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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 300 out of 330
| Title |
Ultrasound characterization of red blood cell aggregtion with intervening attenuating tissue-mimicking phantoms. |
| Author |
Franceschini E,Yu FTH,Destrempes F. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2010 |
| Abstract |
The analysis of the ultrasonic frequency-dependent backscatter coefficient of aggregating red blood cells reveals information about blood structural properties. The difficulty in applying this technique in vivo is due to the frequency-dependent attenuation caused by intervening tissue layers that distorts the spectral content of signals backscattered by blood. An optimization method is proposed to simultaneously estimate tissue attenuation and blood structure properties, and was termed the structure factor size and attenuation estimator (SFSAE). An ultrasound scanner equipped with a wide-band 25 MHz probe was used to insonify porcine blood sheared in both Couette and tubular flow devices. Since skin is one of the most attenuating tissue layers during in vivo scanning, four skin-mimicking phantoms with different attenuation coefficients were introduced between the transducer and the blood flow. The SFSAE gave estimates with relative errors below 25% for attenuations between 0.115 and 0.411 dBMHz and kR<2.08 (k being the wave number and R the aggregate radius). The SFSAE can be useful to examine in vivo and in situ abnormal blood conditions suspected to promote pathophysiological cardiovascular consequences. |
| Title |
Ultrasound "sees" tumors. |
| Author |
Ewing A. |
| Journal |
Sci News Lett |
| Volume |
|
| Year |
1965 |
| Abstract |
Photographs of the pattern of reflected ultrasound waves introduced into the brain and displayed on an oscilloscope can help detect mass lesions in the brain. |
| Title |
Ultrasound : Propagation in aqueous medium, generation of free radicals and the safety of its biomedical and other applications. |
| Author |
Chatterjee SN. |
| Journal |
PINSA |
| Volume |
|
| Year |
1999 |
| Abstract |
A brief introductory account of the nature, mode of propagation in aqueous medium and diverse beneficial uses of ultrasound has been included with a view to presenting the main theme of this review in the proper context for the readers belonging to different disciplines of the biomedical sciences. Production of cavitation, both stable and transient, and the basic mechanism of production of free radicals within the aqueous medium subjected to the exposure to ultrasound of different frequencies have been explained with supporting experimental data. Up to date research findings on the harmful effects of ultrasound on the biomolecules, cells, tissues, animals and humans (including the possible teratogenic and embryotoxic effects) have been reviewed. The role of free radicals generated by ultrasound in the causation of biological damage, in vitro and also in vivo, has been critically analysed in the context of the available experimental data. The paucity of experimental data in the literature on the long term effects of ultrasound on animals and humans has been highlighted and the need for further research in this line emphasized. The basic mechanisms of causing biological damage by ultrasound have been analysed and several recommendations put forward toward adopting or evolving safety measures
against human exposures to ultrasound. In the context of all the positive and negative information presented here, this review advocates that any indiscreet and/or avoidable-use of ultrasound in human diagnosis and therapy and in any of its applications involving human beings should be discontinued now onwards as a precautionary measure.
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| Title |
Ultrasound a useful adjunct to breast mammography. |
| Author |
Pearce RB. |
| Journal |
Diagn Imaging |
| Volume |
|
| Year |
1986 |
| Abstract |
No abstract available. |
| Title |
Ultrasound absorption in mixtures of triethylamine with carboxylic acids. |
| Author |
Bobik M. |
| Journal |
Adv Mol Relax Proc |
| Volume |
|
| Year |
1977 |
| Abstract |
Ultrasound absorption spectra have been measured in the frequency range of 5-60 MHz for binary mixtures of triethylamine with acetic, propionic, trifluoroacetic, and 2,2-dimethylpropionic acids. One acid relaxation, the rotational relaxation of the amine, and 3 different complex relaxations could be found. These 3 relaxations may be attributed to a 1:1, a 2:1, and a 3:1 (acid:amine) aggregate, though bond orientation and stability may be very different. The coincidence of six coupled reactions makes a full evaluation of reaction rate constant and reaction enthalpy impossible. Besides estimates, a reaction rate constant could only be evaluated for the trifluoroacetic acid-triethylamine 1:1-complex, as in this case relaxations due to other complexes were absent... |
| Title |
Ultrasound acoustic stimulated emission for controlling thermal surgery. |
| Author |
Karjalainen T, Thierman JS, Kynynen K. |
| Journal |
Proc IEEE Ultrason Symp |
| Volume |
|
| Year |
1999 |
| Abstract |
Vibro-acoustography, a relatively new imaging modality, is applied to imaging ex vivo liver tissue from calves and New Zealand white rabbits. In the first series of experiments, calf liver tissue was heated while the USAE response and temperature were recorded. This demonstrated a strong temperature dependence of the USAE signal. In the second series of experiments lesions were created with focused ultrasound and then raster scanned in the focal plane by the two intersecting focused ultrasound fields. The FWHM of these USAE-amplitude scans correlates well with the lesion sizes measured in histological studies. This method successfully rendered high-resolution images of the necrosed lesions in the liver tissue. In addition, a correlation between the time after sonication and amplitude of the USAE response was observed. |
| Title |
Ultrasound acoustic stimulated emission for controlling thermal surgery. |
| Author |
Karjalainen T, Thierman JS, Kynynen K. |
| Journal |
Proc IEEE Ultrason Symp |
| Volume |
|
| Year |
1999 |
| Abstract |
Vibro-acoustography, a relatively new imaging modality, is applied to imaging ex vivo liver tissue from calves and New Zealand white rabbits. In the first series of experiments, calf liver tissue was heated while the USAE response and temperature were recorded. This demonstrated a strong temperature dependence of the USAE signal. In the second series of experiments lesions were created with focused ultrasound and then raster scanned in the focal plane by the two intersecting focused ultrasound fields. The FWHM of these USAE-amplitude scans correlates well with the lesion sizes measured in histological studies. This method successfully rendered high-resolution images of the necrosed lesions in the liver tissue. In addition, a correlation between the time after sonication and amplitude of the USAE response was observed. |
| Title |
Ultrasound activation of new drugs for killing cancer cells. |
| Author |
Tachibana K, Uchida T. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1998 |
| Abstract |
No abstract available. |
| Title |
Ultrasound and cells. |
| Author |
El'piner I. |
| Journal |
Sov Sci Rev |
| Volume |
|
| Year |
1972 |
| Abstract |
It is well known that ultrasound can destroy biological structures but hitherto its mode of action has not been understood with any degree of precision. The researches of the author and his co-workers have made available more detailed information on the effects of this form of energy on the fine structure of cells. Perhaps with the aid of this research tool a better understanding will be gained of the three-dimensional ultrastructure within the cell. |
| Title |
Ultrasound and chromosome aberrations. |
| Author |
Brock RD, Peacock WJ, Geard CR, Kossoff G, Robinson DE. |
| Journal |
Med J Aust |
| Volume |
|
| Year |
1973 |
| Abstract |
Human and marsupial whole blood and blood-medium mixtures were irradiated with various doses of 2.25 MHz ultrasound and gamma rays. Doses of ultrasonic irradiation orders of magnitude higher than those used for diagnostic studies produced very few chromosome aberrations. A large proportion of the chromosome aberrations observed were gaps, rather than true breaks. If gaps are excluded from the analysis, our data show no significant induction of chromosome damage by ultrasound. High doses of ultrasound did, however, cause mitotic inhibition. Although very little chromosome damage was observed, there is still the possibility of induced genetic damage which is undetectable at the cytological level; consideration of this possibility should be given in clinical applications. |
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