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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...
Carotid plaque rupture is a primary cause of ischemic strokes and transient ischemic attacks (TIAs). Probability of stroke and TIAs depend on the mechanical stability of plaque. Ultrasound strain can provide a non-invasive assessment of plaque stiffness to assess mechanical stability. We report on ultrasound strain indices from multiple regions of interest (ROI) in plaque as biomarkers for plaque...
Atherosclerosis in the carotid artery (CA) elevates the risk for cerebral events. Strain imaging has demonstrated to be a technique capable of identifying plaque composition. For strain imaging of carotid cross-sections, compound techniques have been developed to solve the poor strain estimation quality perpendicular to the ultrasound beam direction. This study assesses the performance of radial and...
Because conventional geophysical measurements cannot directly measure the microstructure or pore fluids of rocks, new measurement approaches are needed as well as one that can select regions of interest. The aim of this study is to utilize the nonlinear interaction of two co-propagating longitudinal waves to characterize induced viscoelastic changes occurring in the rock microstructure. Our experimental...
Fast acquisition sequences enable >200Hz 2D cardiac B-mode imaging with little compromise in image quality. Fast imaging minimizes frame to frame decorrelation, enabling radiofrequency (RF)-based tracking for enhanced signal-to-noise ratio (SNR) in motion and deformation imaging. Our objective was to compare the performance and clinical usefulness of Fast RF-based Tracking (FRFT) to the established...
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....
Assessing the response of heart failure (HF) patients to Cardiac Resynchronization Therapy (CRT) currently relies on the ECG and left ventricular (LV) ejection fraction. Electromechanical Wave Imaging (EWI) is a high frame-rate (2000 Hz) ultrasound-based technique capable of non-invasively mapping the electromechanical activation in all four cardiac chambers in vivo. In this study, we aim to show...
An effective imaging modality to delineate the ablated region after microwave ablation (MWA) therapy is crucial to yield promising treatment outcomes. Ultrasound B mode imaging is widely used to guide the ablation needle. However, the image quality suffers from relatively low imaging contrast due to the similar echogenicity between the ablated and surrounding liver tissue. In this study, we applied...
Speckle tracking echocardiography (STE) is a very promising technique for the assessment of left ventricular (LV) function. Nevertheless, to date, it did not become part of clinical routine due to: i) inter-vendor variability; ii) difficulties in data interpretation. Anthropomorphic patient characteristics (APC) are known to affect the LV strain values as studies have shown the effect of gender, age,...
Individuals infected with the human immunodeficiency virus (HIV) are prone to develop cardiovascular disease (CVD) because the HIV infection and combination antiretroviral therapy (cART) produces atherosclerosis. Clinicians need sensitive tests to monitor interventions designed to prevent CVD in patients with HIV on long term cART. We hypothesize that vascular elastography can fulfill this role. To...
Strain imaging is gaining traction as a means to assess cardiac function by tracking the cyclic deformation of the myocardium. Compared to traditional measures such as ejection fraction, global myocardial strain has been shown to be an earlier and more sensitive measure of overall ventricular function. Similarly, regional myocardial strain has been shown to be useful for identifying ischemia and myocardial...
Myocardial elastance, derived from pressure-volume (PV) loops in the left ventricle (LV), can be used to assess LV function and myocardial performance. This method requires an invasive intracardiac pressure-volume catheter to be inserted in the LV, limiting the method's utility in clinical screening and monitoring. Strain echocardiography and cardiac acoustic radiation force impulse (ARFI) imaging...
Current elastography techniques can measure mechanical properties of soft tissues by estimating the elastic shear modulus, μ0. Recently, the assessment of tissue nonlinearity using acoustoelasticity (AE) has shown some promising results in differentiating healthy from malignant tissue by estimating a third-order nonlinear coefficient A. To fully characterize the nonlinear properties of the tissue,...
Investigating myocardial dynamics through the assessment of mechanical properties of heart is a challenging problem in a murine model as the heart rate is high. The objective of this study was to compare displacements estimated using radiofrequency (RF) signals with Cardiac Elastography (CE) and Speckle Tracking Echocardiography (STE) for quantifying myocardial dynamics.
High speed ultrasound imaging is a new imaging method particularly applicable to cardiology. At Duke we have developed a real time high speed imaging system capable of producing up to 2500 images per second while maintaining the live imaging feature so essential in clinical scanning. For high speed 2D the Duke system, T5, uses 96 transmitters and 96 receivers at 32:1 parallel processing in conjunction...
In fascioscapulohumeral muscular dystrophy (FSHD) and many other neuromuscular disorders there is a need for biomarkers to diagnose, quantify and longitudinally follow muscle disease. Furthermore, the pathophysiological mechanisms leading to muscle weakness in most neuromuscular disorders are not completely understood. Speckle tracking allows to quantify muscle deformation. This dynamic information...
Speckle tracking echocardiography (STE) is a well-established method to assess regional cardiac function. Traditionally, the left ventricular (LV) walls are divided into 18 segments (6 LV walls each with 3 segments) and the deformation parameters are measured for each of the segments. However, usually, segmental deformation curves are obtained by taking the average of an underlying strain field that...
Quasi-static elastography is a widely applied ultrasound method in which RF data acquired in tissue at different states of deformation are correlated to estimate displacements and strain (displacement gradient). A recent development is the introduction of ultrafast plane-wave imaging where element data are beam-formed after collection to reconstruct the image lines. Several beam-forming strategies...
P92 martensitic ferritic steels are an attractive material for critical components in power industries due to the excellent creep property. However, these steels are usually susceptible to creep strength degradation during a long service period under the elevated temperature and pressure. Creep damage evaluation is of concern to quantitatively assess the remaining lifespan of the critical components...
Arterial stiffness is a strong indicator of atherosclerosis, and can be evaluated by computing the arterial strain in the carotid artery using ultrasound elastography. Researchers have used axial strain to visualize the radial motion in the longitudinal plane of the carotid artery. However, axial strains can be influenced by the geometry of the vessel (Fig. 1 a, b), and thus could limit the scope...
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