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.
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...
As the medical ultrasound signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape. Thus, their reconstruction using adaptive beamformer (BF) become indispensable in order to improve the quality of the image. Generalized Side Lobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
Color Doppler and Vector Flow imaging are ultrasound imaging modalities that are primarily used for qualitative measurements or navigation. One main challenge before these modalities can be used quantitatively in clinical applications, is that clutter suppression filters or residual clutter signal lead to bias and variance in the blood velocity estimates which varies throughout the cardiac cycle....
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...
Ultrasound imaging of blood flow in the coronary arteries is hampered by small vessel diameters and rapid myocardial motion. This combination makes clutter suppression challenging, resulting in flashing artefacts and signal dropouts. This work investigates whether high frame-rate 3D ultrasound imaging in conjunction with eigen-based clutter filtering can be used to mitigate these problems, making...
Ultrafast plane wave microvessel imaging significantly improves ultrasound Doppler sensitivity. The rich spatiotemporal plane wave data enables robust clutter filtering based on singular value decomposition (SVD). However, due to the lack of transmit focusing, plane wave microvessel imaging is very susceptible to noise. The mid-to-deep region of the microvessel image is typically saturated by noise,...
Power Doppler (PD) is the preferred technique for accessing weakly scattering blood cells with low-velocity flow. However, strong clutter decreases sensitivity of the blood signals, which degrades micro-vasculature imaging. Eigen-based filtering methods have been developed to separate the independent scattering sources using both spatial and slow-time statistics of echo data. We recently found that...
We recently introduced a spread-spectrum color Doppler imaging method that produces high-resolution, highframe-rate images without the use of compounding, thereby eliminating the tradeoffs among beam quality, frame rate, and the maximum unaliased Doppler frequency that exist for standard plane-wave imaging methods. In this manuscript, we extend the spread-spectrum method to significantly reduce tissue...
To obtain accurate blood flow velocity estimates it is important to remove the clutter signal originating from tissue. Conventionally, the clutter signal has been separated from the blood signal based on the difference of their spectral frequencies. However, this approach is not enough for obtaining vector flow measurements, since the spectra overlaps at high beam-to-flow angles. In this work a distinct...
Off-axis clutter is a significant cause of image degradation in ultrasound. Adaptive weighting methods based on signal coherence, and adaptive beamforming approaches based on signal direction of arrival, have been proposed to address this problem. Clutter removal is also an important component of pre-processing prior to flow estimation, and adaptive clutter filters based on singular value decomposition...
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...
Off-axis clutter is a significant cause of image degradation in ultrasound. We propose an adaptive approach for clutter reduction based on the principle that off-axis signals show as relatively high spatial frequencies in the per-channel data. For each pixel, an M∗N per-channel data matrix is extracte from the aligned data received from different observations of that pixel (N = number of channels,...
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...
Eigen-filters with attenuation response adapted to clutter statistics in color flow imaging (CFI) have shown improved flow detection sensitivity in the presence of tissue motion. However, its practical adoption for routine use in clinical scanners is hindered by the long processing time required to derive the eigen-components. In this work, we seek to overcome this issue by formulating a parallel-computing...
This study used 3D nonlinear ultrasound simulations to identify the sources of error when estimating the in situ Peak Rarefaction Pressure (PRP) as compared to linear derating in the context of the Mechanical Index (MI) measurement. We found that varying material nonlinearity within the range of soft tissue (5 < B/A < 10) does not affect PRP estimation. We also found that for large apertures...
Signal from tissue will always be present within the lumen of vessels or in the heart. To image blood flow, this clutter needs to be suppressed sufficiently for the weaker blood signal to appear. As the magnitude and direction both of surrounding tissue and blood flow varies throughout the cardiac cycle, non-adaptive clutter filters will inevitably either yield dropouts or a significant tissue velocity...
Keloid is a kind of benign dermal lesion that caused by the collagen deposition and growth beyond the boundaries of the original wound margin. Many studies have reported that the density of blood vessel within keloid is higher than normal skin. Therefore, the density of blood vessel is the potential determinant for understanding the pathogenesis of keloids. However, to date, the techniques for extracting...
The beamformer plays a crucial role in increasing the quality of images acquired with an ultrasound imaging system. Numerous beamforming methods have been introduced, evaluated and reported with substantial improvement in resolution and contrast, compared with conventional delay-and-sum (DAS) beamforming. Better beamforming should not only provide high quality images, but the image should also be...
In medical ultrasound B-mode imaging, by increasing the image contrast, spatial and temporal resolution, it will help to improve the diagnostic and decision making process. Previously the unsharp masking (UM) techniques have been successfully implemented for digital image processing as edge enhancement techniques. However, the outcomes of the method are limited and influenced by the image formats...
Singular value decomposition (SVD)-based clutter filtering has demonstrated superior clutter rejection performance in the emerging field of ultrasound microvessel imaging. To alleviate the computational burden of SVD, here we present a fast and robust clutter filter using randomized SVD (rSVD) and randomized spatial downsampling (rSD). rSVD accelerates SVD by approximating and removing the first k-order...
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.