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Higher microvascular density with tortuous and irregular vessels are hallmarks of cancer vasculature. These alterations can be captured by contrast ultrasound dispersion imaging (CUDI) and acoustic angiography (AA) at different scales: CUDI aims at obtaining an implicit measure of structural alteration by determining the dispersion kinetics of contrast agents. At a smaller scale, AA images the vascular...
Treatment of renal cell carcinoma (RCC) using ablation techniques is becoming increasingly common as a means for preserving renal function in poor surgical candidates. Despite concerns related to renal insufficiency, which is common in patients with renal disease, the current standard for imaging surveillance following ablation remains contrast-enhanced CT or MRI. Contrast-enhanced ultrasound (CEUS)...
Liquids density measurements are highly required in both research and industrial applications, from process control in petrochemical industry to product monitoring in food processing. Commercial devices are often expensive or unwieldy; therefore, in a previous work, a cheap and handy resonant sensor, based on a piezoelectric bimorph, was introduced. The operating principle is based on the variation...
Subharmonic emission from gas-filled microbubbles is of interest because it can improve the sensitivity of contrast-enhanced ultrasound imaging. However, subharmonic emission exhibits a delay between the insonification and its generation. In this study, we investigated the impact of applied acoustic pressure and microbubbles gas composition on the time dependent emission of subharmonics of five phospholipid...
Multi-element transducers enabling novel cost-effective fabrication of imaging arrays for medical applications have been presented earlier. Due to favorable low lateral coupling of the printed PZT, the elements can be defined by the top electrode pattern, leading to a kerf-less design with low cross-talk between the elements. The linear arrays have proved to be compatible with a commercial ultrasonic...
Wireless Sensor Networks (WSNs) technology is considered an excellent compromise for supporting monitoring applications on old trains operated by railway systems around the world. Although WSNs are optimized for energy management with regards to sensor nodes and communication protocols, their lifetimes remain limited by battery capacity. Deployment of new sensors or replacement of empty batteries...
Growing demand for bedside medical imaging with increased ease of access has motivated development of more cost-effective ultrasound systems. Multimodal imaging techniques such as Microwave-induced Thermoacoustic (TA) tomography can simplify system design by providing enhanced imaging contrast. The introduction of continuous-wave (CW) TA has made this technique more cost-effective by reducing device...
Drilled shaft is an important substructure foundation in building construction. A drilled shaft needs to be placed precisely in high accuracy and satisfy the diameter precision requirement. In order to measure the verticality and the diameter of a shaft, the M-superimposed Gaussian Echoes Model (GEM) is used to estimate the time of flight (TOF) of ultrasound. Compared to the conventional threshold...
Ultrasonic guided leaky Lamb waves are widely used for nondestructive evaluation of layered, fluid-loaded, elastic structures. When used in fluid-immersed structures with a frequency-thickness product in the range of 1 to 3 MHz·mm, fundamental Lamb modes can be selectively excited by a suitable combination of broadband pulse and oblique incidence angle. Lamb modes exhibit dispersion, and an intersection...
Residual stress caused by Foreign object damage(FOD) plays an important role in predicting the rate of crack initiation and propagation, which will lead to the failure of aero-engine blades. At present, many studies focus on the measurements of residual stress on flat surface by ultrasonic testing methods, which are not fit for curved surface. To evaluate the local residual stress on curved aero-engine...
A novel type of hybrid resonator based on BAW transformation into SAW in a ridged layered structure was fabricated and characterized. Bulk waves are excited by micromachined piezoelectric AlScN pillars located on the non-piezoelectric Si and sapphire substrates. The effect of film thickness and etching depth on the electromechanical coupling and velocity dispersion were calculated by finite element...
Peculiarities of anisotropic light diffraction in a periodic acoustic field excited by a phased array transducer with the phase shift by π are studied theoretically. Possibilities of this system application for control of unpolarized optical radiation are discussed.
In this research, piezoelectric micromachined ultrasonic transducer (pMUT) array was used for stimulation of mechanosensitive channel of HEK293T cells. The fabricated pMUT array was made by microelectromechanical system (MEMS) technology such as photo process, etching, sputtering, and sol-gel method. The resonance frequency and acoustic positive peak pressure were 2.07 MHz and 3.94 kPa, respectively...
The advent of ultrafast ultrasound imaging proved beneficial for capturing transient flow patterns which was never readily achievable before. Velocity estimation methods based on 2D block-matching outperform Doppler based methods by offering higher frame rate with the cost of increased uncertainty in presence of out-of-plane motion as a result of turbulent flow.
Prototypes of a PZT-based ultrasound needle-actuating device have shown the ability to reduce needle penetration force and enhance needle visibility during needle insertion for tissue biopsy and regional anaesthesia. Further demand for smaller devices and the need for high performance transducers has motivated the investigation of a different configuration of needle actuation transducer, utilizing...
Stroke is commonly caused by thromboembolic events originating from vulnerable atherosclerotic plaque in the carotid vasculature. The purpose of this study was to evaluate the ability of acoustic radiation force impulse (ARFI) imaging, a noninvasive elastography imaging technique, to assess the composition of carotid artery plaques using histologic examination as the gold standard. Twenty-five patients...
In the last decade, photoacoustic techniques have been used extensively to acquire label free oxygen saturation (SO2) images of blood vessels both in vivo and ex vivo. Recent advances in photoacoustic microscopy have pushed the in vivo resolution limit of photoacoustic SO2 mapping to that of a single cell. In this work, we use a photoacoustic microscope equipped with a 0.9 GHz ultrasound transducer...
Improving the ultrasound image contrast ratio (CR) and contrast to noise ratio (CNR) has many clinical advantages. Breast cancer detection is one example. Anechoic cysts which fill with clutter noise can be easily misinterpreted and classified as malignant lesions instead of benign. Beamforming techniques contribute to off-axis side lobes and clutter. These two side effects inherent in beamforming...
Plane-wave (PW) imaging achieves narrow lateral beam width using boxcar apodization but at the expense of high side-lobes, which degrade the performance of vascular elastography. The goal of this study was to investigate various imaging techniques for improving the performance of PW imaging. More specifically, we evaluated the quality of elastograms produced with: (1) fixed apodization beamforming...
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