Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2022
Multi-covariate imaging of sub-resolution targets (MIST) is a statistical, model-based image formation technique that smooths speckles and reduces clutter. MIST decomposes the measured covariance of the element signals into modeled contributions from mainl ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · October 2020
Multi-covariate Imaging of Sub-resolution Targets (MIST) is an estimation-based method of imaging the statistics of diffuse scattering targets. MIST estimates the contributions of a set of covariance models to the echo data covariance matrix. Models are de ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2020
Coherence-based imaging methods suffer from reduced image quality outside the depth of field for focused ultrasound transmissions. Synthetic aperture methods can extend the depth of field by coherently compounding time-delayed echo data from multiple trans ...
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Journal ArticleThe Journal of the Acoustical Society of America · September 2019
The van Cittert-Zernike (VCZ) theorem describes the propagation of spatial covariance from an incoherent source distribution, such as backscatter from stochastic targets in pulse-echo imaging. These stochastic targets are typically assumed statistically st ...
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Journal ArticleIEEE transactions on medical imaging · July 2019
Conventional B-mode ultrasound imaging assumes that targets consist of collections of point scatterers. Diffraction, however, presents a fundamental limit on a scanner's ability to resolve individual scatterers in most clinical imaging environments. Well-k ...
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Journal ArticleAnnals of biomedical engineering · May 2016
Uncontrolled bleeding threatens patients undergoing major surgery and in care for traumatic injury. This paper describes a novel method of diagnosing coagulation dysfunction by repeatedly measuring the shear modulus of a blood sample as it clots in vitro. ...
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Journal ArticleThrombosis research · February 2016
BackgroundImpaired platelet function may underlie bleeding associated with cardiopulmonary bypass (CPB) and at present is incompletely evaluated with existing diagnostic technologies. Sonorheometry (SR) is a recently developed ultrasound-based tec ...
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Conference2015 IEEE International Ultrasonics Symposium, IUS 2015 · November 13, 2015
Effective management of clinical bleeding requires rapid diagnosis of its physiological cause. Abundant literature has shown that measurement of the evolving shear modulus of an in vitro clot yields valuable insights into the causes of bleeding. In this pa ...
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Journal ArticleJournal of neuroimaging : official journal of the American Society of Neuroimaging · April 2013
Background and purposeAs magnetic resonance-guided focused ultrasound (MRgFUS) sonothrombolysis relies on mechanical rather than thermal mechanisms to achieve clot lysis, thermometry is not useful for the intraoperative monitoring of clot breakdow ...
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Journal ArticleUltrasonics · March 2012
This paper proposes a novel receive beamformer architecture for broadband imaging systems that uses unique finite impulse response (FIR) filters on each channel. The conventional delay-and-sum (DAS) beamformer applies receive apodization by weighting the s ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2010
Bias and variance errors in motion estimation result from electronic noise, decorrelation, aliasing, and inherent algorithm limitations. Unlike most error sources, decorrelation is coherent over time and has the same power spectrum as the signal. Thus, red ...
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Journal ArticleUltrasound in medicine & biology · June 2010
Image reconstruction is central to many scientific fields, from medical ultrasound and sonar to computed tomography and computer vision. Although lenses play a critical reconstruction role in these fields, digital sensors enable more sophisticated computat ...
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Journal ArticleClinica chimica acta; international journal of clinical chemistry · May 2010
BackgroundViscoelastic diagnostics that monitor the hemostatic function of whole blood (WB), such as thromboelastography, have been developed with demonstrated clinical utility. By measuring the cumulative effects of all components of hemostasis, ...
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Journal ArticleClinica chimica acta; international journal of clinical chemistry · January 2010
BackgroundUnregulated hemostasis represents a leading cause of mortality and morbidity in the developed world. Being able to recognize and quantify defects of the hemostatic process is critical to reduce mortality and implement appropriate treatme ...
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Journal ArticleUltrasound in medicine & biology · August 2009
Ultrasound motion estimation is a fundamental component of clinical and research techniques that include color flow Doppler, spectral Doppler, radiation force imaging and ultrasound-based elasticity estimation. In each of these applications, motion estimat ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2009
We previously described a beamformer architecture that replaces the single apodization weights on each receive channel with channel-unique finite impulse response (FIR) filters. The filter weights are designed to optimize the contrast resolution performanc ...
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Journal ArticleUltrasonics · May 2009
This paper presents a new approach to improve the in silico modeling of ultrasound transducer arrays. While current simulation tools accurately predict the theoretical element spatio-temporal pressure response, transducers do not always behave as theorized ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2009
Existing methods for characterizing the imaging performance of ultrasound systems do not clearly quantify the impact of contrast, spatial resolution, and signal-to-noise ratio (SNR). Although the beamplot, contrast resolution metrics, SNR measurements, ide ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · January 1, 2009
This paper presents a novel motion estimator, termed the principal component displacement estimator (PCDE), which takes advantage of the signal separation capabilities of principal component analysis (PCA) to reject source signals representing decorrelatio ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · January 1, 2009
Over-activation or under-regulation of hemostasis plays a central role in the onset of diseases that represent leading causes of morbidity and mortality in the developed world. Current diagnostic technologies have had limited success in characterizing hemo ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · January 1, 2009
The Sonic Window is a pocket-sized, C-scan ultrasound device designed to expand ultrasound into clinical settings and applications that have yet to benefit from its utility. The low component cost, compact form factor with integrated 2D transducer array, a ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · January 1, 2009
We have recently developed a model-based adaptive image reconstruction algorithm, called dTONE, which significantly increases both image contrast and resolution by conducting a global optimization based on a model of sparse hypothetical scatterer locations ...
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ConferenceConference Record - Asilomar Conference on Signals, Systems and Computers · December 1, 2008
Recently, we have developed a model-based adaptive beamforming algorithm, entitled dTONE, which significantly increases both image contrast and resolution by conducting a global optimization based on a model of a sparse set of hypothetical source locations ...
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Journal ArticleAnnals of biomedical engineering · December 2008
Image registration and motion estimation play central roles in many fields, including RADAR, SONAR, light microscopy, and medical imaging. Because of its central significance, estimator accuracy, precision, and computational cost are of critical importance ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · September 2008
We previously presented a highly accurate, spline-based time delay estimator that directly determines subsample time delay estimates from sampled data. The algorithm uses cubic splines to produce a continuous time representation of a reference signal, and ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · May 7, 2008
Various methods are used in ultrasound beamforming to increase signal-to-noise ratio (SNR) and improve spatial resolution. SNR is typically improved by exploiting coherence in the RF channel data, for example summing channel data after applying focal delay ...
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Journal ArticleIEEE transactions on bio-medical engineering · February 2008
A system prototype of a future compact, low-cost medical ultrasound device is described and presented with experimental results. The prototype system consists of a 32 x 32 element, fully sampled 2-D transducer array and a printed circuit board (PCB) contai ...
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Journal ArticleIEEE transactions on medical imaging · January 2008
For nearly four decades, adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look directi ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2007
The delay-and-sum (DAS) beamformer, utilized in current state of the art ultrasound imaging systems, applies time delays on each receive channel to focus the returning echoes and weights the focused RF data on each receive channel prior to beamsummation. A ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2007
Adaptive beamforming (ABF) algorithms reduce the contribution of undesired off-axis signals, while maintaining a desired response along a specific look direction. Previously, we have described a novel ABF that can be applied to medical ultrasound, entitled ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2007
Inappropriate blood coagulation is a significant contributing factor in the onset of potentially fatal thrombotic events such as myocardial infarction, stroke, deep vein thrombosis (DVT), and pulmonary embolism (PE). The ability to recognize and quantify t ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2007
Traditional focused transducers use multiple elements with individual delays, or a single element and lens to achieve focusing. These approaches involve significant cost, or acoustic losses respectively, and are not well suited to low-cost applications, fo ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · October 15, 2007
Image registration, or equivalently motion estimation, plays a central role in a broad range of ultrasound applications including elastography, estimation of blood or tissue motion, radiation force imaging, and extended field of view imaging. Because of it ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2007
Computer simulations are an essential tool for the design of phased-array ultrasonic imaging systems. FIELD II, which determines the two-way temporal response of a transducer at a point in space, is the current de facto standard for ultrasound simulation t ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2007
This paper describes a metric that can be used to characterize the resolution of arbitrary broadband coherent imaging systems. The metric is particularly suited to medical ultrasound because it characterizes scanner performance using the contrast obtained ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · February 2007
Aperture weighting functions are critical design parameters in the development of ultrasound systems because beam characteristics affect the contrast and point resolution of the final output image. In previous work by our group, we developed a metric that ...
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ConferenceIEEE transactions on ultrasonics, ferroelectrics, and frequency control · February 2007
In the first part of this work, we introduced a novel general ultrasound apodization design method using constrained least squares (CLS). The technique allows for the design of system spatial impulse responses with narrow mainlobes and low sidelobes. In th ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2007
The problem of protecting or isolating extremely sensitive receive circuitry from high-voltage transmit circuitry is commonly addressed through the use of diode bridges, transformers, or high-voltage switches, which prove to be prohibitively expensive, bul ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · January 1, 2007
Aperture weighting functions are critical design parameters in the development of ultrasound systems because beam characteristics determine the contrast and point resolution of the final image. In previous work by our group, we developed a general apodizat ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2006
In medical ultrasound, motion estimation is used to align images in extended field of view applications, estimate blood or tissue motion, and estimate radiation force or mechanically induced displacements for elasticity imaging. In all of these application ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2006
Computer simulation is an important tool for the design of phased array ultrasonic systems. FIELD II, which determines the two-way temporal response of a transducer at a point in space, is the current de facto standard for ultrasound simulation tools [1]. ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2006
For over fifty years adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look direction. ...
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ConferenceConference Record - Asilomar Conference on Signals, Systems and Computers · December 1, 2006
For over fifty years adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look direction. ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · June 30, 2006
Medical Ultrasound Imaging is widely used clinically because of its relatively low cost, portability, lack of ionizing radiation, and real-time nature. However, even with these advantages ultrasound has failed to permeate the broad array of clinical applic ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · March 2006
We previously presented a novel time-delay estimator that uses cubic splines to estimate continuous time delays from sampled data. Previous simulation results showed that the spline-based algorithm yields superior performance when compared to the normalize ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
This paper will focus on the development of the second generation Sonic Window prototype, which will occupy a package the size of a deck of cards and be capable of forming C-mode ultrasound images in real-time. An array of 3,600 full receive channels - con ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
The performance of subarray processing as a means of reducing overall beamforming computational load for a low cost C-Scan imaging device is analyzed. Unlike the case encountered in B-Mode imaging, the C-Scan format is characterized by a large channel coun ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
The development of a new system that consists of a custom printed circuit board housed in and controlled by a standard PC is described. All transmit and receive electronics, prior to digitization, are placed on one PCI bus compatible card. The transmit cir ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
For over thirty years adaptive beamforming (AB) algorithms have been applied in RADAR and SONAR signal processing. Higher resolution and contrast is attainable using those algorithms at the price of an increased computational load. In this paper we conside ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
This work relates to efficient and low cost acquisition of beamformer data for C-Scan imaging. In our previously described Directly Sampled In-phase and Quadrature (DSIQ) approach [1], as few as one complex sample per array element is used. In the 'Synthet ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2005
We have previously described a metric that characterizes the 3D resolution of broadband ultrasound systems [1]. Resolution is expressed as the size of a spherical anechoic cyst, embedded in a speckle generating background, that is required to generate a sp ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · March 2005
Several important clinical applications depend on accurate ultrasound image frame-to-frame motion estimation. Assuming that there is a degree of finite noise in the image frames and that speckle partially decorrelates between successive frames during freeh ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2005
Time delay estimation (TDE) lies at the heart of signal processing algorithms in a broad range of application areas, including communications, coherent imaging, speech processing, and acoustics. In medical ultrasound for example, TDE is used in blood flow ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2004
We have previously presented a highly accurate, spline-based time delay estimator (TDE) that directly determines sub-sample time delay estimates from sampled data. The algorithm uses cubic splines to produce a continuous time representation of a reference ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2004
The first generation prototype of a portable, low-cost medical ultrasound device is described along with experimental results. The prototype system consists of a fully sampled 2D transducer array, sixteen custom receive circuitry chips multiplexed into two ...
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ConferenceConference Record - Asilomar Conference on Signals, Systems and Computers · December 1, 2004
In this paper we present a highly accurate, spline-based time delay estimator (TDE) that directly determines sub-sample time delay estimates from sampled data. The algorithm uses cubic splines to produce a continuous time representation of a reference sign ...
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ConferenceConference Record - Asilomar Conference on Signals, Systems and Computers · December 1, 2004
Conventional coherent imaging systems map the energy which is reflected directly back towards the transducer. While extremely useful, these systems fail to utilize information in the energy field which has been scattered at other angles. Angular scatter im ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2004
Angular scaner imaging has been proposed as a new source of image contrast in medical ultrasound and as a parameter for tissue characterization. We describe a new method of acquiring angular scatter data that combines the Translating Apertures Algorithm (T ...
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ConferenceProceedings - IEEE Ultrasonics Symposium · December 1, 2004
The resolution of medical ultrasound systems is usually characterized by the width of the mainlobe, typically the full width at half maximum (FWHM), in beamplots. The FWHM has, however, been shown to sometimes provide misleading information about systems. ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · December 1, 2004
A method for coherently acquiring backscatter and angular scatter information was described using a synthetic aperture based approach on a 1D linear array. The method of angular scatter imaging uses a single element synthetic aperture approach to acquire r ...
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ConferenceProgress in Biomedical Optics and Imaging - Proceedings of SPIE · December 1, 2004
We describe a very low cost handheld ultrasound system that we are currently developing for routine applications such as image guided needle insertion. We provide a system overview and focus discussion on our beamforming strategy, direct sampled I/Q (DSIQ) ...
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Chapter · December 1, 2004
As we age, substantial mechanical and structural alterations occur in the vitreous. These changes are believed to induce a series of vision threatening conditions, including retinal detachment and nuclear sclerotic cataracts. We have developed an acoustic ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · September 2004
A wide variety of beamforming approaches are applied in modern ultrasound scanners, ranging from optimal time domain beamforming strategies at one end to rudimentary narrowband schemes at the other. Although significant research has been devoted to improvi ...
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Journal ArticleAnnals of biomedical engineering · May 2004
Inappropriate blood coagulation plays a central role in the onset of myocardial infarction, stroke, pulmonary embolism, and other thrombotic disorders. The ability to screen for an increased propensity to clot could prevent the onset of such events by appr ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2003
In this paper we present a new time delay estimator that directly determines continuous time delay estimates from sampled data. The technique forms a spline-based piecewise continuous representation of the reference signal and then solves for the minimum o ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2003
Preliminary work on a fully sampled (32 × 32 element) 2D array is presented. This forms a component of a planned system capable of C-Scans (and ultimately B-Scans) of shallow blood vessels as a guide for intravenous needle insertion. Amongst the challenges ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2003
We describe a new beamforming strategy designed to support the development of an extremely low cost hand held ultrasound system. Our size and cost constraints for this system are too aggressive to make conventional beamforming feasible. We propose a radica ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2003
Extended Field of View imaging depends on accurate frame-to-frame motion estimation of ultrasound images. Using smaller frame increments will result in less decorrelation-related inaccuracy but present greater potential for cumulative error due to the incr ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2003
A design is presented, with prototype component experimental results, of a portable, low-cost 3D ultrasound system that utilizes innovative integrated circuit (IC) topologies and beamforming algorithms to condense the beamforming process into a small custo ...
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ConferenceProceedings of SPIE - The International Society for Optical Engineering · September 12, 2003
Adaptive beamforming has been widely used as a way to correct phase and amplitude aberration errors in medical ultrasound. A less-studied concern in ultrasound beamforming is the deleterious contribution of off-axis bright targets. We describe a new approa ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2003
It is well-known that changes in the mechanical properties of tissues are correlated with the presence of disease. In the eye, for example, the vitreous body undergoes dramatic changes in mechanical properties during age-related degradation. These changes ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2003
Time-delay estimation (TDE) is a common operation in ultrasound signal processing. In applications such as blood flow estimation, elastography, phase aberration correction, and many more, the quality of final results is heavily dependent upon the performan ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2003
The design of transmit and receive aperture weightings is a critical step in the development of ultrasound imaging systems. Current design methods are generally iterative, and consequently time consuming and inexact. We describe a new and general ultrasoun ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2003
In the first part of this work, we introduced the minimum sum squared error (MSSE) technique of ultrasound beamformer design. This technique enables the optimal design of apertures to achieve arbitrary system responses. In the MSSE technique, aperture weig ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2002
Several groups have proposed the use of acoustic radiation force as a means to characterize the mechanical properties of biological tissues. These approaches are based on the estimation of time delays between successively acquired echo lines when an intern ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2002
The design of transmit and receive aperture weightings is a critical step in the development of ultrasound imaging systems. Current design methods are generally iterative, and consequently time-consuming and inexact. We have previously described a general ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2002
The translating apertures algorithm (TAA) can be successfully applied to the measurement of tissue and phantom angular scatter properties. Such properties provide a new source of image contrast. Thus, shift variant filters should improve image depth of fie ...
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ConferenceConference Record of the Asilomar Conference on Signals, Systems and Computers · December 1, 2002
Ultrasonic imaging plays a critical diagnostic role in a broad range of medical specialties; however, there continue to be areas of clinical medicine where the advantages of ultrasound cannot be brought to bear because the targets of most interest do not e ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2002
An alternate approach for elasticity imaging was proposed. This technique applies a shear displacement to the tissue surface and uses 2-D speckle tracking to measure the resultant displacement field. Results indicate that shear elastography have good resol ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2002
Adaptive beamforming has been widely used as a way to improve image quality in medical ultrasound applications by correcting phase and amplitude aberration errors resulting from tissue inhomogeneity. A less-studied concern in ultrasound beamforming is the ...
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Journal ArticleIEEE Trans Ultrason Ferroelectr Freq Control · November 2002
In many medical ultrasound applications tissue-mimicking phantoms are of fundamental importance for the performance of controlled experiments. Traditionally, such phantoms have been constructed using gelatin and agar gels. Although the use of these materia ...
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Journal ArticleBiophysical journal · April 2002
A cell-scaled microbead system was used to analyze the force-dependent kinetics of P-selectin adhesive bonds independent of micromechanical properties of the neutrophil's surface microvilli, an elastic structure on which P-selectin ligand glycoprotein-1 (P ...
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ConferenceProceedings of SPIE - The International Society for Optical Engineering · January 1, 2002
Inappropriate blood coagulation plays an important role in diseases including stroke, heart attack, and deep vein thrombosis (DVT). DVT arises when a blood clot forms in a large vein of the leg. DVT is detrimental because the blood flow may be partially or ...
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ConferenceProceedings of SPIE - The International Society for Optical Engineering · January 1, 2002
Conventional techniques used to design transducer apertures for medical ultrasound are generally iterative and ad-hoc. They do not guarantee optimization of parameters such as mainlobe width and sidelobe levels. We propose a dynamic aperture weighting tech ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2001
Time delay estimation (TDE) is a common operation in ultrasound signal processing. A variety of TDE algorithms have been developed and applied in medical ultrasound, sonar, radar, and other fields. In this paper we analyze the performances of the widely us ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2001
Current aperture design techniques do not allow for the design of apertures that produce a beam pattern optimally similar to the desired pattern. A flexible beamforming technique that enables the optimal design of apertures for a desired system response is ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2001
It is well known that changes in the mechanical properties of tissues are correlated with the presence of disease. In the eye, the vitreous body goes through mechanical changes with age, which may eventually lead to the formation of retinal detachment. We ...
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Journal ArticleBiophysical journal · October 2001
Single particle tracking has seen numerous applications in biophysics, ranging from the diffusion of proteins in cell membranes to the movement of molecular motors. A plethora of computer algorithms have been developed to monitor the sub-pixel displacement ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · March 2001
Conventional ultrasonic imaging systems depict tissue backscatter, that is, the ultrasonic energy reflected directly back toward the transmitter. Although diagnostically useful, these systems fail to exploit the information available in components of the s ...
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Journal ArticleProceedings of SPIE - The International Society for Optical Engineering · January 1, 2001
Medical ultrasound research is typically performed using either video image data, or summed Radio Frequency (RF) data. While such data has led to improved understanding of ultrasound image formation, and in the development of novel image formation and sign ...
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ConferenceProceedings of SPIE - The International Society for Optical Engineering · January 1, 2001
The correlation between ultrasonic speckle patterns acquired with different system configurations determines the effectiveness of spatial and frequency compounding, phase aberration correction, elastography, and other applications. For some algorithms, suc ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · January 1, 2001
A method of acquisition that utilizes the translating apertures algorithm (TAA) to reliably separate target-specific angular scatter information from the effects of changing acquisition geometry was implemented in real-time on a clinical linear array syste ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 2000
The Translating Apertures Algorithm (TAA) is a novel method for imaging angular scatter. This paper presents analysis of the TAA using k-space theory, and simulations performed using a simulation tool, PSF. The effective depth of field of the TAA is calcul ...
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Journal ArticlePhysics in medicine and biology · June 2000
Acoustic radiation force has been proposed as a method of interrogating the mechanical properties of tissue. One simple approach applies a series of focused ultrasonic pulses to generate an acoustic radiation force, then processes the echoes returned from ...
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Journal ArticleProceedings of SPIE - The International Society for Optical Engineering · January 1, 2000
A new method of acquiring and processing angular scatter data in ultrasonic imaging is presented. This method, based on the translating apertures algorithm, eliminates system-dependent changes in the received point spread function (psf) that are associated ...
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Journal ArticleProceedings of SPIE - The International Society for Optical Engineering · January 1, 2000
We are developing a method that uses acoustic radiation force to image the stiffness of the vitreous body and other soft materials. This approach applies acoustic radiation force through a series of ultrasonic pulses to generate small displacements in tiss ...
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ConferenceAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1999
Studies suggest that selectin mediated rolling requires a relatively low reactive bond compliance compared to antigen-monoclonal antibody interactions. Based on in vivo and in vitro evidence, selectin tethers were directly measured at high temporal resolut ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 1999
Conventional ultrasound systems depict tissue backscatter; that is, the energy reflected directly back to the transmitter. While diagnostically useful, these systems fail to exploit information available in the echoes scattered in other directions (angular ...
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ConferenceASEE Annual Conference Proceedings · December 1, 1999
In the fall of 1996, faculty in engineering, mathematics, and physics departments at Auburn University launched an experimental pre-engineering program. The 2-year program consists of a team-taught sequence of mathematics, engineering, and physics courses ...
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Chapter · December 1, 1999
A new method of vitreous imaging which attempts to image tissue stiffness by applying acoustic radiation force is presented. The method yields the dynamic response of targets to the applied forces. For demonstration purposes, the B-Mode, maximum displaceme ...
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Journal ArticleThe Journal of the Acoustical Society of America · April 1999
Tissue elasticity estimation is a growing area of ultrasound research. One proposed approach would apply acoustic radiation force to displace tissue and use ultrasonic motion tracking techniques to measure the resultant displacement. Such a technique might ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1998
K-space is a frequency domain description of imaging systems and targets that can be used to gain insight into image formation. Although originally proposed in ultrasound for the analysis of experiments involving anisotropic scattering and for the design o ...
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ConferenceProceedings of the IEEE Ultrasonics Symposium · December 1, 1997
Wide-band aperture domain velocity estimator (WAVE) and narrow-band aperture domain velocity estimator (NAVE) represent a new approach to blood velocity estimation. When operating on data acquired from one dimensional arrays, these algorithms can yield two ...
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Journal ArticleIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control · December 1, 1997
Tissue speed of sound inhomogeneities cause significant degradation of medical ultrasound images. In some cases these inhomogeneities may be modeled as a thin time delay screen located at the face of the transducer. The effects of such near-field aberratio ...
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OtherProceedings of the IEEE Ultrasonics Symposium · December 1, 1997
Kinetic acoustic retinal evaluation (KARE) technique is developed which would noninvasively generate and image vitreal motion. A two step method is also developed for noninvasive repair of retinal detachments. In the first step, acoustic retinal manipulati ...
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Journal ArticleThe Journal of the Acoustical Society of America · April 1997
Tissue speed of sound inhomogeneities cause significant degradation of medical ultrasound images. In certain cases these inhomogeneities can be modeled as a thin, spatially varying time delay screen located at the face of the transducer. Correction of such ...
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Journal ArticleIEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1997
Acoustic velocity inhomogeneities in tissue result in aberration of ultrasound images. These aberrations can be modeled as a near field thin phase screen or as a distributed aberrator. The effect of a near field thin phase screen is to time shift the recei ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1996
Phase aberration correction techniques require highly correlated signals at different receiver positions in order to estimate and correct for the time shifts imposed by the aberrator. The translating transmit aperture algorithm is a technique for improving ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1995
Speed of sound inhomogeneities cause significant degradation of ultrasonic images. In some parts of the body inhomogeneities can be modeled as a thin time delay screen at the surface of the skin. Such aberrators may be compensated for by adjusting time del ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1995
Acoustic velocity inhomogeneitis in tissue result in aberration of ultrasonic images. These aberrations can be modelled as a near field thin phase screen or as a distributed aberrator. Current techniques for the correction of distributed aberrators are lim ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1995
K-Space is a frequency domain description of ultrasonic imaging systems and targets which can be used to gain insight into their interaction during image formation. Although originally proposed as a technique for the analysis of imaging problems involving ...
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Journal ArticleIEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control · January 1, 1995
Delay estimation is used in ultrasonic imaging to estimate blood or soft tissue motion, to measure echo arrival time differences for phase aberration correction, and to estimate displacement for tissue elasticity measurements. In each of these applications ...
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Journal ArticleUltrasound in medicine & biology · January 1995
The feasibility of a new ultrasonic technique to distinguish cysts from solid lesions is explored. High intensity pulses are used to induce acoustic streaming in cyst fluid, and this motion is detected using Doppler techniques. Acoustic streaming cannot be ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1994
Improvements in medical ultrasonic image resolution are typically accompanied by significant increases in the number of piezoelectric array elements and beamformer channels. The synthetic receive aperture (SRA) imaging technique achieves dramatic improveme ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1994
Signal alignment is performed in phase aberration correction and measurement, tissue elasticity estimation, and tissue and blood velocity estimation. The performance of all these techniques is limited by errors in the alignment of signals received from spe ...
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ConferenceAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1994
A translation system has been assembled to assist in high speed acquisition of parallel planes of ultrasonic data from phantoms and human tissue. Using a previously developed system that measures two-dimensional velocities in real time by tracking speckle ...
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Journal ArticleIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control · September 1, 1994
Cross correlation and similar operations are used in ultrasonic imaging to estimate blood or soft tissue motion in one or more dimensions and to measure echo arrival time differences for phase aberration correction. These estimates are subject to large err ...
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Journal ArticleIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control · January 1, 1994
Cross correlation and similar operations are used in ultrasonic imaging to estimate blood or soft tissue motion in one or more dimensions and to measure echo arrival time differences for phase aberration correction. These estimates are subject to large err ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · January 1, 1994
Results from both a pilot clinical study and phantom studies performed to evaluate a new ultrasonic technique to distinguish cysts from solid lesions are presented. High intensity pulses are used to induce acoustic streaming in cyst fluid, and this motion ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1993
Cross correlation and similar operations are used for displacement (delay) estimation in medical ultrasound. We apply the Cramer-Rao Lower Bound to derive analytical expressions to predict the magnitude of errors in displacement estimation using radio freq ...
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Journal ArticleProceedings of the IEEE Ultrasonics Symposium · December 1, 1993
Tumors in soft tissues are often detected because of their higher stiffness relative to surrounding tissues. A number of groups have constructed systems which attempt to estimate stiffness by imaging the propagation of low frequency (<1 KHz) mechanical wav ...
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