• Publications
  • Influence
A fundamental limit on delay estimation using partially correlated speckle signals
  • W. Walker, G. Trahey
  • Physics
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 1 March 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 forExpand
  • 462
  • 45
A spline-based algorithm for continuous time-delay estimation using sampled data
  • F. Viola, W. Walker
  • Computer Science, Medicine
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 28 February 2005
TLDR
Time delay estimation (TDE) lies at the heart of signal processing algorithms in a broad range of application areas, including communications, coherent imaging, speech processing, and acoustic. Expand
  • 193
  • 17
A constrained adaptive beamformer for medical ultrasound: initial results
  • J. Mann, W. Walker
  • Computer Science
  • IEEE Ultrasonics Symposium, . Proceedings.
  • 8 October 2002
TLDR
Adaptive beamforming has been widely used as a way to improve image quality in medical ultrasound applications by correcting phase and amplitude aberration errors resulting from tissue inhomogeneity. Expand
  • 126
  • 11
A comparison of the performance of time-delay estimators in medical ultrasound
  • F. Viola, W. Walker
  • Mathematics, Medicine
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 7 May 2003
Time-delay estimation (TDE) is a common operation in ultrasound signal processing. In applications such as blood flow estimation, elastography, phase aberration correction, and many more, the qualityExpand
  • 217
  • 7
The application of k-space in pulse echo ultrasound
  • W. Walker, G. Trahey
  • Computer Science, Medicine
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 1998
TLDR
This paper presents analytical and conceptual techniques for estimating the k-space representation of pulse echo imaging systems with arbitrary transmit and receive array geometries and apodizations. Expand
  • 77
  • 6
A fundamental limit on the performance of correlation based phase correction and flow estimation techniques
  • W. Walker, G. Trahey
  • Physics
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 1 September 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 phaseExpand
  • 110
  • 5
Radiation force imaging of viscoelastic properties with reduced artifacts
  • F. Viola, W. Walker
  • Materials Science, Medicine
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 9 July 2003
It is well-known that changes in the mechanical properties of tissues are correlated with the presence of disease. In the eye, for example, the vitreous body undergoes dramatic changes in mechanicalExpand
  • 78
  • 4
Adaptive signal processing in medical ultrasound beamforming
For over thirty years adaptive beamforming (AB) algorithms have been applied in RADAR and SONAR signal processing. Higher resolution and contrast is attainable using those algorithms at the price ofExpand
  • 56
  • 3
A speckle target adaptive imaging technique in the presence of distributed aberrations
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 ofExpand
  • 81
  • 2
Cystic resolution: A performance metric for ultrasound imaging systems
This paper describes a metric that can be used to characterize the resolution of arbitrary broadband coherent imaging systems. The metric is particularly suited to medical ultrasound because itExpand
  • 48
  • 2