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A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. Since the transmit and receive 1-D arrays are orthogonal to each other, only one-way focusing is possible in each transmit or receive plane. By transmitting with row elements and receiving the echoes through column elements, a rectilinear volume in front of the array can be beamformed. This study suggests to use...
In the last decade the number of beamforming methods has exploded. Many innovative ideas have been proposed, but we lack the tools to compare the different techniques efficiently. The PICMUS challenge (IUS 2016, Tours) was a pioneering step that made clear that two things are required to establish a fair comparison: a common data format, and a body of methods to process that data.
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...
3D Ultrasound systems present several technical challenges, particularly the large number of elements in a 2D array, high electrical impedance, and image acquisition time. Crossed electrode arrays address some of these issues, especially the huge reduction in number of elements. However, creating a two-way focused 3D image in real-time is difficult with these arrays because azimuth and elevation dimensions...
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...
A hybrid beamforming approach combining the strengths of diverging wave compounding (DWC) and multi-line-transmit beamforming (MLT) (i.e., multi-plane-transmit, MPT) was previously proposed by our labs for 3D imaging [1]. Although we demonstrated this approach to be superior to 3D DWC and 3D MLT, we did not account for artifacts induced by motion. The aim of this study was therefore to propose a motion...
Currently there are two main categories of adaptive beamforming applied to medical ultrasound imaging: minimum-variance-related beamforming(MV) and coherence-factor-related beamforming (CF), both of which have been applied to suppress side/granting lobe and clutter for plane-wave imaging. Unfortunately, due to low SNR/SINR, the resulting images may suffer from deficiencies: deteriorated speckle pattern,...
3D diverging wave compounding (DWC) was recently demonstrated to be capable of providing high-frame-rate imaging, but at the risk of introducing motion artifacts. As an alternative, a hybrid beamforming approach combining the features of DWC and multi-line-transmit (MLT) beamforming was proposed (i.e., multi-plane-transmit, MPT), showing some superiority when compared with 3D DWC [1]. However, in...
Transcranial Doppler Ultrasound (TCD) is a non-invasive approach that has been used in both diagnosis and therapy of stroke. However, current TCD devices are highly operator dependent and a 2D sparse array transducer can help reduce the operator dependency with its improved imaging and focusing capabilities. This paper compares the potential of three aperiodic sparse array configurations: random array;...
The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment. Among several techniques proposed for these purposes, many employ either a thresholding process or a peak search process. The thresholding process uses the intensity...
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...
Ultrafast imaging based on coherent plane-wave compounding improves image quality and allows for much faster acquisition. This method, however, is limited by severe computational loads stemming from delay-and-sum beamforming (DAS BF) that creates a major bottleneck for real-time implementation. Spatial-temporal (ST) processing yields the entire frame without a need for DAS BF of each image line. First,...
A dual beam vector Doppler method was proposed (DOI: 10.1016/j.ultrasmedbio.2009.11.004), in which one beam is continuously tracked perpendicular to the flow direction, and the second one is used to perform velocity measurements with known Doppler angle. Since two consecutive transmission (TX) and reception (RX) events (one for each beam) are needed, the effective Doppler pulse repetition frequency...
Ultrafast imaging based on plane wave (PW) / diverging wave (DW) is an active area of research in ultrasound acquisitions because of its capacity of reaching high frame rate. Beamforming of received echoes in Fourier domain provides comparable image quality but lower computational complexity with respect to the conventional DAS approach [Zhang et al., UFFC, 2016]. However, the current state-of-the-art...
Multi-planar reformatting (MPR) in 3-D ultrasound imaging provides the viewer with planar cross-sectional images extracted from the 3-D data. To produce the MPR imaging from the acquired 3-D volume data, the 3-D scan conversion (SC), which transforms the acquired data in the 3-D polar coordinate system to the 3-D Cartesian coordinate system, is performed for display. Direct 3-D SC and separable 3-D...
Multi-line transmission (MLT) is a recently developed method for high frame rate cardiac ultrasound imaging. However, a potential pitfall of this method is the presence of artifacts due to cross-talk between the MLT beams. Low complexity adaptive beamforming (LCA) is a high resolution adaptive beamforming method that chooses a weighting function out of a predefined set of apodization functions assembled...
Most commercially available ultrasound imaging systems currently implement the delay and sum (DAS) beamforming. Alternative beamformers have been presented, offering higher performance at the expense of computational complexity, which has so far limited their actual implementation. In particular, the Filtered-Delay Multiply and Sum (F-DMAS) beamformer, which adds the computation of signed square roots,...
Syntethic Aperture Sequential Beamforming (SASB) has been proven to achieve a better resolution and penetration depth than Dynamic Receive Focusing (DRF). SASB has also shown great potential for use in a handheld device. SASB with a low F# (<= 0.5) has shown even better resolution at the cost of high grating lobes, which cause loss of contrast in the final image. The hypothesis is that Spatial...
Given the limited spatiotemporal resolution of 3D echocardiography, simultaneous assessment of all ventricular myocardial segments can clinically be performed using multi-plane acquisitions (MP) — i.e. biplane (BP) or triplane (TP). However, the wider field of view of MP impairs spatiotemporal resolution, thus hindering the performance of e.g. speckle tracking. Multi Line Transmit (MLT) beam forming...
A challenge in the clinical application of shear wave elastography is the level of measurement variance or noise compared to clinically significant changes in shear wave speed. For instance, liver fibrosis staging is challenged by the relatively high variance of shear wave velocity estimates in comparison to the modulus difference between early (F1-F3) fibrosis stages. Recent work has shown that ultrasound...
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