The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Diverging wave imaging is the most prominent transmit sequence in fast cardiac imaging. Indeed, as this type of ultrasound transmit insonifies a significant part of the region of interest at once, less transmit events are required to reconstruct an entire image leading to an improved time resolution. However, the flipside of this approach is that image quality reduces in terms of spatial resolution,...
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...
The development of ultrafast ultrasound imaging brings great opportunities to improve imaging technologies such as shear wave elastography and ultrafast Doppler imaging. In ultrafast imaging, there are trade-offs among image signal-to-noise ratio (SNR), resolution, and the high frame rate. Multiplane wave (MW) imaging is proposed to solve this tradeoff by encoding multiple plane waves with positive/negative...
In the present study, chirp coded pulses are investigated with respect to high frequency imaging. These pulses were used drive broadband polymer transducers assembled from an adhesive-free layer-be-layer deposition method. The image quality obtained from using a long chirp coded pulse was compared with images generated from shorter pulses. This includes the Ricker wavelet and the square pulse most...
The Delay-Multiply-And-Sum (DMAS) beamformer has recently been presented in the context of medical ultrasound image formation. Images obtained with the DMAS beamformer present improved contrast resolution and noise rejection when compared to images obtained with the standard Delay-And-Sum (DAS) beamformer. We study here the signal statistics for a homogeneous medium using both the DAS and DMAS beamformers...
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...
Plane-wave imaging plays a highly significant role o wing to the special demand for high frame rate, however, its po or image quality hinders its application in ultrasound industrie s. Many scholars have attempted to give a wide variety of soluti ons to improve the image quality, however, each of them has li mitations or compromises. In this study, we improve the spatio -temporally smoothed factor...
Stroke is commonly caused by thromboembolic events originating from a ruptured carotid plaque. Histological studies have shown that plaque rupture potential is related to plaque composition rather than degree of stenosis. The use of Acoustic Radiation Force Impulse (ARFI) ultrasound imaging has enabled assessment of carotid plaque composition and structure. In particular, a previous study has shown...
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...
For new-generation thermal power plants, off-line non-destructive testing 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 ∼600°C. Since operation temperature of new-generation thermal power plant will be ∼700°C, it...
Large and small CMUT membranes were fabricated in an interlaced fashion to create a multi-frequency array using a modified standard silicon-nitride sacrificial release process on a scale smaller than the wavelength to ensure the minimization of grating lobes. A 7 mm by 7 mm multi-frequency array with 20 elements was fabricated and wire-bonded to custom printed circuit boards (PCBs) mounted onto a...
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...
Photoacoustic imaging is often used to visualize point-like targets, including circular cross sections of small cylindrical implants like brachytherapy seeds as well as circular cross sections of metal needles. When imaging these pointlike targets in the presence of highly echogenic structures, the resulting image will suffer due to reflection artifacts which appear as true signals in the traditional...
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...
The generation of complex diffraction limited acoustic fields from a simple planar transducer is possible using cheap 3-D printable kinoforms. This approach is extremely promising for several areas of physical acoustics. However, one drawback is that the acoustic field generated from a given kinoform is fixed, limiting flexibility. In this work, multi-frequency acoustic kinoforms are investigated...
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.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.