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Key points
The vasodilatory response to reactive hyperaemia is impaired with advancing age, but it is unclear whether this is because of an altered wall shear rate (WSR) stimulus or an altered flow‐mediated dilatation (FMD) response.
Using new technology that allows detailed WSR measurement, we assessed the WSR–FMD response in healthy older people.
Our data show that older people have a markedly...
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...
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...
In a few years, ultrasound research platforms, also known as open scanners, have become a great tool for facilitating the experimental activities of ultrasound labs. An ideal platform should be easily programmed to permit the transmission of arbitrary sequences of arbitrary waveforms, the acquisition of huge amounts of raw echo-data, the visualization of the region of interest and, possibly, the real-time...
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...
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,...
Magnetomotive ultrasound (MMUS) imaging indirectly enables visualization of magnetic nanoparticles (MNPs) with ultrasound. An external time varying magnetic field displaces MNPs and thus their closest surrounding, the induced displacement is tracked in the US data and color-coded on B-mode images. However, images are currently processed offline, which is time consuming and precludes clinical use of...
The last decade has seen an extraordinary evolution of vector Doppler techniques, allowing the investigation of full 2D regions of interest (ROI). In particular, we recently proposed a method (DOI: 10.1109/ULTSYM.2016.7728428), which transmits plane waves (PWs), beamforms 8 parallel lines distributed over the ROI, and estimates the flow speed in real-time by using 16 independent sub-apertures in reception...
Conventional ultrasound (US) diagnosis of cardiovascular diseases adopts spectral Doppler methods to estimate the velocity of blood in vessels. We recently proposed a real-time method that estimates the flow speed vectors along 8 parallel lines of interest, arbitrarily distributed over the region of interest. It employs the transmission of plane waves that, however, inefficiently spreads the energy...
As compared to piezoelectric technology, MEMS technology employed for Capacitive Micromachined Ultrasonic Transducer (CMUT) fabrication provides increased compatibility with 3D packaging methods, enabling the possible development of advanced transducer-electronics multi-chip modules (MCM) for medical imaging applications. Interconnection of 2D CMUT arrays and analog front end integrated circuits (IC)...
As compared to piezoelectric technology, MEMS technology employed for Capacitive Micromachined Ultrasonic Transducer (CMUT) fabrication provides increased compatibility with 3D packaging methods, enabling the possible development of advanced transducer-electronics multi-chip modules (MCM) for medical imaging applications. In this paper, an acoustically optimized 3D packaging method for the interconnection...
Ultrasound Harmonic Imaging (HI) exploits the second harmonic component of backscattered signals generated by non-linear propagation in tissues. HI provides images with improved resolution and contrast, but with lower signal-to-noise ratio, compared to standard fundamental imaging (FI) mode. The Filtered-Delay Multiply And Sum (F-DMAS) non-linear beamformer (doi: 10.1109/TMI.2014.2371235) was recently...
There is an increasing interest for sparse 2D arrays as an alternative to full gridded arrays used in commercial systems. This work presents an effective and straightforward solution to perform 3D ultrasound imaging by driving a reduced number of elements of a commercial 2D array. The selection of 128, 192 or 256 elements out of a 32×32 array was based on simulated annealing to produce radiated beam...
Enabling detection of nanoparticles with ultrasound can open new application avenues for the ultrasound technique. Magnetomotive ultrasound (MMUS) is a technique under development which indirectly visualizes magnetic nanoparticles. In MMUS, an external time-varying magnetic field acts to displace the nanoparticles, and thus their closest surrounding. This induced displacement is subsequently detected...
Recent advancements of ultrasound vector Doppler techniques have boosted the investigation of 2D regions of interest (ROIs). Several methods were proposed, but their implementation on commercial systems is still limited by technical difficulties. First, the investigation of wide ROIs at high frame rate requires the transmission of plane waves and parallel beamforming in reception. Furthermore, the...
In parallel with the increasing interest for 3D ultrasound imaging, different design techniques have been investigated to find the best configurations of 2D sparse arrays to scan an entire volume of interest [Trucco, IEEE UFFC99], [Diarra, IEEE TBME13]. In particular, we recently addressed the issue of driving a full 2D array of 1024 elements with a reduced number of channels (128, 192 or 256): the...
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 practical real-time implementation. In particular, the Filtered-Delay Multiply and Sum (F-DMAS) beamformer, which adds the computation of signed...
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