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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 221 out of 330
| Title |
Role of pulse repetition frequency and exposure duration on the superthreshold behavior of ultrasound-induced lung hemorrhage in adult mice and rats. |
| Author |
O'Brien WD Jr Frizzell LA Schaeffer DJ Zachary JF. |
| Journal |
Proc Ultrason Symp IEEE |
| Volume |
|
| Year |
2000 |
| Abstract |
Superthreshold behavior for ultrasound-induced lung haemorrhage was investigated in 150 mice and 150 rats at 2.8 MHz to assess the role of pulse repetition frequency (PRF) and exposure duration (ED). Each species was divided into 15 exposure groups (10 per group) for a 3?5 randomized factorial design (3 EDs of 5, 10 and 20 s; and 5 PRFs of 25, 50, 100, 250 and 500 Hz). The in situ peak rarefactional pressure (12.3 MPa) and pulse duration (1.42 μs) were the same for all ultrasonically exposed animals. Also, for both species, 15 sham-exposed animals were randomized into both studies, none of which had lesions. Factorial analysis of variance was used to evaluate effects of PRF and ED on the proportion of lesions, lesion depth and lesion surface area. The proportion of lesions in both species was related statistically to PRF and ED, with the exception that PRF in rats was not quite significant. The PRF, but not ED, significantly affected lesion depth in both species. Both PRF and ED significantly affected lesion surface area in mice, while neither affected area in rats. The PRF?ED interaction (number of pulses) for these measures was not significant for either species. Species significantly affected lesion production and size; there were fewer lesions in mice, and the lesion size was greater in rats. The characteristics of the lesions produced in both species were similar to those described in studies by our research group and others, suggesting a common pathogenesis for the initiation and propagation of the lesions at the gross and microscopic levels. |
| Title |
Role of thermal mechanisms in the alteration of nervous system by ultrasound. |
| Author |
Lele PP, Hsu W. |
| Journal |
Proc Twenty-third ACEMB - Washington D.C. |
| Volume |
|
| Year |
1970 |
| Abstract |
No abstract available. |
| Title |
Role of ultrasonic shear rate estimation errors in assessing inflammatory response and vascular risk. |
| Author |
Tsou JK, Liu J, Barakat AI, Insana MF. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2008 |
| Abstract |
Atherosclerotic lesions preferentially originate in arterial regions that experience low wall shear stress (WSS) and reversing flow patterns. Therefore, routinely monitoring arterial WSS may help to identify the potential sites of early atherosclerosis. A new noninvasive ultrasonic method implemented with coded excitation techniques was utilized to improve WSS estimation accuracy and precision by providing high spatial and temporal resolution. WSS measurement errors were quantified in a model system by scanning a linearly varying WSS field (0.3 to 1.9 Pa) within a flow chamber. A 13-bit optimal code (Opt) was found to be most effective in reducing bias and standard deviation in WSS estimates down to approximately 10% and approximately 8%. The measurement errors slowly increased with input WSS for all imaging pulses. The expression of endothelial cellular adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and endothelial-leukocyte adhesion molecule-1 (E-selectin) was investigated over a similar shear range (0 to 1.6 Pa) to study the impact of relating shear-mediated cellular adhesion molecule (CAM) expression to inaccuracies in WSS measurements. We quantified this influence as the prediction error, which accounts for the ultrasonic measurement errors and the sensitivity of CAM expression within certain shear ranges. The highest prediction errors were observed at WSS <0.8 Pa, where CAM expression is most responsive to WSS. The results emphasize the importance of minimizing estimation errors, especially within low shear regions. Preliminary two-dimensional in vivo shear imaging is also presented to provide information about the spatial heterogeneity in arterial WSS distribution. |
| Title |
Role of ultrasound in obstetrics and gynecology. |
| Author |
Doust BD. |
| Journal |
Hosp Pract |
| Volume |
|
| Year |
1973 |
| Abstract |
The indications for ultrasound in obstetrics and gynecology are diverse; they include the diagnosis of pregnancy at as early as five or six weeks, determining that fetal death or growth retardation has occurred, locating a missing IUD, ruling placenta previa out (or in), among others. Innocuous and easily repeatable, the technique is rapidly gaining new adherents and new uses -- in a variety of disciplines. |
| Title |
Routine ultrasonography in utero and school performance at age 8-9 years. |
| Author |
Salvesen KA, Bakketeig LS, Eik-nes SH, Undheim JO, Okland O. |
| Journal |
Lancet |
| Volume |
|
| Year |
1992 |
| Abstract |
Most fetuses in developed countries are exposed in utero to diagnostic ultrasound examination. Many pregnant women express concern about whether the procedure harms the fetus. Since most routine ultrasound examinations are done at weeks 16-22, when the fetal brain is developing rapidly, effects on neuronal migration are possible. We have sought an association between routine ultrasonography in utero and reading and writing skills among children in primary school. At the age of 8 or 9 years, children of women who had taken part in two randomised, controlled trials of routine ultrasonography during pregnancy were followed-up. The women had attended the clinics of 60 general practitioners in central Norway during 1979-81. The analysis of outcome was by intention to treat: 92% of the "screened" group had been exposed to ultrasound screening at weeks 16-22, and 95% of controls had not been so exposed, but there was some overlap. 2428 singletons were eligible for follow-up, and the school performance of 2011 children (83%) was assessed by their teachers on a scale of 1-7; the teachers were unaware of ultrasound exposure status. A subgroup of 603 children underwent specific tests for dyslexia. There were no statistically significant differences between children screened with ultrasound and controls in the teacher-reported school performance (scores for reading, spelling, arithmetic, or overall performance). Results from the dyslexia test sample showed no differences between screened children and controls in reading, spelling, and intelligence scores, or in discrepancy scores between intelligence and reading or spelling. The test results classified 21 of the 309 screened children (7% [95% confidence interval 3-10%]) and 26 of the 294 controls (9%.[4-12%]) as dyslexic. The risk of having poor skills in reading and writing was no greater for children whose mothers had been offered routine ultrasonography than for those whose mothers had not been offered the procedure. |
| Title |
Safety and long-term effects of ultrasound: what to tell your patients. |
| Author |
Kremkau FW. |
| Journal |
Clin Obstet Gynecol |
| Volume |
|
| Year |
1984 |
| Abstract |
No abstract available |
| Title |
Safety and potential hazards in the current applications of ultrasound in obstetrics and gynecology. |
| Author |
Lele PP. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1979 |
| Abstract |
The safety and potential hazards in the current applications of ultrasound in obstetrics and gynecology are discussed. The author has made an attempt to provide a perspective to enable interpretation of future experimental results in terms of health hazards for humans. |
| Title |
Safety code 23: guidelines for the safe use of ultrasound part I ; medical and paramedical applications. |
| Author |
Environmental Health Directorate Health Protection Branch. |
| Journal |
Rep Monister of Natl Health and Welfare |
| Volume |
|
| Year |
1980 |
| Abstract |
No abstract available. |
| Title |
Safety code 24: guidelines for the safe use of ultrasound Part II - industrial and commercial applications. |
| Author |
Environmental Health Directorate Health Protection Branch. |
| Journal |
Rep Monister of Natl Health and Welfare |
| Volume |
|
| Year |
1980 |
| Abstract |
No abstract available. |
| Title |
Safety considerations for diagnostic ultrasound. |
| Author |
Bioeffects committee of the American Institute of Ultrasound in Medicine; chaired by Frizzell LA. |
| Journal |
Rep AIUM |
| Volume |
|
| Year |
1984 |
| Abstract |
No abstract available. |
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