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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 50 out of 330
| Title |
Beam steering with linear arrays. |
| Author |
Von Ramm OT, Smith SW. |
| Journal |
IEEE Trans Biomed Eng |
| Volume |
|
| Year |
1983 |
| Abstract |
The principles and techniques of real-time imaging with phased array ultrasound scanners are reviewed. Topics include 1) the geometric optics of beam steering and focusing with a linear array in the transmit and receive modes; 2) limitations on image data acquisition due to ultrasound propagation velocity; 3) optical diffraction theory for linear arrays including effects of amplitude grating lobes. Limitations on the image quality of phased array imaging systems are also discussed, including 1) nonideal response of array transducers; 2) target ambiguities caused by phase error grating lobes; 3) refraction errors; 4) delay line design. Finally, an analysis is presented of current techniques for improving ultrasound image quality using phased array methods including phase compensation, spatial compounding, frequency compounding, and parallel processing. |
| Title |
Behavioral effects of prenatal exposure to pulsed-wave ultrasound in unanesthetized rats. |
| Author |
Fischer JE Jr, Acuff-Smith K, Schilling MA, Meyer RA, Smith NB, Moran MS, O'Brien WD Jr, Vorhees CV. |
| Journal |
Teratology |
| Volume |
|
| Year |
1996 |
| Abstract |
The present experiment examined the developmental neurotoxicity of pulsed-wave (pw) ultrasound in rats, using an exposure system designed to eliminate restraint or anesthesia from the exposure conditions. Pregnant Sprague-Dawley CD rats trained to remain immobile in a water-filled ultrasound exposure tank were scanned with 3-MHz pw ultrasound at spatial peak temporal average intensities (ISPTA) of 0, 2, 20, or 30 W/cm2 on embryonic days 4-20 for approximately 10 min/day. The data showed that such insonation produced no adverse effects on maternal weight gain or reproductive outcome, nor on the postnatal growth or survival of the offspring. No exposure-related alterations in behavioral development were observed in the offspring of rats scanned with pw ultrasound during gestation. In addition, there was no consistent evidence of an ultrasound-associated change in the adult offspring behaviors tested; i.e., no treatment effects were found on measures of locomotor activity, water maze learning, and acoustic startle reactivity. An effect on tactile startle was observed on some trials in the low exposure group male offspring, but this effect was neither dose dependent nor consistent with any other finding. Overall, these results indicate that the neurobehavioral development of rats was not altered by prenatal exposure to pw ultrasound at ISPTA levels of up to 30 W/cm2. |
| Title |
Behavioral teratologic effects of prenatal exposure to continuous-wave ultrasound in unanesthetized rats. |
| Author |
Vorhees CV, Acuff-Smith KD, Schilling MA, Fisher JE Jr, Meyer RA, Smith NB, Ellis DS, O'Brien WD Jr. |
| Journal |
Teratology |
| Volume |
|
| Year |
1994 |
| Abstract |
While there are no known risks associated with diagnostic ultrasound, uncertainty about the safety of prenatal ultrasound exposure remains. The purpose of the present experiment was to evaluate the behavioral teratogenic potential of continuous-wave (cw) ultrasound in rats, in the absence of maternal anesthesia or restraint. Pregnant CD rats, trained to remain immobile in a water-filled ultrasound exposure tank, were scanned with 3 MHz cw ultrasound at levels of 0, 2, 10, 20, or 30 W/cm2 ISPTA (spatial peak, temporal average intensity) on gestational days 4-20 for approximately 10 min/day. Offspring were examined postnatally for survival, growth, physical landmarks of development, behavioral development, and the adult functions of locomotor activity, learning and memory, and startle reactivity. No effects of prenatal ultrasound were found on maternal characteristics, offspring survival or growth, physical or behavioral landmarks of development, or adult.tests of passive avoidance or startle. Effects at the highest intensity were obtained on corner and side locomotor activity and in a multiple-T water maze on measures of errors of commission and time spent finding the goal. The results showed that prenatal cw ultrasound in rats can induce effects on some postnatal neurobehavioral functions at high exposure intensities (30 W/cm2), but at lower intensities (2-20 W/cm2) no consistent evidence of neurobehavioral effects was observed. |
| Title |
Beneficial effects of ultrasound on plants - a review. |
| Author |
Gordon AG. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1971 |
| Abstract |
A significantly beneficial effect of ultrasound can be produced in plant material, but it is clear that the causes of, and inconsistencies in, the effect are barely understood. |
| Title |
Benefits of ultrasound still outweigh risks. |
| Author |
Lewin PA, Goldberg BB. |
| Journal |
Diagn Imaging Int |
| Volume |
|
| Year |
1989 |
| Abstract |
No abstract available. |
| Title |
Beta-thromboglobulin release from human platelets after in vivo ultrasound irradiation. |
| Author |
Williams AR, Chater BV, Sanderson JH, Taberner DA, May SJ, Allen KA, Sherwood MR. |
| Journal |
Lancet |
| Volume |
|
| Year |
1977 |
| Abstract |
No abstract available. |
| Title |
Beyond cervical length: |
| Author |
McFarlin BL |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2015 |
| Abstract |
|
| Title |
Beyond cervical length: a pilot study of ultrasonic attenuation for early detection of preterm birth risk |
| Author |
McFarlin BL, Kumar V, Bigelow TA, Simpson DG, White-Traut RC, Abramowicz JS, O'Brien WD Jr. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2015 |
| Abstract |
The purpose of this study was to determine whether cervical ultrasonic attenuation could identify women at risk of spontaneous preterm birth. During pregnancy, women (n567) underwent from one to five transvaginal ultrasonic examinations to estimate cervical ultrasonic attenuation and cervical length. Ultrasonic data were obtained with a Zonare ultrasound system with a 5- to 9-MHz endovaginal transducer and processed offline. Cervical ultrasonic attenuation was lower at 17–21 wk of gestation in the SPTB group (1.02 dB/cm-MHz) than in the full-term birth groups (1.34 dB/cm-MHz) (p 5 0.04). Cervical length was shorter (3.16 cm) at 22–26 wk in the SPTB group than in the women delivering full term (3.68 cm) (p50.004); cervical attenuation was not significantly different at this time point. These findings suggest that low attenuation may be an additional early cervical marker to identify women at risk for SPTB. (E-mail: bmcfar1@uic.edu) |
| Title |
Bio-effects ultrasound under "low intensity" conditions. |
| Author |
Miller DL, Nyborg WL, Whitcomb CC. |
| Journal |
Ultrasound Med |
| Volume |
|
| Year |
1978 |
| Abstract |
No abstract available. |
| Title |
Biocidal mechanisms of saturated dialdehydes and their potentiation by ultrasound. |
| Author |
Boucher RMG, Last AJ, Smith DK. |
| Journal |
Proc West Pharmacol Soc |
| Volume |
|
| Year |
1973 |
| Abstract |
No abstract available. |
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