The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Multi-frequency transducers may have a number of emerging applications including multi-scale imaging, superharmonc contrast imaging and imaging-therapy applications. For imaging-therapy applications low-frequencies are typically needed for therapeutic heating or contrast agent destruction, while higher-frequencies are required for high-resolution imaging. However, development of these multi-frequency...
Laser Induced Phased Arrays (LIPAs) use post processing to focus and steer the generated ultrasonic beam, synthesizing a phased array. Their principle is based on laser ultrasonics where lasers are used to generate and detect ultrasound. The technique is broadband, non-contact, and couplant free, making LIPAs suitable for large stand-off distances, inspection of components of complex geometries and...
Electromagnetic [1] and acoustic [2] metamaterials that exhibit linear dispersion at a nonzero frequency and a wave vector (k) of zero, leading to a conical dispersion surface or so-called Dirac cone dispersion, have been demonstrated recently. These materials display unusual behavior associated with the occurrence of a finite group velocity at k = 0, leading to a wave which propagates with a uniform...
To facilitate the development and application of ultrasound shear wave elastography (SWE) in arteries, it is necessary to understand the nature of shear waves (SWs) propagating in pressurized anisotropic tubes embedded in softer surrounding tissues and blood. Phantom models are widely used to study SWE in tubular settings mimicking arterial geometry without yet considering anisotropy. To investigate...
Fast cardiac imaging using diverging waves (DW) is receiving much attention. Coherent compounding is important to keep spatial resolution and CNR acceptable. Two approaches have been presented in literature to do so: i) the full aperture of the probe is used and the virtual focus is moved along an arc centered at the center of the probe (ARC); ii) a sub-aperture is used and the virtual focus is linearly...
Automated tow placement has become a widely-used fabrication technique, especially for large aerospace structures. Robotic heads lay down strips of pre-impregnated fiber (called tows) along programmed paths. While the intention is to lay adjacent tows abutted to one another, occasionally a tow is placed leaving a non-zero gap between it and the previously-placed tow. In order to preserve the intended...
Harmonic imaging techniques are widely used in B-mode abdominal imaging and motion tracking in shear wave elasticity imaging (SWEI) to reduce clutter and improve data quality. Harmonic imaging can be both signal-to-noise (SNR) and penetration depth (PD) limited, resulting in decreased diagnostic utility. This work evaluates B-mode harmonic imaging and SWEI harmonic tracking data quality between imaging...
A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. Since the transmit and receive 1-D arrays are orthogonal to each other, only one-way focusing is possible in each transmit or receive plane. By transmitting with row elements and receiving the echoes through column elements, a rectilinear volume in front of the array can be beamformed. This study suggests to use...
Ultrasound based carotid strain imaging (CSI) developed in our laboratory utilizes physiological deformation in response to arterial pressure variations. We have shown that strain indices are capable of quantifying vulnerability of carotid plaque, enhancing their validity as vascular biomarkers. However, a critique of CSI has been the lack of normalization of the maximum and peak-to-trough strain...
Intravascular ultrasound (IVUS) is a well-established diagnostic method that has been applied frequently for providing high-resolution images of vessel wall and atherosclerotic plaques. Side looking transducer has been employed in a catheter for delineating the structure of vessel wall and lesions. However, it is difficult to get the flow distribution in the vessel by side looking transducer as the...
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...
It is widely accepted that cell membrane rupture induced by bubbles oscillating beside the cells is a maj or mechanism of sonoporation; however, elucidation of bubble dynamics by high-speed observation is still important because the behavior is highly dependent on their surrounding conditions. In this study, a new observation chamber was developed. The observation chamber allows observation of bubble-cell...
Many structural health monitoring techniques rely on the full field analysis related to stress guided waves propagation. Such techniques can be quite slow as in general the acquisition of the full wave field and its processing, aimed at extracting damage related information, are time consuming processes. Therefore, strategies to reduce the acquisition time and improve the damage detection and quantification...
Ultrasound B-scan imaging systems operate under some well known resolution limits. To improve resolution, the concept of stable pulses, having bounded inverse filters, were described for lateral deconvolution (Chen and Parker, Enhanced resolution, J Med Imaging, 2016). This framework has been extended to the axial direction, enabling two-dimensional deconvolution.
Ultrasounds (US) are a proven medical tool to assess a myriad of biological processes, including breast cancer screening, fetal development and blood flow. However, US also have the potential to deliver power and telemetry capability to deeply implanted devices, surpassing some challenges faced by coils or antennas operating inside the human body. In this study we present an implantable device powered...
Blood clotting, a process to avoid bleeding, involves vasoconstriction, platelet plug build-up, coagulation, clot retraction and fibrinolysis. During coagulation, blood changes from liquid to gel, and the clot viscoelastic properties continue modifying until fibrinolysis. Tests to analyze bleeding disorders and anticoagulant therapy include clot-based assays, to detect the end-point of fibrin network...
In conventional ultrasonic monitoring of high intensity focused ultrasound (HIFU) treatment, it has been difficult to track the target region when the tissue to be treated deviates from the imaging plane along the elevation axis of the 1-D probe. A 2-D phased array probe providing 3-D imaging capability requires a large number of elements and it is very expensive to build a system to drive all channels...
We have recently demonstrated the feasibility of vascular guided wave imaging (VGWI) in non-invasive estimation of bi-plane (i.e., longitudinal and transverse) transmural arterial Young's modulus (ELV, ETV) in tubular phantoms using phase velocity (cph) (Guo et al., ITEC 2016). In this study, we further compare the ETV estimated from the circumferential Lamb type (CLT) wave by VGWI with ETP from the...
The ability to measure perfusion rates of tissues in a non-invasive and label-free way could enable powerful diagnostic applications to peripheral vascular disease, ischemia, tumor hypoxia, ulcer characterization, and general tissue health. However, current medical techniques of measuring perfusion rates, which include contrast-enhanced ultrasound imaging, perfusion MR imaging require contrast agents...
Arbitrary excitation waveforms are desirable in HIFU array systems. In trans-skull therapy this is necessary to compensate for phase aberrations and achieve even heating of the skull. To facilitate this, wave form generators and large, costly class A RF amplifiers are used. High element counts are commonplace and so the portability of these systems is greatly reduced. We propose using switched mode...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.