Gregg E. Trahey
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View article: Spatial Ambiguity Correction in Coherence-Based Average Sound Speed Estimation
Spatial Ambiguity Correction in Coherence-Based Average Sound Speed Estimation Open
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, bea…
View article: In Vivo Demonstration of a Real-Time Temporal SNR Acoustic Output Adjustment Method
In Vivo Demonstration of a Real-Time Temporal SNR Acoustic Output Adjustment Method Open
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…
View article: Human Observer Sensitivity to Temporal Noise During B-Mode Ultrasound Scanning: Characterization and Imaging Implications
Human Observer Sensitivity to Temporal Noise During B-Mode Ultrasound Scanning: Characterization and Imaging Implications Open
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…
View article: Large-Array Deep Abdominal Imaging in Fundamental and Harmonic Mode
Large-Array Deep Abdominal Imaging in Fundamental and Harmonic Mode Open
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 explore…
View article: Adaptive Models for Multi-Covariate Imaging of Sub-Resolution Targets (MIST)
Adaptive Models for Multi-Covariate Imaging of Sub-Resolution Targets (MIST) Open
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 contrib…
View article: An Automated Region-Selection Method for Adaptive ALARA Ultrasound Imaging
An Automated Region-Selection Method for Adaptive ALARA Ultrasound Imaging Open
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 …
View article: Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging—Part I: Simulation Studies
Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging—Part I: Simulation Studies Open
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 selectio…
View article: Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging—Part II: Phantom and In Vivo Experiments
Spatial Coherence Adaptive Clutter Filtering in Color Flow Imaging—Part II: Phantom and In Vivo Experiments Open
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 compani…
View article: Frequency-Dependent Spatial Coherence in Conventional and Chirp Transmissions
Frequency-Dependent Spatial Coherence in Conventional and Chirp Transmissions Open
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 …
View article: An Automated <scp>ALARA</scp> Method for Ultrasound
An Automated <span>ALARA</span> Method for Ultrasound Open
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 sugges…
View article: Optical tracking of acoustic radiation force impulse-induced dynamics in a tissue-mimicking phantom
Optical tracking of acoustic radiation force impulse-induced dynamics in a tissue-mimicking phantom Open
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-μm microspheres were tracked axially…
View article: Spatial coherence in human tissue: implications for imaging and measurement
Spatial coherence in human tissue: implications for imaging and measurement Open
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 th…
View article: Resolution and Speckle Reduction in Cardiac Imaging
Resolution and Speckle Reduction in Cardiac Imaging Open
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 resul…
View article: Coherence-based quantification of acoustic clutter sources in medical ultrasound
Coherence-based quantification of acoustic clutter sources in medical ultrasound Open
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 …
View article: Intrinsic Tradeoffs in Multi-Covariate Imaging of Sub-Resolution Targets
Intrinsic Tradeoffs in Multi-Covariate Imaging of Sub-Resolution Targets Open
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 matr…
View article: Blocked Elements in 1-D and 2-D Arrays—Part I: Detection and Basic Compensation on Simulated and <italic>In Vivo</italic> Targets
Blocked Elements in 1-D and 2-D Arrays—Part I: Detection and Basic Compensation on Simulated and In Vivo Targets Open
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…
View article: Incoherent Clutter Suppression Using Lag-One Coherence
Incoherent Clutter Suppression Using Lag-One Coherence Open
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 indivi…
View article: Synthetic Aperture Focusing for Multi-Covariate Imaging of Sub-Resolution Targets
Synthetic Aperture Focusing for Multi-Covariate Imaging of Sub-Resolution Targets Open
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 fr…
View article: The Impact of Acoustic Clutter on Large Array Abdominal Imaging
The Impact of Acoustic Clutter on Large Array Abdominal Imaging Open
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 lat…
View article: UltraDuke Version 1
UltraDuke Version 1 Open
DukeUltrasound is an ultrasound dataset collected at Duke University with a Verasonics c52v probe. It contains delay-and-sum (DAS) beamformed data as well as data post-processed with Siemens Dynamic TCE for speckle reduction, contrast enha…
View article: Speckle coherence of piecewise-stationary stochastic targets
Speckle coherence of piecewise-stationary stochastic targets Open
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…
View article: Simultaneous Photoacoustic Imaging and Cavitation Mapping in Shockwave Lithotripsy
Simultaneous Photoacoustic Imaging and Cavitation Mapping in Shockwave Lithotripsy Open
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 …
View article: Multi-covariate Imaging of Sub-resolution Targets
Multi-covariate Imaging of Sub-resolution Targets Open
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 env…
View article: Short-Lag Spatial Coherence Imaging in 1.5-D and 1.75-D Arrays: Elevation Performance and Array Design Considerations
Short-Lag Spatial Coherence Imaging in 1.5-D and 1.75-D Arrays: Elevation Performance and Array Design Considerations Open
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 acr…
View article: Lag-One Coherence as a Metric for Ultrasonic Image Quality
Lag-One Coherence as a Metric for Ultrasonic Image Quality Open
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)…
View article: Effect of Transmit Beamforming on Clutter Levels in Transthoracic Echocardiography
Effect of Transmit Beamforming on Clutter Levels in Transthoracic Echocardiography Open
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 motio…