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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...
Flow velocity estimation is an important feature in ultrasound imaging. However, in conventional color Doppler imaging, only parallel flow components can be estimated, the velocity information is not simultaneously measured throughout the region of interest (ROI) due to sequential firing of the ultrasound beams, and the size of the ROI is limited under frame rate concerns. On the other hand, ultrafast...
Controlling cell functions for drug development and therapeutic purposes has been an important method in clinic to treat critical diseases such as cancer and neurodegenerative diseases. Modulation of cancer cells and finding specific mutations in cancer are methods to investigate mechanism of outbreak of cancer. The advancement in molecular biology introduced tools to precisely edit genome of cells...
Pathologic microvasculature plays a key role in the leading causes of blindness including diabetic retinopathy, retinal vein occlusions, and macular degeneration. Current treatments, including laser therapy, photodynamic therapy (PDT), and anti-vascular endothelial growth factor (VEGF) therapy, impose significant burdens on patients, their families, and our health system because of frequent administration,...
Tumor growth requires formation of new angiogenic vessels, which differ in their morphology from those of healthy tissue. These vascular abnormalities result in altered blood flow dynamics, which can be assessed by dynamic contrast-enhanced ultrasound (DCE-US). Two distinct approaches are typically employed in DCE-US following an intravenous injection of ultrasound contrast agent: assessment of perfusion...
Cardiovascular disease, including atherosclerosis and critical limb ischemia, affects millions of people worldwide. There is a clinical need to base treatment decisions on quantitative analysis of the plaque composition. However, no reliable clinical methods to quantify the mechanical properties of plaque components and detect plaque vulnerability currently exist, particularly for coronary disease...
Understanding of the propagation of ultrasound through a bubbly medium is a challenging task because of the nonlinear dynamics of the bubbles and their effect on the attenuation and sound speed of the medium. The majority of the studies on this subject apply linear models, which will generate inaccurate results, especially at higher-pressure excitations. These studies have also ignored the effect...
Modification of dissolved gas content by nucleation of acoustic droplet vaporization (ADV) has been proposed for several therapeutic applications. Reducing dissolved oxygen could inhibit reactive oxygen species production during reperfusion of ischemic tissue, such as during coronary interventions to rescue myocardium. Localization of the effect may be achieved using intravascular ultrasound (IVUS),...
Single Track Location Shear Wave Elasticity Imaging (STL-SWEI) creates high resolution shear wave speed maps by comparing the tissue motion at each tracking location between spatially-offset radiation force excitations. While STL-SWEI circumvents the resolution-limiting effects of speckle noise, it requires a series of excitation-tracking ensembles to build up a lateral field of view, increasing the...
I describe recent progress in machine learning in medical ultrasound imaging. At a high level, the two technologies appear to be well-matched as the former attempts to make sense of complex patterns, and the latter can generate images of complex acoustic patterns. Thus, the general challenge to the image analysis practitioner is to design machine learning architectures that model the patterns in real...
Endoscopy and colonoscopy are the clinically recognised standards for imaging and diagnosis of diseases of the gastrointestinal (GI) tract. While 'scope-based approaches combine optical and ultrasound imaging to allow both imaging of the surface and full thickness of the bowel wall, they are limited in their ability to access the full length of the GI tract particularly the small bowel. Wireless video...
Accurate diagnosis of non-alcoholic steatohepatitis (NASH) is a critical issue in current clinical practice. Non-invasive diagnosis of NASH can be achieved by quantitative ultrasound (QUS), which requires a detailed understanding tissue-specific acoustic microstructure at cellular scale (i.e., 10 μm). Therefore, QUS methods would benefit from the knowledge of the acoustic properties of organelles...
Elastic properties of the ocular tissues are significantly affected by intraocular pressure (IOP) in the eye. For example, the speed of the elastic wave in the cornea dramatically increases with IOP. In our previous studies using ultrasound shear wave imaging we demonstrated that, for the lens, the increase in IOP does not result significant changes in the wave velocity. Compared with ultrasound imaging,...
One of the primary motivations for using ultrasound reflectometry for fingerprint imaging is the promise of increased spoof resistance over conventional optical or capacitive sensing approaches due to the ability for ultrasound to determine the elastic impedance of the imaged material. A fake 3D printed plastic finger can therefore be easily distinguished from a real finger. However, ultrasonic sensors...
Pulse wave velocity (PWV) is a reliable index of arterial stiffness. To date, reflected pulse wave interference is still a major challenge for regional PWV estimation using ultrasound imaging methods. In this study, a high-resolution Radon transform (HRT) method is proposed to eliminate the reflected wave interferences in PWV estimation.
Previous study has demonstrated that pulsed HIFU with tens of microseconds pulse duration (PD) and 10kHz PRF is effective for cavitation generation. Meanwhile, with the assistance of PFC nanodroplets, cavitation can be further enhanced. Despite of higher efficiency, we also need cavitation to be precisely controlled and confined for sake of therapeutic safety, especially during the implementation...
Rodents are used extensively in research to study disease and evaluate drugs. Preclinical imaging systems allow for non-invasive assessments of animals. High frequency ultrasound systems have emerged over the last 15 years as valuable tools for evaluating numerous diseases and organs. When compared against other anatomical imaging systems, such as MRI and CT, ultrasound is the most cost effective,...
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...
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...
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