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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 132 out of 330
| Title |
Generation of ultrasound by a dielectric transducer. |
| Author |
Legros D, Lewiner J, Biquard P. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1972 |
| Abstract |
In this paper we report the generation of ultrasonic waves in solids, at frequencies varying from 10 to 200 MHz, using a dielectric transducer. It is shown that the dominant process involved is the effect of electrostatic forces acting directly on the propagation medium, and not piezoelectricity or electrostriction of the central dielectric. |
| Title |
Geometric and intensity distortion in echography. |
| Author |
LaFollette PS Jr., Ziskin MC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1986 |
| Abstract |
Anatomic structures possessing varying sonic propagation velocities refract ultrasonic beams and create distortions in the sonographic image. The distortions consist of inaccurate positioning of echogenic locations (geometric distortions) and of inaccurate display of ultrasonic intensities (intensity distortions). Artifacts of both types occur in the region distal to a structure of circular cross section with an internal sonic propagation velocity lower than that of its surroundings. In an attempt to better understand these distortions, a model is developed from first principles of the production of sonograms of such a region. Assuming a uniform ultrasonic beam and uniform echogenicity of the surrounding tissue, a mathematical expression has been derived for the intensity of the sound arriving at each point and returning to the transducer. Computer simulations of the resulting sonographic image are provided for visualization. In spite of many simplifying assumptions, the model is shown to be consistent with several known artifacts, and provides insight into the mechanisms of their production. |
| Title |
Geometric modeling of the carotid bifurcation in humans: Implications in ultrasonic doppler and radiologic investigations. |
| Author |
Forster FK, Chikos PM, Frazier JS. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1985 |
| Abstract |
A geometric representation of the carotid bifurcation is presented with data obtained from biplane angiograms of normal branches and branches exhibiting less than 5% vessel diameter reduction. Three features are identified that are of importance in the interpretation of ultrasonic Doppler velocity information and in the design of engineering flow models for evaluation of carotid branch hemodynamics: the variability of the bifurcation angles, the degree of tortuosity, and the nonplanar nature of the branches. In addition, data collected demonstrate the potential usefulness of the common carotid artery as a reference diameter in evaluating stenosis of the carotid bulb... |
| Title |
Geometrical spectrum broadening in ultrasonic Doppler systems. |
| Author |
Newhouse VL, Varner LW, Bendick PJ. |
| Journal |
IEEE Trans Biomed Eng |
| Volume |
|
| Year |
1977 |
| Abstract |
The bandwidth of the output spectrum of blood flow meters may prove of value in estimating flow parameters such as the degree of turbulence. It is therefore important to determine the various factors which affect this bandwidth. It is shown that scatterers moving in the near field of the sound beam generated by a single transducer ultrasound Doppler system produce a spectrum whose breadth is primarily determined by the range of angles over which backscattered ultrasound is received by the transducer. An empirical method of calculating the bandwidth of the output spectrum is described, and the results are compared with direct Doppler measurements. Since the spectrum broadening depends on the angle between the target path and the ultrasound beam, it is suggested that the phenomenon may be usable to provide an independent measure of this angle. |
| Title |
Glycine and alanine synthesis from formaldehyde and hydroxylamine in the field of ultrasound waves. |
| Author |
Sokolskaya A. |
| Journal |
Orig Life |
| Volume |
|
| Year |
1976 |
| Abstract |
High intensity ultrasound waves coupled with other form of energy obviously were initiators of pre-biochemical reactions; these reactions occurred in the water masses of the primordial Earth. Essential biological substances like formaldehyde,.ammonia, hydrocyanic acid, and amino acids compounds similar to carbohydrates by their properties were synthesized in the field of ultrasound waves in model experiments. The main partners of these reactions are water and gases of reductional atomosphere: hydrogen, carbon monoxide, methane, nitrogen and argon. Formation of amino acids takes place in aqueous solutions of formaldehyde and hydroxylamine. The sonication yielded alanine and glycine, 2.0 X 10(-7) and 1.8 X 10(-7) molecules per 100 eV respectively. |
| Title |
Granulocyte colony-stimulating factor facilitates the angiogenesis induced by the ultrasonic microbubble destruction. |
| Author |
Miyake Y, Ohmori K, Yoshida J, Ishizawa M, Mizukawa M, Yukiir K, Kohno M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2007 |
| Abstract |
Ultrasonic destruction of microbubbles (US/MB) in the microcirculation causes local inflammatory cell infiltration, which has been shown to induce angiogenesis. Granulocyte colony-stimulating factor (G-CSF), which mobilizes myelomonocytic cells from the bone marrow and enhances vascular endothelial growth factor (VEGF) release from these cells, has also been applied to therapeutic angiogenesis induction. In the present study, we sought to examine the potential of G-CSF pretreatment to enhance the angiogenic effect of US/MB. Ischemic hindlimbs in mice were treated with either a predetermined minimal effective dose (300 μg/kg) of G-CSF, US/MB alone or G-CSF pretreatment followed by US/MB at seven days after removal of the femoral artery. Ultrasonic destruction of microbubbles was performed as intermittent pulsed local insonation using a diagnostic ultrasound scanner at a peak negative pressure of 1.4 MPa after intravenous injection of perfluorocarbon microbubbles. At 21 days after the treatment, we quantified the surface vascularity using a grid method and the capillary density using an alkaline phosphatase stain. Relative to the capillary density in normal muscle, the capillary density in the treated limbs was restored to 74 ± 13% by G-CSF alone and 90 ± 20% by US/MB alone (p < 0.05 vs. both untreated and G-CSF alone), and further increased to 101 ± 21% by G-CSF pretreatment. The collateral growth induced by the combination of G-CSF pretreatment and US/MB was 2.8- and 1.4-fold greater than the growth induced by G-CSF alone and US/MB alone, respectively (p < 0.05 for both). Thus, pretreatment with a single minimal effective dose of G-CSF can augment the angiogenic effect of US/MB. |
| Title |
Granulocyte colony-stimulating factor facilitates the angiogenesis induced by ultrasonic microbubble destruction. |
| Author |
Miyake Y, Ohmori K, Yoshida J, Ishizawa M, Mizukawa M, Yukiiri K, Kohno M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2007 |
| Abstract |
Ultrasonic destruction of microbubbles (US/MB) in the microcirculation causes local inflammatory cell infiltration, which has been shown to induce angiogenesis. Granulocyte colony-stimulating factor (G-CSF), which mobilizes myelomonocytic cells from the bone marrow and enhances vascular endothelial growth factor (VEGF) release from these cells, has also been applied to therapeutic angiogenesis induction. In the present study, we sought to examine the potential of G-CSF pretreatment to enhance the angiogenic effect of US/MB. Ischemic hindlimbs in mice were treated with either a predetermined minimal effective dose (300 μg/kg) of G-CSF, US/MB alone or G-CSF pretreatment followed by US/MB at seven days after removal of the femoral artery. Ultrasonic destruction of microbubbles was performed as intermittent pulsed local insonation using a diagnostic ultrasound scanner at a peak negative pressure of 1.4 MPa after intravenous injection of perfluorocarbon microbubbles. At 21 days after the treatment, we quantified the surface vascularity using a grid method and the capillary density using an alkaline phosphatase stain. Relative to the capillary density in normal muscle, the capillary density in the treated limbs was restored to 74 ± 13% by G-CSF alone and 90 ± 20% by US/MB alone (p < 0.05 vs. both untreated and G-CSF alone), and further increased to 101 ± 21% by G-CSF pretreatment. The collateral growth induced by the combination of G-CSF pretreatment and US/MB was 2.8- and 1.4-fold greater than the growth induced by G-CSF alone and US/MB alone, respectively (p < 0.05 for both). Thus, pretreatment with a single minimal effective dose of G-CSF can augment the angiogenic effect of US/MB. |
| Title |
Gray scale echography of soluble protein and protein aggregate fluid collections (in vitro study). |
| Author |
Cunningham JJ, Wooten W, Cunningham MA |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1976 |
| Abstract |
Soluble protein fluid collections ranging from 0.5 to 21 gm/100 ml and collections of protein microaggregates with a particle size less than 700 microns are indistinguishable from water when these collections are examined qualitatively by gray scale echography in a laboratory setting. Echography of protein macroaggregate collections of 1-3 mm particle size gives rise to images.showing strong internal echoes and poor margin definition and may simulate solid structures. Protein macroaggregates may be the source of error when complex biological fluids simulate solid lesions on gray scale echograms. |
| Title |
Gray scale ultrasonography in the diagnosis of thyroid swellings. (work in progress) |
| Author |
Taylor KJW, Carpenter DA, Barrett JJ. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1974 |
| Abstract |
Thyroid masses which fail to concentrate radioactive iodine may be benign or malignant cysts or solid tumors. A-scan examination through any thyroid mass permits the differentiation of a solid from a cystic consistency. The nature of solid masses is difficult to determine using the conventional B-scan ultrasound equipment. Our experience to date suggests that the difficulty can be resolved by the use of high quality gray-scale techniques which display the structure of normal glandular tissue, while malignant replacement is apparent as defects in this normal anatomy. The size and site of the thyroid implies that greatly improved resolution could be obtained by scanners dedicated to the examination of small superficial organs. |
| Title |
Growth and development of mice exposed in utero to ultrasound. |
| Author |
Stratmeyer ME, Simmons LR, Pinkavitch FZ. |
| Journal |
Proc Symp Biol Eff Character Ultrasound Sour |
| Volume |
|
| Year |
unknown (late 1970's) |
| Abstract |
Perhaps the broadest and most common use of diagnostic ultrasound, both pulsed (B-scan imaging) and continuous wave (Doppler fetal detection and monitoring) is in the field of obstetrics and gynecology. The extent of use of diagnostic ultrasound devices during pregnancy and the recognized susceptibility of the conceptus to a variety of insults necessities and assessment of the potential risk associated with in utero ultrasound exposure. To facilitate such an assessment, an automated ultrasonic exposure system was developed at the Bureau of Radiological Health that would allow precise, reproducible exposures of biological specimens (12). Some of the effects observed in mice exposed in utero to continuous wave ultrasound in this facility include early postpartum morality (3) and reduced fetal weight (4). The purpose of the ongoing experiment is to further identify the effects of continuous wave ultrasound on the growth and development of mice exposed in utero by measuring gross morphological endpoints. It is intended to use the resulting information to examine for more specific and more sensitive endpoints in future work. |
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