Scholars@Duke
Gregg E. Trahey

Gregg E. Trahey

Robert Plonsey Distinguished Professor Emeritus of Biomedical Engineering
Biomedical Engineering
gregg.trahey@duke.edu
Box 90281, Durham, NC 27708-0281
275 Engineering Annex, Durham, NC 27708

Scholarly Works

Clutter-Generating Phantom Material. Part I: Development of a Tunable, Acoustic Clutter-Generating Layer for Use With Ultrasound Tissue-Mimicking Phantoms.

Journal article Ultrasound in medicine & biology · May 2025 ObjectiveAcoustic clutter is a major source of image degradation for in vivo ultrasound imaging. However, clutter is often not represented in laboratory testing of ultrasound equipment. A phantom material is proposed that can be used to add calibr ... Full text Cite

Spatial Ambiguity Correction in Coherence-Based Average Sound Speed Estimation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · October 2024 Sound speed estimation can potentially correct the focusing errors in medical ultrasound. Maximizing the echo spatial coherence as a function of beamforming sound speed is a known technique to estimate the average sound speed. However, beamformation with c ... Full text Cite

In Vivo Demonstration of a Real-Time Temporal SNR Acoustic Output Adjustment Method.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · August 2024 This work proposes a novel method of temporal signal-to-noise ratio (SNR)-guided adaptive acoustic output adjustment and demonstrates this approach during in vivo fetal imaging. Acoustic output adjustment is currently the responsibility of sonographers, bu ... Full text Link to item Cite

Human Observer Sensitivity to Temporal Noise During B-Mode Ultrasound Scanning: Characterization and Imaging Implications.

Journal article Ultrason Imaging · May 2024 This work measures temporal signal-to-noise ratio (SNR) thresholds that indicate when random noise during ultrasound scanning becomes imperceptible to expert human observers. Visible noise compromises image quality and can potentially lead to non-diagnosti ... Full text Link to item Cite

Evaluation of Myocardial Stiffness in Cardiac Amyloidosis Using Acoustic Radiation Force Impulse and Natural Shear Wave Imaging.

Journal article Ultrasound Med Biol · August 2023 OBJECTIVE: Increased myocardial stiffness (MS) is an important hallmark of cardiac amyloidosis (CA) caused by myocardial amyloid deposition. Standard echocardiography metrics assess MS indirectly via downstream effects of cardiac stiffening. The ultrasound ... Full text Link to item Cite

Large-Array Deep Abdominal Imaging in Fundamental and Harmonic Mode.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2023 Deep abdominal images suffer from poor diffraction-limited lateral resolution. Extending the aperture size can improve resolution. However, phase distortion and clutter can limit the benefits of larger arrays. Previous studies have explored these effects u ... Full text Cite

Adaptive acoustic power and frequency adjustment in color Doppler imaging

Conference IEEE International Ultrasonics Symposium Ius · January 1, 2023 Automated, real-time adjustment of ultrasound imaging parameters could speed up scanning sessions, decrease operator dependence, and improve reproducibility. This study examines adaptive frequency and acoustic output adjustment in color Doppler imaging to ... Full text Cite

An Automated Region-Selection Method for Adaptive ALARA Ultrasound Imaging.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · July 2022 The objective of this work was to develop an automated region of the interest selection method to use for adaptive imaging. The as low as reasonably achievable (ALARA) principle is the recommended framework for setting the output level of diagnostic ultras ... Full text Link to item Cite

Adaptive Models for Multi-Covariate Imaging of Sub-Resolution Targets (MIST).

Journal article IEEE 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 ... Full text Cite

Spatial Coherence in Medical Ultrasound: A Review.

Journal article Ultrasound in medicine & biology · June 2022 Traditional pulse-echo ultrasound imaging heavily relies on the discernment of signals based on their relative magnitudes but is limited in its ability to mitigate sources of image degradation, the most prevalent of which is acoustic clutter. Advances in c ... Full text Cite

Reverberation Clutter Suppression Using 2-D Spatial Coherence Analysis.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2022 Diffuse reverberation clutter often significantly degrades the visibility of abdominal structures. Reverberation clutter acts as a temporally stationary haze that originates from the multiple scattering within the subcutaneous layers and has a narrow spati ... Full text Cite

Occult Regions of Suppressed Coherence in Liver B-Mode Images.

Journal article Ultrasound Med Biol · January 2022 Ultrasound is an essential tool for diagnosing and monitoring diseases, but it can be limited by poor image quality. Lag-one coherence (LOC) is an image quality metric that can be related to signal-to-noise ratio and contrast-to-noise ratio. In this study, ... Full text Link to item Cite

Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging-Part I: Simulation Studies.

Journal article IEEE open journal of ultrasonics, ferroelectrics, and frequency control · January 2022 The appropriate selection of a clutter filter is critical for ensuring the accuracy of velocity estimates in ultrasound color flow imaging. Given the complex spatio-temporal dynamics of flow signal and clutter, however, the manual selection of filters can ... Full text Cite

Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging-Part II: Phantom and In Vivo Experiments.

Journal article IEEE open journal of ultrasonics, ferroelectrics, and frequency control · January 2022 Conventional color flow processing is associated with a high degree of operator dependence, often requiring the careful tuning of clutter filters and priority encoding to optimize the display and accuracy of color flow images. In a companion paper, we intr ... Full text Cite

An adaptive acoustic output selection method feasible for implementation on existing clinical systems

Conference IEEE International Ultrasonics Symposium Ius · January 1, 2022 Previous work has demonstrated acoustic output can be adaptively adjusted to follow the ALARA (as low as reasonably achievable) principle. Here, a refined ALARA approach is introduced based on capturing a system's underlying noise power and using it, along ... Full text Cite

Human observer sensitivity to temporal noise in ultrasound imaging

Conference IEEE International Ultrasonics Symposium Ius · January 1, 2022 The impact of temporal noise on ultrasound image quality can be decreased with use of higher acoustic output. Acoustic output increases amplify receive signal strength relative to the temporal noise floor, improving the temporal signal-to-noise ratio (SNR) ... Full text Cite

Frequency-Dependent Spatial Coherence in Conventional and Chirp Transmissions.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2021 The development of adaptive imaging techniques is contingent on the accurate and repeatable characterization of ultrasonic image quality. Adaptive transmit frequency selection, filtering, and frequency compounding all offer the ability to improve target co ... Full text Cite

Resolution and Speckle Reduction in Cardiac Imaging.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · April 2021 Cardiac imaging depends on clear visualization of several different structural and functional components to determine left ventricular and overall cardiac health. Ultrasound imaging is confounded by the characteristic speckle texture resulting from subwave ... Full text Link to item Cite

Mechanisms affecting ALARA MI selected in adaptive ultrasound imaging

Conference IEEE International Ultrasonics Symposium Ius · January 1, 2021 Adaptive acoustic output selection in ultrasound imaging promises to improve adherence to the ALARA (as low as reasonably achievable) principle. Demonstrated imaging sequences have balanced image quality and safety considerations based on transducer channe ... Full text Cite

An Automated ALARA Method for Ultrasound: An Obstetric Ultrasound Feasibility Study.

Journal article J Ultrasound Med · December 2, 2020 OBJECTIVES: Ultrasound users are advised to observe the ALARA (as low as reasonably achievable) principle, but studies have shown that most do not monitor acoustic output metrics. We developed an adaptive ultrasound method that could suggest acoustic outpu ... Full text Link to item Cite

Intrinsic Tradeoffs in Multi-Covariate Imaging of Sub-Resolution Targets.

Journal article IEEE 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 ... Full text Cite

UltraNet: Deep Learning Tools for Modeling Acoustic Wall Clutter

Conference IEEE International Ultrasonics Symposium Ius · September 7, 2020 Ultrasonic image quality is often challenged by speckle noise and acoustic clutter which reduces the anatomical conspicuity of medically relevant features. Deep learning approaches show promise in correcting these sources of noise, but there currently lack ... Full text Cite

Implementation of adaptive transmit parameter adjustment in ultrasound imaging

Conference IEEE International Ultrasonics Symposium Ius · September 7, 2020 The coherence of signals received by neighboring transducer array elements, the lag-one coherence (LOC), provides a local measure of clutter and temporally varying noise. Increasing transmit intensity decreases the impact of temporal noise on image quality ... Full text Cite

Congruence of frequency-dependent spatial coherence between linear frequency-modulated pulses and conventional pulses

Conference IEEE International Ultrasonics Symposium Ius · September 7, 2020 Adaptive transmit frequency selection, filtering, and frequency compounding all offer the ability to improve target conspicuity by balancing the effects of imaging resolution, signal-to-clutter ratio, and speckle texture, but the use of pilot pulses at a s ... Full text Cite

Incoherent Clutter Suppression Using Lag-One Coherence.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · August 2020 The lag-one coherence (LOC), derived from the correlation between the nearest-neighbor channel signals, provides a reliable measure of clutter which, under certain assumptions, can be directly related to the signal-to-noise ratio of individual channel sign ... Full text Cite

Coherence-based quantification of acoustic clutter sources in medical ultrasound.

Journal article The Journal of the Acoustical Society of America · August 2020 The magnitudes by which aberration and incoherent noise sources, such as diffuse reverberation and thermal noise, contribute to degradations in image quality in medical ultrasound are not well understood. Theory predicting degradations in spatial coherence ... Full text Cite

Synthetic Aperture Focusing for Multi-Covariate Imaging of Sub-Resolution Targets.

Journal article IEEE 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 ... Full text Cite

MimickNet, Mimicking Clinical Image Post- Processing Under Black-Box Constraints.

Journal article IEEE transactions on medical imaging · June 2020 Image post-processing is used in clinical-grade ultrasound scanners to improve image quality (e.g., reduce speckle noise and enhance contrast). These post-processing techniques vary across manufacturers and are generally kept proprietary, which presents a ... Full text Cite

The Impact of Acoustic Clutter on Large Array Abdominal Imaging.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2020 Abdominal imaging suffers from a particularly difficult acoustic environment-targets are located deep and overlying tissue layers with varying properties generate acoustic clutter. Increasing array size can overcome the penetration and lateral resolution p ... Full text Cite

Simultaneous Photoacoustic Imaging and Cavitation Mapping in Shockwave Lithotripsy.

Journal article IEEE transactions on medical imaging · February 2020 Kidney stone disease is a major health problem worldwide. Shockwave lithotripsy (SWL), which uses high-energy shockwave pulses to break up kidney stones, is extensively used in clinic. However, despite its noninvasiveness, SWL can produce cavitation in viv ... Full text Cite

Force-Map Normalization for ARFI Imaging

Conference IEEE International Ultrasonics Symposium Ius · October 1, 2019 Acoustic Radiation Force Impulse (ARFI) images are used to visualize spatial variations in soft tissue elasticity by showing the displacement of each pixel in response to an applied radiation force. However, accommodations for spatial variations in the app ... Full text Cite

K-space Compounding for Improved Endocardial Border Detection

Conference IEEE International Ultrasonics Symposium Ius · October 1, 2019 Visualization of the endocardial border is essential in determining left ventricular and overall cardiac function. Ultrasound imaging systems typically rely on image post-processing for contrast and detail enhancement. Spatial compounding is a physics-base ... Full text Cite

MimickNet, Matching Clinical Post-Processing under Realistic Black-Box Constraints

Conference IEEE International Ultrasonics Symposium Ius · October 1, 2019 Image post-processing is used in clinical-grade ultrasound scanners to improve image quality (e.g., reduce speckle noise and enhance contrast). These post-processing techniques vary across manufacturers and are generally kept proprietary, which presents a ... Full text Cite

Speckle coherence of piecewise-stationary stochastic targets.

Journal article The 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 ... Full text Cite

Multi-covariate Imaging of Sub-resolution Targets.

Journal article IEEE 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 ... Full text Cite

Measuring Intraventricular Pressure Using Ultrasound Elastography.

Journal article Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine · May 2019 ObjectivesIntraventricular pressure (IVP) is one of the most important measurements for evaluating cardiac function, but this measurement is not currently easily assessable in the clinic. The primary reason for this is the absence of a noninvasive ... Full text Cite

Non-invasive Measurement of Dynamic Myocardial Stiffness Using Acoustic Radiation Force Impulse Imaging.

Journal article Ultrasound Med Biol · May 2019 Myocardial stiffness exhibits cyclic variations over the course of the cardiac cycle. These trends are closely tied to the electromechanical and hemodynamic changes in the heart. Characterization of dynamic myocardialstiffness can provide insights into the ... Full text Link to item Cite

Short-lag Spatial Coherence Imaging in 1.5-D and 1.75-D Arrays: Elevation Performance and Array Design Considerations.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · March 2019 Short-lag spatial coherence (SLSC) imaging has demonstrated improved performance over conventional B-Mode ultrasound imaging. Previous work has evaluated the performance of SLSC using 2-D matrix arrays in simulation and in vivo studies across various level ... Full text Cite

Implementation and Clinical Evaluation of a Fetal ALARA Ultrasound System

Conference IEEE International Ultrasonics Symposium Ius · December 17, 2018 The US Food and Drug Administration (FDA) provides guidelines for acoustic output to ensure that ultrasound remains a safe imaging modality used widely in applications such as obstetrics. However, even within these limits, additional acoustic output that d ... Full text Cite

Investigating the Degree of Shear Wave Speed Anisotropy as a Function of Studied Ventricular Zone

Conference IEEE International Ultrasonics Symposium Ius · December 17, 2018 In order for shear wave elastography (SWE)to be a quantitative imaging tool for myocardial stiffness, it is important to eliminate or reduce the non-disease related factors that affect myocardial stiffness estimation. It is known for shear wave speed repre ... Full text Cite

A Real-Time Lag-One Coherence Tool for Adaptive Imagmg

Conference IEEE International Ultrasonics Symposium Ius · December 17, 2018 Ultrasound imaging is the product of numerous pulse sequence and processing design choices, but it is impossible to optimize for every clinical imaging case with a single set of parameters. Many sonographers do not take advantage of even the limited set of ... Full text Cite

Implications of Lag-One Coherence on Real- Time Adaptive Frequency Selection

Conference IEEE International Ultrasonics Symposium Ius · December 17, 2018 Hepatic image quality has been shown to be degraded by the clutter-generating effects of the abdominal wall, and while beamforming and signal processing methods exist to minimize clutter, there is currently no automated method by which parameters such as i ... Full text Cite

Lag-One Coherence as a Metric for Ultrasonic Image Quality.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · October 2018 Reliable assessment of image quality is an important but challenging task in complex imaging environments such as those encountered in vivo. To address this challenge, we propose a novel imaging metric, known as the lag-one coherence (LOC), which leverages ... Full text Cite

Effect of Transmit Beamforming on Clutter Levels in Transthoracic Echocardiography.

Journal article Ultrason Imaging · July 2018 Transmit beamforming has a strong impact on several factors that govern image quality, field-of-view, and frame-rate in ultrasound imaging. For cardiac applications, the visualization of fine structures and the ability to track their motion is equally impo ... Full text Link to item Cite

Clinical Utility of Fetal Short-Lag Spatial Coherence Imaging.

Journal article Ultrasound Med Biol · April 2018 In this study, we evaluate the clinical utility of fetal short-lag spatial coherence (SLSC) imaging. Previous work has documented significant improvements in image quality with fetal SLSC imaging as quantified by measurements of contrast and contrast-to-no ... Full text Link to item Cite

Evaluation of Large-Aperture Imaging Through the ex Vivo Human Abdominal Wall.

Journal article Ultrasound in medicine & biology · March 2018 Current clinical abdominal imaging arrays are designed to maximize angular field of view rather than the extent of the coherent aperture. We illustrate, in ex vivo experiments, the use of a large effective aperture to perform high-resolution imaging, even ... Full text Cite

Assessment of Diastolic Function Using Ultrasound Elastography.

Journal article Ultrasound in medicine & biology · March 2018 Shear wave elasticity imaging (SWEI) is a novel ultrasound elastography technique for assessing tissue stiffness. In this study, we investigate the potential of SWEI for providing diastolic functional assessment. In 11 isolated rabbit hearts, pressure-volu ... Full text Cite

Anisotropic Constructive Shearwave Interference Measurement of Transversely Anisotropic Materials

Conference IEEE International Ultrasonics Symposium Ius · January 1, 2018 Fibrous tissues, such as skeletal muscle, tendons, and myocardium, have been shown to support orientation-dependent shear wave propagation. It has been shown that shear waves can be induced and measured with ultrasound to assess such anisotropy. Existing m ... Full text Cite

Thee-Dimensional Single-Track-Location Shear Wave Elasticity Imaging.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · December 2017 Conventional multiple-track-location shear wave elasticity imaging (MTL-SWEI) is a powerful tool for noninvasively estimating tissue elasticity. The resolution and noise levels of MTL-SWEI systems, however, are limited by ultrasound speckle. Single-track-l ... Full text Cite

Coherence beamforming and its applications to the difficult-to-image patient

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Poor quality ultrasound images and inadequate or suboptimal visualization of imaging targets is a common problem in individuals that are overweight or obese. Acoustic reverberation is an incoherent noise source that is a common factor in overweight and obe ... Full text Cite

Notice of Removal: Translation of fetal short-lag spatial coherence (SLSC) imaging into clinical practice: A pilot study

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Fetal short-lag spatial coherence (SLSC) imaging has demonstrated 64-85% increases in CNR and 17-29% increases in contrast relative to conventional B-mode imaging. However, despite its proven technical efficacy, the viability of fetal SLSC in the clinical ... Full text Cite

Notice of Removal: Spatio-temporal consistency of transthoracic ARFI-derived metrics of myocardial function

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Cardiac function has traditionally been studied using pressure-volume (PV) loop analysis. PV loops can be used to derive functional indices such as end-systolic pressure volume relationship (ESPVR) - a measure of myocardial contractility, end-diastolic pre ... Full text Cite

A novel drift compensation algorithm for improved beat-to-beat repeatability of myocardial strain imaging: Preliminary in vivo results

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Myocardial strain imaging has been shown to add significant prognostic and diagnostic value to echocardiography. While the reliability of ultrasound-based strain measurement techniques has improved considerably in terms of regional consistency and inter-re ... Full text Cite

Notice of Removal: A novel strain-based drift compensation algorithm for improved beat-to-beat repeatability of myocardial strain imaging: Preliminary in vivo results

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Strain imaging is gaining traction as a means to assess cardiac function by tracking the cyclic deformation of the myocardium. Compared to traditional measures such as ejection fraction, global myocardial strain has been shown to be an earlier and more sen ... Full text Cite

Notice of Removal: Clinical feasibility of a noninvasive method to interrogate myocardial function via strain and acoustic radiation force-derived stiffness

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Myocardial elastance, derived from pressure-volume (PV) loops in the left ventricle (LV), can be used to assess LV function and myocardial performance. This method requires an invasive intracardiac pressure-volume catheter to be inserted in the LV, limitin ... Full text Cite

Notice of Removal: Parameters impacting accuracy of ARFI-derived stiffness ratios: A simulation study with implications on measurement of dynamic myocardial stiffness

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Measurement of myocardial stiffness using ultrasound-based transient elastography has received significant attention in recent years. The mechanical properties of myocardium not only undergo cyclic dynamic changes over the cardiac cycle but also change on ... Full text Cite

Single track location comb-push ultrasound shear elastography (STL-CUSE)

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Single Track Location Shear Wave Elasticity Imaging (STL-SWEI) creates high resolution shear wave speed maps by comparing the tissue motion at each tracking location between spatially-offset radiation force excitations. While STL-SWEI circumvents the resol ... Full text Cite

Calibration of ARFI displacements using diastolic shear wave speeds for estimating systolic elasticity

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 ARFI displacements have been shown to share an inverse relationship with shear wave speed - based estimates of tissue elasticity. Both ARFI and shear wave elasticity imaging (SWEI) have been used to track the stiffening and softening of myocardium through ... Full text Cite

Notice of Removal: Swept synthetic study of large aperture imaging through ex vivo human abdominal wall

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Lateral resolution and therefore image quality in ultrasound is tied to aperture size. While this relationship is understood in ideal imaging conditions, the utility of a large aperture in the presence of clutter is unknown. This problem is particularly re ... Full text Cite

Calibration of ARFI displacements using diastolic shear wave speeds for estimating systolic elasticity

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 ARFI displacements have been shown to share an inverse relationship with shear wave speed - based estimates of tissue elasticity. In transthoracic imaging, induced shear waves have been observed during diastole, but only ARFI displacements have been accura ... Full text Cite

Single track location Comb-Push Ultrasound Shear Elastography (STL-CUSE)

Conference IEEE International Ultrasonics Symposium Ius · October 31, 2017 Comb-Push Ultrasound Shear Elastography (CUSE) uses ultrasound beams focused simultaneously at multiple laterally-offset positions to induce shear waves in tissue, and uses the local propagation of the waves to estimate tissue elasticity everywhere in the ... Full text Cite

Quantifying Image Quality Improvement Using Elevated Acoustic Output in B-Mode Harmonic Imaging.

Journal article Ultrasound Med Biol · October 2017 Tissue harmonic imaging has been widely used in abdominal imaging because of its significant reduction in acoustic noise compared with fundamental imaging. However, tissue harmonic imaging can be limited by both signal-to-noise ratio and penetration depth ... Full text Link to item Cite

Scanned 3-D Intracardiac ARFI and SWEI for Imaging Radio-Frequency Ablation Lesions.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2017 Radio-frequency ablation (RFA) is used to locally disrupt electrical propagation in myocardium and treat arrhythmias, and direct visualization of ablation lesions by acoustic radiation force methods may benefit RFA procedures. This paper compares four imag ... Full text Cite

Impact of beamforming strategies and regularisation on ultrasound displacement estimation using RF-based image registration

Conference Proceedings International Symposium on Biomedical Imaging · June 15, 2017 In the context of ultrasound (US) deformation imaging it has been shown that lateral motion estimation can be improved by simultaneously combining transverse oscillation (TO) beamforming with dedicated motion estimators and regularisation techniques. This ... Full text Cite

Blocked Elements in 1-D and 2-D Arrays-Part II: Compensation Methods as Applied to Large Coherent Apertures.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2017 In Part I of this paper, we detected elements blocked by ribs during simulated and in vivo transcostal liver scans, and we turned those elements OFF to compensate for the loss in visibility of liver vasculature. Here, we apply blocked-element detection and ... Full text Cite

Blocked Elements in 1-D and 2-D Arrays-Part I: Detection and Basic Compensation on Simulated and In Vivo Targets.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2017 During a transcostal ultrasound scan, ribs and other highly attenuating and/or reflective tissue structures can block parts of the array. Blocked elements tend to limit the acoustic window and impede visualization of structures of interest. Here, we demons ... Full text Cite

Evaluation of the Transverse Oscillation Technique for Cardiac Phased Array Imaging: A Theoretical Study.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · February 2017 The transverse oscillation (TO) technique can improve the estimation of tissue motion perpendicular to the ultrasound beam direction. TOs can be introduced using plane wave (PW) insonification and bilobed Gaussian apodization (BA) on receive (abbreviated a ... Full text Cite

Quantifying Myocardial Contractility Changes Using Ultrasound-Based Shear Wave Elastography.

Journal article Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography · January 2017 BackgroundMyocardial contractility, a significant determinant of cardiac function, is valuable for diagnosis and evaluation of treatment in cardiovascular disorders including heart failure. Shear wave elasticity imaging (SWEI) is a newly developed ... Full text Cite

Single track location Shear Wave Elasticity Imaging of the liver with reduced propagation windows

Conference IEEE International Ultrasonics Symposium Ius · November 1, 2016 Shear Wave Elasticity Imaging (SWEI) measures the elastic properties of the liver noninvasively, with application to staging liver fibrosis. To make a useful estimate, a shear wave of sufficient amplitude must be generated in the liver. Tracking speckle si ... Full text Cite

Large coherent apertures: Improvements in deep abdominal imaging and fundamental limits imposed by clutter

Conference IEEE International Ultrasonics Symposium Ius · November 1, 2016 Reverberation and aberration clutter can significantly degrade the ability to image deep abdominal structures in clinical practice. Despite increased hardware complexity and computing power, modern ultrasound arrays are still commonly limited to a length o ... Full text Cite

Synthetic aperture imaging with thinned linear sensor arrays for medical ultrasound

Conference Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop · September 15, 2016 In this paper, we exploit motion for improving the ultrasound (US) imaging performance of thinned sensor array systems. Thinned arrays provide reduced system cost and allows for the reduction of bulky channel cables. However, thinned array systems suffer f ... Full text Cite

A Comparison of Acoustic Radiation Force-Derived Indices of Cardiac Function in the Langendorff Perfused Rabbit Heart.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · September 2016 In the past decade, there has been an increased interest in characterizing cardiac tissue mechanics utilizing newly developed ultrasound-based elastography techniques. These methods excite the tissue mechanically and track the response. Two frequently used ... Full text Cite

Feasibility of Swept Synthetic Aperture Ultrasound Imaging.

Journal article IEEE transactions on medical imaging · July 2016 Ultrasound image quality is often inherently limited by the physical dimensions of the imaging transducer. We hypothesize that, by collecting synthetic aperture data sets over a range of aperture positions while precisely tracking the position and orientat ... Full text Open Access Cite

Synthetic tracked aperture ultrasound imaging: design, simulation, and experimental evaluation.

Journal article Journal of medical imaging (Bellingham, Wash.) · April 2016 Ultrasonography is a widely used imaging modality to visualize anatomical structures due to its low cost and ease of use; however, it is challenging to acquire acceptable image quality in deep tissue. Synthetic aperture (SA) is a technique used to increase ... Full text Cite

Detection of and compensation for blocked elements using large coherent apertures: Ex vivo studies

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2016 When imaging with ultrasound through the chest wall, it is not uncommon for parts of the array to get blocked by ribs, which can limit the acoustic window and significantly impede visualization of the structures of interest. With the development of large-A ... Full text Cite

Acoustic radiation force-based ultrasound elastography for cardiac imaging applications

Book section · January 1, 2016 This chapter reviews the current research and applications for acoustic radiation force (ARF)‐based methods, namely ARF impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) methods, in the diagnosis and treatment of cardiac diseases. ARFI imagin ... Full text Cite

In vivo transthoracic measurements of acoustic radiation force induced displacements in the heart over the cardiac cycle

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 Myocardial elasticity is an important indicator of cardiac function and is affected in many disorders associated with heart failure. Ultrasound based interrogation of cardiac stiffness has been extensively studied in ex-vivo, open chest and intracardiac im ... Full text Cite

Phantom and in vivo demonstration of swept synthetic aperture imaging

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 Ultrasound imaging of deep abdominal targets suffers from low lateral resolution due to limited aperture size and low-frequency transmit pulses. We demonstrate phantom and in vivo imaging results using a device that allows a tracked mechanical sweep of a c ... Full text Cite

Real-time high-framerate in vivo cardiac SLSC imaging with a GPU-based beamformer

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 Echocardiography is widely used to evaluate cardiovascular function in real-time; however, endocardial borders are often inadequately visualized due to clutter. Contrast agents, while effective, increase cost and examination time. SLSC imaging is a coheren ... Full text Cite

Eliminating speckle noise with three-dimensional single-track-location shear wave elasticity imaging (STL-SWEI)

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 Conventional multiple track location shear wave elasticity imaging (MTL-SWEI) is a powerful tool for noninvasively estimating tissue elasticity. The resolution and noise of MTL-SWEI systems, however, are limited by ultrasound speckle. Single track location ... Full text Cite

Speckle bias as a 3-D offset for the tracking location of shear wave imaging

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 In conventional, multiple track location shear wave elasticity imaging (MTL-SWEI), shear wave speeds are estimated by imaging wave propagation at multiple positions in the tissue with high speed ultrasound and comparing the motion measured at each location ... Full text Cite

Regularized, weighted temporal multiresolution speckle tracking of small displacements in ultrasound

Conference 2015 IEEE International Ultrasonics Symposium Ius 2015 · November 13, 2015 A new referencing scheme for estimating axial displacements with ultrasound is presented. The multiresolution scheme combines estimates made at multiple temporal spacings into a single, noise robust, high resolution estimate. The problem is framed as an ov ... Full text Cite

Comparison of Acoustic Radiation Force Impulse Imaging Derived Carotid Plaque Stiffness With Spatially Registered MRI Determined Composition.

Journal article IEEE Trans Med Imaging · November 2015 Measurements of plaque stiffness may provide important prognostic and diagnostic information to help clinicians distinguish vulnerable plaques containing soft lipid pools from more stable, stiffer plaques. In this preliminary study, we compare in vivo ultr ... Full text Link to item Cite

Evaluation of the transverse oscillation method using the Cramer-Rao lower bound.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2015 The transverse oscillation method enables lateral displacement tracking by generating an oscillation orthogonal to the conventional RF signal. The widely varying methods used in the field to create such oscillations and perform displacement estimation make ... Full text Cite

The Evolution of Tissue Stiffness at Radiofrequency Ablation Sites During Lesion Formation and in the Peri-Ablation Period.

Journal article Journal of cardiovascular electrophysiology · September 2015 IntroductionElastography imaging can provide radiofrequency ablation (RFA) lesion assessment due to tissue stiffening at the ablation site. An important aspect of assessment is the spatial and temporal stability of the region of stiffness increase ... Full text Cite

A multiresolution approach to shear wave image reconstruction.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · August 2015 Shear wave imaging techniques build maps of local elasticity estimating the local group velocity of induced mechanical waves. Velocity estimates are formed using the time delay in the motion profile of the medium at two or more points offset from the shear ... Full text Cite

Resolution and brightness characteristics of short-lag spatial coherence (SLSC) images.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2015 We previously described a novel beamforming method that images the spatial correlation of an echo wave field with demonstrated applications to clutter reduction in high-noise environments. In this paper, several characteristics of the resolution and bright ... Full text Cite

In vivo application of short-lag spatial coherence and harmonic spatial coherence imaging in fetal ultrasound.

Journal article Ultrason Imaging · April 2015 Fetal scanning is one of the most common applications of ultrasound imaging and serves as a source of vital information about maternal and fetal health. Visualization of clinically relevant structures, however, can be severely compromised in difficult-to-i ... Full text Link to item Cite

Single- and multiple-track-location shear wave and acoustic radiation force impulse imaging: matched comparison of contrast, contrast-to-noise ratio and resolution.

Journal article Ultrasound in medicine & biology · April 2015 Acoustic radiation force impulse imaging and shear wave elasticity imaging (SWEI) use the dynamic response of tissue to impulsive mechanical stimulus to characterize local elasticity. A variant of conventional, multiple-track-location SWEI, denoted single- ... Full text Cite

Ultrasound shear wave elasticity imaging quantifies coronary perfusion pressure effect on cardiac compliance.

Journal article IEEE transactions on medical imaging · February 2015 Diastolic heart failure (DHF) is a major source of cardiac related morbidity and mortality in the world today. A major contributor to, or indicator of DHF is a change in cardiac compliance. Currently, there is no accepted clinical method to evaluate the co ... Full text Cite

Equivalence of time and aperture domain additive noise in ultrasound coherence.

Journal article The Journal of the Acoustical Society of America · January 2015 Ultrasonic echoes backscattered from diffuse media, recorded by an array transducer and appropriately focused, demonstrate coherence predicted by the van Cittert-Zernike theorem. Additive noise signals from off-axis scattering, reverberation, phase aberrat ... Full text Cite

Implementation of swept synthetic aperture imaging

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2015 Ultrasound imaging of deep targets is limited by the resolution of current ultrasound systems based on the available aperture size. We propose a system to synthesize an extended effective aperture in order to improve resolution and target detectability at ... Full text Cite

Ultrasound coherence imaging using hardware receive beamforming and broad transmit beams

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2015 Conventional B-mode ultrasound images suffer from clutter composed of reverberation and aberration that exhibit only partial spatial coherence, making it possible to suppress these confounding signals using coherence- based imaging techniques. Coherence is ... Full text Cite

Synthetic aperture ultrasound imaging with robotic aperture extension

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2015 Synthetic aperture (SA) is a technique that enhances the image resolution by synthesizing information from multiple subapertures. The application of this technique for medical ultrasound imaging has been an active research area, but the resolution improvem ... Full text Cite

Acoustic Radiation Force-Based Elasticity Imaging

Book section · January 1, 2015 8.1 Introduction Since ancient Egyptian medicine, manual palpation has been used to detect the size, location, and stiffness of superficial structures within the body [1]. By assessing the elasticity (i.e., stiffness) of structures compared with surroundin ... Full text Cite

Feasibility of near real-time lesion assessment during radiofrequency catheter ablation in humans using acoustic radiation force impulse imaging.

Journal article J Cardiovasc Electrophysiol · December 2014 BACKGROUND: Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can ... Full text Link to item Cite

Spatial coherence in human tissue: implications for imaging and measurement.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · December 2014 The spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer array are investigated. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes rever ... Full text Cite

Sparse sampling methods for efficient spatial coherence estimation

Conference IEEE International Ultrasonics Symposium Ius · October 20, 2014 Short-lag spatial coherence (SLSC) imaging, a coherence-based alternative beamforming technique, creates images related to the spatial covariance in backscatter. Because spatial covariance estimation is a computationally intensive process, efficient techni ... Full text Cite

M-mode ARFI imaging demonstrates the effect of coronary perfusion on cardiac stiffness

Conference IEEE International Ultrasonics Symposium Ius · October 20, 2014 Myocardial stiffness is an important clinical indicator of cardiac function. One of the contributors to stiffness in the heart is coronary perfusion. The interaction between cardiac tissue and coronary vasculature has been studied for several decades using ... Full text Cite

Transcostal imaging with large coherent apertures: Ex vivo studies

Conference IEEE International Ultrasonics Symposium Ius · October 20, 2014 In order to implement and evaluate a basic blocked-element detection and compensation algorithm on large arrays we acquired large synthetic 2-D aperture data sets on canine ribs ex vivo. Elements that were blocked by the ribs exhibited significantly lower ... Full text Cite

Micro-elasticity (μ-E): CNR and resolution of acoustic radiation force impulse imaging and single- and multiple track location shear wave elasticity imaging for visualizing small targets

Conference IEEE International Ultrasonics Symposium Ius · October 20, 2014 Acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) use the dynamic response of tissue to impulsive mechanical stimulus to characterize local elasticity. A variant of conventional, multiple track location SWEI (MTL-SWEI ... Full text Cite

Medical imaging safety in the developing world

Book section · October 1, 2014 Attention to matters of safety is important in any imaging facility. In the context of the developing world, limited resources may complicate the attempt to set up and operate an imaging facility with the highest standards of safety, but it is nonetheless ... Full text Cite

Short-lag spatial coherence imaging on matrix arrays, part 1: Beamforming methods and simulation studies.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2014 Short-lag spatial coherence (SLSC) imaging is a beamforming technique that has demonstrated improved imaging performance compared with conventional B-mode imaging in previous studies. Thus far, the use of 1-D arrays has limited coherence measurements and S ... Full text Cite

Short-lag spatial coherence imaging on matrix arrays, part II: Phantom and in vivo experiments.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2014 In Part I of the paper, we demonstrated through simulation the potential of volumetric short-lag spatial coherence (SLSC) imaging to improve visualization of hypoechoic targets in three dimensions. Here, we demonstrate the application of volumetric SLSC im ... Full text Cite

The feasibility of myocardial infarct visualization using atrial kick induced strain (AKIS) contrast.

Journal article Ultrasound Med Biol · June 2014 The most common mechanical measure of the heart integrates ventricular strain between end-diastole and end-systole in order to provide a measure of contraction. Here an approach is described for estimating a correlate to local passive mechanical properties ... Full text Link to item Cite

Contrast in intracardiac acoustic radiation force impulse images of radiofrequency ablation lesions.

Journal article Ultrason Imaging · April 2014 We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displace ... Full text Open Access Link to item Cite

The effect of acute coronary perfusion change on cardiac function measured by Shear Wave Elasticity Imaging.

Conference Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2014 The possibility of measuring cardiac function noninvasively has generated wide interest in elastography imaging techniques. Shear Wave Elasticity Imaging (SWEI) is an ultrasound-based elastography technique used to measure stiffness of tissues. While this ... Full text Cite

A harmonic tracking method for improved visualization of arterial structures with acoustic radiation force impulse imaging

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 Acoustic Radiation Force Impulse (ARFI) imaging has shown improved visualization of arterial structures that may provide for a more reliable assessment of atherosclerotic risk than conventional B-mode imaging. Existing ARFI imaging methods, however, are li ... Full text Cite

Identification and impact of blocked elements in 1-D and 2-D arrays

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 In an attempt to characterize the signals on the blocked elements and to assess the image degradation they cause we collected the individual-channel signals from a clinical matrix array on a phantom through a layer of absorbing rubber and on the human live ... Full text Cite

Volumetric SLSC imaging of vasculature on a clinical matrix array

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 We extended the concept of Short-lag Spatial Coherence imaging to matrix arrays and used it to improve the quality of vessel images. Specifically, we collected signals from the individual channels of a clinical matrix array while imaging a flow phantom and ... Full text Cite

Spatial coherence and its relationship to human tissue: An analytical description of imaging methods

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 This paper describes the spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes multipl ... Full text Cite

In vivo demonstration of a real-time simultaneous B-mode/spatial coherence GPU-based beamformer

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 SLSC imaging is an advanced ultrasound beamforming technique that generates images of the coherence in the backscattered echo and has been shown to suppress image degradation due to clutter. However, the computational demand and the need for access to chan ... Full text Cite

Apodization schemes for short-lag spatial coherence imaging

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 Short-lag spatial coherence (SLSC) imaging has been used to reduce clutter in ultrasound imaging by using echo coherence instead of signal magnitude as a contrast mechanism. Apodization strategies used to reduce off-axis scattering in conventional B-mode i ... Full text Cite

Spatial coherence and its relationship to human tissue: An analytical description of imaging methods

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 This paper describes the spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes multipl ... Full text Cite

A comparison of intracardiac ARFI and SWI for imaging radiofrequency ablation lesions

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 Radiofrequency ablation (RFA) is commonly used to treat cardiac arrhythmias, by generating a contiguous series of discrete radiofrequency ablation (RFA) lesions in the myocardium to destroy or isolate arrhythmogenic conduction pathways. The size of each le ... Full text Cite

Acute and chronic myocardial infarct differentiation using atrial kick induced strain (AKIS) imaging

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 We have previously shown that the passive ventricular stretch induced during the active filling phase of the heart can be used to make images correlated to the passive mechanical stiffness of the ventricles. In the initial feasibility study chronic infarct ... Full text Cite

Three-dimensional fusion of Shear Wave Imaging and electro-anatomical mapping for intracardiac radiofrequency ablation monitoring

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2013 Electroanatomical Mapping (EAM) provides electrophysiologists with a three-dimensional visualization of endocardial geometry and electrical activity, used to guide transcatheter ablation (TCA) treatment of arrhythmia. Acoustic Radiation Force Impulse (ARFI ... Full text Cite

Harmonic tracking of acoustic radiation force-induced displacements.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2013 Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estima ... Full text Cite

Short-lag spatial coherence imaging of cardiac ultrasound data: initial clinical results.

Journal article Ultrasound Med Biol · October 2013 Short-lag spatial coherence (SLSC) imaging is a novel beamforming technique that reduces acoustic clutter in ultrasound images. A clinical study was conducted to investigate clutter reduction and endocardial border detection in cardiac SLSC images. Individ ... Full text Link to item Cite

Synthetic aperture focusing for short-lag spatial coherence imaging.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · September 2013 It has been demonstrated that short-lag spatial coherence (SLSC) ultrasound imaging can provide improved speckle SNR and lesion CNR compared with conventional Bmode images, especially in the presence of noise and clutter. Application of the van Cittert-Zer ... Full text Cite

Intracardiac acoustic radiation force impulse (ARFI) and shear wave imaging in pigs with focal infarctions.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · August 2013 Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with ... Full text Open Access Cite

A GPU-based real-time spatial coherence imaging system

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 5, 2013 Advanced ultrasonic beamforming techniques are often computationally intensive and difficult to implement in real-time. GPU computing has become a vital tool for software beamforming because of its massive parallel computing capabilities. However, GPU-base ... Full text Cite

A synthetic aperture study of aperture size in the presence of noise and in vivo clutter

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 5, 2013 Conventional wisdom in ultrasonic array design drives development towards larger arrays because of the inverse relationship between aperture size and resolution. We propose a method using synthetic aperture beamforming to study image quality as a function ... Full text Cite

Acoustic radiation force elasticity imaging in diagnostic ultrasound.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2013 The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue propert ... Full text Cite

In vivo application of short-lag spatial coherence imaging in human liver.

Journal article Ultrasound Med Biol · March 2013 We present the results of a patient study conducted to assess the performance of two novel imaging methods, namely short-lag spatial coherence (SLSC) and harmonic spatial coherence imaging (HSCI), in an in vivo liver environment. Similar in appearance to t ... Full text Link to item Cite

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis.

Journal article Journal of biomechanics · January 2013 Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques mo ... Full text Cite

Bayesian speckle tracking. Part I: an implementable perturbation to the likelihood function for ultrasound displacement estimation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2013 Accurate and precise displacement estimation has been a hallmark of clinical ultrasound. Displacement estimation accuracy has largely been considered to be limited by the Cramer-Rao lower bound (CRLB). However, the CRLB only describes the minimum variance ... Full text Cite

Bayesian speckle tracking. Part II: biased ultrasound displacement estimation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2013 Ultrasonic displacement estimates have numerous clinical uses, including blood flow estimation, elastography, therapeutic guidance, and acoustic radiation force imaging (ARFI). These clinical tasks could be improved with better ultrasonic displacement esti ... Full text Cite

Confirmation of cardiac radiofrequency ablation treatment using intra-procedure acoustic radiation force impulse imaging

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 Recurrence of atrial fibrillation after transcatheter ablation (TCA) is common because there is no imaging modality that can visually confirm the presence of radiofrequency ablation (RFA) lesions. We have previously shown that acoustic radiation force impu ... Full text Cite

Application of synthetic aperture focusing to short-lag spatial coherence

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 It has been demonstrated that short-lag spatial coherence (SLSC) ultrasound imaging can provide improved SNR and CNR compared to conventional B-mode images, especially in the presence of noise and clutter. Application of the van Cittert-Zernike theorem pre ... Full text Cite

Clinical realization of short-lag spatial coherence imaging on 2D arrays

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 To improve image quality in 3D ultrasound we extended a coherence-based imaging method named Short-lag Spatial Coherence (SLSC) imaging to 2D arrays. Specifically, we collected partially beamformed channel signals from a clinical matrix array and 3D ultras ... Full text Cite

A harmonic tracking method for Acoustic Radiation Force Impulse (ARFI) imaging

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 Ultrasound-based elasticity imaging methods, such as Acoustic Radiation Force Impulse (ARFI) imaging, rely upon the accurate estimation of displacements to characterize the mechanical response of soft tissues. Sources of clutter, such as off-axis scatterin ... Full text Cite

Improved visualization of endocardial borders with Short-Lag Spatial Coherence imaging of fundamental and harmonic ultrasound data

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 Endocardial border visualization, a common task in echochardiography, is typically challenged by the presence of acoustic clutter. This study investigates endocardial border visibility in co-registered fundamental and harmonic data when utilizing the Short ... Full text Cite

Efficient strategies for estimating spatial coherence on matrix probes

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 Short-lag spatial coherence (SLSC) imaging has recently been introduced as a clutter reducing imaging technique. Thus far, SLSC has been implemented solely on one-dimensional (1D) array transducers, and the present definition is not readily applicable to t ... Full text Cite

Feasibility and safety of transthoracic cardiac acoustic radiation force impulse imaging methods

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 This work examines clinical feasibility of using non-invasive transthoracic echocardiography techniques to visualize temporal variations of stiffness through the cardiac cycle using acoustic radiation force impulse (ARFI) imaging. © 2012 IEEE. ... Full text Cite

Intracardiac ARF-driven shear wave velocimetry to estimate regional myocardial stiffness and contractility in pigs with focal infarctions

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with ... Full text Cite

2D and 3D Bayesian displacement estimation

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2012 Bayesian displacement estimation has been previously demonstrated in 1D and shown to reduce estimation and jitter and often bias. Here it is shown that the 1D implementation is directly extendable to 2D and 3D. © 2012 IEEE. ... Full text Cite

Intracardiac acoustic radiation force impulse imaging: a novel imaging method for intraprocedural evaluation of radiofrequency ablation lesions.

Journal article Heart Rhythm · November 2012 BACKGROUND: Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities cou ... Full text Open Access Link to item Cite

Intracardiac echocardiography measurement of dynamic myocardial stiffness with shear wave velocimetry.

Journal article Ultrasound in medicine & biology · July 2012 Acoustic radiation force (ARF)-based methods have been demonstrated to be a viable tool for noninvasively estimating tissue elastic properties, and shear wave velocimetry has been used to measure quantitatively the stiffening and relaxation of myocardial t ... Full text Cite

A method for direct localized sound speed estimates using registered virtual detectors.

Journal article Ultrasonic imaging · July 2012 Accurate sound speed estimates are desirable in a number of fields. In an effort to increase the spatial resolution of sound speed estimates, a new method is proposed for direct measurement of sound speed between arbitrary spatial locations. The method use ... Full text Cite

Acoustic radiation force impulse imaging of mechanical stiffness propagation in myocardial tissue.

Journal article Ultrasonic imaging · July 2012 Acoustic radiation force impulse (ARFI) imaging has been shown to be capable of imaging local myocardial stiffness changes throughout the cardiac cycle. Expanding on these results, the authors present experiments using cardiac ARFI imaging to visualize and ... Full text Cite

Harmonic spatial coherence imaging: an ultrasonic imaging method based on backscatter coherence.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2012 We introduce a harmonic version of the short-lag spatial coherence (SLSC) imaging technique, called harmonic spatial coherence imaging (HSCI). The method is based on the coherence of the second-harmonic backscatter. Because the same signals that are used t ... Full text Cite

Effect of prior probability quality on biased time-delay estimation.

Journal article Ultrasonic imaging · April 2012 When properly constructed, biased estimators are known to produce lower mean-square errors than unbiased estimators. A biased estimator for the problem of ultrasound time-delay estimation was recently proposed. The proposed estimator incorporates knowledge ... Full text Cite

Clutter reduction in echocardiography with short-lag spatial coherence (SLSC) imaging

Journal article Proceedings International Symposium on Biomedical Imaging · January 1, 2012 Clutter, a problematic noise artifact in echocardiography, appears as a diffuse haze that obscures endocardial borders and inhibits accurate diagnoses. Several approaches are available to reduce clutter in cardiac images, yet difficult-to-image patients st ... Full text Cite

Direct in vivo myocardial infarct visualization using 3D ultrasound and passive strain contrast

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2011 An approach for myocardial elastography is presented for infarct visualization. Infarcts are visualized using passive strain in the ventricles induced by atrial contraction. Results are compared against ARFI and delay-enhanced contrast MR. © 2011 IEEE. ... Full text Cite

In vivo application of SLSC imaging in human liver

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 The ability of an ultrasound system to differentiate signals in the presence of clutter is of key clinical importance. There are several sources of clutter but assessing their relative importance and developing methods of reducing them remain areas of acti ... Full text Cite

Comparative resolution and tracking performance in B-mode and short-lag spatial coherence (SLSC) images

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 Short-lag spatial coherence (SLSC) imaging is a novel imaging technique based on measurements of the spatial coherence of backscattered ultrasound waves received by individual transducer elements. SLSC images are formed by integrating spatial coherence mea ... Full text Cite

Development and evaluation of pulse sequences for freehand ARFI imaging

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 Acoustic Radiation Force Impulse (ARFI) imaging techniques can be used to non-invasively evaluate the relative stiffness of tissue; potentially aiding in the identification of stiff cancerous lesions or vulnerable soft lipid filled plaques in vasculature. ... Full text Cite

Comparative evaluation of wavefront coherence imaging methods in the presence of clutter

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 There are a number of mechanisms that contribute to poor image quality in ultrasonic imaging. Numerous algorithms have been designed to compensate for phase aberrations, but recently it was shown that reverberation clutter plays a significant role in degra ... Full text Cite

Characteristics of the spatial coherence function from backscattered ultrasound with phase aberration and reverberation clutter

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 Clutter is acoustic noise that significantly degrades ultrasound image quality, and often results from multiple reflections between tissue layers. There is currently little characterization of this complex phenomenon and how it depends on tissue structure. ... Full text Cite

Generalized Bayesian speckle tracking applied to strain and ARFI displacements

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 Biased estimators with mean square error surpassing that described by the Cramer-Rao lower bound are implemented using Bayes' Theorem. In order to use Bayes' Theorem a new likelihood function was developed specifically for the ultrasound time-delay estimat ... Full text Cite

Intracardiac shear wave velocimetry using Acoustic Radiation Force (ARF) excitations: In vivo results

Journal article IEEE International Ultrasonics Symposium Ius · December 1, 2011 Acoustic Radiation Force (ARF)-driven shear wave velocimetry is a validated way of quantitatively measuring tissue elasticity. Open-chest velocimetry experiments have been able to measure regional myocardial contractility, a potentially useful diagnostic p ... Full text Cite

The development and potential of acoustic radiation force impulse (ARFI) imaging for carotid artery plaque characterization.

Journal article Vascular medicine (London, England) · August 2011 Stroke is the third leading cause of death and long-term disability in the USA. Currently, surgical intervention decisions in asymptomatic patients are based upon the degree of carotid artery stenosis. While there is a clear benefit of endarterectomy for p ... Full text Cite

Short-lag spatial coherence of backscattered echoes: imaging characteristics.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2011 Conventional ultrasound images are formed by delay-and-sum beamforming of the backscattered echoes received by individual elements of the transducer aperture. Although the delay-and-sum beamformer is well suited for ultrasound image formation, it is corrup ... Full text Cite

Acoustic radiation force-driven assessment of myocardial elasticity using the displacement ratio rate (DRR) method.

Journal article Ultrasound in medicine & biology · July 2011 A noninvasive method of characterizing myocardial stiffness could have significant implications in diagnosing cardiac disease. Acoustic radiation force (ARF)-driven techniques have demonstrated their ability to discern elastic properties of soft tissue. Fo ... Full text Cite

Noninvasive assessment of wall-shear rate and vascular elasticity using combined ARFI/SWEI/spectral Doppler imaging system.

Journal article Ultrasonic imaging · July 2011 The progression of atherosclerotic disease is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of cardiovascular stiffness and ... Full text Cite

A novel imaging technique based on the spatial coherence of backscattered waves: Demonstration in the presence of acoustical clutter

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 8, 2011 In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are ofte ... Full text Cite

Improved detectability of hypoechoic regions with short-lag spatial coherence imaging: Experimental validation

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 8, 2011 The ability of an ultrasound system to differentiate signals in the presence of clutter is of key clinical importance. There are several sources of clutter but assessing their relative importance and developing methods of reducing them remain areas of acti ... Full text Cite

Feasability of a ARFI/B-mode/Doppler system for real-time, freehand scanning of the cardiovascular system

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 8, 2011 Acoustic radiation force impulse (ARFI) imaging has been previously described for the visualization of the cardiovascular system, including assessment of cerebral and lower-limb vascular disease, myocardial function, and cardiac RF ablation monitoring. Giv ... Full text Cite

The development of a combined b-mode, ARFI, and spectral Doppler ultrasound imaging system for investigating cardiovascular stiffness and hemodynamics

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 8, 2011 The progression of atherosclerotic disease, caused by the formation of plaques within arteries, is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesi ... Full text Cite

Sources of image degradation in fundamental and harmonic ultrasound imaging: a nonlinear, full-wave, simulation study.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2011 A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain. This numerical method is used to simulate propagation of a diagnostic ultrasound pulse through ... Full text Cite

Sources of image degradation in fundamental and harmonic ultrasound imaging using nonlinear, full-wave simulations.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2011 A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). This numerical method is used to simulate propagation of a diagnostic ultrasound pulse ... Full text Cite

Lesion detectability in diagnostic ultrasound with short-lag spatial coherence imaging.

Journal article Ultrasonic imaging · April 2011 We demonstrate a novel imaging technique, named short-lag spatial coherence (SLSC) imaging, which uses short distance (or lag) values of the coherence function of backscattered ultrasound to create images. Simulations using Field II are used to demonstrate ... Full text Cite

Comparison of physiological motion filters for in vivo cardiac ARFI.

Journal article Ultrasonic imaging · April 2011 Acoustic radiation force impulse (ARFI) imaging is being utilized to investigate mechanical properties ofcardiac tissue. The underlying physiological motion, however, presents a major challenge. This paper aims to investigate the effectiveness of various p ... Full text Cite

TU‐G‐220‐01: Quantitative Elasticity Imaging with Acoustic Radiation Force Induced Shear Waves

Conference Medical Physics · January 1, 2011 Purpose: Shear waves can be generated in soft tissues using impulsive acoustic radiation force (ARFI), and the resulting shear wave speeds (SWS) can be related to the shear moduli (G) by SWS = sqrt(G/rho). Time‐of‐flight (TOF) algorithms can be used to tra ... Full text Cite

Short-lag spatial coherence imaging

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2010 Conventional ultrasound images are formed by delay-and-sum beamforming ofthe backscattered echoes received by the transducer aperture. Although thedelay-and-sum beamformer is well suited for ultrasound image formation, it ischallenged under non-ideal circu ... Full text Cite

Intracardiac measurements of elasticity using Acoustic Radiation ForceImpulse (ARFI) methods: Temporal and spatial stability of shear wave velocimetry

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2010 Acoustic Radiation Force Impulse (ARFI) methods have been validated formeasuring tissue elastic properties, with shear wave velocimetry emerging as aquantitative way to measure stiffness. Using ultrasound to interrogate cardiacelasticity holds promise for ... Full text Cite

Parametric pressure-volume analysis and acoustic radiation force impulse imaging of left ventricular function

Conference Proceedings IEEE Ultrasonics Symposium · December 1, 2010 Extensive research has been devoted to the quantification of left ventricular (LV) function via an elasticity metric known as elastance. Similar to a stress-strain relation, yielding stiffness, myocardial elastance is measured from the pressure-volume (PV) ... Full text Cite

An in vitro assessment of acoustic radiation force impulse imaging for visualizing cardiac radiofrequency ablation lesions.

Journal article J Cardiovasc Electrophysiol · May 2010 INTRODUCTION: Lesion placement and transmurality are critical factors in the success of cardiac transcatheter radiofrequency ablation (RFA) treatments for supraventricular arrhythmias. This study investigated the capabilities of catheter transducer based a ... Full text Link to item Cite

Acoustic radiation force impulse imaging on ex vivo abdominal aortic aneurysm model.

Journal article Ultrasound in medicine & biology · May 2010 A method for reliable, noninvasive estimation of abdominal aortic aneurysms (AAA) wall mechanics may be a useful clinical tool for rupture prediction. An in vitro AAA model was developed from an excised porcine aorta with elastase treatment. The AAA model ... Full text Cite

3-D phantom and in vivo cardiac speckle tracking using a matrix array and raw echo data.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2010 Cardiac motion has been tracked using various methods, which vary in their invasiveness and dimensionality. One such noninvasive modality for cardiac motion tracking is ultrasound. Three-dimensional ultrasound motion tracking has been demonstrated using de ... Full text Cite

The effects of image degradation on ultrasound-guided HIFU

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2010 High-intensity focused ultrasound (HIFU) has recently found a wide range ofapplications. In the case of ultrasound-guided HIFU, clutter andphase-aberration can degrade the image quality such that visualization of thetarget can be significantly diminished. ... Full text Cite

A motion-based approach to abdominal clutter reduction.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2009 In ultrasound images, clutter is a noise artifact most easily observed in anechoic or hypoechoic regions. It appears as diffuse echoes overlying anatomical structures of diagnostic importance, obscuring tissue borders and reducing image contrast. A novel c ... Full text Cite

Optical tracking of acoustic radiation force impulse-induced dynamics in a tissue-mimicking phantom.

Journal article The Journal of the Acoustical Society of America · November 2009 Optical tracking was utilized to investigate the acoustic radiation force impulse (ARFI)-induced response, generated by a 5-MHz piston transducer, in a translucent tissue-mimicking phantom. Suspended 10-microm microspheres were tracked axially and laterall ... Full text Cite

In vivo cardiac, acoustic-radiation-force-driven, shear wave velocimetry.

Journal article Ultrasonic imaging · July 2009 Shear wave elasticity imaging (SWEI) was employed to track acoustic radiation force impulse (ARFI)-induced shear waves in the mid-myocardium of the left ventricular free wall (LVFW) of a beating canine heart. Shear waves were generated and tracked with a l ... Full text Cite

Novel acoustic radiation force impulse imaging methods for visualization of rapidly moving tissue.

Journal article Ultrasonic imaging · July 2009 Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing changes in local myocardial stiffness through a normal cardiac cycle. As a beating heart involves rapidly-moving tissue with cyclically-varying myocardial st ... Full text Cite

Simulation and experimental analysis of ultrasonic clutter in fundamental and harmonic imaging

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 19, 2009 Harmonic imaging has been shown to yield significant improvements in image quality over conventional ultrasound imaging. It has been proposed that harmonic imaging generates these improvements by the reduction in clutter from reverberation in the tissue la ... Full text Cite

Acoustic radiation force-induced shear wave propagation in cardiac tissue

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 19, 2009 Shear wave elasticity imaging (SWEI) was employed to track acoustic radiation force (ARF)-induced shear waves in the myocardium of a beating heart. Shear waves were generated in and tracked through the myocardium of the left ventricular free wall (LVFW) in ... Full text Cite

Acoustic radiation force impulse imaging for noninvasive characterization of carotid artery atherosclerotic plaques: a feasibility study

Journal article Ultrasound In Medicine And Biology · May 2009 Atherosclerotic disease in the carotid artery is a risk factor for stroke. The susceptibility of atherosclerotic plaque to rupture, however, is challenging to determine by any imaging method. In this study, acoustic radiation force impulse (ARFI) imaging i ... Cite

Lower-limb vascular imaging with acoustic radiation force elastography: demonstration of in vivo feasibility.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2009 Acoustic radiation force impulse (ARFI) imaging characterizes the mechanical properties of tissue by measuring displacement resulting from applied ultrasonic radiation force. In this paper, we describe the current status of ARFI imaging for lower-limb vasc ... Full text Cite

A Heterogeneous Nonlinear Attenuating Full-Wave Model of Ultrasound

Journal article Ieee Transactions On Ultrasonics Ferroelectrics And Frequency Control · March 2009 A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). Three-dimensional solutions of the equation are verified with water tank measurements o ... Cite

Optical tracking of superficial dynamics from an acoustic radiation force-induced excitation.

Journal article Ultrasonic imaging · January 2009 Acoustic radiation force (ARF) has become a common excitation mechanism in elasticity imaging. The high acoustic intensities and subsequent generation of harmonics, however, hamper the effectiveness of using conventional radiofrequency (rf) tracking to inv ... Full text Cite

Image quality, tissue heating, and frame rate trade-offs in acoustic radiation force impulse imaging.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2009 The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation ... Full text Cite

Clutter and sources of image degradation in fundamental and harmonic ultrasound imaging

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2009 Although harmonic imaging is used extensively, the mechanisms for image quality improvement are still poorly understood. In the simplified case of a homogeneous medium the improvements in harmonic imaging can be linked to reductions in the main lobe width ... Full text Cite

Acoustic radiation force impulse imaging of cardiac tissue

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2009 Cardiovascular disease remains the most likely cause of death in developed countries, accounting for approximately 870,000 deaths in the United States alone in 2004. Virtually every form of cardiovascular disease involves modifications in tissue stiffness. ... Full text Cite

Sources and characterization of clutter in cardiac B-mode images

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2009 In echocardiography, clutter is one of the most problematic image artifacts, often obscuring ventricular borders and introducing stationary noise in blood flow measurements. Clutter in transthoracic cardiac images is widely understood to originate from rev ... Full text Cite

On the characterization of left ventricular function with acoustic radiation force impulse imaging

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2009 Extensive research has been dedicated to investigating the assessment of left ventricular (LV) function via myocardial elasticity. Previous research has demonstrated acoustic radiation force impulse (ARFI) imaging to be capable of visualizing variations in ... Full text Cite

3-D motion tracking using raw data and a matrix array: Phantom and in vivo cardiac studies

Journal article Proceedings IEEE Ultrasonics Symposium · January 1, 2009 Three dimensional ultrasound motion tracking has been previously demonstrated using detected data at low volume rates. However, the effects of volume rate, kernel size and data type (raw and detected) have not been sufficiently explored. First comparisons ... Full text Cite

Magnitude, origins, and reduction of abdominal ultrasonic clutter

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2008 Clutter is a noise artifact in ultrasound images, from multiple sources. Experiments were conducted urine-filled in vivo bladders to differentiate among various sources. Successive-frame image acquisitions with varying PRFs were used to determine the clutt ... Full text Cite

In vivo guidance and assessment of liver radio-frequency ablation with acoustic radiation force elastography.

Journal article Ultrasound Med Biol · October 2008 The initial results from clinical trials investigating the utility of acoustic radiation force impulse (ARFI) imaging for use with radio-frequency ablation (RFA) procedures in the liver are presented. To date, data have been collected from 6 RFA procedures ... Full text Open Access Link to item Cite

Quantitative assessment of the magnitude, impact and spatial extent of ultrasonic clutter.

Journal article Ultrasonic imaging · July 2008 Clutter is anoise artifact in ultrasound images that appears as diffuse echoes overlying signals of interest. It is most easily observed in anechoic or hypoechoic regions, such as in cysts, blood vessels, amniotic fluid, and urine-filled bladders. Clutter ... Full text Cite

A novel motion compensation algorithm for acoustic radiation force elastography.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2008 A novel method of physiological motion compensation for use with radiation force elasticity imaging has been developed. The method utilizes a priori information from finite element method models of the response of soft tissue to impulsive radiation force t ... Full text Cite

Intracardiac echocardiography and acoustic radiation force impulse imaging of a dynamic ex vivo ovine heart model.

Journal article Ultrasonic imaging · April 2008 Intracardiac echocardiography (ICE) has demonstrated utility in providing high-resolution cardiac ultrasound images for guidance of numerous catheter-based interventions, including radiofrequency ablations (RFA). However, the training of interventionalists ... Full text Cite

A comparison of time-domain solutions for the full-wave equation and the parabolic wave equation for a diagnostic ultrasound transducer

Journal article Ieee Transactions On Ultrasonics Ferroelectrics And Frequency Control · March 2008 A study of numerical solutions to the linear wave equation and the parabolic wave equation is presented. Finite-difference, time-domain methods are used to calculate the acoustic field emitted from a phased diagnostic ultrasound transducer in a non-attenua ... Cite

In vivo visualization of abdominal malignancies with acoustic radiation force elastography.

Journal article Phys Med Biol · January 7, 2008 The utility of acoustic radiation force impulse (ARFI) imaging for real-time visualization of abdominal malignancies was investigated. Nine patients presenting with suspicious masses in the liver (n = 7) or kidney (n = 2) underwent combined sonography/ARFI ... Full text Open Access Link to item Cite

Modeling of shock wave propagation in large amplitude ultrasound

Journal article Ultrasonic Imaging · January 2008 The Rankine-Hugoniot relation for shock wave propagation describes the shock speed of a nonlinear wave. This paper investigates time-domain numerical methods that solve the nonlinear parabolic wave equation, or the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equ ... Cite

Transthoracic cardiac acoustic radiation force impulse imaging: A feasibility study

Conference Proceedings IEEE Ultrasonics Symposium · December 1, 2007 We describe new non-invasive techniques for visualizing local variations of stiffness in cardiac tissue through the use of transthoracic acoustic radiation force impulse (ARFI) imaging. Custom M-mode and two-dimensional ARFI sequences were implemented on t ... Full text Cite

Clutter from multiple scattering and aberration in a nonlinear medium

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2007 Aberration, clutter, and reverberation degrade the quality of ultrasonic images. When an acoustic pulse propagates through tissue these effects occur simultaneously and it is difficult to obtain independent estimates for the precise source of the point spr ... Full text Cite

In vivo Acoustic Radiation Force Impulse imaging of abdominal lesions

Conference Proceedings IEEE Ultrasonics Symposium · December 1, 2007 The initial results from an ongoing clinical study investigating the utility of Acoustic Radiation Force Impulse (ARFI) imaging for in vivo visualization of abdominal lesions are presented. To date, 13 patients with lesions located in the liver (n = 11) or ... Full text Cite

Acoustic radiation force impulse imaging of mechanical stiffness propagation within myocardial tissue

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2007 Acoustic radiation force impulse (ARFI) imaging has been shown to be capable of imaging the local myocardial stiffness changes of heart throughout the cardiac cycle. Expanding on these results, we have experimentally assessed cardiac ARFI imaging to be a s ... Full text Cite

Full-wave simulation of finite-amplitude ultrasound in heterogeneous media

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2007 A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). Three dimensional solutions of the equation are verified with water tank measurements o ... Full text Cite

In vivo assessment of myocardial stiffness with acoustic radiation force impulse imaging.

Journal article Ultrasound in medicine & biology · November 2007 Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing variations in local stiffness within soft tissue. Recent advances in ARFI beam sequencing and parallel imaging have shortened acquisition times and lessened ... Full text Cite

Radiation force imaging: Challenges and opportunities

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · October 15, 2007 A number of novel imaging modalities have been developed to interrogate the mechanical properties of tissue. A subset of these methods utilize acoustic radiation force to mechanically excite tissue and form images from the local responses of tissue to thes ... Full text Cite

The impact of physiological motion on tissue tracking during radiation force imaging.

Journal article Ultrasound in medicine & biology · July 2007 The effect of physiological motion on the quality of radiation force elasticity images has been investigated. Experimental studies and simulated images were used to investigate the impact of motion effects on image quality metrics over a range of clinicall ... Full text Cite

Challenges and implementation of radiation-force imaging with an intracardiac ultrasound transducer.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · May 2007 Intracardiac echocardiography (ICE) has been demonstrated to be an effective imaging modality for the guidance of several cardiac procedures, including radiofrequency ablation (RFA). However, assessing lesion size during the ablation with conventional ultr ... Full text Cite

A parallel tracking method for acoustic radiation force impulse imaging

Journal article IEEE Trans. Ultrason. Ferroelectr. Freq. Control (USA) · 2007 Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic radiation force impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radia ... Cite

On the potential for guidance of ablation therapy using acoustic radiation force impulse imaging

Journal article 2007 4th IEEE International Symposium on Biomedical Imaging from Nano to Macro Proceedings · January 1, 2007 Acoustic radiation force imaging methods utilize acoustic radiation force to mechanically excite tissue, and the tissue response is monitored with conventional imaging methods. Radiation force based methods comprise a subset of elasticity imaging, in which ... Full text Cite

Characterization of In Vivo atherosclerotic plaques in the carotid artery with acoustic radiation force impulse imaging

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Acoustic Radiation Force Impulse (ARFI) imaging is a useful method for characterizing the local mechanical properties of tissue. ARFI imaging uses high energy, focused ultrasound pulses to generate small displacements (1-10 um) in tissue. The response of t ... Full text Cite

Parallel tracking and other methods for real-time ARFI imaging systems

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Acoustic Radiation Force Impulse (ARFI) imaging is a useful method for characterizing the local mechanical properties of tissue. Relevant issues in creating a real-time ARFI imaging system include patient exposure, oberservation time per image location, fi ... Full text Cite

Phase aberration correction on a 3D ultrasound scanner using RF speckle from moving targets

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 In 1992, Zhao et al. described a variation of the speckle-brightness algorithm for phase correction on moving targets [1, 2]. By subtracting two beam-summed consecutive interrogations of a region of interest, they were able to remove effects of reverberati ... Full text Cite

Ex Vivo acoustic radiation force impulse imaging of an ovine heart model

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Acoustic radiation force impulse (ARFI) imaging with an intra-cardiac probe has been demonstrated to be a suitable modality to monitor the progress of radiofre-quency ablation (RFA) procedures. In order to continue studies while allowing increased control ... Full text Cite

Shock wave propagation with the KZK equation

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Numerical methods that solve the nonlinear parabolic wave (KZK) equation and satisfy the Rankine-Hugoniot relation for shock wave propagation at all attenuation strengths are described and characterized. By comparison with a known planar solution, it is de ... Full text Cite

Continuous delay estimation with polynomial splines

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Delay estimation is used in ultrasonic imaging to estimate blood flow, determine phase aberration corrections, and to calculate elastographic images. The accuracy of delay estimation methods depends on noise, bandwidth, and delay range. In most cases a sub ... Full text Cite

In Vivo acoustic radiation force impulse imaging of the cardiac cycle

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 In vivo ARFI images of an exposed canine heart were acquired through multiple cardiac cycles. The matched eletrocardiogram (ECG) was also recorded. Sequences with the radiation force pulse amplitude set to zero were also acquired to measure potential artif ... Full text Cite

Volume visualization and error analysis using 3D ARFI imaging data

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 The utility and accuracy of volume visualization using 3D ARFI image data was investigated. Volumes of ARFI data were collected of custom tissue-mimicking phantoms by using a translation stage to increment the position of the imaging transducer through the ... Full text Cite

Dynamic mechanical response of elastic spherical inclusions to impulsive acoustic radiation force excitation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2006 Acoustic radiation force impulse imaging has been used clinically to study the dynamic response of lesions relative to their background material to focused, impulsive acoustic radiation force excitations through the generation of dynamic displacement field ... Full text Cite

Adaptive imaging on a diagnostic ultrasound scanner at quasi real-time rates.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · October 2006 Constructing an ultrasonic imaging system capable of compensating for phase errors in real-time is a significant challenge in adaptive imaging. We present a versatile adaptive imaging system capable of updating arrival time profiles at frame rates of appro ... Full text Link to item Cite

Frame rate considerations for real-time abdominal acoustic radiation force impulse imaging.

Journal article Ultrasonic imaging · October 2006 With the advent of real-time Acoustic Radiation Force Impulse (ARFI) imaging, elevated frame rates are both desirable and relevant from a clinical perspective. However, fundamental limitations on frame rates are imposed by thermal safety concerns related t ... Full text Cite

Liver ablation guidance with acoustic radiation force impulse imaging: challenges and opportunities.

Journal article Phys Med Biol · August 7, 2006 Previous studies have established the feasibility of monitoring radiofrequency (RF) ablation procedures with acoustic radiation force impulse (ARFI) imaging. However, questions remained regarding the utility of the technique in clinically realistic scenari ... Full text Link to item Cite

Phase-aberration correction with a 3-D ultrasound scanner: feasibility study.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · August 2006 We tested the feasibility of using adaptive imaging, namely phase-aberration correction, with two-dimensional (2-D) arrays and real-time, 3-D ultrasound. Because of the high spatial frequency content of aberrators, 2-D arrays, which generally have smaller ... Full text Cite

Ultrasonic tracking of acoustic radiation force-induced displacements in homogeneous media.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2006 The use of ultrasonic methods to track the tissue deformation generated by acoustic radiation force is subject to jitter and displacement underestimation errors, with displacement underestimation being primarily caused by lateral and elevation shearing wit ... Full text Cite

Continuous delay estimation with polynomial splines

Journal article IEEE Trans. Ultrason. Ferroelectr. Freq. Control (USA) · 2006 Delay estimation is used in ultrasonic imaging to estimate blood flow, determine phase aberration corrections, and to calculate elastographic images. Several algorithms have been developed to determine these delays. The accuracy of these methods depends in ... Cite

Rapid tracking of small displacements with ultrasound

Journal article IEEE Trans. Ultrason. Ferroelectr. Freq. Control (USA) · 2006 Time-delay estimators, such as normalized cross correlation and phase-shift estimation, form the computational basis for elastography, blood flow measurements, and acoustic radiation force impulse (ARFI) imaging. This paper examines the performance of thes ... Full text Link to item Cite

Analysis of contrast in images generated with transient acoustic radiation force.

Journal article Ultrasound in medicine & biology · January 2006 Several mechanical imaging methods are under investigation that use focused ultrasound (US) as a source of mechanical excitation. Images are then generated of the tissue response to this localized excitation. One such method, acoustic radiation force impul ... Full text Cite

Peripheral vascular ARFI imaging: Phantom and clinical results

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2005 Non-invasive characterization of focal and diffuse atherosclerosis is difficult with existing techniques, but clinically important in guiding the selection of drug, surgical and other treatments. We describe new non-invasive techniques for monitoring vascu ... Full text Cite

Phase correction of skull aberration with 1.75-D and 2-D arrays using speckle targets

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2005 Wavefront distortion induced by the skull severely impacts transcranial ultrasound. In particular, the skull reduces the ability to monitor flow in the cerebral vasculature. We present B-scan and color flow images, aberratred with polymer casts of skull bo ... Full text Cite

Rapid tracking of small displacements using ultrasound

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2005 Time delay estimators, such as normalized cross correlation and phase shift estimation, form the computational basis for elastography, blood flow measurements and Acoustic Radiation Force Impulse (ARFI) imaging. This paper examines the performance of these ... Full text Cite

Numerical methods for axisymmetric and 3D nonlinear beams

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2005 Time domain algorithms that solve the Khokhlov-Zabolotzskaya-Kuznetsov (KZK) equation are described and implemented. This equation represents the propagation of finite amplitude sound beams in a homogenous thermoviscous fluid for axisymmetric and fully thr ... Full text Cite

In vivo acoustic radiation force impulse imaging of cardiac ablations

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2005 Radiofrequency ablation (RFA) has been demonstrated to be an effective procedure for the treatment of rapid or irregular heartbeats such as atrial fibrillation. Assessing lesion size and growth with ultrasound has been limited, as the changes within conven ... Full text Cite

Acoustic radiation force impulse imaging with an intra-cardiac probe

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · September 19, 2005 Acoustic radiation force impulse (ARFI) imaging has been demonstrated to provide insight into the mechanical properties of tissue. The quality of ARFI images is dependent on the amount of acoustic energy from the radiation force pulse reaching the focus. I ... Full text Cite

Image processing and data acquisition optimization for Acoustic Radiation Force Impulse imaging of in vivo breast masses

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · September 19, 2005 Acoustic Radiation Force Impulse (ARFI) imaging utilizes brief, high-energy acoustic pulses to excite tissue and ultrasonic correlation based tracking methods to monitor the resulting tissue displacement, which reflects the relative mechanical properties o ... Full text Cite

Numerical methods for axisymmetric and 3D nonlinear beams

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · September 19, 2005 Time domain algorithms that solve the Khokhlov-Zabolotzskaya-Kuznetsov (KZK) equation are described and implemented. This equation represents the propagation of finite amplitude sound beams in a homogenous thermoviscous fluid for axisymmetric and fully thr ... Full text Cite

Spatial and temporal aberrator stability for real-time adaptive imaging.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · September 2005 Reported real-time adaptive imaging systems use near-field phase correction techniques, which are desired because of their simple implementation and their compatibility with current system architectures. Aberrator stability is important to adaptive imaging ... Full text Link to item Cite

Acoustic radiation force impulse imaging of the abdomen: demonstration of feasibility and utility.

Journal article Ultrasound Med Biol · September 2005 The feasibility of utilizing acoustic radiation force impulse (ARFI) imaging to assess the mechanical properties of abdominal tissues was investigated. The thermal safety of the technique was also evaluated through the use of finite element method models. ... Full text Link to item Cite

Acoustic radiation force impulse imaging for real-time observation of lesion development during radiofrequency ablation procedures

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · August 16, 2005 When performing radiofrequency ablation (RFA) procedures, physicians currently have little or no feedback concerning the success of the treatment until follow-up assessments are made days to weeks later. To be successful, RFA must induce a thermal lesion o ... Full text Cite

Adaptive imaging and spatial compounding in the presence of aberration.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2005 Spatial compounding reduces speckle and increases image contrast by incoherently averaging images acquired at different viewing angles. Adaptive imaging improves contrast and resolution by compensating for tissue-induced phase errors. Aberrator strength an ... Full text Cite

Acoustic radiation force impulse imaging of myocardial radiofrequency ablation: initial in vivo results.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2005 Acoustic radiation force impulse (ARFI) imaging techniques were used to monitor radiofrequency (RF) ablation of ovine cardiac tissue in vivo. Additionally, ARFI M-mode imaging methods were used to interrogate both healthy and ablated regions of myocardial ... Full text Cite

Real-time acoustic radiation force impulse imaging

Conference Proc. SPIE - Int. Soc. Opt. Eng. (USA) · 2005 Acoustic radiation force impulse (ARFI) imaging uses short duration acoustic pulses to generate and subsequently determine localized displacements in tissue. Time delay estimators, such as normalized cross correlation and phase shift estimation, form the c ... Full text Link to item Cite

Ultrasonic imaging of the mechanical properties of tissues using localized, transient acoustic radiation FORCE

Conference ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · January 1, 2005 Acoustic Radiation Force Impulse (ARFI) imaging utilizes brief, high energy, focused acoustic pulses to generate radiation force in tissue, and ultrasonic correlation-based methods to detect the resulting tissue displacements in order to image the relative ... Full text Cite

Real time 3D ultrasound imaging of the brain

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2004 We tested the feasibility of real time three dimensional ultrasound imaging in the brain with a 2.5MHz 2D array using a Volumetrics Model 1 scanner. In a human subject, the real time 3D scans produced simultaneous transcranial axial, coronal and saggital i ... Cite

Resolution improvement of point targets by real-time phase aberration correction: In vivo results

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2004 Ten patients with suspected microcalcifications receiving treatment at the Duke University Medical Center were scanned with a 9MHz, 8x96 1.75D array transducer and Siemens Antares scanner. Aberration profiles were estimated by cross correlation of individu ... Cite

Spatial and temporal stability of tissue induced aberration

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2004 Real-time adaptive imaging systems employ near-field phase correction techniques, which are desired because of their computational simplicity and compatibility with current imaging system architectures. Aberrator stability is essential to adaptive imaging ... Full text Cite

Acoustic radiation force impulse imaging of in vivo breast masses

Conference Proceedings IEEE Ultrasonics Symposium · December 1, 2004 ARFI datasets were acquired in real time to identify differentiable features between benign and malignant breast masses in ARFI images. A modified Siemens SONOLINE Antares scanner and a VF10-5 probe were programmed to implement ARFI imaging in a multi-foca ... Cite

Complex blind source separation for acoustic radiation force impulse imaging in the peripheral vasculature, in vivo

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2004 Complex blind source separation (CBSS) is presented in application to adaptive clutter filtering for Acoustic Radiation Force Impulse (ARFI) imaging in the peripheral vasculature, in vivo. In addition to the conventional challenges of wall filtering for Do ... Full text Cite

Abdominal acoustic radiation force impulse imaging

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2004 The ability of Acoustic Radiation Force Impulse (ARFI) imaging to interrogate deep-lying abdominal tissues was investigated. Challenges involved in using ARFI imaging at depth include generating sufficient radiation force to measurably displace deep-lying ... Cite

Clinical evaluation of combined spatial compounding and adaptive imaging in breast tissue.

Journal article Ultrason Imaging · October 2004 When spatial compounding is applied to targets with significant acoustic velocity inhomogeneities, the correlation between speckle patterns of the images to be averaged decreases, thereby increasing the speckle reduction nominally obtained. Phase correctio ... Full text Link to item Cite

Acoustic radiation force impulse imaging of the mechanical properties of arteries: in vivo and ex vivo results.

Journal article Ultrasound Med Biol · September 2004 We present results of a pilot study of ex vivo and in vivo acoustic radiation force impulse (ARFI) imaging demonstrating measurements of the mechanical properties of the carotid and popliteal arteries. The results were obtained on a modified commercial sca ... Full text Link to item Cite

Acoustic radiation force impulse imaging of thermally- and chemically-induced lesions in soft tissues: preliminary ex vivo results.

Journal article Ultrasound in medicine & biology · March 2004 The ability of acoustic radiation force impulse (ARFI) imaging to visualize thermally- and chemically-induced lesions in soft tissues was investigated. Lesions were induced in freshly excised bovine liver samples. Chemical lesions were induced via the inje ... Full text Cite

Imaging tissue mechanical properties using impulsive acoustic radiation force

Journal article 2004 2nd IEEE International Symposium on Biomedical Imaging Macro to Nano · January 1, 2004 Acoustic Radiation Force Impulse (ARFI) imaging utilizes brief, high energy, focused acoustic pulses to generate radiation force in tissue, and conventional diagnostic ultrasound methods to detect the resulting tissue displacements in order to image the re ... Full text Cite

Shear wave anisotropy imaging

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Shear Wave Anisotropy Imaging is a novel method that images local variations in tissue shear wave velocity. A commercial ultrasound scanner is used to generate and track propagating shear waves. Radiation force from a brief high-energy pulse generates shea ... Cite

Performance evaluation of combined spatial compounding/adaptive imaging: Simulation, phantom and clinical trials

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Spatial compounding reduces speckle and increases image contrast by incoherently averaging images acquired at different viewing angles. Adaptive imaging improves contrast and resolution by compensating for tissue induced phase errors. Aberrator strength an ... Cite

Real time adaptive imaging with 1.75D, high frequency arrays

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 We have created a system for real-time phase aberration correction functional with a 7.5 MHz, 1×192 element 1D linear array (Siemens) and a 9.5 MHz, 8×96 element, 1.75D linear array (Tetrad), using a Siemens Antares scanner. Aberration profiles are estimat ... Cite

Shear wave anisotropy imaging

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Shear Wave Anisotropy Imaging is a novel method that images local variations in tissue shear wave velocity. A commercial ultrasound scanner is used to generate and track propagating shear waves. Radiation force from a brief high-energy pulse generates shea ... Cite

Off-axis scatterer filters for improved aberration measurements

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Successful adaptive imaging requires accurate measurements of the aberration profile across the array surface. A spatial filter is proposed in this work to obtain more accurate aberration measurements by suppressing wavefronts from off-axis scatterers. App ... Cite

Off-axis scatterer filters for improved aberration measurements

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Successful adaptive imaging requires accurate measurements of the aberration profile across the array surface. A spatial filter is proposed in this work to obtain more accurate aberration measurements by suppressing wavefronts from off-axis scatterers. App ... Cite

Shear-wave generation using acoustic radiation force: in vivo and ex vivo results.

Journal article Ultrasound in medicine & biology · December 2003 Acoustic radiation force impulse (ARFI) imaging involves the mechanical excitation of tissue using localized, impulsive radiation force. This results in shear-wave propagation away from the region of excitation. Using a single diagnostic transducer on a mo ... Full text Cite

Acoustic radiation force impulse imaging: A parametric analysis of factors affecting image quality

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Acoustic Radiation Force Impulse (ARFI) imaging utilizes brief, high energy, focused acoustic pulses to generate radiation force in tissue, and conventional diagnostic ultrasound methods to detect the resulting tissue displacements in order to image the me ... Cite

Blind source separation-based adaptive filtering of physiological and ARFI-induced tissue, blood, and cyst fluid motion, in-vivo

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 In the context of complex tissue motion patterns including physiological and Acoustic Radiation Force Impulse (ARFI) -induced tissue, blood, and cyst fluid motion, the same adaptive blind source separation (BSS)-based filtering method is effective for four ... Cite

ARFI imaging of the cardiovascular system

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 We present results of a pilot study of ex vivo and in vivo acoustic radiation force impulse (ARFI) imaging demonstrating measurements of the mechanical properties of the medial and adventitial layers in the carotid, and popliteal arteries. The data was obt ... Cite

ARFI imaging of thermal lesions in ex vivo and in vivo soft tissues

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 The ability of ARFI imaging to monitor the ablation of soft tissues both ex vivo and in vivo was investigated. Thermal lesions were induced both in freshly excised bovine liver samples and in myocardial tissue of live sheep. While conventional sonography w ... Cite

Blind Source Separation-based velocity estimation (BSSVE): Simulation and clinical results

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 We present a novel, two-dimensional tissue motion estimation method using Blind Source Separation (BSS), which accurately measures both axial and lateral blood velocity components in the common carotid artery. Ensembles (packet length = 20) of raw RF data ... Cite

Two-dimensional phase aberration correction using an ultrasonic 1.75D array: Case study on breast microcalcifications

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 Ultrasound phase aberration resulting from tissue velocity inhomogeneities reduce the focusing ability of ultrasound waves and degrade image quality. Two-dimensional phase aberration measurements and correction with higher-order 1.75D arrays are expected t ... Cite

BSS-based filtering of physiological and ARFI-induced tissue and blood motion.

Journal article Ultrasound in medicine & biology · November 2003 Blind source separation (BSS) for adaptive filtering is presented in application to imaging both physiological and acoustic radiation force impulse (ARFI)-induced tissue and blood motion in the common carotid artery. The collected raw radiofrequency (RF) d ... Full text Cite

Image reconstruction with acoustic radiation force induced shear waves

Conference Proceedings of SPIE the International Society for Optical Engineering · September 12, 2003 Acoustic radiation force may be used to induce localized displacements within tissue. This phenomenon is used in Acoustic Radiation Force Impulse Imaging (ARFI), where short bursts of ultrasound deliver an impulsive force to a small region. The application ... Full text Cite

Arterial stiffness measurements with acoustic radiation force impulse imaging

Conference Proceedings of SPIE the International Society for Optical Engineering · September 12, 2003 We have developed a new method of imaging the mechanical properties of tissues based on very brief (< 1msec) and localized applications of acoustic radiation force and the ultrasonic measurement of local tissues' responses to that force. Initial results wi ... Full text Cite

Performance evaluation of spatial compounding in the presence of aberration and adaptive imaging

Journal article Proceedings of SPIE the International Society for Optical Engineering · September 12, 2003 Spatial compounding has been used for years to reduce speckle in ultrasonic images and to resolve anatomical features hidden behind the grainy appearance of speckle. Adaptive imaging restores image contrast and resolution by compensating for beamforming er ... Full text Cite

Estimates of echo correlation and measurement bias in acoustic radiation force impulse imaging.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · June 2003 Acoustic radiation force impulse (ARFI) imaging is a novel imaging modality in which pulses from a diagnostic ultrasound scanner are used to displace tissue and track its motion. The region displaced has lateral and elevational dimensions of similar scale ... Full text Cite

Synthetic elevation beamforming and image acquisition capabilities using an 8 x 128 1.75D array.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2003 Ultrasound imaging can be improved with higher order arrays through elevation dynamic focusing in future, higher channel count systems. However, modifications to current system hardware could yield increased imaging depth-of-field with 1.75D arrays (arrays ... Full text Cite

Ferromagnetic brachytherapy seed motion in soft tissue: Models, measurements and ultrasound detection

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2002 We have previously reported a technique for identifying modified prostate brachytherapy seeds. In this method, an alternating magnetic field is used to vibrate the seeds in situ with micron amplitudes. These vibrations are detected with Power Doppler or ot ... Cite

A new medical ultrasound research interface

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2002 Under a contract with the National Cancer Institute, we have developed an ultrasound research interface on a commercial scanner. The user can access and control a variety of scanner parameters which are not directly accessible through the clinical user int ... Cite

Adaptive clutter filtering via blind source separation for two-dimensional ultrasonic blood velocity measurement.

Journal article Ultrasonic imaging · October 2002 A method for adaptive clutter rejection via blind source separation (BSS) using principal and independent component analyses is presented in application to blood velocity measurement in the carotid artery. In particular, the filtering method's efficacy for ... Full text Cite

Observations of tissue response to acoustic radiation force: opportunities for imaging.

Journal article Ultrason Imaging · July 2002 Acoustic Radiation Force Impulse (ARFI) imaging is a method for characterizing local variations in tissue mechanical properties. In this method, a single ultrasonic transducer array is used to both apply temporally short localized radiation forces within t ... Full text Link to item Cite

Acoustic radiation force impulse imaging of in vivo vastus medialis muscle under varying isometric load.

Journal article Ultrasonic imaging · April 2002 Acoustic Radiation Force Impulse (ARFI) imaging is a method for characterizing local variations in tissue mechanical properties. In this method, a single ultrasonic transducer array is used to both apply temporally short localized radiation forces within t ... Full text Cite

Acoustic radiation force impulse imaging: in vivo demonstration of clinical feasibility.

Journal article Ultrasound Med Biol · February 2002 The clinical viability of a method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of soft tissue using acoustic radiation force impulse (ARFI) imaging, is investigated in vivo. In this method, focused ultraso ... Full text Link to item Cite

Array elevation requirements in phase aberration correction using an 8×128 1.75D array

Journal article Proceedings of SPIE the International Society for Optical Engineering · January 1, 2002 Accurate measurement of tissue aberrations is necessary for effective adaptive ultrasound imaging. Higher order arrays provide more elements and a larger array footprint over which echo signals can be acquired. This allows for better sampling of the aberra ... Full text Cite

Acoustic radiation force impulse imaging: Remote palpation of the mechanical properties of tissue

Journal article Proceedings of the IEEE Ultrasonics Symposium · 2002 An overview is given of the Acoustic Radiation Force Impulse (ARFI) imaging. It discusses the derivation of radiation force, the response of tissue to radiation force, and the potential for this imaging method to evaluate the mechanical properties of tissu ... Cite

Adaptive clutter filtering via blind signal separation for lateral blood velocity measurement

Journal article Proceedings of the IEEE Ultrasonics Symposium · January 1, 2002 A method for adaptive clutter rejection via blind signal separation (BSS) is presented in application to angle-independent blood velocity measurement in the carotid artery. Clutter filtering via frequency domain-based approaches is ineffective given short ... Full text Cite

Comparison of normal and harmonic ultrasonic imaging with a multirow array

Conference Proceedings International Symposium on Biomedical Imaging · January 1, 2002 Harmonic ultrasonic imaging is often qualitatively better in the clinical setting than normal ultrasonic imaging in the same frequency range. One possible factor in the differential image quality is the degree of aberration present in the imaged tissue. Th ... Full text Cite

Acoustic radiation force impulse imaging: EX vivo and in vivo demonstration of transient shear wave propagation

Conference Proceedings International Symposium on Biomedical Imaging · January 1, 2002 Acoustic Radiation Force Impulse (ARFI) imaging utilizes brief, high energy, focused acoustic pulses to generate radiation force in remote locations in tissue, and conventional diagnostic ultrasound methods to detect the resulting tissue displacements in o ... Full text Cite

High resolution ultrasound deamforming using synthetic and adaptive imaging techniques

Conference Proceedings International Symposium on Biomedical Imaging · January 1, 2002 Ultrasound image quality can be improved by incorporating elevation information from high-order arrays and adjust the beam-forming techniques to take advantage of the added information. We present the use of 1.75D ultrasound arrays for improving image qual ... Full text Cite

Aberration measurement and correction with a high resolution 1.75D array

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2001 Accurate measurement of tissue induced aberrations is necessary for effective adaptive ultrasound imaging. We acquired single channel RF data on a 6.7 MHz, 8 × 128 array (Tetrad Co.) operating at F/1.0 in azimuth and F/2.89 in elevation. This array was int ... Cite

Evaluation of the mechanical properties of active skeletal muscle using acoustic radiation force impulse imaging

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2001 Acoustic Radiation Force Impulse (ARFI) imaging is a method for characterizing local variations in tissue mechanical response. In this method, a single ultrasonic transducer array is used to both apply temporally short localized radiation forces within tis ... Cite

Adaptive diagnostic ultrasonic imaging

Journal article Comptes Rendus De L Academie Des Sciences Series IV Physics Astrophysics · October 1, 2001 Medical ultrasonic imaging systems assume a constant, fixed acoustic propagation velocity in tissue. This assumption allows the focusing of ultrasonic pulses in a simple way with transducer arrays with electronic delay lines. However, soft tissue acoustic ... Full text Cite

On the feasibility of remote palpation using acoustic radiation force.

Journal article The Journal of the Acoustical Society of America · July 2001 A method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of tissue, is under investigation. In this method, focused ultrasound is used to apply localized (on the order of 2 mm3) radiation force within tissue. ... Full text Cite

Wavefront estimation in the human breast

Journal article Proceedings of SPIE the International Society for Optical Engineering · January 1, 2001 We acquired conventional and harmonic channel r.f. ultrasound echo data using a 3×80 element, 8.5 MHz multirow array from the breasts of eight volunteers. The data acquisition was interleaved to allow direct comparison normal and harmonic echo wavefronts. ... Full text Cite

In vivo breast tissue backscatter measurements with 7.5- and 10-MHz transducers.

Journal article Ultrasound Med Biol · January 2001 Measurements of the ultrasound (US) backscatter coefficient (BSC) of fibroglandular and fatty breast tissues in vivo from 5.25 through 13 MHz, using the reference phantom method, are presented. Radiofrequency echo data were collected at a series of locatio ... Full text Link to item Cite

2-D motion estimation using two parallel receive beams

Journal article IEEE Trans. Ultrason. Ferroelectr. Freq. Control (USA) · 2001 We describe a method for estimating 2-D target motion using ultrasound. The method is based on previous ensemble tracking techniques, which required at least four parallel receive beams and 2-D pattern matching. In contrast, the method described requires o ... Full text Link to item Cite

Investigation of real-time remote palpation imaging

Journal article Proceedings of SPIE the International Society for Optical Engineering · January 1, 2001 We are investigating a novel ultrasonic method for remote palpation, which provides images of local variations in tissue stiffness. Acoustic radiation force is applied to small volumes of tissue, and the resulting displacement patterns are imaged using ult ... Full text Cite

In vivo demonstration of acoustic radiation force impulse (ARFI) imaging in the thyroid, abdomen, and breast

Journal article Proceedings of the IEEE Ultrasonics Symposium · 2001 Acoustic Radiation Force Impulse (ARFI) imaging is proposed as a method for characterizing local variations in tissue mechanical response. In this method, a single ultrasonic transducer array is used to both apply localized radiation forces within tissue a ... Cite

Lateral blood velocity measurement in the carotid artery via speckle tracking

Journal article Proceedings of the IEEE Ultrasonics Symposium · January 1, 2001 A method for measurement of lateral blood velocity in the carotid artery is presented. Conventional Doppler methods are not capable of measuring lateral velocities since they quantify only the axial component of blood flow. 2D Speckle Tracking methods meas ... Full text Cite

Automatic image registration for MR and ultrasound cardiac images

Conference Lecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2001 The Statistics Based Image Registration (SBR) method for automatic image registration is presented with application to magnetic resonance (MR)and ultrasound (US) cardiac time series images. SBR is demonstrated for MR myocardial perfusion assessment and US ... Full text Cite

Acoustic remote palpation: Initial in vivo results

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2000 An ultrasonic method for remote palpation of tissue is under investigation. In this method, a single ultrasonic transducer array is used to both apply localized radiation forces within tissue and to track the resulting displacements. The magnitude of the t ... Cite

In vivo comparison of fundamental and harmonic lateral transmit beam shapes

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2000 Harmonic imaging has been shown to provide superior image quality in clinical studies, but few quantitative analyses of image quality have been performed. To better understand the improvements in image quality attained in vivo using harmonic imaging, we ha ... Cite

Adaptive imaging using an 8 X 128 array

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 2000 Adaptive imaging using an 8×128 array is analyzed. The array consists of switches in the handle that enables any combination of 8 rows to be selected for transmit and a different set of rows is selected for receive. The elevation aperture is changed for ea ... Cite

The impact of sound speed errors on medical ultrasound imaging

Journal article J. Acoust. Soc. Am. (USA) · 2000 The results of a quantitative study of the impact of sound speed errors on the spatial resolution and amplitude sensitivity of a commercial medical ultrasound scanner are presented in the context of their clinical significance. The beamforming parameters o ... Full text Link to item Cite

A finite element model for simulating acoustic streaming in cystic breast lesions with experimental validation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2000 Streaming detection is an ultrasonic technique that can be used to distinguish fluid-filled lesions, or cysts, from solid lesions. With this technique, high intensity ultrasound pulses are used to induce acoustic streaming in cyst fluid, and this motion is ... Full text Cite

Speckle tracking for multi-dimensional flow estimation

Journal article Ultrasonics (Netherlands) · 2000 Speckle tracking methods overcome the major limitations of current Doppler methods for flow imaging and quantification: angle dependence and aliasing. In this paper, we review the development of speckle tracking, with particular attention to the advantages ... Full text Link to item Cite

A novel interpolation strategy for estimating subsample speckle motion

Journal article Phys. Med. Biol. (UK) · 2000 Multidimensional, high-resolution ultrasonic imaging of rapidly moving tissue is primarily limited by sparse sampling in the lateral dimension. In order to achieve acceptable spatial resolution and velocity quantization, interpolation of laterally sampled ... Full text Link to item Cite

A finite element model of remote palpation of breast lesions using radiation force: factors affecting tissue displacement.

Journal article Ultrasonic imaging · January 2000 The early detection of breast cancer reduces patient mortality. The most common method of breast cancer detection is palpation. However, lesions that lie deep within the breast are difficult to palpate when they are small. Thus, a method of remote palpatio ... Full text Cite

Optimizing visualization of breast microcalcifications

Journal article Proceedings of the IEEE Ultrasonics Symposium · January 1, 2000 We combine our results from a series of clinical, experimental, and analytical studies to present comprehensive recommendations for the improved visualization of breast microcalcifications with ultrasound. Such improved visualization would extend the utili ... Full text Cite

Finite element analysis of radiation force induced tissue motion with experimental validation

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 1999 An ultrasonic radiation force-based method for remote palpation of tissue is investigated. The use of radiation force to image tissue stiffness has been proposed by several researchers. In this paper, the potential for using a diagnostic ultrasound system ... Cite

Adaptive imaging in the breast

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1999 Various adaptive imaging methods have been proposed to compensate for the image degradation caused by the non-uniform acoustic velocity in soft tissues. Most adaptive imaging methods employ measurements of echo arrival times at the receive array to modify ... Cite

In vivo breast tissue backscatter study with 7.5 MHz and 10 MHz probes

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1999 An on-going study of the backscatter coefficient (BSC) of fibroglandular breast tissue in vivo from 5-13 MHz is discussed. Initial results of the study are compared to published values for this tissue. The implications of these findings for the ultrasound ... Cite

The use of acoustic streaming in breast lesion diagnosis: a clinical study.

Journal article Ultrasound in medicine & biology · January 1999 Results from a clinical study are presented, in which ultrasonically-induced acoustic streaming was successfully used to differentiate fluid-filled lesions (cysts) from solid lesions in the breast. In this study, high-intensity ultrasound pulses from a mod ... Full text Cite

Adaptive imaging in the thyroid using fundamental and harmonic echo data

Journal article Proceedings of the IEEE Ultrasonics Symposium · January 1, 1999 Normal (9 MHz) and harmonic (9 MHz) element r.f. data were obtained for a 3×80 element array from the thyroids of ten subjects. The obtained data suggest that phase aberration is very mild in the thyroid, and that harmonic imaging reduces the effects of of ... Cite

Application of sound speed estimation and mapping to multi-layer media and in vivo data

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1998 The application of a pulse-echo sound speed estimation technique to multi-layered and biological media is discussed and demonstrated in simulation, phantom, and clinical experiments. We have recently described and demonstrated a technique which estimates t ... Cite

Microcalcifications as elastic scatterers under ultrasound.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · 1998 One of the fundamental limitations of medical ultrasound in the imaging of the breast is the inability of current practice to reliably visualize microcalcifications in the size range of clinical interest. Microcalcifications (MCs) are small crystals of cal ... Full text Link to item Cite

The application of k-space in pulse echo ultrasound.

Journal article IEEE 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 ... Full text Cite

The direct estimation of sound speed using pulse-echo ultrasound

Journal article J. Acoust. Soc. Am. (USA) · 1998 A method for the direct estimation of the longitudinal speed of sound in a medium is presented. This estimator derives the speed of sound through analysis of pulse-echo data received across a single transducer array following a single transmission, and is ... Full text Link to item Cite

Speckle decorrelation due to two-dimensional flow gradients.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1998 The performance of ultrasonic velocity estimation methods is degraded by speckle decorrelation, the change in received echoes over time. Because ultrasonic speckle is formed by the complex sum of echoes from subresolution scatterers, it is sensitive to the ... Full text Cite

Ensemble tracking for 2D vector velocity measurement: Experimental and initial clinical results

Journal article IEEE Trans. Ultrason. Ferroelectr. Freq. Control (USA) · 1998 We describe a new method, called ensemble tracking, for estimating two-dimensional velocities with ultrasound. Compared to previous speckle tracking techniques, ensemble tracking measures motion over smaller times and distances, increasing maximum velociti ... Full text Link to item Cite

Aberrator integration error in adaptive imaging

Journal article IEEE 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 ... Full text Cite

Wavefront distortion measurements in the human breast

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1997 Published wavefront distortion (phase aberration) measurements for the human breast ranged from mild phase aberrations (8 ns r.m.s) to severe phase aberrations (67 ns r.m.s.). These measurements are required to specify arrays and assess the potentials of a ... Cite

Comparison of algorithms for tracking sub-pixel speckle motion

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1997 We have previously described Ensemble Tracking, a speckle tracking method that uses parallel receive processing and 2D pattern matching to generate a vector velocity map with high spatial and temporal resolution. Due to the mismatch in axial and lateral sp ... Cite

Utilization of acoustic streaming to classify breast lesions in vivo

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 1997 Results from a clinical study in which Streaming Detection was used to successfully differentiate fluid-filled lesions (cysts) from solid lesions in the breast are presented. Streaming Detection is an ultrasonic technique in which high intensity ultrasound ... Cite

Speckle coherence and implications for adaptive imaging.

Journal article The 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 ... Full text Cite

A speckle target adaptive imaging technique in the presence of distributed aberrations.

Journal article IEEE 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 ... Full text Cite

Parallel processing techniques for the speckle brightness phase aberration correction algorithm.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1997 The speckle brightness adaptive algorithm has previously been implemented in approximately real-time on low frequency, one-dimensional arrays. To increase the speed of this technique, a temporally parallel algorithm and a spatially parallel algorithm are d ... Full text Cite

The detection of breast microcalcifications with medical ultrasound.

Journal article J Acoust Soc Am · January 1997 Microcalcifications are small crystals of calcium apatites which form in human tissue through a number of mechanisms. The size, morphology, and distribution of microcalcifications are important indicators in the mammographic screening for and diagnosis of ... Full text Link to item Cite

Initial experimental results using ensemble tracking for 2D vector velocity measurement

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1996 We have previously described a time-domain speckle tracking method, called Ensemble Tracking, for two dimensional vector velocity measurement. Ensemble Tracking involves parallel receive processing, 2D pattern matching, and interpolation of the resulting t ... Cite

Streaming detection: improvements in sensitivity

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 1996 Streaming Detection is a new ultrasonic technique proposed to distinguish fluid-filled lesions, or cysts, from solid lesions in the breast. In this technique, high intensity ultrasound pulses are used to induce acoustic streaming in cyst fluid, and this mo ... Cite

Improvement of signal correlation for adaptive imaging using the translating transmit aperture algorithm

Journal article Proceedings 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 ... Cite

Microcalcifications as elastic scatterers under ultrasound: implications for medical imaging

Journal article Proceedings of the IEEE Ultrasonics Symposium · 1996 Microcalcifications are small crystals of calcium phosphates which form in human tissue through a number of mechanisms. The size, morphology, and distribution of microcalcifications (MCs) are important indicators in the mammographic screening for and diagn ... Cite

Relative performance of two-dimensional speckle-tracking techniques: normalized correlation, non-normalized correlation and sum-absolute-difference

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1995 We present computer simulations that compare the performance of three two-dimensional block-matching algorithms as applied to ultrasonic speckle. The three algorithms, normalized correlation, non-normalized correlation and Sum Absolute Difference (SAD), we ... Cite

Ensemble tracking: a new method for 2D vector velocity measurement

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1995 We described a new method, called ensemble tracking, for quantifying two dimensional velocities. Compared to previous two-dimensional speckle tracking techniques, ensemble tracking measures motion over smaller translations, thereby reducing errors due to s ... Cite

Limits on the performance of near field phase aberration correction

Journal article Proceedings 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 ... Cite

New technique for adaptive imaging in the presence of distributed aberrations

Journal article Proceedings 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 ... Cite

Application of K-space in medical ultrasound

Journal article Proceedings 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 ... Cite

A Fundamental Limit on Delay Estimation Using Partially Correlated Speckle Signals

Journal article IEEE 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 ... Full text Cite

A novel ultrasonic technique for differentiating cysts from solid lesions: preliminary results in the breast.

Journal article Ultrasound 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 ... Full text Cite

Experimental velocity profiles and volumetric flow via two-dimensional speckle tracking.

Journal article Ultrasound in medicine & biology · January 1995 The performance of a two-dimensional speckle tracking system in measuring in vitro laminar flow is evaluated. The system uses a pattern matching algorithm to track subresolution-sized speckle regions between successive ultrasonic 2D pulse-echo acquisitions ... Full text Cite

Evaluation of the ultrasonic detectability of microcalcifications

Journal article Proceedings of the IEEE Ultrasonics Symposium · 1995 Microcalcifications are small crystals of calcium apatites which form in human tissue through a number of mechanisms. The size, morphology, and distribution of microcalcifications are important indicators in the mammographic screening for and diagnosis of ... Cite

Three-dimensional flow images by reconstruction from two-dimensional vector velocity maps.

Journal article J Am Soc Echocardiogr · 1995 A method for constructing three-dimensional images of flow is described. The technique involves the acquisition of numerous closely spaced planes, each comprised of a map of the two-dimensional velocities measured in that plane. Each such vector velocity m ... Full text Link to item Cite

Real-time synthetic receive aperture imaging: experimental results

Journal article Proceedings 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 ... Cite

Fundamental limit on the accuracy of speckle signal alignment

Journal article Proceedings 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 ... Cite

Three-dimensional flow visualization via reconstruction from successive two-dimensional vector velocity maps

Conference Annual 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 ... Cite

Volumetric flow measured in a laminar jet phantom using a two-dimensional speckle tracking system

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1994 A two-dimensional speckle tracking system was used to measure volumetric flow rates in a free laminar jet in vitro. The system utilized the Sum-Absolute-Difference (SAD) pattern matching algorithm to track small speckle regions between successive pulse-ech ... Cite

Fundamental limit on the performance of correlation based phase correction and flow estimation techniques

Journal article IEEE 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 ... Cite

A Fundamental Limit on the Performance of Correlation Based Phase Correction and Flow Estimation Techniques

Journal article IEEE 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 ... Full text Cite

A Comparative Evaluation of Several Algorithms for Phase Aberration Correction

Journal article IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · January 1, 1994 A common framework is presented to classify several phase correction techniques. A subset of these techniques are evaluated through simulations which utilize 2-D phase aberration profiles measured in the breast. The techniques are compared based on their a ... Full text Cite

Generation and detection of acoustic streaming to differentiate between solid and cystic breast lesions

Journal article Proceedings 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 ... Full text Cite

Fundamental limit on the performance of phase aberration correction and correlation based flow estimates in medical ultrasound

Journal article Proceedings 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 ... Cite

Parallel processing system for real-time phase aberration correction using an improved phase extraction technique

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1993 The speckle brightness phase aberration correction technique has been modified to use data from only selected elements. Simulations have demonstrated that this modification improves phase extraction performance. Initial results indicate that it performs we ... Cite

Wall filtering challenges in two-dimensional vector velocity estimation

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 1993 To formulate a clinically viable methodology for tracking blood flow in two dimensions using ultrasound, one must address some challenges posed by the physical limitations of the imaging modality. At the frequencies of interest in medical diagnostic imagin ... Cite

Real-time imaging of tissue vibration using a two-dimensional speckle tracking system

Journal article Proceedings 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 ... Cite

A real time system for quantifying and displaying two-dimensional velocities using ultrasound.

Journal article Ultrasound in medicine & biology · January 1993 This paper describes a system that has been developed for measuring two-dimensional velocities in real time using ultrasound. The instrument tracks interframe speckle pattern motion using a Sum-Absolute-Difference (SAD) algorithm in order to produce a vect ... Full text Cite

Real-time system for angle-independent US of blood flow in two dimensions: initial results.

Journal article Radiology · January 1993 The authors developed an ultrasound system that enables the speckle patterns produced by echoes from moving blood to be tracked in real time. Unlike current color Doppler flow imagers, this system allows the measurement of blood velocities in any direction ... Full text Cite

Two dimensional ultrasonic beam distortion in the breast: in vivo measurements and effects.

Journal article Ultrason Imaging · October 1992 Two dimensional arrival time data was obtained for the propagation of ultrasound across the breasts of 7 female volunteers. These profiles were extracted through the use of cross-correlation measurements and a simulated annealing process that maintained ph ... Full text Link to item Cite

Two-dimensional arrays for medical ultrasound.

Journal article Ultrasonic imaging · July 1992 The design, fabrication and evaluation of two-dimensional transducer arrays are described for medical ultrasound imaging. A 4 x 32, 2.8 MHz array was developed to use new signal processing techniques for improved B-scan imaging including elevation focusing ... Full text Cite

Phase aberration correction using echo signals from moving targets. II: Experimental system and results.

Journal article Ultrasonic imaging · April 1992 A method for correcting errors due to near-field tissue inhomogeneities in phased array ultrasound images is evaluated experimentally. The method uses the brightness of a moving speckle-generating target, such as blood, as a quality factor to correct for u ... Full text Cite

Phase aberration correction using echo signals from moving targets. I: Description and theory.

Journal article Ultrasonic imaging · April 1992 Inhomogeneous acoustic velocity in human tissue introduces phase aberration in ultrasonic imaging systems and degrades image quality. A novel technique that employs echo signals from moving diffuse targets, such as flowing blood, as an image quality factor ... Full text Cite

Synthetic receive aperture imaging with phase correction for motion and for tissue inhomogeneities. II. Effects of and correction for motion.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1992 For Pt.I see ibid., vol.39, p.489 (1992). The effects of tissue/transducer motion and artifacts from adaptive focusing on synthetic receive aperture (SRA) imaging are explored using experiment, simulation, and theory. The impact of these issues on the sele ... Full text Cite

Synthetic receive aperture imaging with phase correction for motion and for tissue inhomogeneities. I. Basic principles.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1992 The use of a synthetic receive aperture (SRA) system to increase the resolution, of a phased-array imaging system severalfold, by utilizing the available number of parallel receiver channels to address a larger number of transducer elements through a multi ... Full text Cite

A statistical analysis of phase aberration correction using image quality factors in coherent imaging systems.

Journal article IEEE transactions on medical imaging · January 1992 A fundamental analysis of phase aberration correction techniques which use speckle brightness-based image equality factors (QFs) to iteratively reduce phase errors is presented. Phase aberration arises from the spatial inhomogeneity of acoustic velocity in ... Full text Cite

Initial results with the real-time SAD vector velocity estimation system: Constant velocity calibration

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1992 Doppler flow imaging systems are limited by angledependence and aliasing. We have constructed a velocity estimator which uses the Sum Absolute Difference (SAD) algorithm [1] to track the motion of speckle in two dimensions between successive ultrasonic fra ... Full text Cite

Large aperture phase error measurement and effects

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1992 Clinical measurements and computer simulations were conducted to determine the effects of phase errors on image quality in large aperture systems. Using a 3.5MHz 24.5mm receive aperture, phase errors were measured across the left breasts of 6 female volunt ... Full text Cite

Physical factors affecting the performance of two-dimensional vector flow imaging

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1992 We have previously proposed a two-dimensional correlation technique capable of measuring target velocities in any direction in the imaging plane and related its performance to the fundamental characteristics of speckle size and speckle decorrelation rates ... Full text Cite

A system for high resolution ultrasonic breast imaging

Journal article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1991 The authors have designed and performed simulations of a synthetic receive aperture system (SRA) which can be used to address a large number of phased array channels with a relatively small number of parallel receive channels in the formation of high-resol ... Cite

The impact of acoustic velocity variations on target detectability in ultrasonic images of the breast.

Journal article Invest Radiol · September 1991 Experimentally obtained ultrasonic phase aberration profiles in the breast were used to investigate the impact of acoustic velocity variations on images of simulated breast lesions. The imaging properties of several phased-array transducers with varying fr ... Full text Link to item Cite

Potential and limitations of angle-independent flow detection algorithms using radio-frequency and detected echo signals.

Journal article Ultrasonic imaging · July 1991 New techniques to estimate local blood and tissue velocities have been developed by several groups, including our own. The performance of these techniques is ultimately limited by the characteristics of ultrasonic imaging systems that determine the second- ... Full text Cite

A novel method for angle independent ultrasonic imaging of blood flow and tissue motion.

Journal article IEEE transactions on bio-medical engineering · March 1991 Tracking the speckle patterns produced by moving targets has been shown effective for angle independent imaging of blood flow and tissue motion. While speckle tracking overcomes major limitations of Doppler-based flow imaging, the computational complexity ... Full text Cite

Comparisons of image quality factors for phase aberration correction with diffuse and point targets: theory and experiments.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1991 The use of several alternative image-brightness-based quality factors for phase aberration correction with diffuse and point targets in coherent ultrasonic imaging systems is explored. The factors are similar to the sharpness functions proposed by R.A. Mul ... Full text Cite

In vivo measurements of ultrasonic beam distortion in the breast.

Journal article Ultrason Imaging · January 1991 The phase aberrations encountered by ultrasonic pulses propagating through breast tissue in twenty-two female volunteers were measured. The experiments were designed to assess the impact of these aberrations on clinical ultrasonic image quality for a varie ... Full text Link to item Cite

A real-time system for angle-independent velocity detection

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1991 The first real-time angle-independent velocity detection system for ultrasound has been constructed. The system detects both the axial and lateral components of velocity using the SAD algorithm, a novel time-domain method for tracking speckle patterns. In ... Full text Cite

Two-dimensional arrays for medical ultrasound

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1991 The design, fabrication and evaluation of twodimensional transducer arrays are described for medical ultrasound imaging. A 4 x 32, 2.8 MHz array was developed to use new signal processing techniques for improved B-scan imaging including elevation focusing, ... Full text Cite

An evaluation of transducer design and algorithm performance for two dimensional phase aberration correction

Conference Proceedings IEEE Ultrasonics Symposium · January 1, 1991 In vivo measurements of phase aberration profiles in the breast are used to investigate the geometric requirements for phased arrays to be used in adaptive imaging. Simulation studies are then described which compare the performance of several proposed tec ... Full text Cite

Two algorithms for correcting phase aberration in a computer-controlled ultrasonic imaging system

Journal article undefined · December 1, 1990 Spatial inhomogeneities in the acoustic velocity of tissues degrade the performance of medical ultrasonic imaging systems. Two algorithms which can correct the phase aberration induced by the inhomogeneities are presented. The first algorithm adjusts the p ... Cite

Synthetic aperture imaging in medical ultrasound with correction for motion artifacts

Journal article Ultrasonics Symposium Proceedings · December 1, 1990 The authors state that a synthetic receive aperture (SRA) system of a relatively simple design could increase the resolution of a phased-array imaging system several-fold, by utilizing a given number of parallel receive channels to address a larger number ... Cite

A novel phase aberration correction technique based on local target motion

Journal article Ultrasonics Symposium Proceedings · December 1, 1990 Inhomogeneity in acoustic velocity in tissue can introduce phase errors to diagnostic ultrasonic imaging systems and therefore degrade image quality. A novel technique for phase correction, based on the mean difference of specific brightness, that employs ... Cite

Real time ultrasonic flow imaging

Journal article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1990 The research program of Unit 2.1B, Real-Time Ultrasonic Flow Imaging, of the National Science Foundation/Engineering Research Center (NSF/ERC) is described. The objective of the unit's research is to develop effective techniques and prototype instrumentati ... Cite

A real-time adaptive ultrasonic imaging system.

Journal article Investigative radiology · September 1990 The performance of an experimental, adaptive, phased array imaging system in improving the quality of abdominal organ images in healthy volunteers was assessed. Trials were conducted under usual clinical imaging conditions and when phase aberrators of know ... Cite

Quality factors for phase aberration correction in medical ultrasound

Journal article Proceedings of SPIE the International Society for Optical Engineering · July 1, 1990 Spatial inhomogeneities in the acoustic velocity of tissues degrade the contrast and resolution of diagnostic ultrasonic images. A system which iteratively adjusts the phases of signals transmitted and received from individual elements in a phased array sc ... Full text Cite

Preliminary investigations: A real-time adaptive ultrasonic imaging system

Journal article Investigative Radiology · January 1, 1990 The performance of an experimental, adaptive, phased array imaging system in improving the quality of abdominal organ images in healthy volunteers was assessed. Trials were conducted under usual clinical imaging conditions and when phase aberrators of know ... Full text Cite

Experimental results with a real-time adaptive ultrasonic imaging system for viewing through distorting media.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1990 An online adaptive phased-array ultrasonic imaging system capable of markedly improving the detectability of targets viewed through inhomogeneous media is described. An online adaptive phase correction technique implemented on a research phased-array scann ... Full text Cite

System for real-time, adaptive ultrasonic imaging

Journal article Ultrasonics Symposium Proceedings · December 1, 1989 A real-time adaptive ultrasonic imaging system capable of markedly and quickly improving the quality of images degraded by aberrating media is described. The system employs one of several possible functions of regional image brightness as a quality factor. ... Cite

Phase aberration measurement and correction in medical ultrasound

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1989 An apparatus to measure time-of-flight profiles in living tissues and an experimental phased-array imaging system capable of correcting unknown phase errors induced by inhomogeneities in the acoustic velocities in tissue are presented. The procedure utiliz ... Cite

Phase aberration correction in medical ultrasound using speckle brightness as a quality factor.

Journal article The Journal of the Acoustical Society of America · May 1989 Medical ultrasonic images are degraded by tissues with inhomogeneous acoustic velocities. The resulting phase aberration raises the off-peak response of the imaging system's point spread function (PSF), decreasing dynamic range. In extreme cases, multiple ... Full text Cite

Angle independent ultrasonic blood flow detection by frame-to-frame correlation of B-mode images.

Journal article Ultrasonics · September 1988 We have previously reported initial clinical results of a novel blood velocity imaging technique utilizing a two-dimensional correlation search applied to consecutively acquired echoes. In this paper, we describe both the physical principles underlying thi ... Full text Cite

Properties of acoustical speckle in the presence of phase aberration. Part II: Correlation lengths.

Journal article Ultrasonic imaging · January 1988 In recent years, analysis of the second order statistics of ultrasound speckle has led to accurate prediction and measurements of the average speckle size in the transducer focal zone. In this paper, that work has been extended to the average speckle size ... Full text Cite

Properties of acoustical speckle in the presence of phase aberration. Part I: First order statistics.

Journal article Ultrasonic imaging · January 1988 The first order statistical properties of acoustical speckle patterns are studied as a function of several types of random and structured phase error. Such errors may arise from tissue velocity inhomogeneities or limitations in the acoustical imaging syste ... Full text Cite

MEASUREMENT OF LOCAL SPECKLE PATTERN DISPLACEMENT TO TRACK BLOOD FLOW IN TWO DIMENSIONS.

Journal article Ultrasonics Symposium Proceedings · December 1, 1987 A velocity imaging technique is described which operates on the envelope-detected echo signal and uses a two-dimensional correlation search method. Several experiments were performed to define the potentials and limitations of this technique. The results i ... Cite

Angle independent ultrasonic detection of blood flow.

Journal article IEEE transactions on bio-medical engineering · December 1987 Full text Cite

Speckle reduction achievable by spatial compounding and frequency compounding: Experimental results and implications for target detectability

Journal article Proceedings of SPIE the International Society for Optical Engineering · September 10, 1987 The degree of speckle reduction achievable by spatial and frequency compounding is a function of the rates of speckle pattern change induced by varying the imaging system’s illumination angle and acoustic frequency, respectively. We have measured these rat ... Full text Cite

Angle independent ultrasonic detection of blood flow

Journal article IEEE Trans. Biomed. Eng. (USA) · 1987 A technique for blood velocity imaging based on tracking the motion of the speckle pattern produced by blood is presented. Unlike Doppler velocity determinations, these are angle-independent. Initial in vivo experiments yield promising results ... Cite

International symposium on pattern recognition and acoustical imaging

Journal article Ultrasound in Medicine and Biology · January 1, 1987 Full text Cite

SPECKLE SNR VS. LATERAL RESOLUTION IN ULTRASOUND IMAGING: WHAT'S THE TRADEOFF?

Journal article Ultrasonics Symposium Proceedings · December 1, 1986 The rates of ultrasonic B-mode speckle pattern changes are measured as a function of changes in the imaging angle under a variety of experimental conditions. The results of these experiments were used to design an imaging system that optimizes speckle redu ... Cite

A quantitative approach to speckle reduction via frequency compounding.

Journal article Ultrasonic imaging · July 1986 Coherent speckle is a source of image noise in ultrasonic B-mode imaging. The use of multiple imaging frequencies has been suggested as a technique for speckle contrast reduction. This technique involves the averaging of images whose speckle patterns have ... Full text Cite

Phased array ultrasound imaging through planar tissue layers.

Journal article Ultrasound in medicine & biology · March 1986 Conventional ultrasound imaging devices are designed based on the assumption of a homogeneous tissue medium of constant acoustic velocity = 1540 m/sec. However, the body consists of tissue layers of varying thicknesses and velocities which range from 1470 ... Full text Cite

Speckle reduction in medical ultrasound via spatial compounding

Journal article Proc. SPIE - Int. Soc. Opt. Eng. (USA) · 1986 In order to design improved spatial compounding ultrasound scanning systems it is necessary to determine the correlation of speckle patterns as a function of aperture translation. The authors have conducted experiments measuring the speckle correlation as ... Cite

SPECKLE PATTERN CHANGES WITH VARYING ACOUSTIC FREQUENCY: EXPERIMENTAL MEASUREMENT AND IMPLICATIONS FOR FREQUENCY COMPOUNDING.

Journal article Ultrasonics Symposium Proceedings · January 1, 1986 The authors have measured the rates of ultrasonic B-mode speckle pattern changes as a function of the change in center frequency of the transmitted acoustical pulse under a variety of experimental conditions. Experimental results agree with a previous theo ... Full text Cite

Speckle pattern correlation with lateral aperture translation: experimental results and implications for spatial compounding.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1986 Full text Cite

Safety and efficacy of hypo/hyperthermia machine after proposed modification

Journal article Journal of Clinical Engineering · January 1, 1982 Full text Cite

Temperature regulation during surgery.

Journal article Anaesthesia and intensive care · November 1981 Cite