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Ultrafast 3D Doppler imaging can provide volumetric high frame rate and high resolution mapping of the vascular anatomy and function [1]. Current approach relies on the use of matrix arrays connected to high count of electronics channel which remain complex and costly. Row Column Addressed (RCA) approaches have been proposed as a low complexity alternative to matrix probe for imaging of blood flows...
The pulse-echo method based on transmission of an ultrasonic pulse and time-of-flight determination of a reflected echo is one of the typical methods of ultrasonic distance measurement. To improve the SNR of the reflected echo, pulse compression using an M-sequence is employed in the pulseecho method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect The Doppler-shifted...
Echocardiography is the most used modality for the evaluation of cardiac function. To obtain a time-resolved volumetric quantification of cardiac motion, ultrafast 3-D imaging is required. Ultrafast ultrasound imaging with diverging waves has demonstrated its potential for clinical 2-D echocardiography. It has been shown that MoCo (motion compensation) strategies based on a triangle transmit arrangement...
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....
Transcranial Doppler Ultrasound (TCD) is one of the techniques that have been used for stroke diagnosis. This paper compares the potential of three aperiodic sparse array configurations: random array; sunflower spiral array; and log spiral array for application to TCD. To cover the full temporal window, a 30mm diameter circular aperture is selected, with a 2MHz operating frequency to match current...
Vector Doppler techniques are ready to substitute the standard Doppler methods currently employed in clinical blood velocity investigations. However, like in classic Pulse-Wave modes, the maximum detectable velocity is related to the Pulse Repetition Frequency (PRF), which is limited by the maximum depth and/or by hardware constraints. Unfortunately, the blood velocity, e.g. in stenotic vessels, can...
Robust detection of the smallest circulating cerebral microemboli is an efficient way of preventing cerebrovascular accidents (CVA). Transcranial Doppler ultrasound is widely considered as the most convenient system for the detection of microemboli. Standard detection used in commercial device is achieved through the whole Doppler energy spectrum where constant empirical thresholds are implemented...
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,...
Tissue Doppler Imaging (TDI) is an excellent tool for early detection of myocardial dysfunction, as well as for prognosis and follow-up of the myocardial function after surgical treatment. However, since it exploits the same principles of color flow imaging, TDI requires to balance frame rate with field of view. A novel TDI technique based on multiline transmission (MLT), i.e. the simultaneous transmission...
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...
Tissue Doppler Imaging (TDI) is an excellent tool for early detection of myocardial dysfunction, as well as for prognosis and follow-up of myocardial function after surgical treatment. However, since it exploits the same principles of color flow imaging, TDI requires to balance frame rate with field of view. A novel TDI technique, based on multi-line transmission and multi-line acquisition, was shown...
While tissue-mimicking phantoms have been useful in the validation of ultrasonic equipment and image processing techniques, they are often restricted to simple vascular geometries due to limitations in fabrication techniques. To address this need, a novel technique has been employed to fabricate 3D-printed photo-curable poly(ethylene glycol) (PEG) hydrogel constructs containing complex, small-scale...
Streaming velocity mainly depends on the intensity and absorption of ultrasound in the media. For high frequencies exceeding 20 MHz the speed of streaming in blood is also affected by scattering effects on the blood cells and contrast agent microbubbles. According to theoretical calculations, 12.2 % increase in streaming velocity for 1 g/l starch concentration rise should be expected. The theory has...
Contrast-enhanced ultrasound (CEUS) permits quantification and monitoring of tumor vascular changes in response to anti-angiogenic treatment with the goal of informing targeted therapy. Conventional mean-intensity-based CEUS analysis discounts additional information that may be available from the first-order speckle statistics in a CEUS image. We demonstrate that our compound speckle model for analysis...
Photoacoustic (PA) imaging has been proposed for cancer treatment monitoring. Tumor oxygen saturation (sO2) should in principle be related to vascular parameters such as blood flow. In this work, in-vivo PA estimates of sO2 were compared to power Doppler (pD) measures of vascularity hours after the administration of microbubbles (MB), radiation therapy (XRT), individually or combined (MB-XRT).
We have studied a non-contact nondestructive acoustic inspection method to detect internal defects of concrete structures using a long range acoustic device (LRAD) and a scanning laser Doppler vibrometer (SLDV). As an actual concrete structure, we measured the concrete floor slab of a huge bridge from a distance of about 33 m. And an internal defect of concrete was detected and visualized. Next, for...
Dysfunctions on the coronary circulation can lead to adverse and severe clinical outcomes, e.g., ischemic heart failure (IHF) or coronary artery disease (CAD). The evaluation of coronary vasculature is consequently of extreme importance to the diagnosis of these conditions. However, intramyocardial coronary vasculature cannot yet be imaged in-vivo in humans with current angiography techniques or transthoracic...
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...
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