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A new formulation for obtaining the absolute backscatter coefficient from pulse-echo measurements is presented. Using this formulation, performing the diffraction correction and system calibration is straightforward. The diffraction correction function for the measurement of backscatter coefficient and the acoustic coupling function for a pulse-echo system(More)
The effect of ultrasound on the rate of fibrinolysis has been investigated using an in vitro system. Plasma or blood clots containing a trace label of 125I fibrin were suspended in plasma containing plasminogen activator and intermittently exposed to continuous wave 1-MHz ultrasound at intensities up to 8 W/cm2. Plasma clot lysis at 1 h with 1 microgram/ml(More)
INTRODUCTION One form of the hereditary long-QT syndrome, LQT3-Delta KPQ, is associated with sustained inward sodium current during membrane depolarization. Ranolazine reduces late sodium channel current, and we hypothesized that ranolazine would have beneficial effects on electrical and mechanical cardiac function in LQT3 patients with the SCN5A-DeltaKPQ(More)
PURPOSE To determine the magnitude and duration of peripheral vascular and cardiac Doppler signal enhancement after intravenous administration of contrast agent SH U 508A. MATERIALS AND METHODS Suboptimal cardiac or peripheral vascular Doppler examinations were evaluated. A total of 75 intravenous bolus injections were made in 30 patients. Spectral audio(More)
The right and left heart kinetics of a saccharide-based microbubble echo contrast agent were measured in 11 anesthetized dogs using Doppler intensity as a measure of microbubble concentration while controlling for the dose administered, weight of the subject and cardiac output. A two-phase Doppler time-intensity curve was noted in all vascular regions. A(More)
An approximate solution for the acoustic coupling factor (the diffraction correction function) from a focused transducer to a flat plate and back to the transducer is provided. This function is useful for system calibrations where a pulse-echo system or transmit-receive system is used. Numerical solutions are provided for the important case where the flat(More)
Our purpose was to test the hypothesis that second harmonic imaging preferentially detects backscatter from microbubbles compared with tissue structural components. A prototype second harmonic scanner was used to image a flow channel in a tissue-mimicking rubber phantom (liver density). Video time-intensity curves were calculated from repeated bolus(More)
A 54-year-old man with end-stage cirrhosis of the liver presented for evaluation of dyspnea. Intrapulmonary arteriovenous shunting was suspected. Transthoracic echocardiography with agitated saline contrast injection from the right antecubital vein was performed. Late arrival of saline contrast bubbles in the left atrium by pulmonary veins leading to(More)
The radiation pattern of a focused transducer is reexamined. The radiation field is divided into an illuminated zone and a shadow zone. A numerically convergent solution of the pressure distribution in terms summations of Bessel functions is provided. This solution is computationally more advantageous than earlier results where a double or single integral(More)
OBJECTIVE To assess the feasibility of using contrast enhanced colour Doppler echocardiography to determine left ventricular (LV) mass and to compare its accuracy with LV mass obtained by magnetic resonance imaging (MRI). METHODS Images were acquired in the short axis plane of the heart, derived from coronal and sagittal scout views and double oblique(More)