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Catheter-delivered ultrasound has been widely utilized for intravascular therapies such as thrombolysis, drug delivery, and plaque removal. High amplitude pressure is required for cavitation induced-microstreaming, which is considered main factor for therapeutic efficiency. Precise spatiotemporal control of insonation is important to relieve concerns on ultrasound-induced damaging of surrounding healthy...
Phase-Contrast MRI (PC-MRI) is capable of 4D flow imaging and considered a gold standard for blood velocity measurements, but is currently cumbersome and time consuming. Ultrasound is bedside applicable, but is typically limited to a 1D velocity measurement. In this work we measure 3D blood flow velocity fields using high frame rate 3D ultrasound blood speckle tracking (BST) without contrast and compare...
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...
Lateral resolution and therefore image quality in ultrasound is tied to aperture size. While this relationship is understood in ideal imaging conditions, the utility of a large aperture in the presence of clutter is unknown. This problem is particularly relevant to abdominal imaging where thick tissue layers and deep targets create a challenging imaging environment. Previous studies have focused on...
Barium titanate (BaTiO3) is a well-known ferroelectric material which was intensively studied in the early 50's. Indeed, BaTiO3 has been rapidly substituted by lead zirconate titanate (PZT) materials, which exhibit higher piezoelectric properties. However, PZT materials contain lead and their increasing success is associated to health and environmental problems. Therefore tremendous efforts have been...
Radiofrequency and microwave ablation procedures are commonly used for treating hepatocellular carcinoma in patients that are not candidates for surgical resection. Ablation is a minimally invasive procedure which involves insertion of an ablation needle (electrode) into the tumor which produces localized heating to kill the surrounding cancerous cells. Ultrasound can be a valuable tool for real-time...
Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN), which makes it an upcoming piezoelectric material for next generation RF filters, sensors, actuators and energy harvesting devices. In this work, process-microstructure-property relationships of such ASN films containing up to 40 at% Sc were investigated. Hereby, the influence...
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...
Focused ultrasound can effectively treat tumors by thermal ablation, but treatment times associated with mechanical or electronic scanning of single foci can be prohibitively long. Maximizing the energy efficiency of focused ultrasound ablation may decrease treatment time while also decreasing sensitivity to perfusion. One proposed approach [Mast et al., US Patent 9132287, 2015] creates multiple foci...
Novel methods for determining rupture risk in abdominal aortic aneurysms (AAAs) have focused primarily on CT-based wall stress analysis using finite element models (FEMs). Recent studies have demonstrated ultrasound (US) based FEM, and the possibility of using inverse FEM analysis: matching displacements between the models and US to find patient specific aortic stiffness. This requires an accurate...
Fast cardiac imaging requires a reduction of the number of transmit events. This is typically achieved through multi-line-transmission (MLT) and/or multi-line-acquisition (MLA) techniques. However, restricting the field-of-view (FOV) to the anatomically relevant domain, e.g. the myocardium, can increase frame rate (FR) further. Using computer simulations, we previously proposed an anatomical scan...
The backbone of modern infrastructure is concrete, yet modern ultrasonic characterization techniques often fail to be accurate and repeatable. Recent advances in low frequency ultrasonic array hardware have generated a new potential for improved material and structural characterization of concrete. However, the analysis and interpretation associated with the new array based hardware is more difficult...
Histotripsy with ultrasound is an emerging noninvasive therapeutic modality that uses cavitation to precisely destroy diseased soft tissue. Accurate simulations of histotripsy are needed for treatment planning and device design. These simulations are performed in the time-domain, span hundreds of wavelengths, and must handle strong shocks and discontinuities between materials, such as the brain and...
Quantum Spin Hall Effects(QSHE) underpins most of the design in topological insulators. The intrinsic spin-0 of the phononics, yet, continue to be the main barrier in designing acoustic topological insulators. Previous research proposed a solution using external fields such as clockwise and counter-clockwise circulating fluids to create artificial acoustic spin-1/2 states. Most recently, several papers...
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...
Many high-end power machines demand greater bearing performance in terms of running speed, precision, reliability, longevity, noise reduction, etc. An ultrasonic bearing based on Near-Field Acoustic Levitation (NFAL) effect is a kind of emerging noncontact gas bearing. Due to its self-aligning capability, the ultrasonic bearing can steadily run at a high speed — tens of thousands of revolutions per...
The production and the characterization of high-quality ScAlN films, whose electromechanical coupling and bandwidth are larger than those of traditional AlN films, is attracting interest to develop the next generation of bulk acoustic wave resonators for telecommunication devices operating above 5 GHz.
Research on Deep Learning algorithms has progressed rapidly in recent years. Since the inception of deep learning, numerous architectures have been proposed for various applications targeting pattern recognition, image, audio and information analysis. For example, often audio signal classifications use variations of Deep Belief Networks (DBN), while a Deep Neural Network (DNN) called AlexNet is widely...
The study of beampatterns and their use in imaging systems has a long history in optics and acoustics. In addition, the topic of limited diffraction fields has received increasing attention since the characterization of Bessel beams in optics. The class of “localized waves” include X-beams, Airy beams, and related monochromatic and broadband solutions.
Cardiac pathologies are often characterized by important changes of myocardial properties such as the myocardial stiffness, re-organization of muscle fiber structure, modification of the microcirculation flow, all of which remain challenging to assess quantitatively and non-invasively in vivo. Over the last decade, the advent of software-based systems has enabled the implementation of ultrafast ultrasound...
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