A5044539145- Ultrasound Imaging and Elastography
- Photoacoustic and Ultrasonic Imaging
- Ultrasonics and Acoustic Wave Propagation
- Microwave Imaging and Scattering Analysis
- Seismic Imaging and Inversion Techniques
- Ultrasound and Hyperthermia Applications
- Flow Measurement and Analysis
- Bone fractures and treatments
- Seismic Waves and Analysis
- Medical Imaging Techniques and Applications
- Trauma and Emergency Care Studies
- Slime Mold and Myxomycetes Research
- Radiation Dose and Imaging
- Advanced X-ray and CT Imaging
- Electrical and Bioimpedance Tomography
- Differential Equations and Boundary Problems
- Elbow and Forearm Trauma Treatment
- Optical Coherence Tomography Applications
- Orbital Angular Momentum in Optics
- Infrared Thermography in Medicine
- Orthopedic Surgery and Rehabilitation
- Advanced Memory and Neural Computing
- Hydraulic Fracturing and Reservoir Analysis
- Geophysical Methods and Applications
- Hip and Femur Fractures
University of Rochester
2023-2025
University of Rochester Medical Center
2022-2024
Stanford Medicine
2018-2023
Farooq Hospital
2023
Stanford University
2017-2022
Palo Alto University
2017-2022
Georgia Institute of Technology
2016
A model and method to accurately estimate the local speed of sound in tissue from pulse-echo ultrasound data is presented. The relates speeds along a wave propagation path average over path, allows one avoid bias sound-speed estimates that can result overlying layers subcutaneous fat muscle tissue. Herein, using approach by Anderson Trahey measured, then authors solve proposed for via gradient descent. estimator was tested series simulation ex vivo phantom experiments two-layer media as...
Phase aberration is widely considered a major source of image degradation in medical pulse-echo ultrasound. Traditionally, near-field phase correction techniques are unable to account for distributed aberrations due spatially varying speed sound the medium, while most require use point-like sources and impractical clinical applications where diffuse scattering dominant. Here, we present two that utilize estimates from tomographic estimator builds on our previous work with layered media. We...
Ultrasound tomography fundamentally relies on low-frequency data to avoid cycle skipping in full-waveform inversion (FWI). In the absence of sufficiently data, we can extrapolate content from existing high-frequency signals by using same approach used frequency-difference beamforming. This is then kickstart FWI and at higher frequencies. simulations, structural similarity index measure peak signal-to-noise ratio reconstructed image improve 0.28 8.6 dB, respectively, as a result frequency...
Ultrasound tomography is an emerging imaging modality that uses the transmission of ultrasound through tissue to reconstruct images its mechanical properties. Initially, ray-based methods were used these images, but their inability account for diffraction often resulted in poor resolution. Waveform inversion overcame this limitation, providing high-resolution tissue. Most clinical implementations, directed at breast cancer imaging, currently rely on a frequency-domain waveform reduce...
Phase aberration, reverberation clutter, and off-axis scattering have been identified as major sources of image degradation in medical ultrasound. Near-field mid-field phase aberration correction techniques make assumptions about the sound speed distribution imaging medium that limit their efficacy presence distributed aberrations. Although potential to perform better, many existing limited capability media composed diffuse scatterers. We propose a technique, based on local estimates, aims...
Our previous methodology in local sound speed estimation utilized time delays measured by the cross correlation of delayed full-synthetic aperture channel data to estimate average sound. However, focal distortions this lead biased estimates sound, which, turn, leads Here, we demonstrate bias and introduce a coherence-based estimator that eliminates is computationally much cheaper practice. Because approach medium over an equally spaced grid depth rather than time, derive refined model...
Objective. Speed of sound has previously been demonstrated to correlate with fat concentration in the liver. However, estimating speed liver noninvasively can be biased by tissue layers overlying Here, we demonstrate a noninvasive local estimator, which is based on layered media assumption, that accurately capture We validate estimator using an obese Zucker rat model non-alcoholic fatty disease and steatosis.Approach.We estimated global average 4 lean rats fed normal diet 16 high for up 8...
Robust recovery of multistatic synthetic aperture data from conventional ultrasound sequences can enable complete transmit-and-receive focusing at all points in the field view without drawbacks virtual-source and further enables more advanced imaging applications, such as backscatter coherence, sound speed estimation, phase aberration correction. Recovery set has previously been demonstrated on a steered transmit sequence for phased arrays using an adjoint-based method. We introduce two...
NestMC is a new multicompartment neural network simulator currently under development as collaboration between the Simulation Lab Neuroscience at Forschungszentrum Jülich, Barcelona Supercomputing Center and Swiss National Center.NestMC will enable scales classes of morphologically detailed neuronal simulations on current future supercomputing architectures.A number "many-core" architectures such GPU Intel Xeon Phi based systems are available.To optimally use these emerging architecture...
Investigations into Fourier beamforming for medical ultrasound imaging have largely been limited to plane-wave and single-element transmissions. The main aim of this work is generalize enable synthetic aperture with arbitrary transmit sequences. When applied focused beams, the proposed approach yields a full-waveform-based alternative virtual-source aperture, which has implications both coherence sound speed estimation. compared retrospective encoding conventional sequences (REFoCUS),...
Sound speed estimation is a promising quantitative parameter in ultrasound for both it's potential as biomarker, where sound known to be correlated with biological changes, and aberration correction, knowledge of the allows correction distortions image. Previous methods rely on use an a-priori beamforming, from which sound-speed estimates are then calculated. However, this assumption introduces bias technique, because errors lead Here we present method that avoids by estimating without beamforming.
The convergence of waveform inversion in ultrasound tomography is heavily impacted by the choice starting model. Ray often used as model for inversion; however, artifacts resulting from ray can continue to persist during inversion. On other hand, a homogeneous may result cycle skipping if frequency transmitted too high or error between and ground-truth large. Clinical vivo breast data suggests that sufficient an accurate reconstruction speed sound close enough average medium sufficiently low...
This work presents refraction-corrected sound speed reconstruction techniques for transmission-based ultrasound computed tomography using a circular transducer array. Pulse travel times between element pairs can be calculated from slowness (the reciprocal of speed) the eikonal equation. Slowness is posed as nonlinear least squares problem where objective to minimize error measured and forward-modeled pulse times. The Gauss-Newton method used convert this into sequence linear least-squares...
We present full-waveform ultrasound computed tomography (USCT) for sound speed reconstruction based on the angular spectrum method using linear transducer arrays. first a transmission scenario in which plane-waves are emitted by transmitting array and received an opposite side of object interest. These arrays rotated around interest to interrogate medium from di↵erent view angles. Waveform inversion is demonstrated numerical breast phantom, varied 1486 1584 m/s. This example used isolate...
Spatial variation in sound speed causes aberration medical ultrasound imaging. Although our previous work has examined correction the presence of a spatially varying speed, practical implementations were limited to layered media due estimation process involved. Unfortunately, most models do not capture lateral variations that have greatest aberrative effect on image. Building upon Fourier split-step migration technique from geophysics, this introduces an iterative and distributed can model...
Our previous work on estimating the local speed of sound from average assumes a perfectly layered medium where is only allowed to vary axially away transducer surface. This layered-medium approach relies inverting relationship between interval speeds in each layer and effective up particular imaging depth. The primary limitation this that estimation can become inaccurate presence lateral variations or curved To better estimate these non-idealities, we propose travel-time tomographic accounts...
Spontaneous symmetry breaking instabilities are the most common mechanism for how biological, chemical, and physical systems produce spatial patterns. Beginning with Turing's original paper, so-called lateral inhibition---in which negative feedback has greater spread than positive feedback---has been underlying pattern formation in biological models. Despite this, there many that exhibit but do not have inhibition. In this we present an example of such a system is able to generate robust...
Speed-of-sound (SoS) reconstruction in pulse-echo ultrasound can reduce aberrations imaging and provide quantitative biomarkers for diagnostics. State-of-the-art SoS requires beamformed data time-delay estimation. This translates either into multi-layered models, where absolute delays <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{t}_\mathrm{i}$</tex> at multiple depths are fitted to axial variations, or a perturbation approach,...
Stroke is a significant cause of mortality and disability in America. Due to differences ischemic hemorrhagic stroke, imaging must be performed before administration therapeutic medication; however, the nature both CT MRI can induce delays triage time. Recent work suggests that ultrasound tomography (UST) capable vivo tissue properties may have potential as diagnostic tool during stroke treatment which could at patient's location rather than local hospital. In this work, we investigate...
Accurate recovery of the full-synthetic aperture (FSA)dataset from focused transmissions can enable synthetic transmit focusing without drawbacks single-element and virtual-element a wide array imaging techniques that require FSA dataset. Recovery dataset has previously been performed using an adjoint-based method on steered sequence for phased-arrays. We present regularized inversion allows wider variety specifications is intended to perform more accurately in walking sequences. The goal...
Fourier beamforming techniques for medical ultrasound imaging have largely been limited to linear transducer arrays. This work extends the angular spectrum method curvilinear arrays and demonstrates a migration-based technique that has implications sound speed estimation distributed aberration correction abdominal applications. When compared Field II simulations, proposed simulates pressure field from focused transmission within 3.7% normalized root mean square error. The resulting is then...
Distal radius fracture is one of the most common injuries presented to emergency department and can be in any age group. In young patients cause Road Traffic Accident (RTA), while old patient history fall cause. Different surgical options are available treat this injury. This study aims compare outcome volar buttress plate vs across wrist external fixator for Arbeitsgemeinschaft für Osteosynthesefragen (AO) type C2/C3 distal radius.A retrospective comparative between July 2020 June 2021 at...