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.
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.
High-intensity focused ultrasound (HIFU) have been an attractive research topic for some time now. HIFU studies have started with single-element transducers, but using arrays provide the opportunity to scan the focal point electronically. Modular and scalable driving systems that can be used with custom-made transducer elements to drive these arrays are needed and at the present time there are few...
Fast acquisition sequences enable >200Hz 2D cardiac B-mode imaging with little compromise in image quality. Fast imaging minimizes frame to frame decorrelation, enabling RF-based tracking for enhanced signal-to-noise ratio (SNR) in motion and deformation imaging. Our objective was to evaluate the performance and hypothesize on the clinical usefulness of Fast RF-based Tracking (FRFT) in comparison...
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...
Compared with traditional rotary-percussive drills driven by electromagnetic motors, ultrasonic drills show advantages of small size, low power, low weight on bit, and lubrication free, making them available for the extraterrestrial rock sampling, especially for the minor planet with a weak gravitational field. To solve the problem that the conventional percussive ultrasonic drills cannot remove cuttings...
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...
In the present study, chirp coded pulses are investigated with respect to high frequency imaging. These pulses were used drive broadband polymer transducers assembled from an adhesive-free layer-be-layer deposition method. The image quality obtained from using a long chirp coded pulse was compared with images generated from shorter pulses. This includes the Ricker wavelet and the square pulse most...
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...
Clinical diagnostic imaging modalities of breast cancer are still having certain limitations such as low sensitivity in dense breast in mammography and low specificity of the B-mode ultrasound [1, 2]. Photoacoustic (PA) imaging has been introduced as an enabling tool to acquire important functional information of the pathologic tissues as well as molecular imaging of cancer when it is augmented with...
Although 3D ultrasound plays an increasingly important role, 2D echocardiography remains the main clinical imaging modality for cardiac function assessment in daily practice. This requires precise delineation of the myocardium at end diastole (ED) and systole (ES). Because of intrinsic high variability in image quality, manual interactions are still needed. In this study, we investigate a machine...
The pulse-echo method based on transmission of an ultrasonic pulse and time-of-flight determination of a reflected echo is one of the typical methods of ultrasonic distance measurement. To improve the SNR of the reflected echo, pulse compression using an M-sequence is employed in the pulseecho method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect The Doppler-shifted...
Carotid plaque rupture is a primary cause of ischemic strokes and transient ischemic attacks (TIAs). Probability of stroke and TIAs depend on the mechanical stability of plaque. Ultrasound strain can provide a non-invasive assessment of plaque stiffness to assess mechanical stability. We report on ultrasound strain indices from multiple regions of interest (ROI) in plaque as biomarkers for plaque...
The Delay-Multiply-And-Sum (DMAS) beamformer has recently been presented in the context of medical ultrasound image formation. Images obtained with the DMAS beamformer present improved contrast resolution and noise rejection when compared to images obtained with the standard Delay-And-Sum (DAS) beamformer. We study here the signal statistics for a homogeneous medium using both the DAS and DMAS beamformers...
Over the last decade, clinical studies show a strong interest for real-time 3D imaging. This calls for ultrasound probes with high-element-count 2D matrix transducer array, interfaced to an imaging system using an in-probe Application Specific Integrated Circuit (ASIC) that takes care of element selection, signal amplification, sub-array beamforming, etc. Since the ASIC is based on silicon and is...
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.