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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 302 out of 330
| Title |
Ultrasound and microbubbles: Their generation, detection and potential utilization in tissue and organ therapy--experimental. |
| Author |
Fry FJ, Sanghvi NT, Foster RS, Bihrle R, Hennige C. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1995 |
| Abstract |
Ultrasound-induced cavitation in tissue and organs has been well recognized and documented. Generally, this phenomenon has been seen as something to be avoided except in cases such as lithotripsy, where its production is considered an essential part of the treatment process or as a desirable contrast media in some areas of visualization enhancement. This article covers three areas in which the phenomenon has been observed, and shows how the effect can or may be therapeutically beneficial. Studies in the pig show that implanted human gallstones and the gallbladder itself can be eliminated in a nonsurgical procedure using ultrasound-induced cavitation in the gallbladder. In the dog brain, relatively stable cavitation-induced microbubbles have been transported through the vascular system to regions outside a focal seeding site. These bubbles produce ablation of tissue volumes at a remote site when irradiated with appropriate ultrasound. The cavitation phenomenon has been observed in the dog and human prostate. In the human prostate, microbubbles transported from ultrasound-induced focal seeding sites can be readily visualized with ultrasound and may be potentially useful under controlled conditions in tissue debulking for the treatment of benign prostatic hyperplasia (BPH). A similar microbubble transport has not been seen in the dog prostate under similar ultrasound treatment parameters. The ability to detect cavitation-induced microbubbles, follow their transportation through the vascular system and excite them at the appropriate time and place provides interesting possibilities for therapy. Of course, the entire microbubble process can be avoided by working below the cavitation threshold, thereby using only the absorption of ultrasound in tissue to produce focal thermal lesions. The term microbubble is used here in the context of those bubbles which can be transported in the vascular system down to vessels diameters below the 100-microns range. This is the vessel size in the vascular field into which microbubbles are transported and can be both visualized as well as disrupted with ultrasound. |
| Title |
Ultrasound and phakometry measurements of the primate eye. |
| Author |
Young FA, Leary GA, Farrer DN |
| Journal |
Am J Optom Arch Am Acad Optom |
| Volume |
|
| Year |
1966 |
| Abstract |
No abstract available. |
| Title |
Ultrasound and plantar warts: a double blind study. |
| Author |
Braatz JH, McAlistar BR, Broaddus MD. |
| Journal |
Mil Med |
| Volume |
|
| Year |
1974 |
| Abstract |
No abstract available. |
| Title |
Ultrasound and scintigraphy in the differential diagnosis of obstructive jaundice. |
| Author |
Taylor KJW, Carpenter DA, McCready VR. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1974 |
| Abstract |
Eight cases of obstructive jaundice are described to illustrate how diagnostic ultrasonography may be used to differentiate between intra- and extrahepatic jaundice, especially in patients with malignancy. Ultrasound can also provide accurate anatomical localization of the tumor site and can reveal the cause of the obstruction. The ultrasound results are compared with the isotopic findings. Cold areas in the scintigram caused by dilatation of the biliary tree may be misinterpreted. The ability of ultrasound to differentiate between solid and cystic tumors produces more diagnostic data than can be obtained by isotopic scanning. Because of the limitations of radiological procedures in the deeply jaundiced patient, ultrasound is the method of choice for initial investigations. |
| Title |
Ultrasound and spermatogenesis in the rat. |
| Author |
Urry RL, Dougherty KA, Child SA, Fernandez F, Linke CA, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1988 |
| Abstract |
Using exposure conditions comparable to those which have been associated by.others with positive results, we tested for effects of ultrasound on sperm.production over a period of 12 weeks following treatment. Continuous wave.exposure with spatial average intensities of 1, 2 and 4 W/cm2 and exposure times.up to 10 minutes were used. In some experiments, the exposures were repeated.after an elapsed time of 48 h. No significant changes in spermatogenesis were.related to any of the exposure conditions in spite of the fact that some of the.treatments caused thermal tissue damage near bone. No effects of exposure were.found in weights of the testis, prostate, seminal vesicle, or whole body. |
| Title |
Ultrasound and the ultramicroscopic structure of Rhizopus nigricans. |
| Author |
Hrazdira I, Havelkova M. |
| Journal |
Naturwissenschaften |
| Volume |
|
| Year |
1966 |
| Abstract |
No abstract available. |
| Title |
Ultrasound as an approach to assessing body composition. |
| Author |
Fanelli MT, Kuczmarski RJ. |
| Journal |
Am J Clin Nutr |
| Volume |
|
| Year |
1984 |
| Abstract |
Body composition is an important indicator of nutritional status. The most commonly used indirect method for estimating body fat is based on measurements of.subcutaneous fat tissue. It has been suggested that ultrasonic measurements may be more precise than those of the caliper and therefore may yield more accurate.measures of subcutaneous fat tissue. This study was designed to correlate ultrasonic and caliper measurements of subcutaneous fat with body density determined by.hydrostatic weighing. Subcutaneous fat thickness was measured at seven body sites (triceps, biceps, subscapula, waist, suprailiac, thigh, and calf) with a Lange.skinfold caliper and an ADR ultrasonic scanner, equipped with a display-screen, 7MHz transducer, and electronic calipers. Regression equations to predict body.density, and hence body fat, were derived for each technique using a minimal number of body sites. The sample consisted of 124 white men, aged 18 to 30 yr. Mean.body density determined by hydrostatic weighing was 1.07 g/ml (SD +/- 0.01) and mean body fat was 12.7% (SD +/- 5.8). Both ultrasonic and caliper.measurements of waist, thigh, and triceps had the highest correlation with body density. Regression equations using these three sites in all possible two-site.combinations were derived for each technique. The predictions of body density from these equations did not differ significantly. These results suggest that in.free-living, nonobese, white men, body fat can be estimated with nearly the same degree of accuracy using either the caliper or ultrasonic technique. . |
| Title |
Ultrasound assessment of angiogenesis in a matrigel model in rats. |
| Author |
Stieger SM, Bloch SH, Foreman O, Wisner ER, Ferrara KW, Dayton PA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2006 |
| Abstract |
Matrigel, a basement membrane extract, has been extensively used in in vivo angiogenesis. Contrast ultrasound imaging (CUI) of implanted Matrigel plugs with (+bFGF) and without basic fibroblast growth factor (−bFGF) was performed 7 and 14 d after implantation, followed by histologic analysis. Statistically significant differences between +bFGF and −bFGF plugs were apparent at d 7 in both plug size and contrast enhancement (both p < 0.05). Histopathology revealed differences in microvessel density (MVD) between +bFGF and −bFGF at d 7 and d 14. A significant correlation between MVD and both power Doppler contrast-enhanced area (r = 0.65, p < 0.05) and fraction of plug enhanced (r = 0.59, p < 0.05) was present. CUI of Matrigel plugs was shown to be a robust method for distinguishing between two different angiogenic states. Ultrasound measurements of blood flow in the plugs correlated with MVD, a histologic technique used to quantify tumor angiogenesis. (E-mail: smstieger@ucdavis.edu)
Key Words: Contrast ultrasound imaging; Angiogenesis; Matrigel; Tumor; Power Doppler; Rat |
| Title |
Ultrasound attenuation and backscatter in the liver during prednisone administration. |
| Author |
Lu ZF, Zagzebski JA, O'Brien RT, Steinberg H. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1997 |
| Abstract |
Ultrasound attenuation and backscatter changes resulting from glucocorticoid administration were investigated in a dog model. Ten beagle dogs were randomized into two groups: five were given 2 mg/kg/day IM injections of prednisone to induce steroid hepatopathy and five served as controls. Histology showed vacuolization in most hepatocytes of treated animals on the third day of treatment, and larger, midzonally distributed vacuoles from day 7 on. An increase in both ultrasonic attenuation and backscatter was observed in treated dogs during in vivo measurements. Pooled data from the two groups suggest that attenuation elevations precede backscatter changes. Attenuation was significantly higher in the treated animals than in the controls by day 7. Both attenuation and backscatter were significantly higher in livers of treated than untreated dogs when measured by direct application of the transducer on the liver following euthanasia. We conclude that attenuation and backscatter coefficients can detect early changes in the liver associated with steroid hepatopathy. This may be a useful model to investigate detection of diffuse liver disease with ultrasound tissue characterization. |
| Title |
Ultrasound attenuation estimation using backscattered echoes from multiple sources. |
| Author |
Bigelow TA. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2008 |
| Abstract |
The objective of this study was to devise an algorithm that can accurately estimate the attenuation along the propagation path (i.e., the total attenuation) from backscattered echoes. It was shown that the downshift in the center frequency of the backscattered ultrasound echoes compared to echoes obtained in a water bath was calculated to have the form Deltaf=mf(o)+b after normalizing with respect to the source bandwidth where m depends on the correlation length, b depends on the total attenuation, and f(o) is the center frequency of the source as measured from a reference echo. Therefore, the total attenuation can be determined independent of the scatterer correlation length by measuring the downshift in center frequency from multiple sources (i.e., different f(o)) and fitting a line to the measured shifts versus f(o). The intercept of the line gives the total attenuation along the propagation path. The calculations were verified using computer simulations of five spherically focused sources with 50% bandwidths and center frequencies of 6, 8, 10, 12, and 14 MHz. The simulated tissue had Gaussian scattering structures with effective radii of 25 mum placed at a density of 250 mm(3). The attenuation of the tissue was varied from 0.1 to 0.9 dB / cm-MHz. The error in the attenuation along the propagation path ranged from -3.5+/-14.7% for a tissue attenuation of 0.1 dB / cm-MHz to -7.0+/-3.1% for a tissue attenuation of 0.9 dB / cm-MHz demonstrating that the attenuation along the propagation path could be accurately determined using backscattered echoes from multiple sources using the derived algorithm. |
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