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Color flow mapping has become an important clinical tool, for diagnosing a wide range of vascular diseases. Only the velocity component along the ultrasonic beam is estimated, so to find the actual blood velocity, the beam to flow angle has to be known. Because of the unpredictable nature of vascular hemodynamics, the flow angle cannot easily be found as the angle is temporally and spatially variant...
Although the nanoparticles are broadly applied to biomedical field in recent decades, the uptake mechanism of cells has still not known very well. Endothelial cell is the inner layer of the vascular and directly contact all substance in blood. In this study, we will discuss the bioeffects and cell activities of nanoparticles before and after ultrasound stimulation.
The purpose of this study is to assess platelet and fibrin targeted ultrasound contrast microbubbles ability to adhere to fresh platelet and platelet poor clots in vitro with the assistance of radiation force. Whole blood from healthy volunteers (25 ml) was collected and centrifuged at 1100 rpm for 15 min to separate platelet-rich plasma (PRP), which was separated and centrifuged (3000 rpm, 5 min)...
Pulse-inversion sequences are sensitive to the nonlinear echoes from microbubbles allowing an improvement in the blood-to-tissue contrast. However, at larger mechanical indexes, this contrast is reduced by harmonics produced during nonlinear propagation. A method for tissue harmonics cancellation exploiting time-reversal is experimentally implemented using a 128-channel 12-bit emitter-receiver. The...
Application of ultrasound (US) has been demonstrated as an effective way to realize thrombus dissolution. Cavitation is hypothesized to be an important mechanism of US thrombolysis, but the relationship between quantified cavitation and thrombolysis efficiency has not been studied extensively. The purpose of this work was to study focused US thrombolysis feasibility and the relationship between cavitation...
Quantitative high-frequency ultrasound (QHFU) imaging methods are under investigation to evaluate their ability to detect small nodal metastases in lymph nodes freshly dissected from cancer patients. To apply these methods, a critical preprocessing step is 3D segmentation of the lymph-node ultrasound echo-signal dataset. Segmenting the residual fat layer and the lymph node is critical in order to...
Spectral Doppler is a common way to estimate blood velocities in medical ultrasound (US). The standard way of estimating spectrograms is by using Welch's method (WM). WM is dependent on a long observation window (OW) (about 100 transmissions) to produce spectrograms with sufficient spectral resolution and contrast. Two adaptive filterbank methods have been suggested to circumvent this problem: the...
In conventional Doppler ultrasound (US) the blood velocity is only estimated along the US beam direction. The estimate is angle corrected assuming laminar flow parallel to the vessel boundaries. As the flow in the vascular system never is purely laminar, the velocities estimated with conventional Doppler US are always incorrect. Three angle independent vector velocity methods are evaluated in this...
Red blood cell (RBC) aggregation, which is one of the induces showing blood viscosity, plays an important role in blood rheology. RBC aggregation is formed by adhension of RBCs because electrostatic repulsion between RBCs weakens as protein and saturated fatty acid in blood increase. Excessive RBC aggregation promotes various circulatory diseases in the clinical situation. The purpose of this study...
Compression cardiac assist device aims to help patients with end-stage dilated heart failures. Currently the compression cardiac assist devices under development are driven by air or liquids, in which tubes are needed for connecting devices with outside pumps through the skin. These flexible tubes may cause infections and inconvenience of mobility for patients. Therefore, it is necessary to exploit...
The thrombus-targeted ultrasound contrast agent with tirofiban, a glycoprotein IIb/IIIa antagonist that can specifically bind to activated platelets in the thrombus, was designed to enhance both the image contrast and the cavitation effect. The targeting ability to thrombi was confirmed by microphotography and high frequency ultrasound (40 MHz) images (3.34plusmn0.30 dB enhancement). Our inertial...
It is important to accurately determine the severity of valvular regurgitation as surgery is indicated only in severe regurgitations. The evaluation of, for example, mitral regurgitation is complex and the current methods have limitations. We have developed a 3D ultrasound Doppler method to estimate the cross-sectional area and the geometry of a regurgitant jet at the vena contracta just downstream...
A high-speed photoacoustic tomography (PAT) data acquisition system has been developed using a commercial ultrasound (US) unit. Since the US unit supports simultaneous signal acquisition from 64 parallel receive channels, PAT data from a 64-element US array aperture can be acquired using a single laser firing. This arrangement enables an object to be scanned in both US imaging and PAT modes using...
Developments on ultrasound contrast-specific imaging methods make it possible to detect the deep microvessel and evaluate blood perfusion noninvasively. In this study, we attempt to implement the perfusion parametric imaging to quantitatively assess blood perfusion of organs with the low-cost diagnostic ultrasound equipment. A novel ultrasound contrast imaging method called pulse inversion harmonic...
Current thrombolytic techniques have significant drawbacks including risks of excessive bleeding and infection. The purpose of this study was to evaluate histotripsy as a new method of thrombolysis. Histotripsy uses short, intense ultrasound pulses to fractionate soft tissue through controlled cavitation. Histotripsy was applied to clots in-vitro using a 1-MHz focused transducer, 5-cycle pulses at...
We present a Monte Carlo study on ultrasound backscattering by three-dimensional distributions of aggregated red blood cells (RBCs). In this study, particles were allowed to interact attractively with neighbors to form aggregates. The interaction potential energy profile between a pair of particles was mimicked by the Morse potential. The strength of pair interaction energy was controlled by fixing...
The blood-brain barrier (BBB) is a specialized brain protection system consisting of endothelial cell, tight junctions and glial processes. BBB is the major limiting factor to therapeutic agents to the brain for disease treatment. Focused ultrasound (FUS) in the presence of microbubbles has the capability to deliver large molecules across BBB. In this study, we qualitatively and quantitatively analyzed...
The purpose of this study was to demonstrate a prototype design of a low-frequency multiple-channel hemispherical focused-ultrasound phased-array system for transcranial disruption of the blood-brain barrier (BBB). In this study, we have presented a prototype design of a multiple-channel ultrasound hemispherical phased-array system to perform localized BBB disruption. To our knowledge this is the...
This paper describes the development of a bidirectional pulsed-wave ultrasound Doppler blood flow measuring system using a miniature CMUT array suitable for minimally invasive diagnosis. On this flowmeter, the CMUT devices, integrated on a silicon probe smaller in diameter than a human' hair, were used both for ultrasound transmission and reception. The Doppler shift was recognized by comparing the...
Conventional ultrasound methods for acquiring color flow images of the blood motion are restricted by a relatively low frame rate and angle dependent velocity estimates. The Plane Wave Excitation (PWE) method has been proposed to solve these limitations. The frame rate can be increased, and the 2-D vector velocity of the blood motion can be estimated. The transmitted pulse is not focused, and a full...
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