Дисертації з теми "Biomedical Ultrasound Imaging"
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Wang, Zhaohui. "Biomedical Applications of Acoustoelectric Effect." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/204330.
Повний текст джерелаChuang, Brian. "Ultrasound parametric imaging and image analysis for breast cancer characterisation and treatment monitoring." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:aa12f720-f3c6-4e55-83c0-f063ea0ed7e2.
Повний текст джерелаEljaaidi, Abdalla Agila. "2D & 3D ultrasound systems in development of medical imaging technology." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2193.
Повний текст джерелаUltrasound is widely used in most medical clinics, especially obstetrical clinics. It is a way of imaging methods that has important diagnostic value. Although useful in many different applications, diagnostic ultrasound is especially useful in antenatal (before delivery) diagnosis. The use of two-dimensional ultrasound (2DUS) in obstetrics has been established. However, there are many disadvantages of 2DUS imaging. Several researchers have published information on the significance of patients being shown the ultrasound screen during examination, especially during three- and four-dimensional (3D/4D) scanning. In addition, a form of ultrasound, called keepsake or entertainment ultrasound, has boomed, particularly in the United States. However, long-term epidemiological studies have failed to show the adverse effects of ultrasound in human tissues. Until now, there is no proof that diagnostic ultrasound causes harm in a human body or the developing foetus when used correctly. While ultrasound is supposed to be absolutely safe, it is a form of energy and, as such, has effects on tissues it traverses (bio-effects). The two most important mechanisms for effects are thermal and non-thermal. These two mechanisms are indicated on the screen of ultrasound devices by two indices: The thermal index (TI) and the mechanical index (MI). These are the purposes of this thesis: • evaluate end-users’ knowledge regarding the safety of ultrasound; • evaluate and make a comparison between acoustic output indices (AOI) in B-mode (2D) and three-dimensional (3D) ultrasound – those measured by thermal (TI) and mechanical (MI) indices; • assess the acoustic output indices (AOI) to benchmark current practice with a survey conducted by the British Medical Ultrasound Society (BMUS); and • review how to design 2D and 3D arrays for medical ultrasound imaging
Lai, Puxiang. "PHOTOREFRACTIVE CRYSTAL-BASED ACOUSTO-OPTIC IMAGING IN THE NEAR-INFRARED AND ITS APPLICATIONS." Thesis, Boston University, 2010. https://hdl.handle.net/2144/1378.
Повний текст джерелаBernard M. Gordon Center for Subsurface and Imaging Systems (CenSSIS) via the NSF ERC award number EEC-9986821.
Malcolm, Alison Louise. "An investigation into ultrasonic methods of imaging the tissue ablation induced during focused ultrasound surgery." Thesis, Institute of Cancer Research (University Of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267923.
Повний текст джерелаvon, Lavante Etienne. "Segmentation and sizing of breast cancer masses with ultrasound elasticity imaging." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:81225f61-6b83-405b-aed5-17b316ed586a.
Повний текст джерелаSolorio, Luis Jr. "Application of Ultrasound Imaging for Noninvasive Characterization of Phase Inverting Implants." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1332258338.
Повний текст джерелаRademeyer, Paul. "A new technique for microbubble characterisation and the implications to contrast enhanced ultrasound." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:2f5b0002-83e0-4251-b69a-de78c9895277.
Повний текст джерелаDevaraju, Vadivel Lewin Peter A. "Design, development and characterization of wideband polymer ultrasonic probes for medical ultrasound applications /." Philadelphia : Drexel University, 2003. http://dspace.library.drexel.edu/handle/1721.1/95.
Повний текст джерелаSalgaonkar, Vasant Anil. "Passive Imaging and Measurements of Acoustic Cavitation during Ultrasound Ablation." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1259075197.
Повний текст джерелаFosnight, Tyler R. "Echo Decorrelation Imaging of In Vivo HIFU and Bulk Ultrasound Ablation." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447691239.
Повний текст джерелаComeau, Roch. "Intraoperative ultrasound imaging for the detection and correction of tissue movement in image-guided neurosurgery." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36799.
Повний текст джерелаA surgical guidance system has been developed that combines pre-operative image information (e.g. MRI or CT) and intraoperative ultrasound imaging to detect brain tissue deformation during IGNS. The system includes hardware and software to track the ultrasound transducer during image acquisition, and visualization software to view the live ultrasound and co-planar MRI images. The software includes tools to delineate structures in either modality and overlay these images on one another, and warp the preoperative image based on the delineated structures.
The thesis includes a discussion of techniques, instruments and results, using a novel calibration tool and a multi-modality deformable phantom. Finally, the clinical experience from the use of this system in the operating room are presented.
Abbass, Mohamed A. M. S. "Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468911083998.
Повний текст джерелаTsakalakis, Michail. "Design of A Novel Low – Cost, Portable, 3D Ultrasound System with Extended Imaging Capabilities For Point-of-Care Applications." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1441017459.
Повний текст джерелаChandrana, Chaitanya K. "Development of A Focused Broadband Ultrasonic Transducer for High Resolution Fundamental and Harmonic Intravascular Imaging." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1244664717.
Повний текст джерелаStevenson, Gordon N. "Toward functional imaging of the placenta." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1d459989-7e03-4cfe-b1b9-98833e5db854.
Повний текст джерелаMadaris, Aaron T. "Characterization of Peripheral Lung Lesions by Statistical Image Processing of Endobronchial Ultrasound Images." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1485517151147533.
Повний текст джерелаSmiley, Aref. "DESIGN OF A LOW PROFILE CONFORMAL ARRAY FOR TRANSCRANIALULTRASOUND IMAGING." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1525860103122672.
Повний текст джерелаMela, Christopher Andrew. "MULTIMODAL IMAGING, COMPUTER VISION, AND AUGMENTED REALITY FOR MEDICAL GUIDANCE." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1542642892866467.
Повний текст джерелаWang, Jing. "A Study of Limited-Diffraction Array Beam and Steered Plane Wave Imaging." University of Toledo / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1146240142.
Повний текст джерелаPashaei, Vida. "Flexible Body-Conformal Ultrasound Systems for Autonomous Image-Guided Neuromodulation." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1621006180331273.
Повний текст джерелаTeixeira, Ribeiro Rui Agostinho Fernandes. "Spectral analysis of breast ultrasound data with application to mass sizing and characterization." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:8768959f-cc5a-476d-b924-5a5d7df31b8d.
Повний текст джерелаGoodman, Garrett G. "Design of a Novel Wearable Ultrasound Vest for Autonomous Monitoring of the Heart Using Machine Learning." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1607605597491118.
Повний текст джерелаNagle, Anna S. "Biomechanical Measurements of the Human Female Levator Ani Muscle Ex Vivo and In Vivo." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439561849.
Повний текст джерелаSmith, Bryan Ronain. "Nanoparticulate platforms for molecular imaging of atherosclerosis and breast cancer." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150309580.
Повний текст джерелаHernandez, Christopher. "Stabilized Nanobubbles for Diagnostic Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1521123706295258.
Повний текст джерелаSweeney, Sean. "Multimodal nanoparticles for image-guided delivery of mesenchymal stem cells in the treatment of myocardial infarction." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/3200.
Повний текст джерелаZanella, Fabio Pieroni. "Sistema multicanal de geração e recepção de ondas ultra-sonicas para transdutor matricial linear." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258954.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: O ultra-som na medicina tem passado por enorme evolução nas últimas décadas e ocupado posição de destaque cada vez maior como ferramenta para terapia e diagnóstico. Isso é devido principalmente ao fato de que os equipamentos de diagnóstico por ultra-som são de relativo baixo custo, o ultra-som é uma radiação não-ionizante e permite realização de exame por método não-invasivo e as imagens são geradas e visualizadas em tempo real. Na geração de imagens deste tipo, é comum a utilização de transdutores matriciais. Entretanto, o Brasil apresenta defasagem tecnológica com respeito à construção destes transdutores e à eletrônica envolvida em sua operação. O objetivo deste trabalho consistiu no desenvolvimento de circuitos eletrônicos com 12 canais de geração e de recepção de ondas ultra-sônicas para operação com transdutor matricial linear. O sistema é capaz de excitar transdutores piezoelétricos e receber ecos ultra-sônicos na faixa de 0,5 a 30 MHz e tem seus circuitos de recepção protegidos contra a alta tensão dos pulsos gerados para a excitação do transdutor. Os disparos dos elementos do transdutor e o tempo de corte dos sinais nos circuitos de recepção, para evitar receber sinais indesejáveis referentes ao período inicial de oscilação do transdutor, são controlados via circuito com microcontrolador PIC 16F877 que, juntamente com o programa de controle, foram desenvolvidos para conectar o sistema a um microcomputador. Os 12 canais foram caracterizados eletricamente e verificou-se seu funcionamento utilizando um transdutor piezoelétrico linear de 12 elementos com 1 MHz de freqüência central, especialmente desenvolvido para este trabalho. Os resultados mostraram que o sistema funciona adequadamente, gerando imagem de um phantom construído em nosso laboratório
Abstract: Ultrasound in medicine has gone through great evolution in the last few decades and has occupied important position as a tool for therapy and diagnosis. This is due to the ultrasound equipment be of relatively low-cost, ultrasound is a non-ionizing radiation, is a non-invasive imaging method, and the images are created and seen in real time. It is common the use of transducer arrays in order to generate this kind of image. There is a lack of know how in Brazil relative to the construction of these transducers and the involved electronics in their operation. The objective of this work was the development of a multi-purpose 12 channel pulser/receiver electronic circuitry to operate with linear transducer arrays. The system is able to fire ultrasound piezoelectric transducers and to receive ultrasound echo signals in the range 0.5-30 MHz. The system has reception circuits with protection against high voltage pulses. The firing of transducer elements and cutting time of the reception circuits, to avoid unwanted signals of natural initial transducer oscillations, can be controlled via PIC 16F877 hardware and software designed to connect the system to a microcomputer. The electrical characteristics of the 12 channel pulser/receiver and its use in firing a specially constructed 1 MHz 12 element PZT transducer array has been carried out and the images of a specially constructed phantom showed that it can be used in laboratory conditions
Mestrado
Engenharia Biomedica
Mestre em Engenharia Elétrica
Cheng, Jiqi. "A Study of Wave Propagation and Limited-Diffraction Beams for Medical Imaging." University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1133820434.
Повний текст джерелаMallory, Ann Elizabeth. "Measurement of Meningeal Motion Using B-Mode Ultrasound as a Step Toward Understanding the Mechanism of Subdural Hematoma." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1387797814.
Повний текст джерелаSMITH, DENISE ANNE BUSH. "In vitro Characterization of Echogenic Liposomes (ELIP) for Ultrasonic Delivery of Recombinant Tissue-type Plasminogen Activator (rt-PA)." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1214234148.
Повний текст джерелаQin, Yingying. "Early breast anomalies detection with microwave and ultrasound modalities." Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG058.
Повний текст джерелаImaging of the breast for early detec-tion of tumors is studied by associating microwave (MW) and ultrasound (US) data. No registration is enforced since a free pending breast is tackled. A 1st approach uses prior information on tissue boundaries yielded from US reflection data. Regularization incorporates that two neighboring pixels should exhibit similar MW properties when not on a boundary while a jump allowed otherwise. This is enforced in the distorted Born iterative and the contrast source inversion methods. A 2nd approach involves deterministic edge preserving regularization via auxiliary variables indicating if a pixel is on an edge or not, edge markers being shared by MW and US parameters. Those are jointly optimized from the last parameter profiles and guide the next optimization as regularization term coefficients. Alternate minimization is to update US contrast, edge markers and MW contrast. A 3rd approach involves convolutional neural networks. Estimated contrast current and scattered field are the inputs. A multi-stream structure is employed to feed MW and US data. The network outputs the maps of MW and US parameters to perform real-time. Apart from the regression task, a multi-task learning strategy is used with a classifier that associates each pixel to a tissue type to yield a segmentation image. Weighted loss assigns a higher penalty to pixels in tumors when wrongly classified. A 4th approach involves a Bayesian formalism where the joint posterior distribution is obtained via Bayes’ rule; this true distribution is then approximated by a free-form separable law for each set of unknowns to get the estimate sought. All those solution methods are illustrated and compared from a wealth of simulated data on simple synthetic models and on 2D cross-sections of anatomically-realistic MRI-derived numerical breast phantoms in which small artificial tumors are inserted
Ferreira, Leticia Alves. "Uma aplicação stand-alone multiplataforma para a quantificação semi-automatica da perfusão miocardica em imagens de ecocardiografia com contraste." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258946.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Os scanners ultra-sônicos atuais oferecem ferramentas específicas para estudos de Ecocardiografia do Miocárdio por Contraste de Microbolhas (ECM) e apesar do potencial comprovado para a análise quantitativa não invasiva da perfusão miocárdica, seu uso se restringe praticamente à interpretação qualitativa (visual) das imagens clínicas. O objetivo desta tese foi desenvolver e criar uma aplicação stand-alone multiplataforma baseada nos algoritmos criados por Lopes (2005) e implementados em seu protótipo MCEToolRS. A aplicação proposta, denominada JMCETool, tem como principais características ser de fácil utilização e não comprometer a precisão, exatidão e robustez nos processos que envolvem a quantificação da perfusão miocárdica. Assim como no protótipo desenvolvido, os principais algoritmos do processo de quantificação são: o alinhamento automático baseado em Template Matching, técnicas de busca rápida e correlação; a colocação automática das ROIS sobre a parede do miocárdio; e a quantificação da perfusão miocárdica. Entre as diferenças do protótipo desenvolvido em Matlab® e da aplicação desenvolvida em Java, destacam-se a criação de uma interface mais amigável ao usuário, a implantação de uma arquitetura de software, melhor tratamento de exceções e uma nova forma de correção manual do alinhamento das imagens. A aplicação foi testada com 15 seqüências de ECM (288 imagens), sendo 14 seqüências provenientes de estudos com animais e uma proveniente de estudos com humanos. Os resultados obtidos são comparáveis aos obtidos por Lopes (2005), testes quantitativos demonstraram precisão média no processo de alinhamento de 1 pixel (para translação) e 1 grau (para rotação), com exatidão aproximada de ± 1 pixel e de ± 1 grau.
Abstract: Current commercial ultrasound scanners incorporate tools for Myocardial Contrast Echocardiography (MCE) and techniques which have a great potential for non-invasive quantitative myocardial perfusion analysis, although its use is practically restricted to qualitative (visual) reading of clinical data. The objective of this thesis was to create a new easy-to-use multiplatform standalone application for quantification of myocardium perfusion in a MCE sequence of images based on the algorithms developed by Lopes (2005) and their implementation, the prototype, called MCEToolRS. The main objective of the proposed application, called JMCETool, is the execution of these algorithms with no loss of precision, accuracy and robustness of the quantification process, compared to the first prototype. The main algorithms of the quantification process are: the automatic alignment, based on Template Matching, fast search algorithms and correlation; the automatic ROI's placement over the myocardium wall; and the quantification of myocardium perfusion. Among other features, compared to the prototype, the application JMCETool handles the algorithms exceptions and has a more user-friendly interface, including changes in the interface for manual alignment. Fifteen MCE sequences (288 images) were used during the application trials. Fourteen out of fifteen sequences belong to studies with animals (dogs) and only one belongs to studies with humans. Performance tests demonstrated that our results were similar to those of Lopes (2005), Quantitative tests have shown mean precision of 1 pixel (translation) and 1 degree (rotation) in the alignment process, and accuracy around ± 1 pixel and ± 1 degree.
Mestrado
Engenharia Biomedica
Mestre em Engenharia Elétrica
(8787980), Elizabeth E. Niedert. "High Frequency Ultrasound Imaging of Tumbling Magnetic Microrobots." Thesis, 2020.
Знайти повний текст джерелаThe diminutive size of microrobots makes them advantageous for minimally invasive operations and precise, localized treatment. One such application is aiding in localized drug delivery for colorectal cancer as microrobots could offer reduced patient trauma, lower risk of side effects, and higher drug retention rates. In this study, we evaluate the abilities of a magnetic microrobot in a variety of conditions using a high frequency ultrasound system. Under the influence of an external rotating magnetic field, the microrobot tumbles end-over-end to propel itself forward. Cytotoxicity tests demonstrated the constituent materials of polydimethylsiloxane (PDMS) and SU-8 were nontoxic to murine fibroblasts. Then, we quantified robot locomotion in an ex vivo porcine colon, testing the materials, the tumbling orientation, and three magnet rotation frequencies. Significant differences were found between materials and tumbling orientation, revealing that SU-8 lengthwise microrobots were the fastest with an average velocity of 2.12±0.25mm/s at a frequency of 1Hz. With this finding, the next tests were completed at 1Hz frequency with SU-8 lengthwise microrobots. We used in vitro agarose gels to maneuver the robot through a variety of trajectories, tested the microrobots in situ and in vivo murine colons as well. Average velocities were calculated for all tests with the in vivo murine colon tests finding an average velocity of 2.07±0.05mm/s. Finally, the microrobots were coated with a fluorescein payload and were shown to release a payload over a one-hour time period. These findings suggest microrobots are promising for targeted drug delivery and other in vivo biomedical applications.
Chou, Derrick Ren-yu. "Piezoelectric Micromachined Ultrasound Transducers for Medical Imaging." Diss., 2011. http://hdl.handle.net/10161/4978.
Повний текст джерелаPiezoelectric micromachined ultrasound transducer (pMUT) two-dimensional (2D) arrays have been proposed as an alternative to conventional bulk-PZT thickness-mode transducers for high frequency, forward-looking, catheter-based ultrasound imaging of the cardiovascular system. The appeal of pMUTs is based on several key advantages over conventional transducer technologies, including high operational frequencies, small element size, and low cost due to their microelectromechanical system (MEMS) silicon-based fabrication. While previous studies have demonstrated acoustic performance characteristics suitable for ultrasound image formation, pulse-echo B-mode imaging of tissue and tissue-like phantoms using 2D pMUT arrays small enough for forward-looking catheter-based applications have been demonstrated only at Duke University by Dausch et al.
Having demonstrated the suitability of 2D pMUT arrays for tissue imaging, an important step is to demonstrate effective design control. The frequency of operation is a fundamental component of transducer design. Previous modeling efforts for pMUT vibration have used classical/Kirchoff thin plate theory (CPT) or Mindlin thick plate theory, however pMUTs with geometric dimensions similar to those explored here, have not been modeled with experimental comparison to physical devices.
It is hypothesized that the frequency of vibration of pMUTs can be predictively modeled based on experimental data from various pMUT configurations. Experimental frequency results were acquired and used to develop an empirical model based on a modified Mindlin thick plate theory. This dissertation presents the development of the frequency design theory culminating in a set of predictive design equations for the frequency of vibration of 2D pMUT arrays aimed at improving their use in high-frequency, forward-looking, catheter-based ultrasound imaging applications.
Dissertation
Wilson, Katheryne Elizabeth. "Biomedical photoacoustics beyond thermal expansion : photoacoustic nanoDroplets." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5386.
Повний текст джерелаtext
Khezerloo, Solmaz. "Gradient-driven and reduced-rate beamforming for biomedical ultrasound." Thesis, 2009. http://hdl.handle.net/1828/3096.
Повний текст джерелаHerickhoff, Carl Dean. "Ultrasound Catheter Transducers for Intracranial Brain Imaging and Therapy." Diss., 2011. http://hdl.handle.net/10161/3839.
Повний текст джерелаEach year, over 13,000 people in the United States die from a primary malignant brain tumor. Currently, primary BTs are treated most commonly by surgery, radiotherapy, and systemic chemotherapy, though each of these methods carries a risk of complications or acute side effects.
Ultrasound hyperthermia has been investigated as way to open the blood-brain barrier for improved chemotherapeutic drug delivery, but previous methods have involved either invasively removing skull bone via surgery or non-invasively dealing with the high ultrasound attenuation, reflection, and phase aberration resulting from the skull and its variable thickness. Dual-mode ultrasound transducers for image-guided therapy have also been investigated for several applications; in some instances, phased arrays are ideal, allowing control over the ultrasound energy deposition pattern and inherent spatial registration between imaging, treatment, and monitoring.
Additionally, thermosensitive liposomes can be configured to encapsulate drugs and actively target regions of tumor angiogenesis. When used in combination with localized hyperthermia, thermosensitive liposomes can provide targeted control of drug release that may enhance chemotherapeutic efficacy in many clinical settings. Meanwhile, catheter devices and endovascular techniques are used by interventional neuroradiologists to treat various intracranial diseases, including intracranial aneurysm and dural venous sinus thrombosis. These procedures can be extended to the treatment of intracranial tumors (advancement of a 5 Fr catheter as far as the frontal portion of the superior sagittal sinus has been demonstrated).
The objective of the work presented in this dissertation was the realization of a dual-mode catheter transducer for a minimally-invasive, vascular approach to deliver localized, image-guided ultrasound hyperthermia to an intracranial tumor target. Toward this end, a series of prototype ultrasound transducers were designed, simulated, built, and tested for imaging and therapeutic potential.
Two 14-Fr phased-array prototypes were built with PZT-5H ceramic and tested for real-time 3D intracranial imaging and focused-beam hyperthermia capability. These were able to visualize the lateral ventricles and Circle of Willis in a canine model, and generate a temperature rise over 4°C at a 2-cm focal distance in excised tissue.
Single-channel intravascular ultrasound (IVUS) coronary imaging catheters as small as 3.5 Fr were then considered as a construction template; several possible transducer apertures were simulated before fabricating prototypes with PZT-4. The transducers exhibited a dual-frequency response, due to the presence of thickness-mode and width-mode resonances. A thermal model was developed to estimate the +4°C thermal penetration depth for a given transducer aperture, predicting an effective therapeutic range of up to 12 mm with a 5 × 0.5 mm aperture.
A 3.5-Fr commercial mechanical IVUS catheter was retrofitted with a PZT-4 transducer and tested for 9-MHz imaging performance in several animal studies, successfully visualizing anatomical structures in the brain and navigating a minimally-invasive vascular pathway toward the brain. An identical PZT-4 transducer was used to build a 3.3-MHz therapy prototype, which produced a temperature rise of +13.5°C at a depth of 1.5 mm in live xenograft brain tumor tissue in the mouse model.
These studies indicate that a minimally-invasive catheter transducer can be made capable of visualizing brain structures and generating localized hyperthermia to trigger drug release from thermosensitive liposomes in brain tumor tissue.
Dissertation
Albulayli, Mohammed. "Migration-based image reconstruction methods for plane-wave ultrasound imaging." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/9879.
Повний текст джерелаGraduate
David, Guillaume. "Time-domain Compressive Beamforming for Medical Ultrasound Imaging." Thesis, 2016. https://doi.org/10.7916/D8M90964.
Повний текст джерелаChen, Cherry Chen. "Engineering Microbubbles with the Buried-Ligand Architecture for Targeted Ultrasound Molecular Imaging." Thesis, 2011. https://doi.org/10.7916/D8WD46JD.
Повний текст джерелаFeshitan, Jameel A. "Engineering Lipid-stabilized Microbubbles for Magnetic Resonance Imaging guided Focused Ultrasound Surgery." Thesis, 2012. https://doi.org/10.7916/D8BZ647V.
Повний текст джерелаLong, Xian. "Frequency smoothed robust Capon beamformer applied to medical ultrasound imaging." Master's thesis, 2014. http://hdl.handle.net/1885/13799.
Повний текст джерелаIvancevich, Nikolas M. "Phase Aberration Correction for Real-Time 3D Transcranial Ultrasound Imaging." Diss., 2009. http://hdl.handle.net/10161/1243.
Повний текст джерелаPhase correction has the potential to increase the image quality of real-time 3D (RT3D) ultrasound, especially for transcranial ultrasound. Such improvement would increase the diagnostic utility of transcranial ultrasound, leading to improvements in stroke diagnosis, treatment, and monitoring. This work describes the implementation of the multi-lag least-squares cross-correlation and partial array speckle brightness methods for static and moving targets and the investigation of contrast-enhanced (CE) RT3D transcranial ultrasound.
The feasibility of using phase aberration correction with 2D arrays and RT3D ultrasound was investigated. Using the multi-lag cross-correlation method on electronic and physical aberrators, we showed the ability of 3D phase aberration correction to increase anechoic cyst identification, image brightness, contrast-to-noise ratio (CNR), and, in 3D color Doppler experiments, the ability to visualize flow. With a physical aberrator, CNR increased by 13%, while the number of detectable cysts increased from 4.3 to 7.7.
We performed an institutional review board (IRB) approved clinical trial to assess the ability of a novel ultrasound technique, namely RT3D CE transcranial ultrasound. Using micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 82% of subjects, we identified the ipsilateral circle of Willis from the temporal window, and in 65% we imaged the entire circle of Willis. From the sub-occipital window, we detected the entire vertebrobasilar circulation in 22% of subjects, and in 50% the basilar artery.
We then compared the performance of the multi-lag cross-correlation method with partial array reference on static and moving targets for an electronic aberrator. After showing that the multi-lag method performs better, we evaluated its performance with a physical aberrator. Using static targets, the correction resulted in an average contrast increase of 22.2%, compared to 13.2% using moving targets. The CNR increased by 20.5% and 12.8%, respectively. Doppler signal strength and number of Doppler voxels increased, by 5.6% and 14.4%, respectively, for the static method, and 9.3% and 4.9% for moving targets.
We performed two successful in vivo aberration corrections. We used this data and measure the isoplanatic patch size to be an average of 10.1°. The number of Doppler voxels increased by 38.6% and 19.2% for the two corrections. In both volunteers, correction enabled the visualization of a vessel not present in the uncorrected volume. These results are promising, and could potentially have a significant impact on public health.
Lastly, we show preliminary work testing the feasibility of a unique portable dedicated transcranial ultrasound system capable of simultaneous scanning from all three acoustic windows. Such a system would ideally be used in a preclinical setting, such as an ambulance.
Dissertation
(8066234), Gurneet S. Sangha. "Dual-modality Photoacoustic and Ultrasound Imaging for Murine Atherosclerosis Characterization." Thesis, 2019.
Знайти повний текст джерелаDort, Sarah. "Vector flow mapping using plane wave ultrasound imaging." Thèse, 2013. http://hdl.handle.net/1866/10859.
Повний текст джерелаClinical diagnosis of cardiovascular disease is dominated by colour-Doppler ultrasound despite its limitations: angle-dependent velocity measurements and low frame-rate from conventional focusing. Two studies, varying in their approach, address these limitations using plane-wave imaging, post-processed with the delay-and-sum and autocorrelation methods. The aim of this study is to re-implement these methods, investigating some parameters which affect blood velocity estimation accuracy using 2D vector-Doppler. Through in vitro experimentation on stationary parabolic flow, using a Verasonics system, four parameters were tested on mapping accuracy: number of tilts per orientation, ensemble length for single titled images, cycles per transmit pulse, and orientation angle at various flow-rates. The optimal estimates were found for 7 compounded tilts per image, oriented at ±15° with 6 cycles per pulse. Reconstruction accuracies were comparable to conventional Doppler; however, maintaining frame-rates more than 10 to 20 times faster, allowing better characterization of fast transient events requiring higher temporal resolution.
Hou, Yi. "Biomechanical Assessment and Monitoring of Thermal Ablation Using Harmonic Motion Imaging for Focused Ultrasound (HMIFU)." Thesis, 2014. https://doi.org/10.7916/D8FJ2DR5.
Повний текст джерелаGuo, Yuan. "Techniques for Quantitation of Left Ventricular Volume in Ultrasound Using 4DViz." Thesis, 2012. http://hdl.handle.net/10161/5869.
Повний текст джерелаIn the United States, heart failure is a leading cause of hospitalization. The medical industry places great emphasis on diagnosing heart disease through cardiac metrics like ejection fraction. Left ventricular ejection fraction is a commonly used diagnostic indicator for heart efficiency and is measured with echocardiography through different volume calculation techniques. However, ejection fraction results can drastically vary from one examiner to another. Generally cardiologists still give ejection fraction measurements a plus or minus 10 percent error range.
A program developed at Duke called 4DViz is robust enough for users to process 3D ultrasound data. 4DViz allows examiners to determine heart chamber volumes by constructing a surface model over an imaged heart chamber with many mouse click inputs. Through 4DViz programming, a viable approach for calculating ejection fraction is attempted in this thesis. Using feature tracking, surface drawing, and voxel filling, the new approach aims to reduce examiner input and improve ejection fraction consistency. Water filled balloons were used to calibrate the algorithm's parameters. In testing, several volunteers were asked to use the 4DViz. Their results are compared to volume measurements where user input was standard. The results show promise and may remove some of the inconsistency behind ejection fraction measurements.
Thesis
Rosenzweig, Stephen Joseph. "Implementation and Algorithm Development of 3D ARFI and SWEI Imaging for in vivo Detection of Prostate Cancer." Diss., 2014. http://hdl.handle.net/10161/9062.
Повний текст джерелаProstate cancer (PCa) is the most common non-cutaneous cancer in men with an estimated almost 30,000 deaths occurring in the United States in 2014. Currently, the most widely utilized methods for screening men for prostate cancer include the digital rectal exam and prostate specific antigen analysis; however, these methods lack either high sensitivity or specificity, requiring needle biopsy to confirm the presence of cancer. The biopsies are conventionally performed with only B-mode ultrasound visualization of the organ and no targeting of specific regions of the prostate, although recently, multi-parametric magnetic resonance imaging has shown promise for targeting biopsies. Earlier work has demonstrated the feasibility of acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) to visualize cancer in the prostate, however multiple challenges with both methods have been identified.
The aim of this thesis is to contribute to both the technical development and clinical applications of ARFI and SWEI imaging using the latest advancements in ultrasound imaging technology.
The introduction of the Siemens Acuson SC2000 provided multiple technological improvements over previous generations of ultrasound scanners, including: an improved power supply, arbitrary waveform generator, and additional parallel receive beamforming. In this thesis, these capabilities were utilized to improve both ARFI and SWEI imaging and reduce acoustic exposure and acquisition duration. However, the SC2000 did not originally have radiation force imaging capabilities; therefore, a new tool set for prototyping these sequences was developed along with rapid data processing and display code. These tools leveraged the increasing availability of general purpose computing on graphics processing units (GPUs) to significantly reduce the data processing time, facilitating real-time display for ultrasonic research systems.
These technical developments for both acquisition and processing were applied to investigate new methods for ARFI and SWEI imaging. Specifically, the power supply on the SC2000 allowed for a new type of multi-focal zone ARFI images to be acquired, which are shown to provide improved image quality over an extended depth of field. Additionally, a new algorithm for SWEI image processing was developed using an adaptive filter based on a maximum a posteriori estimator, demonstrating increases in the contrast to noise ratio of lesion targets upwards of 50%.
Finally, the optimized ARFI imaging methods were integrated with a transrectal ultrasound transducer to acquire volumetric in vivo data in patients undergoing robotic radical prostatectomy procedures in an ongoing study. When the study was initiated, it was recognized that the technological improvements of Siemens Acuson SC2000 allowed for the off-axis response to the radiation force excitation to be concurrently recorded without impacting ARFI image quality. This volumetric SWEI data was reconstructed retrospectively using the approaches developed in this thesis, but the images were low quality. A further investigation identified multiple challenges with the SWEI sequence, which should be addressed in future studies. The ARFI image volumes were very high quality and are currently being analyzed to assess the accuracy of ARFI to visualize prostate anatomy and clinically significant prostate cancer tumors. After a blinded evaluation of the ARFI image volumes for suspicion of prostate cancer, three readers correctly identified 63% of all clinically significant tumors and 74% of clinically significant tumors in the posterior region, showing great promise for using ARFI in the context of prostate cancer visualization for targeting biopsies, focal therapy, and watchful waiting.
Dissertation
Feliz, Yazmin. "UltrasonOS: The Development of an Open-Source Portable Ultrasound System for Medical Imaging." Thesis, 2021. https://doi.org/10.7916/d8-6vr9-3f26.
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