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The image quality provided by current ultrasound (US) scanners can be increased by extending the effective bandwidth of the US transducers. In 2007, a promising technique, called Resolution Enhancement Compression (REC), was proposed. Combining chirp modulated signals in emission and Modified Wiener Filters (MTF) in reception, REC allows bandwidth enhancement by boosting the energy of the emitted/received...
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...
As new flow imaging methods are actively being developed, there is a growing need to devise appropriate phantoms that can holistically assess the accuracy of the derived flow estimates. Straight-tube models simply cannot serve this purpose, nor can spinning discs that simulate tissue motion instead of flow dynamics. Anthropomorphic bifurcation models are also not ideal, because their geometry does...
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),...
Diverging wave imaging is the most prominent transmit sequence in fast cardiac imaging. Indeed, as this type of ultrasound transmit insonifies a significant part of the region of interest at once, less transmit events are required to reconstruct an entire image leading to an improved time resolution. However, the flipside of this approach is that image quality reduces in terms of spatial resolution,...
For many diseases, such as cancer, simultaneous imaging of different targets can lead to improved diagnosis, better patient prognosis, and therapy guidance/monitoring. PET-CT multiplexing can be cumbersome, costly, and involve radiation exposure. Other modalities such as fluorescent imaging lack clinical and pre-clinical relevance. Therefore, clinically relevant multiplexed imaging is of interest...
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.
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...
Ultrasound elastography is an effective modality for the delineation of thermally ablated regions after liver tumor treatments. Image contrast in elasticity imaging is based on differences in the Young's modulus of local tissue. In this work, we compare our previously introduced electrode displacement elastography (EDE) with a commercially available acoustic radiation force impulse imaging (ARFI)...
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...
Parameters derived from the acoustic backscatter coefficient (BSC) represent quantification on an absolute scale and have been used to characterize tissue microstructure. This motivates their use to detect and quantify microstructural remodeling and ripening of the uterine cervix during pregnancy. This work systematically assessed the ex vivo human cervix microstructure and the effects of cervical...
Based on the linear relationship of channel data between synthetic transmit aperture (STA) and apodized plane wave (PW) firings, we previously proposed compressed sensing (CS) based STA (CS-STA) for linear array, which achieves higher frame rate and higher contrast-to-noise ratio (CNR) than STA while maintaining its high resolution. Because diverging wave (DW) instead of PW is usually adopted in phased...
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...
It was estimated that annual cost of measurable medical errors was higher than $17 billion in 2008. Phantoms are objects manufactured using a tissue mimicking material (TMM) and largely used to test protocols and mimic clinical environment for medical training. TMM should reproduce at least one biological property to allow the association with clinical situation. The gel made by the copolymer styrene-ethylene/butylene-styrene...
Histotripsy uses high-pressure, microsecond-length pulses to generate cavitation microbubbles to fractionate targeted tissue. After the collapse of a cavitation cloud, remnant microbubbles can persist for a second or longer before passively dissolving. These bubbles can act as seed nuclei for subsequent cavitation events reducing treatment efficiency because the nuclei are not well distributed through...
Shear wave elastography is useful for quantitatively evaluating tissue elasticity by measuring the speed of a shear wave induced within the body by acoustic radiation force. We proposed a pushing-and-tracking sequence, coded push-pulse excitation to increase the signal-to-noise ratio (SNR) of the observed shear wave propagation without increasing measurement time and push-pulse amplitude1). In this...
A transparent transducer array is desired in backward-mode photoacoustic imaging (PAI). CMUT technology is especially suitable for this application because of its wide bandwidth and a wide selection of processing materials. We have previously demonstrated a single-element CMUT with an ITO bottom electrode for improved transparency. The device showed 40% to 70% optical transmission from 700 nm to 900...
Multiple research groups have recently innovated image recovery methods for fast pulse-echo ultrasound imaging (UI) that combine inverse scattering techniques with compressed sensing (CS). These methods alleviate the inherent tradeoff between the image quality and the image acquisition rate. The choice of the incident sound field is a crucial degree of freedom to implement the specific requirements...
For drug-resistant epilepsy patients, epilepsy surgery is the only option. In clinic, this is done with subdural electrode array with a disappointing low spatial resolution of ∼ 1cm. In order to improve clinical cure rate, ultrasound imaging technique can be cooperated with Electrocorticography to monitor the maps of seizure. We propose to develop the implanted single ultrasound transducers 3mm×1...
Myocardial deformation imaging at a high frame rate (HFR) has the potential to gain new insights in cardiac mechanics by resolving short-lived mechanical events during the cardiac cycle. In order to achieve such high frame rate, our lab recently proposed to combine multi-line transmit with ‘anatomical imaging’ i.e. imaging only the anatomically relevant spatial domain (e.g. the myocardium). Although...
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