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Magnetomotive ultrasound imaging is the identification of tissue in which magnetic nanoparticle tracers are present by detecting a magnetically induced motion. Although the nanoparticles have a magnetization that depends nonlinearly on the external magnetic field, this has often been neglected and the presence of resulting higher harmonics in the detected motion has not been reported yet. Here, the

Pulse wave velocity (PWV) is the most important index for quantifying the elasticity of an artery. The accurate estimation of the local PWV is of great relevance to the early diagnosis and effective prevention of arterial stiffness. In ultrasonic transit time-based local PWV estimation, the locations of time fiduciary point (TFPs) in the upstrokes of the propagating pulse waves are inconsistent because

Abdominal imaging suffers from a particularly difficult acoustic environment - targets are located deep and overlying tissue layers with varying properties generate acoustic clutter. Increasing array size can overcome the penetration and lateral resolution problems in ideal conditions, but how the impact of clutter scales with increasing array extent is unknown and may limit the benefits in vivo. Previous

The use of mechanically-representative phantoms is important for experimental validation in ultrasound imaging, elastography and image registration. This paper proposes a model to predict the elastic modulus of a soft tissue-mimicking phantom based on two very easily controllable parameters: gelatin concentration and refrigeration duration. The model has been validated on small and large-scale phantoms:

Various modulation approaches, such as amplitude and frequency modulations, have been applied widely to modify the acoustic field and improve the performance of ultrasound imaging and therapy. However, phase modulation (PM) has not been investigated extensively in the ultrasound applications, especially at a long-pulse duration. In this study, the effects of PM on the acoustic field were investigated

Patients with unresectable or nonablatable tumors are difficult to cure, but nanotherapy combining targeted nanoparticles has many severe side effects due to the toxicities of anticancer drugs. We found that acoustic energy can produce a local region with high concentration from a low concentration suspended liquid of nano-SiO 2 particles at 2.5 MHz. Our calculated results show that the main reason

In the last 30 years, the contrast-to-noise ratio (CNR) has been used to estimate the contrast and lesion detectability in ultrasound images. Recent studies have shown that the CNR cannot be used with modern beamformers, as dynamic range alterations can produce arbitrarily high CNR values with no real effect on the probability of lesion detection. We generalize the definition of CNR based on the overlap

Intravascular acoustic radiation force impulse (IV-ARFI) imaging has the potential to identify vulnerable atherosclerotic plaques and improve clinical treatment decisions and outcomes for patients with coronary heart disease. Our long-term goal is to develop a thin, flexible catheter probe that does not require mechanical rotation to achieve high-resolution, real-time IV-ARFI imaging. In this work

In this study, a phase-cancelled backing layer for ultrasound linear array transducer is presented. The proposed backing layer is composed of multiple blocks operated by phase inversion technique. Inside of the proposed backing layer, the phase of the reflected signal can be cancelled by adjusting acoustic impedance, piezoelectric layer contact area, and thickness of each block constituting the backing

The present work is an extension of a model previously developed by our group to simulate the electroacoustic response of CMUT-based (Capacitive Micromachined Ultrasonic Transducers) linear arrays acoustically loaded by a fluid medium. The goal is to introduce the viscoelasticity effects of the propagation medium into the modeling. These effects are mainly due to the passivation layer used to protect

This article presents a resonant cavity-based array design for piezoelectric micromachined ultrasonic transducers (PMUTs). The cavity depth is designed to ensure that its open end achieves a considerably smaller acoustic impedance than the surrounding PMUT cells. The interference acoustic wave generated between every two adjacent PMUT cells at the near surface of the array will take an easy path down

A linear piezoelectric micromachined ultrasound transducer (PMUT) array was fabricated and integrated into a device for photoacoustic imaging (PAI) of tissue phantoms. The PMUT contained 65 array elements, with each element having 60 diaphragms of $60~\mu \text{m}$ diameter and $75~\mu \text{m}$ pitch. A lead zirconate titanate (PZT) thin film was used as the piezoelectric layer. The in-air vibration

Intravascular ultrasound (IVUS) is one of the most useful tools available today to assist intravascular stenting procedures. Having higher resolution is very important for helping doctors to evaluate the nature of atherosclerotic plaques. The current commercial IVUS systems have a spatial resolution of 70– $200~\mu \text{m}$ in the axial direction and 200– $400~\mu \text{m}$ in the lateral direction

Additive manufacture has been heralded as a disruptive technology with the potential to revolutionise manufacturing and transform how products are consumed. Within the power ultrasonic and sonar transducer domain, the capability of additive manufacture technologies to generate highly complex geometries could facilitate a step change in device performance, yet the employment of metallic additive manufactured

Magnetic hysteresis properties are sensitive to stress in ferromagnetic materials. This suggests that magnetic measurements are a potential method to evaluate residual stress in steel products. Nevertheless, nondestructive inspection of residual stress by using magnetic properties has been limited, because bulk properties over the entire sample are usually obtained in conventional hysteresis curve

Nondestructive testing for identifying defects on the surface of metal materials is important for industries and infrastructures. The Rayleigh wave is widely used for detecting these surface defects. For replacing piezoelectric transducers with electromagnetic acoustic transducers (EMATs) for the surface inspection of metal materials, this article proposes a new magnet and coil combination consisting

This article presents the design and testing of a novel two-directional (2-D) piezoelectric stack-based energy harvester for capturing the mechanical energy from the human footstep. The uniqueness of the harvester lies in the fact that the energy of 2-D excitation is scavenged by a single piezoelectric stack transducer, which can reduce the loss of harvestable energy. The harvester is constructed by

We experimentally demonstrate the dynamical tuning of the acoustic field in a surface acoustic wave (SAW) cavity defined by a periodic arrangement of metal stripes on LiNbO3 substrate. Applying a DC voltage to the ends of the metal grid results in a temperature rise due to resistive heating that changes the frequency response of the device up to 0.3%, which can be used to control the acoustic transmission

Lamb waves propagating in piezoelectric plate covered by thin film electrodes with arbitrary conductivity are investigated. The structure consists of three parts, piezoelectric plate, top and bottom thin films with arbitrary conductivities and top and bottom free space. The governing equations in each parts are first solved respectively, and then continuous conditions are used to form the propagating

A novel piezoelectric XY platform driven by a single actuator was presented for large travel range and compact structure. The actuator operated at the inertial mechanism and moved the output platform step-by-step. A dynamic model of the piezoelectric actuator was established based on the Timoshenko beam theory and Galerkin procedure, which was used to aid the structure design. The dynamic model of

We report a high-performance pulsed optically pumped (POP) Rb clock based on a novel magnetron-type microwave cavity. The cavity has a volume of 30 mL, enabling a highly homogenous microwave field distribution. With the laser frequency tuning to the ground-state hyperfine level F=2 of D2 line, we observe a Ramsey fringe contrast of 52% in terms of optical absorption detection. The resultant shot noise

Here, we report the characteristics of zero-bias capacitive micromachined ultrasonic transducers (CMUT) in various aspects, considering the transmission and reception sensitivity and evaluation of the long-term stability with AC transmission in immersion. The main idea of the zero-bias CMUT implementation is that the charge is injected by the dielectric charging effects in an insulation layer in the

A novel quartz crystal resonator (QCR) sensor with a printed-on-crystal conductive coil, named sensor coil, is presented. The sensor coil electromagnetically coupled to an external readout coil allow to perform contactless interrogation of the QCR working as a stand-alone sensor unit. A frequency-domain readout technique is adopted that allows dual-harmonic operation by detecting the QCR frequencies

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Ultrasound is now a clinically accepted modality in the management of osteoporosis. The most common commercial clinical devices assess fracture risk from measurements of attenuation and sound speed in cancellous bone. This review discusses fundamental mechanisms underlying the interaction between ultrasound and cancellous bone. Because of its two-phase structure (mineralized trabecular network embedded

Ultrasound shear wave elastography (SWE) is an increasingly used noninvasive modality for quantitative evaluation of tissue mechanical properties. SWE typically uses an acoustic radiation force to produce laterally propagating shear waves that are tracked in the spatial and temporal domains, in order to obtain the wave velocity. One of the ways to study the viscoelasticity is through studying the shear

Conventional ultrasound imaging probes typically comprise finite-sized arrays of periodically spaced transducer elements which, in the case of phased arrays, can result in severe grating and sidelobe artifacts. Whereas side lobes can be effectively suppressed through amplitude apodization ("AmpA"), grating lobes arising from periodicity in transducer placement can only be suppressed by decreasing the

Polyvinyl chloride plastisol (PVCP) has been increasingly used as a phantom material for photoacoustic and ultrasound imaging. As one of the most useful polymeric materials for industrial applications, its mechanical properties and behavior are well-known. Although the acoustic and optical properties of several formulations have previously been investigated, it is still unknown how these are affected

An algorithm was developed for the correction of ring artifacts in phase-insensitive ultrasound computed tomography attenuation images. Differences in the measurement sensitivity between the ultrasound transducer array elements cause discontinuities in the sinogram which manifest as rings and arcs in the reconstructed image. The magnitudes of the discontinuities are potentially time-varying and dependent

Fast and precise noninvasive evaluation of tissue mechanical properties is of high importance in ultrasound shear wave elastography. In this study, we present an updated, faster version of the local phase velocity-based imaging (LPVI) method used to create images of local phase velocity in soft tissues. The updated LPVI implementation uses 1-D Fourier transforms in spatial dimensions separately in

A 3-D super-resolution (SR) pipeline based on data from a row-column (RC) array is presented. The 3-MHz RC array contains 62 rows and 62 columns with a half wavelength pitch. A synthetic aperture (SA) pulse inversion sequence with 32 positive and 32 negative row emissions is used for acquiring volumetric data using the SARUS research ultrasound scanner. Data received on the 62 columns are beamformed

In conventional focused beamforming (CFB), there is a known tradeoff between the active aperture size of the ultrasound transducer array and the resulting image quality. Increasing the size of the active aperture leads to an increase in the image quality of the ultrasound system at the expense of increased system cost. An alternate approach is to get rid of the requirement of having consecutive active

The measurement of cardiac and aortic pressures enables diagnostic insight into cardiac contractility and stiffness. However, these pressures are currently assessed invasively using pressure catheters. It may be possible to estimate these pressures less invasively by applying microbubble ultrasound contrast agents as pressure sensors. The aim of this study was to investigate the subharmonic response

Most bone loss during the development of osteoporosis occurs in cortical bone at the peripheral skeleton. Decreased cortical thickness (Ct.Th) and the prevalence of large pores at the tibia are associated with reduced bone strength at the hip. Ct.Th and cortical sound velocity, i.e., a surrogate marker for changes of cortical porosity (Ct.Po), are key biomarkers for the identification of patients at

Three-dimensional (3-D) ultrasound elastography can provide 3-D tissue stiffness information that may be used during clinical diagnoses. In the framework of strain elastography, motion tracking plays an important role. In this study, an improved 3-D region-growing motion tracking (RGMT) algorithm based on a concept of exterior boundary points was developed. In principle, the proposed method first determines

Radial modulation imaging improves the detection of microbubbles at high frequency using a dual ultrasonic excitation. However, the synchronization between the imaging pulses is nontrivial because microbubbles need to be interrogated in the compression and the rarefaction phase, and the time-delay difference from dispersion has to be corrected. To address these issues, we propose the use of ultrafast

In standard B mode imaging, a set of ultrasound pulses is used to reconstruct a 2-D image even though some of the assumptions needed to do this are not fully satisfied. For this reason, ultrasound medical images show numerous artifacts which physicians recognize and evaluate as part of their diagnosis since even one artifact can provide clinical information. Understanding the physical mechanisms at

Ultrasound is a continually developing technology that is broadly used for fast, non-destructive mechanical property detection of hard and soft materials in applications ranging from manufacturing to biomedical. In this study, a novel monostatic longitudinal ultrasonic pulsing elastography imaging method is introduced. The existing elastography methods require an acoustic radiational or dynamic compressive

Up to now, low-frequency ultrasonic transducers have been manufactured using different materials and technologies and have been inspired by the biological world, mainly by the biosonar of dolphins and bats. Our research moves in this context, which is dedicated to investigating the feasibility of developing a piezopolymer sensor capable of covering the wide frequency range of a bat's biosonar. We propose

In this article, we report on the analysis of the extended acoustic signature obtained from the pulse-echo method to evaluate the B/A nonlinear parameter in fluids. In the known form of the method, the first acoustic tone burst from the reflector is used for the parameter measurement. The multiple pulse-echo method (MPEM) makes use of several tone bursts coming from the reflector back wall. The distortion

Air-coupled ultrasound (ACU) is increasingly used for nondestructive testing (NDT). With ACU, no contact or coupling agent (e.g., water and ultrasound gel) is needed between transducers and test sample, which provides high measurement reproducibility. However, for testing in production, a minimum separation is often necessary between the sample and the transducers to avoid contamination or transducer

Ultrasonic guided plate waves (Lamb waves) can be used to transfer power along the length of metal plates, achieving longer distance wireless power transfer (WPT), while not being impeded by electromagnetic shielding from the metal plate. In this article, a fundamental study on the performance of Lamb wave WPT is presented, including modeling, simulations, and experimental verification. By using Macro-Fiber

This study reports the design of a novel Butterfly Lamb wave resonator (LWR) employing the S0 mode in the AlN plate, and for the first time, its ultrahigh parallel-resonance quality factor ( Qp ) of 4,021 is demonstrated, indicating an ultralow acoustic loss. Although the series resonance quality factor ( Qs ) is widely used for various loss comparisons, it is inconclusive since Qs is always dominated

Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

In recent years, deep learning has been successfully applied to the analysis and processing of ultrasound images. To date, most of this research has focused on segmentation and view recognition. This paper benchmarks different convolutional neural network algorithms for motion estimation in ultrasound imaging. We evaluated and compared several networks derived from FlowNet2, one of the most efficient

A two dimensional semi-analytical model using the Legendre polynomial approach was applied for modeling the piezoelectric transformer. In the model, the mechanical displacements and the electric potential were expanded in a double series of orthonormal polynomials with an appropriate analytical form. Series and parallel resonance frequencies, input electrical admittance and voltage gain were obtained

Blind Source Separation (BSS) refers to a number of signal processing techniques that decompose a signal into several "source" signals. In recent years, BSS is increasingly employed for the suppression of clutter and noise in ultrasonic imaging. In particular, its ability to separate sources based on measures of independence rather than their temporal or spatial frequency content, makes BSS a powerful

Piezoelectricity in bone is thought to be a mechanism by which ultrasound promotes the healing of bone fractures. However, few studies have been conducted in the more clinically relevant MHz range. To understand the piezoelectricity in bone, we fabricated ultrasound transducers using bone samples as piezoelectric materials and identified the longitudinal ultrasound radiation and reception in the MHz

Doppler ultrasound is the most common technique for non-invasive quantification of blood flow, which in turn is of major clinical importance for the assessment of the cardiovascular condition. In this paper, a method is proposed in which the vessel is imaged in the short axis, which has the advantage of capturing the whole flow profile while measuring the vessel area simultaneously. This view is easier

GOAL Low-intensity focused ultrasound stimulation (LIFUS) has the potential to noninvasively penetrate the intact skull and to modulate neural activity in the cortex and deep brain nuclei. The midbrain periaqueductal gray (PAG) is associated with the generation of defensive behaviors. The aim of this study was to examine whether LIFUS of the PAG induced defensive behaviors in mice. METHODS A 3.8 MHz

Treatment of tumors in organs obscured by the ribs is a challenge for high-intensity focused ultrasound (HIFU) array. The ribs absorb the ultrasound beam's energy causing the temperature of the ribs to rise, the beam to be distorted, and the focal heat deposition to be limited. The challenges presented by the ribs motivated the development of the limited power deposition (LPD) refocusing algorithm

This paper presents corrections to, "The role of viscosity in the impulse diffraction field of elastic waves induced by the acoustic radiation force," (Bercoff et al.), IEEE Trans. Ultrason., Ferroelect., Freq. Control, vol. 51, no. 11, pp. 1523-1536, Nov. 2004, and "Supersonic shear imaging: A new technique for soft tissue elasticity mapping," (Bercoff, J., Tanter, M., and Fink, M.), IEEE Trans. Ultrason

Sparse arrays have been studied mainly to reduce large numbers of elements in 2D arrays. However, they can also provide an effective means of miniaturizing ultrasound 1D array systems for point-of-care applications. Although a variety of sparse array design strategies have been proposed, designing an optimum sparse array to simultaneously satisfy the system specification requirements and performance

In this study, we present a quantitative photoacoustic method for performing absorption measurements on highly absorbing samples. Based on the thermoelastic mechanism, the relative changes in photoacoustic signal amplitude allowed the determination of absorption coefficients of materials in the 0.19 to 2500 cm-1 range, with no prior knowledge of the material's optoacoustic properties required. We have