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The Resolution Enhancement Compression (REC) technique is a coded excitation method developed for improving the axial resolution of ultrasound images. It consists on emitting an amplitude modulated chirp signal that transmits more energy at the frequencies where the ultrasound transducer is less efficient. The focus of this study is to elaborate a new beamforming strategy, which consists of implementing...
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.
Ultrasound-mediated drug delivery using microbubbles is a growing field with applications ranging from targeted chemotherapy to permeating the blood brain barrier. Despite the potential clinical impact of this technique, the precise parameters needed to reliably induce cell sonoporation, or increased cellular permeability, are not well understood. The goal of this work is to use high frame rate imaging...
Contrast echocardiography (CE) ultrasound with microbubble contrast agents have significantly advanced our capability in assessing cardiac function. However in conventional CE techniques with line by line scanning, the frame rate is limited to tens of frames per second, making it difficult to track the fast flow within cardiac chamber. Recent research in high frame-rate (HFR) ultrasound have shown...
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...
Large and small CMUT membranes were fabricated in an interlaced fashion to create a multi-frequency array using a modified standard silicon-nitride sacrificial release process on a scale smaller than the wavelength to ensure the minimization of grating lobes. A 7 mm by 7 mm multi-frequency array with 20 elements was fabricated and wire-bonded to custom printed circuit boards (PCBs) mounted onto a...
Plane wave methods for ultrafast ultrasound imaging suffer from a low signal to noise ratio (SNR) and a limited field of view at greater imaging depths. Imaging using multiple focused coded beams in parallel is one strategy for high speed imaging that may improve on these limitations. However, the SNR and resolution of this strategy are degraded by interference between the beams transmitted in parallel...
EUS is performed with radial imaging perpendicular to the endoscope shaft, and lateral imaging parallel to the shaft and biopsy channel. Radial imaging is preferred for some diagnostic and staging purpose because of ease of use as well as the production of a full 360-degree field of view. For operation smoothly and safety, the smaller external diameter (less than 11mm), the higher optical and ultrasonic...
Focused ultrasound (FUS) combined with microbubbles (MBs) has been shown to locally and temporarily open the blood-brain barrier (BBB). However, concurrent opening BBB (long pulse) and mapping the location of BBB opening (short pulse) by pulsed-wave excitation always conflicts. Previously proposed passive cavitation imaging in brain suffered from degraded axial resolution because of long driving pulse...
To acquire reliable medical ultrasound images and accurately detect vascular diseases, it is inevitable to improve axial resolution and contrast facilitating clearly definition of depth and thickness of blood vessel walls.
Functional Ultrasound (fUS) has shown to be a promising new neuroimaging modality that uses ultrafast plane waves to detect changes in cerebral blood flow for imaging brain activity at high spatiotemporal resolution. An existing challenge is the ultrasound penetration of skull which decreases with frequency. In the initial study (Macé et al., 2011)[1] a craniotomy was required to perform fUS. Since...
Imaging using the total focusing method (TFM) is a popular tool in nondestructive evaluation and it becomes a standard. From full matrix capture, this method consists in focusing at each point of a defined reconstruction zone. It is generally more efficient than conventional phased array focusing that can focus at only a few points. Despite the good quality of TFM images, TFM suffers from a lack of...
Image quality of volumetric intracardiac echocardiography (ICE) catheters is severely limited, especially in the elevation direction, restricted by the catheter diameter. A natural idea is to design a foldable transducer with multiple panes which can be expanded in the heart mechanically to form a large and symmetric 2-D aperture 2–3 times the size of the catheter diameter. Here, the imaging performance...
Angiogenic vasa vasorum (VV) is an important marker for atherosclerotic plaque progression and vulnerability. However, current in vivo imaging of tiny VV near a major vessel is limited. The super-resolution ultrasound imaging (SRI) can be a promising candidate. Microbubbles (MBs) localization technique for common SRI excludes signals from densely distributed MBs, requiring a large number of frames,...
Achieving a high frame rate in echocardiography is highly important for quantifying the short phases of the cardiac cycle that contain valuable information for medical diagnosis. Additionally, the 3D quantitative assessment of the heart would significantly improve the current measurements used in daily clinical routine. Nevertheless, obtaining ultrafast images remains a challenge due to the trade-off...
Despite the progress of focused ultrasound (FUS)-mediated blood-brain barrier (BBB) disruption, neuro-inflammatory responses and the high variability of the FUS transmission through the human skull make the control of the acoustic parameters challenging. In this study, we developed a high-field (7-T) magnetic resonance (MR)-guided FUS system with a feedback control based on passive cavitation detection...
This work shows the feasibility of performing ultrafast 3D ultrasound imaging by producing diverging waves (DW) with 2D sparse arrays. The 3D volumes were experimentally acquired by individually driving the 1024 elements of a full 32×32 matrix array. The volumes obtained with different sparse configurations were compared to those obtained with two references arrays: the full 32×32 array and a dense...
Developing tools to visualize urinary flow dynamics is important, because urinary hydrodynamics is known to have a causal relationship with urethral voiding dysfunction problems. Yet, the design of such an imaging technique is challenging as fine time resolution is essential to track urine passage that can traverse at >2m/s speeds. Previously, we have overcome the time resolvability challenge in...
The recent development of ultrafast ultrasound localization microscopy (Errico et al., Nature, 2015) provides new opportunities for imaging the vasculature with sub-diffraction resolution. However, the large number of images to be recorded requires acquisitions lasting several minutes. Therefore, physiological motion far larger than the achievable resolution presents challenges for moving tissues...
Ultrasound localization microscopy has first been demonstrated to overcome the penetration/resolution trade-off [Couture et al IEEE IUS 2011]. Inspired by FPALM in optics and exploiting ultrafast ultrasound imaging, it allowed the reconstruction of a full velocity map of the rat brain vasculature with a micrometric resolution (8μm) [Errico et al. Nature, 2015]. Despite additional successes for tumour...
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