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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...
As the medical ultrasound signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape. Thus, their reconstruction using adaptive beamformer (BF) become indispensable in order to improve the quality of the image. Generalized Side Lobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
Ultrasound is a widely used imaging modality, both for diagnosis and guidance of interventional procedures such as biopsies. Ultrasound imaging commonly provides 2D data, which can be a limitation for further data processing, since information like out-of-plane motion is inaccessible. In this study, a specific multi-row array transducer — developed for the elastography application — is presented....
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...
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...
A novel ultrasound (US) platform with high channels density is a pre-requisite to open new frontiers in diagnostic and/or therapy by experimental implementation of new enabled advanced techniques. To date, few systems in the world permit to have a full and simultaneous control both in transmit and receive of all single elements of arrays with more than 1000 transducers. This paper presents a powerful...
A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. By transmitting with row elements and receiving the echoes through column elements or vice versa, a rectilinear volume in front of the array can be beamformed. 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. For applications,...
Data acquisition from 2-D transducer arrays has become one of the main challenges for the development of endoscopic and catheter-based 3-D ultrasound imaging devices. Front-end ASICs with sub-array pre-beamforming have been reported that reduce the cable number by an order of magnitude. Further channel reduction requires digitization in the front-end ASIC to facilitate more in-probe data processing...
Recent development of the air-coupled sensing technique provides great potential for practical data measurement in the field; however, an improved data analysis method and careful design of test configuration are required to inspect structures appropriately. Impact-echo (IE) is an efficient method to evaluate delamination-like defects in concrete bridge decks. However, practical application of air-coupled...
An ultrasonic array system is designed for wirelessly powering and communicating with implantable medical devices. A flexible hardware interface is used to drive a 32-element linear phased array with emphasis on programmability and efficiency rather than bandwidth or peak power. Various beam patterns and data modulation schemes are verified at a depth of 6 cm in a tissue phantom with more than sufficient...
Bio-medical ultrasound imaging has recently gained considerable attention. A two-dimensional (2-D) array is essential for three-dimensional (3-D) volumetric imaging. Fully populated 2-D dense array requires thousands of active elements and their interconnections. We present a 2-D CMUT sparse array with 128 elements for 3-D volumetric imaging. This CMUT sparse array with a die size of 6.3 mm × 6.3...
The arrival time detection probability and the measurement range of transit-time ultrasonic flow meters are undermined by the sound drift effect. One solution to this problem is utilizing a phased-array beam steering technique to compensate the bend of the ultrasonic beams. The design, the fabrication and the characterization of two-dimensional flexural ultrasonic phased arrays is investigated in...
Ultrasound (US) therapy is, for a large panel of application, a promising technique which still requires an accurate monitoring system. Therefore, the passive acoustic mapping (PAM) beamforming technique is outlined. It reconstructs cavitation activity maps by beamforming acoustic signals passively recorded by an array. This method has already been explored in 2D with optimizations as phase coherence...
Transit-time ultrasonic flow meters, measuring the time difference between upstream and downstream propagation of ultrasonic beams, have been widely utilized to obtain the average velocity of flow in many applications including natural gas flow rate measurement. The signal-to-noise ratio (SNR) of the ultrasonic signals frequently suffers from the sound drift effect, and thus, the arrival time detection...
In this work, an all-optical ultrasound imaging system that is capable of synthesising arbitrary source aperture geometries is presented. This capability is achieved by delivering focussed excitation light onto a spatially extended generating surface, where ultrasound is generated photoacoustically. Using a scanning mirror, the position of the resulting acoustical source was continuously varied to...
In the past, members of our group developed a model based beamforming method called aperture domain model image reconstruction (ADMIRE). They tuned ADMIRE to improve ultrasound image quality by suppressing sources of image degradation such as off-axis scattering, reverberation, and phase aberration. In addition, the development of ADMIRE demonstrated that beamforming could be posed as a regularized...
As medical ultrasound (MU) signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape; thus, their reconstruction using Adaptive Beamformers (BF) becomes indispensable in order to improve the quality of the imaging system. Generalized Sidelobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
Today, 3-D vector flow imaging (VFI) in a full volume requires a fully populated NxN 2-D matrix array if a sufficient frame rate should be maintained. Such arrays require an expensive ultrasound system, which can handle the enormous data stream created by the N2 channels. As an alternative to the matrix array, N+N 2-D row-column addressed (RCA) arrays were introduced, which reduce the channel count...
Ultrasonic perfusion imaging requires high sensitivity to slow disorganized blood-flow patterns while simultaneously rejecting clutter and noise. We achieve high sensitivity to both vascular flow and perfusion without contrast enhancement by adopting the following sampling pattern. Doppler pulses sampled at 1 kHz were acquired to form a Doppler frame. Frames were recorded at 10 Hz over 10 seconds...
Electromechanical wave imaging (EWI) is an ultrasound-based methodology that can map the electromechanical activation of the heart at high temporal resolution. Previous reports have shown strong correlation between EWI-based and electrical activation times. However, EWI has been performed only with 2D echocardiography, which cannot map the full cardiac volume in a single heartbeat. Our objective in...
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