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Intrauterine growth restriction (IUGR) is an anomaly of fetal growth dynamics, which is mainly caused by alterations in the vascular remodeling of utero-placental arteries. With a prevalence of 10% of pregnancies, IUGR remains the leading cause of perinatal mortality. Doppler velocimetry is the common screening tool for IUGR but this imaging modality remains controversial. In this context, we evaluated...
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...
Carotid plaque vulnerability is difficult to characterize from B-mode ultrasound imaging alone. However, elastographic characterization of plaque mechanical properties may aid in the assessment of vulnerability. As an initial step to understand the complex wave propagation that can occur in plaques, we have developed simulation models that incorporate different shear moduli (μ) of the arterial wall,...
Spectroscopic photoacoustic (sPA) can estimate blood oxygen saturation (SO2), which has been shown to correlate with hypoxia, and therefore could improve cancer diagnosis and treatment monitoring. However, accurate quantification of SO2 is often not straightforward as local fluence varies significantly at depth due to wavelength-dependent optical scattering and absorption. Additionally, assessing...
Dysfunctions on the coronary circulation can lead to adverse and severe clinical outcomes, e.g., ischemic heart failure (IHF) or coronary artery disease (CAD). The evaluation of coronary vasculature is consequently of extreme importance to the diagnosis of these conditions. However, intramyocardial coronary vasculature cannot yet be imaged in-vivo in humans with current angiography techniques or transthoracic...
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,...
In vivo measurement of the mechanical properties of thin-walled soft tissues (e.g., mitral valve, artery and bladder) and in situ mechanical characterization of thin-walled artificial soft biomaterials in service are of great challenge. Those thin-walled structures are usually pre-stressed to achieve and/or improve their functional performance, which further complicate the inverse analysis to identify...
Quantification of local arterial wall elasticity may assist in differentiating lipid rich rupture prone atherosclerotic plaques from stable fibrous plaques. Because lipid cores can be present anywhere along the circumference, we focus on developing a noninvasive shear wave elastography technique for transverse carotid cross-sections. Tracking the induced wave is not trivial because the circular geometry...
Intravascular ultrasound (IVUS) has frequently been used by the cardiologist to diagnose atherosclerosis and guide the interventional procedures. IVUS has gained widely clinical acceptance over the past twenty years because of its superior capability to assess plaque burden and monitor artery remodeling, which also makes it as the irreplaceable image modality for most innovative multimodality intravascular...
Changes in the biomechanical functions of artery serve as important indicators for prediction of cardiovascular disease. Endothelial dysfunction is known to play a role to develop atherosclerosis and cardiovascular disease. Ultrasound measurement of flow-mediated dilation of the brachial artery is a method to quantify endothelial function based on changes in arterial diameter. One challenge of the...
In shear wave elastography (SWE), acoustic radiation forces (ARF) are employed to generate shear waves within the tissue. Although the transmitted pulses are longer than those in conventional clinical ultrasound, they typically obey the mechanical and thermal regulatory limits. In arterial applications, specific safety concerns may arise, as ARF-induced stresses and strain rates could potentially...
Doppler measurements in coronary arteries are difficult due to rapid motion of the myocardium and small vessel dimensions. High frame rate 3D Doppler imaging with retrospective spectral Doppler processing could potentially solve this. However, the combination of low blood flow velocities and excessive tissue motion in parts of the cardiac cycle makes clutter suppression challenging. In the present...
Clinically used Intravascular Ultrasound (IVUS) imaging majorly operates in the 20∼40MHz range, providing resolution on the order of 100μm. Recent reports showed the potential of higher frequency (60–80MHz) of IVUS improving resolution to the level of 30–60μm, but still inferior to the resolution of OCT (10μm). Whether increasing the working frequency a step further could make IVUS comparable to OCT?...
Inspection of large or small pipes is commonly found in many different ultrasonic industrial applications. Pigs are commonly used for large pipes and inspection under working conditions. Small pipes are inspected from inside by using endoscopes, but the distance to be inspected can be limited by the pipe diameter, geometry and section variations. In medical applications, ultrasonic endoscopy are used...
Hemodynamics play an important role in the development of cardiovascular disease, with atherosclerosis and intimal hyperplasia arising at sites with low wall shear stress and disturbed endoluminal mixing. Computational fluid dynamics (CFD) can study blood rheology, however performance relies on precise 3D anatomy and accurate blood flow measurements to seed the initial and boundary conditions. Recently,...
Multiple collagen types are critical for proper function of the vascular system, with type III being responsible for imparting strength in the vessel wall. Patients with mutant gene encoding type III collagen experience arterial ruptures, called vascular Ehlers-Danlos syndrome (vEDS). In order to better characterize their arterial mechanical properties, we developed a Knock-In Gly183Arg mice (col3KI-mice)...
Guided wave elastography (GWE) is promising to measure the local arterial stiffness. However, most studies focus on the longitudinal section, with a guided axial wave (GAW). In addition, the dispersion curve of GAW can be well approximated by immersed Lame wave model only at high frequencies (Li et al, UMB 2017). In the transverse section, guided circumferential wave (GCW) can be utilized to obtain...
The main role of red blood cell (RBC) is oxygen delivery to body tissues via blood flow. When flowing blood is exposed to stasis or low shear rate (the radial gradient of velocity profile) in blood vessels, RBCs become aggregated resulting in alterations of blood viscosity affecting blood flow dynamics. Our group demonstrated that lower shear rate yielded greater aggregation and a higher PA signal...
Perinatal arterial ischemic stroke can result in long-term deficits in motor, cognitive, attention, and executive functions as well as persistent seizures. Rapid diagnosis is critical for newborns who suffer a focal ischemic stroke in order to distinguish prenatal vs. postnatal stroke, and to differentiate perinatal stroke from global hypoxic ischemia (HI). In this study, we present photoacoustic...
Ultrasound imaging of blood flow in the coronary arteries is hampered by small vessel diameters and rapid myocardial motion. This combination makes clutter suppression challenging, resulting in flashing artefacts and signal dropouts. This work investigates whether high frame-rate 3D ultrasound imaging in conjunction with eigen-based clutter filtering can be used to mitigate these problems, making...
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