, and genes that have therapeutic potential for the treatment of brain diseases. Different methods have been used to overcome this limitation, but they are invasive, non-targeted, or require the development of new drugs. We have developed a method that uses MRI-guided focused ultrasound (FUS) combined with circulating microbubbles to temporarily open BBB in and around brain tumors to deliver chemotherapy agents. Here, we tested whether this noninvasive technique could enhance the effectiveness of a chemotherapy agent (Doxil). Using 690 kHz FUS transducer and microbubble (Definity), we induced BBB disruption in intracranially-implanted 9L glioma tumors in rat's brain in three weekly sessions. Animals who received BBB disruption and Doxil had a median survival time of 34.5 days, which was significantly longer than that found in control animals which is 16, 18.5, 21 days who received no treatment, BBB disruption only and Doxil only respectively This work demonstrates that FUS technique has promise in overcoming barriers to drug delivery, which are particularly stark in the brain due to the BBB.

  10. Design and Test of Capacitive Micromachined Ultrasonic Transducer

    National Research Council Canada - National Science Library

    Hongliang Wang; Xiangjun Wang; Changde He; Chenyang Xue; Jijun Xiong; Wendong Zhang; Jing Miao; Yuping Li

    2014-01-01

      Currently, most capacitive micromachined ultrasound transducers, adopting surface sacrificial technology encounter various problems such as difficult cavity etch, low controllability of membrane thickness etc...

  11. Conformal thermal therapy using planar ultrasound transducers and adaptive closed-loop MR temperature control: demonstration in gel phantoms and ex vivo tissues

    Science.gov (United States)

    Tang, K.; Choy, V.; Chopra, R.; Bronskill, M. J.

    2007-05-01

    MRI-guided transurethral ultrasound therapy offers a minimally invasive approach for the treatment of localized prostate cancer. Integrating a multi-element planar transducer with active MR temperature feedback can enable three-dimensional conformal thermal therapy of a target region within the prostate gland while sparing surrounding normal tissues. Continuous measurement of the temperature distribution in tissue enables dynamic compensation for unknown changes in blood flow and tissue properties during treatment. The main goal of this study was to evaluate the feasibility of using active temperature feedback on a clinical 1.5 T MR imager for conformal thermal therapy. MR thermometry was performed during heating in both gel phantoms and excised tissue with a transurethral heating applicator, and the rotation rate and power were varied based on the thermal measurements. The capability to produce a region of thermal damage that matched a target boundary was evaluated. The influence of a cooling gradient (to simulate cooling of the rectum or urethra) on the desired pattern of thermal damage was also investigated in gel phantoms. Results showed high correlation between the desired target boundary and the 55 °C isotherm generated during heating with an average distance error of 0.9 mm ± 0.4 mm (n = 6) in turkey breasts, 1.4 mm ± 0.6 mm (n = 4) in gel phantoms without rectal cooling and 1.4 mm ± 0.6 mm (n = 3) in gel phantoms with rectal cooling. The results were obtained using a temporal update rate of 5 s, a spatial resolution of 3 × 3 × 10 mm for the control point, and a temperature uncertainty of approximately 1 °C. The performance of the control algorithm under these conditions was comparable to that of simulations conducted previously by our group. Overall, the feasibility of generating targeted regions of thermal damage with a transurethral heating applicator and active MR temperature feedback has been demonstrated experimentally. This method of treatment

  12. Conformal thermal therapy using planar ultrasound transducers and adaptive closed-loop MR temperature control: demonstration in gel phantoms and ex vivo tissues

    Energy Technology Data Exchange (ETDEWEB)

    Tang, K [Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 (Canada); Choy, V [Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 (Canada); Chopra, R [Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 (Canada); Bronskill, M J [Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 (Canada)

    2007-05-21

    MRI-guided transurethral ultrasound therapy offers a minimally invasive approach for the treatment of localized prostate cancer. Integrating a multi-element planar transducer with active MR temperature feedback can enable three-dimensional conformal thermal therapy of a target region within the prostate gland while sparing surrounding normal tissues. Continuous measurement of the temperature distribution in tissue enables dynamic compensation for unknown changes in blood flow and tissue properties during treatment. The main goal of this study was to evaluate the feasibility of using active temperature feedback on a clinical 1.5 T MR imager for conformal thermal therapy. MR thermometry was performed during heating in both gel phantoms and excised tissue with a transurethral heating applicator, and the rotation rate and power were varied based on the thermal measurements. The capability to produce a region of thermal damage that matched a target boundary was evaluated. The influence of a cooling gradient (to simulate cooling of the rectum or urethra) on the desired pattern of thermal damage was also investigated in gel phantoms. Results showed high correlation between the desired target boundary and the 55 deg. C isotherm generated during heating with an average distance error of 0.9 mm {+-} 0.4 mm (n = 6) in turkey breasts, 1.4 mm {+-} 0.6 mm (n = 4) in gel phantoms without rectal cooling and 1.4 mm {+-} 0.6 mm (n = 3) in gel phantoms with rectal cooling. The results were obtained using a temporal update rate of 5 s, a spatial resolution of 3 x 3 x 10 mm for the control point, and a temperature uncertainty of approximately 1 deg. C. The performance of the control algorithm under these conditions was comparable to that of simulations conducted previously by our group. Overall, the feasibility of generating targeted regions of thermal damage with a transurethral heating applicator and active MR temperature feedback has been demonstrated experimentally. This method of

  13. Optimal ultrasonic array focusing in attenuative media.

    Science.gov (United States)

    Ganguli, A; Gao, R X; Liang, K; Jundt, J

    2011-12-01

    This paper presents a parametric study on the efficiency of ultrasound focusing in an attenuative medium, using phased arrays. Specifically, an analytical model of ultrasound wave focusing in a homogeneous, isotropic and attenuative fluid with point sources is presented. Calculations based on the model have shown that in an attenuative medium, an optimum frequency exists for the best focusing performance for a particular size of aperture and focal distance. The effect of different f numbers on the focusing performance in the attenuative medium is further investigated. The information obtained from the analytical model provides insights into the design and installation of a phased transducer array for energy efficient wave focusing.

  14. Modeling of higher harmonics formation in medical ultrasound systems

    DEFF Research Database (Denmark)

    Taylor, Louise Kold; Schlaikjer, Malene; Jensen, Jørgen Arendt

    2002-01-01

    The pressure eld emitted from multi-element medical ultrasound transducers can be simulated with Field II in the linear regime. By expanding this program's application to the nonlinear regime, beamforming schemes can be studied under strong focusing and high pressure levels as well, providing...... a valuable tool for simulating ultrasound harmonic imaging. An extended version of Field II is obtained by means of operator splitting. The pressure eld is calculated by propagation of the eld from the transducer through a number of planes. Every plane serves as a virtual aperture for the next plane......, and nonlinear distortion is accounted for by the lossless Burgers' Equation. This method has no plane-wave approximation and the full eects of diraction, attenuation, and nonlinear wave propagation can be observed under electronic focusing of array transducers in medical ultrasound systems. A single example...

  15. Pad-printed thick-film transducers for high-frequency and high-power applications

    Science.gov (United States)

    Wolny, Wanda W.; Ketterling, Jeffrey A.; Levassort, Franck; Lou-Moeller, Rasmus; Filoux, Erwan; Mamou, Jonathan; Silverman, Ronald H.; Lethiecq, Marc

    2011-03-01

    High-frequency-ultrasound transducers are widely used but are typically based either on planar piezoceramic sections that are lapped down to smaller thicknesses or on piezopolymers that may be deformed into more complex geometries. Piezoceramics then require dicing to obtain arrays or can be fractured into spherical geometries to achieve focusing. Piezopolymers are not as efficient for very small element sizes and are normally available only in discrete thicknesses. Thick-film (TF) transducers provide a means of overcoming these limits because the piezoelectric film is deposited with the required thickness, size and geometry, thus avoiding any subsequent machining. Thick-film transducers offer the potential of a wide range of geometries such as single-elements and annular or linear arrays. Here, a single-element focused transducer was developed using a piezoceramic composition adapted to high-power operation which is commonly used at standard MHz frequencies. After fabrication, the transducer was characterized. Using specific transmit-receive electronics and a water tank adapted to high-frequency devices, the transducer was excited using a short pulse to evaluate its bandwidth and imaging capabilities. Finally, it was excited by a one-period sine wave using several power levels to evaluate its capacity to produce high-intensity focused ultrasound at frequencies over 20 MHz.

  16. High-intensity focused ultrasound: noninvasive treatment for local unresectable recurrence of osteosarcoma.

    Science.gov (United States)

    Yu, Wenxi; Tang, Lina; Lin, Feng; Yao, Yang; Shen, Zan; Zhou, Xiaohui

    2015-03-01

    Local unresectable recurrence of osteosarcoma is one of the most challenging tumors to treat. High-intensity focused ultrasound (HIFU) is a new, noninvasive technique with potential to ablate and inactivate tumors. Treatment of solid tumors with HIFU has been reported. In this study, we assessed safety and efficacy of HIFU in treating local unresectable recurrence of osteosarcoma. We performed a retrospective analysis of 27 patients who had local unresectable recurrence of osteosarcoma from 2006 to 2010. Changes of biochemical markers and pain rating, response rate, disease control rate, local disease progression-free survival, progression-free survival (PFS) and overall survival (OS) were used to evaluate efficacy of HIFU treatment. HIFU resulted in a significant change in alkaline phosphatase and lactic acid dehydrogenase and a remarkably relief in pain rating, without severe side effects. According to MRI examination 4-6 weeks after HIFU treatment, 2 (7.4%) patients had complete response (CR), 12 (44.4%) had partial response (PR), 9 (33.3%) had stable disease (SD) and 4 (14.8%) had progression disease (PD). The response rate was 51.8% and the local disease control rate was 85.2%. The 1-, 2-, and 3-year local disease control rates were 59.2%, 40.7% and 33.1%, respectively. The median local disease progression-free time was 14 months, the median progression-free time was 13 months and the median over-all survival time was 21 months. Patients without pulmonary metastasis had a better local disease control rate at 1-,2-,3-year and a longer local disease progression-free time, progression-free time, over-all survival time than patients with pulmonary metastasis. HIFU is a safe and noninvasive treatment for local unresectable recurrence of osteosarcoma, with good local control and without severe complications. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. A new brain drug delivery strategy: focused ultrasound-enhanced intranasal drug delivery.

    Directory of Open Access Journals (Sweden)

    Hong Chen

    Full Text Available Central nervous system (CNS diseases are difficult to treat because of the blood-brain barrier (BBB, which prevents most drugs from entering into the brain. Intranasal (i.n. administration is a promising approach for drug delivery to the brain, bypassing the BBB; however, its application has been restricted to particularly potent substances and it does not offer localized delivery to specific brain sites. Focused ultrasound (FUS in combination with microbubbles can deliver drugs to the brain at targeted locations. The present study proposed to combine these two different platform techniques (FUS+i.n. for enhancing the delivery efficiency of intranasally administered drugs at a targeted location. After i.n. administration of 40 kDa fluorescently-labeled dextran as the model drug, FUS targeted at one region within the caudate putamen of mouse brains was applied in the presence of systemically administered microbubbles. To compare with the conventional FUS technique, in which intravenous (i.v. drug injection is employed, FUS was also applied after i.v. injection of the same amount of dextran in another group of mice. Dextran delivery outcomes were evaluated using fluorescence imaging of brain slices. The results showed that FUS+i.n. enhanced drug delivery within the targeted region compared with that achieved by i.n. only. Despite the fact that the i.n. route has limited drug absorption across the nasal mucosa, the delivery efficiency of FUS+i.n. was not significantly different from that of FUS+i.v.. As a new drug delivery platform, the FUS+i.n. technique is potentially useful for treating CNS diseases.

  18. Training Program for Cardiology Residents to Perform Focused Cardiac Ultrasound Examination with Portable Device.

    Science.gov (United States)

    Siqueira, Vicente N; Mancuso, Frederico J N; Campos, Orlando; De Paola, Angelo A; Carvalho, Antonio C; Moises, Valdir A

    2015-10-01

    Training requirements for general cardiologists without echocardiographic expertise to perform focused cardiac ultrasound (FCU) with portable devices have not yet been defined. The objective of this study was to evaluate a training program to instruct cardiology residents to perform FCU with a hand-carried device (HCD) in different clinical settings. Twelve cardiology residents were subjected to a 50-question test, 4 lectures on basic echocardiography and imaging interpretation, the supervised interpretation of 50 echocardiograms and performance of 30 exams using HCD. After this period, they repeated the written test and were administered a practical test comprising 30 exams each (360 patients) in different clinical settings. They reported on 15 parameters and a final diagnosis; their findings were compared to the HCD exam of a specialist in echocardiography. The proportion of correct answers on the theoretical test was higher after training (86%) than before (51%; P = 0.001). The agreement was substantial among the 15 parameters analyzed (kappa ranging from 0.615 to 0.891; P < 0.001). The percentage of correct interpretation was lower for abnormal (75%) than normal (95%) items, for valve abnormalities (85%) compared to other items (92%) and for graded scale (87%) than for dichotomous (95%) items (P < 0.0001, for all). For the final diagnoses, the kappa value was higher than 0.941 (P < 0.001; 95% CI [0.914, 0.955]). The training proposed enabled residents to perform FCU with HCD, and their findings were in good agreement with those of a cardiologist specialized in echocardiography. © 2015, Wiley Periodicals, Inc.

  19. A new brain drug delivery strategy: focused ultrasound-enhanced intranasal drug delivery.

    Science.gov (United States)

    Chen, Hong; Chen, Cherry C; Acosta, Camilo; Wu, Shih-Ying; Sun, Tao; Konofagou, Elisa E

    2014-01-01

    Central nervous system (CNS) diseases are difficult to treat because of the blood-brain barrier (BBB), which prevents most drugs from entering into the brain. Intranasal (i.n.) administration is a promising approach for drug delivery to the brain, bypassing the BBB; however, its application has been restricted to particularly potent substances and it does not offer localized delivery to specific brain sites. Focused ultrasound (FUS) in combination with microbubbles can deliver drugs to the brain at targeted locations. The present study proposed to combine these two different platform techniques (FUS+i.n.) for enhancing the delivery efficiency of intranasally administered drugs at a targeted location. After i.n. administration of 40 kDa fluorescently-labeled dextran as the model drug, FUS targeted at one region within the caudate putamen of mouse brains was applied in the presence of systemically administered microbubbles. To compare with the conventional FUS technique, in which intravenous (i.v.) drug injection is employed, FUS was also applied after i.v. injection of the same amount of dextran in another group of mice. Dextran delivery outcomes were evaluated using fluorescence imaging of brain slices. The results showed that FUS+i.n. enhanced drug delivery within the targeted region compared with that achieved by i.n. only. Despite the fact that the i.n. route has limited drug absorption across the nasal mucosa, the delivery efficiency of FUS+i.n. was not significantly different from that of FUS+i.v.. As a new drug delivery platform, the FUS+i.n. technique is potentially useful for treating CNS diseases.

  20. Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force.

    Science.gov (United States)

    Ergün, A Sanlı

    2011-10-01

    Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well.

  1. Effects of oxytocin on high intensity focused ultrasound (HIFU) ablation of adenomysis: A prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Zou, Min; Zhang, Cai [Department of Obstetrics and Gynecology, Chongqing Haifu Hospital, Chongqing 401121 (China); He, Jia [Department of Obstetrics and Gynecology, Suining Central Hospital, Sichuan 629000 (China); Mao, Shihua [Department of Obstetrics and Gynecology, Three Gorges Central Hospital, Chongqing 404000 (China); Wu, Qingrong [Department of Obstetrics and Gynecology, Fuling Central Hospital, Chongqing 408099 (China); He, Min [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Department of Obstetrics and Gynecology, Suining Central Hospital, Sichuan 629000 (China); Wang, Jian [Department of Obstetrics and Gynecology, Chongqing Haifu Hospital, Chongqing 401121 (China); Department of Obstetrics and Gynecology, Three Gorges Central Hospital, Chongqing 404000 (China); Zhang, Ruitao [Department of Obstetrics and Gynecology, Chongqing Haifu Hospital, Chongqing 401121 (China); Department of Obstetrics and Gynecology, Fuling Central Hospital, Chongqing 408099 (China); Zhang, Lian, E-mail: lianwzhang@yahoo.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Department of Obstetrics and Gynecology, Chongqing Haifu Hospital, Chongqing 401121 (China)

    2014-09-15

    Objective: To investigate the effects of oxytocin on high-intensity focused ultrasound (HIFU) ablation for the treatment of adenomyosis. Materials and methods: Eighty-six patients with adenomyosis from three hospitals were randomly assigned to the oxytocin group or control group for HIFU treatment. During HIFU treatment, 80 units of oxytocin was added in 500 ml of 0.9% normal saline running at the rate of 2 ml/min (0.32 U/min) in the oxytocin group, while 0.9% normal saline was used in the control group. Both patients and HIFU operators were blinded to oxytocin or saline application. Treatment results, adverse effects were compared. Results: When using oxytocin, the non-perfused volume (NPV) ratio was 80.7 ± 11.6%, the energy-efficiency factor (EEF) was 8.1 ± 9.9 J/mm{sup 3}, and the sonication time required to ablate 1 cm{sup 3} was 30.0 ± 36.0 s/cm{sup 3}. When not using oxytocin, the non-perfused volume ratio was 70.8 ± 16.7%, the EEF was 15.8 ± 19.6 J/mm{sup 3}, and the sonication time required to ablate 1 cm{sup 3} was 58.2 ± 72.7 S/cm{sup 3}. Significant difference in the NPV ratio, EEF, and the sonication time required to ablate 1 cm{sup 3} between the two groups was observed. No oxytocin related adverse effects occurred. Conclusion: Oxytocin could significantly decrease the energy for ablating adenomyosis with HIFU, safely enhance the treatment efficiency.

  2. Investigation of cellular and molecular responses to pulsed focused ultrasound in a mouse model.

    Directory of Open Access Journals (Sweden)

    Scott R Burks

    Full Text Available 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 cy