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Harmonic imaging techniques are widely used in B-mode abdominal imaging and motion tracking in shear wave elasticity imaging (SWEI) to reduce clutter and improve data quality. Harmonic imaging can be both signal-to-noise (SNR) and penetration depth (PD) limited, resulting in decreased diagnostic utility. This work evaluates B-mode harmonic imaging and SWEI harmonic tracking data quality between imaging...
Shear wave elastography is useful for quantitatively evaluating tissue elasticity by measuring the speed of a shear wave induced within the body by acoustic radiation force. We proposed a pushing-and-tracking sequence, coded push-pulse excitation to increase the signal-to-noise ratio (SNR) of the observed shear wave propagation without increasing measurement time and push-pulse amplitude1). In this...
Fast acquisition sequences enable >200Hz 2D cardiac B-mode imaging with little compromise in image quality. Fast imaging minimizes frame to frame decorrelation, enabling radiofrequency (RF)-based tracking for enhanced signal-to-noise ratio (SNR) in motion and deformation imaging. Our objective was to compare the performance and clinical usefulness of Fast RF-based Tracking (FRFT) to the established...
Non-contrast blood perfusion imaging with ultrasound is difficult due to tissue clutter caused by patient physiological and sonographer hand motion. This motion causes spectral broadening of the tissue clutter signal, which then overlaps with the perfusion signal. To address this problem, we previously introduced an adaptive frequency and amplitude demodulation scheme to reduce the bandwidth of the...
Pulse compression is a well-known technique widely used within the Non-Destructive Testing community [1]. Although pulse compression helps in increasing Signal-to-Noise ratio, the presence of side-lobes in the impulse response retrieved by its use, hampers the range resolution performance. A widely-used approach to face this problem consists in tapering the signal excitation by windowing it in time...
Recently, ultrafast Doppler techniques have been proposed for imaging brain and other slow flow targets. These techniques rely on synthetic focusing and the use of large ensemble lengths to separate slow-flow signal from the stationary clutter, but are susceptible to high acoustic and thermal noise. We have recently developed the short-lag angular coherence (SLAC) method, which suppresses the incoherent...
Synthetic aperture (SA) ultrasound imaging is a well-known technique in which RF signals for every transmit and receive element combinations is first obtained and a 2-way-focused image is synthetically formed afterwards. Despite its benefits, one of its main shortcomings is reduced penetration depth caused by low acoustic power from single element firing. To address this challenge, we propose a spatial...
Plane wave methods for ultrafast ultrasound imaging suffer from a low signal to noise ratio (SNR) and a limited field of view at greater imaging depths. Imaging using multiple focused coded beams in parallel is one strategy for high speed imaging that may improve on these limitations. However, the SNR and resolution of this strategy are degraded by interference between the beams transmitted in parallel...
Spectroscopic photoacoustic (sPA) can estimate blood oxygen saturation (SO2), which has been shown to correlate with hypoxia, and therefore could improve cancer diagnosis and treatment monitoring. However, accurate quantification of SO2 is often not straightforward as local fluence varies significantly at depth due to wavelength-dependent optical scattering and absorption. Additionally, assessing...
Photoacoustic imaging is a useful technique that is often hampered by acoustic reflections from nearby, hyperechoic ultrasound structures. Current beamforming methods are not well suited to remove these reflection artifacts. The objective of this work is to evaluate the potential of a region-based convolutional neural network (RCNN) to identify and remove reflection artifacts.
Functional Ultrasound (fUS) has shown to be a promising new neuroimaging modality that uses ultrafast plane waves to detect changes in cerebral blood flow for imaging brain activity at high spatiotemporal resolution. An existing challenge is the ultrasound penetration of skull which decreases with frequency. In the initial study (Macé et al., 2011)[1] a craniotomy was required to perform fUS. Since...
In the last 10 years the advent of high frame rate ultrasound imaging has allowed the visualization and study of mechanical wave propagation in order to estimate the elastic properties of tissue. Theses waves are detected through the estimation of motion induced by the wave propagation. Despite efficient motion estimator such as speckle tracking or Tissue Doppler Imaging (TDI), the detection of mechanical...
Wireless SAW resonant sensors have been widely used in many applications, especially in harsh environment. The sensor is detected when the echo signal spectrum processed by Fourier transform exceeds a threshold. Because of complicated noise and electromagnetic interference in wireless channel, the threshold should be adaptive to interference in order to detect the sensor accurately. However, few researches...
Ultrafast compound Doppler imaging enables high-sensitivity microvascular imaging using the large amount of spatial and temporal samples within a short acquisition time. In addition, the longer ensemble length from the ultrafast transmit strategy facilitates efficient clutter rejection filtering. However, the ultrafast microvascular imaging using plane-wave excitation, which is widely used in linear...
Deep brain stimulation (DBS) is an effective therapy for dyskinesia associated with treatments for Parkinson's disease (PD). While current surgical placement of a DBS implant depends on stereotactic coordinates with computed tomography and magnetic resonance imaging for precise localization of the electrode sites, the actual current densities produced by the DBS are not directly observed. This study...
Concrete is the most widely used material to construct critical large infrastructure systems such as dams, bridges and nuclear power plants. These concrete structures are generally subjected to various degradation mechanisms including alkali-silica reaction (ASR), freezing-thawing cycles and steel bar corrosion during their service life. Prolonged and repeated exposure to these mechanisms can result...
Off-line ultrasonic non-destructive testing (NDT) is used to inspect defects in thermal power plants. However, for new-generation thermal power plants, off-line NDT is not sufficient and long-term monitoring at high temperature is desired. In the previous study, ultrasonic transducers made by CaBi4Ti4O15 (CBT)/Pb(Zr, Ti)O3 (PZT) were investigated and maximum operation temperature was estimated as...
Ultrafast ultrasound imaging offers great opportunities to new imaging technologies such as shear wave elastography and ultrafast Doppler. Multiplane wave (MW) imaging is a new technique in which multiple positively or negatively encoded plane waves are emitted successively with short interleaved time during one transmission event (i.e. pulse-echo event), aiming at increasing the signal-to-noise ratio...
The biomechanics of the sclera can play a critical role in glaucoma diagnosis and monitoring new treatment methods. Previous studies have used strain elastography and investigated the relationship between scleral stiffness and intraocular pressure. However, applying shear wave elastography (SWE) to scleral tissue is challenging because sclera (100–1000 kPa) is significantly stiffer than normal soft...
Spatial angular compounding (SAC) with plane wave has been proposed to improve the performance of motion and strain estimation at high frame rate. A previous study shows that the accuracy of 2D estimation depends on the number of steering angles, maximum steering angle, and accuracy of axial estimation at different angles (He et al, Ultrasonics 2017). We have demonstrated (Pan et al, TUFFC 2015) that...
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