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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...
Conventionally, images are normally displayed by amplitude or intensity information. However, the frequency information is significantly important in acoustic images since the frequency information can reflect the object characteristics (surface profiles, structures hidden under surfaces, and material properties of objects). In this study, we propose a method of displaying frequency information in...
Medical imaging through a targeting agent promises to improve the specificity and sensitivity of cancer detection. Nanoparticles (NPs) may provide advantages for targeted photoacoustic (PA) imaging due to their unique physical and optical properties. In our previous study, we developed a phase-change contrast agent made from a biodegradable polymer, poly(lactic-co-glycolic acid) (PLGA) and loaded...
To elicit bio-effects, ultrasound (US) stimulated microbubbles (MBs) must be in proximity to their target and this is not always the case (e.g. sonothrombolysis). Radiation forces can direct MBs to clots and our previous work suggested clot degradation patterns (Fig A) could be influenced by ‘transport pulses’. However, this is a complex process involving a population of MBs, with size-dependent radiation...
A U-shaped linear piezoelectric ultrasonic motor (PUM) was proposed, designed and tested in this work, in which three longitudinal transducers were used together to achieve the linear driving by two feet synchronously. Longitudinal vibrations of the transducers were generated with certain temporal shift to form the desired elliptical movements on the two driving feet. Finite element method (FEM) was...
With the ongoing drive to integrate more functionality and processing power on the same semiconductor area, the device structures have become 3D. Such structures, like FinFETs and their successors Gate-All-Around (GAA) nanowire FETs, bring on new challenges to measure their geometry and material properties non-destructively at the nanometer scale. Photo Thermal Acoustic Imaging (PTAI) is a potential...
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...
We report on the fabrication, experimental characterization, and theoretical modeling of delay lines fabricated on a lithium niobate X-cut thin film substrate. We demonstrate the feasibility of fabricating delay lines on lithium niobate suspended thin films to take advantage of the high electromechanical coupling of Lamb waves in this material. Specifically, we design the delay lines with an orientation...
Color Doppler and Vector Flow imaging are ultrasound imaging modalities that are primarily used for qualitative measurements or navigation. One main challenge before these modalities can be used quantitatively in clinical applications, is that clutter suppression filters or residual clutter signal lead to bias and variance in the blood velocity estimates which varies throughout the cardiac cycle....
Point shear wave elastography (pSWE) provides noninvasive measures of mechanical stiffness of biological tissue. Over the past decade, research has demonstrated that pSWE is effective at diagnosing a multitude of pathologies such as liver fibrosis and cancer. Life science researchers stand to benefit tremendously from access to pSWE but a number of challenges have limited its use in small animals...
Cardiovascular diseases are the leading cause of death globally. Such diseases may affect the left ventricular function, which in turn is closely related to the left ventricular stiffness. Estimation of cardiac deformation can give information on the myocardial stiffness, and may therefore be important in assessment of cardiovascular diseases. A 3D motion estimation scheme is necessary to measure...
High-frequency ultrasound (>20 MHz) imaging has gained widespread attention due to its high spatial resolution being useful for basic cardiovascular and cancer research involving small animals. The sampling rate of the analog-to-digital converter in a high-frequency ultrasound system usually needs to be higher than 120-MHz to satisfy the Nyquist requirement. However, the sampling rate is typically...
Keloids are benign dermal disease that are characterized by the collagen deposition and growth beyond the boundaries of the original wound position. Many studies on keloids have showed that the density of blood vessel within keloids is higher than normal skin, which is a determinant of the physiological conditions of the tissue and also important for understanding the pathogenesis and radiotherapy...
A highly sensitive capacitive micromachined ultrasound transducer (CMUT) cell with an ultra-narrow gap was investigated. The electromechanical coupling coefficient (kT) as a figure of merit of sensitivity of ultrasound transducers was 0.67 in a 30-MHz CMUT cell with a 30-nm height vacuum gap and in 100-nm thick dielectric layers, and the coefficient was superior to that of piezoelectric transducers...
Microembolization during PCI for acute myocardial infarction can cause microvascular obstruction (MVO). MVO severely limits the success of reperfusion therapies and is linked to worse prognosis, including death. A recent clinical trial showed that adjunct short pulse MB+US therapy prior to and following PCI in first STEMI patients, improved angiographic recanalization prior to PCI and ejection fraction...
Transcranial Doppler Ultrasound (TCD) is one of the techniques that have been used for stroke diagnosis. This paper compares the potential of three aperiodic sparse array configurations: random array; sunflower spiral array; and log spiral array for application to TCD. To cover the full temporal window, a 30mm diameter circular aperture is selected, with a 2MHz operating frequency to match current...
Our earlier work on support vector machines (SVM) and ultrasonic flaw detection algorithms demonstrated i) highly accurate classifier performance and ii) the feasibility of the algorithm for real-time implementation on low-cost embedded systems with graphical processing units (GPU) and CUDA library (a parallel computing platform and programming model) support. This works extends the implementation...
ARFI displacements have been shown to share an inverse relationship with shear wave speed — based estimates of tissue elasticity. In transthoracic imaging, induced shear waves have been observed during diastole, but only ARFI displacements have been accurately measured through both diastole and systole. We propose here a method for using diastolic shear wave speeds to calibrate ARFI displacement magnitudes,...
Traumatic spinal cord injury (tSCI) often leads to debilitating neurological disabilities that in addition to the loss of sensory and motor capabilities, also includes other issues with the bladder, heart and respiration. Overall, tSCI results in a drastic decrease in the quality of life. Traumatic spinal cord injury causes an almost complete loss of blood flow at the site of injury (primary injury)...
Suppression of the SH-SAW response is mandatory to design TC SAW devices on θ degree rotated Y-cut LiNbO3. However, it is not easy because K2 for SH SAW changes rapidly with θ, and its optimal value in terms of the SH-SAW suppression is dependent on electrode and SiO2 thicknesses. The authors found that the optimal θ always locates close to θ where difference in velocities of two SAWs is minimum....
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