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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 318 out of 330
| Title |
Ultrasound tomography of the adult brain. |
| Author |
von Ramm OT, Smith SW, Kisslo JA. |
| Journal |
Proc Twenty-second Annu Meet AIUM |
| Volume |
|
| Year |
1977 |
| Abstract |
No abstract available. |
| Title |
Ultrasound transducers for pulse-echo medical imaging. |
| Author |
Hunt JW, Arditi M, Foster FS. |
| Journal |
IEEE Trans Biomed Eng |
| Volume |
|
| Year |
1983 |
| Abstract |
The transducer is probably the single most important component of any ultrasonic imaging system. A basic introduction to the problems and paradoxes of transducer design is given. After introducing the piezoelectric equations and discussing important transducer material such as lead zirconate titanate and polyvinylidene difluoride, the techniques for modeling the electromechanical impulse response are reviewed. Quarter-wave matching and short pulse techniques are discussed. The prediction of the ultrasound field of plane, spherical, and conical transducers is reviewed with emphasis on the spatio-temporal impulse response technique. Finally, the use of the above approaches is illustrated in a very practical fashion for three interesting transducer geometries: (1) a split aperture device with two focal lengths, (2) a five-element annular array, and (3) a 37.5 degree conical/annular array hybrid transducer. |
| Title |
Ultrasound transmission and reflection computerized tomography for imaging bones and adjoining soft tissues. |
| Author |
Sehgal CM, Lewallen DG, Nicholson JA, Greenleaf JF. |
| Journal |
Proc IEEE Ultrasonic Symposium |
| Volume |
|
| Year |
1988 |
| Abstract |
Several attempts have been made in the past to use ultrasound to characterize properties of normal, diseased, and injured bones. The majority of these studies were carried out by using two transducers to measure sound speed and attenuation along the propagation path, i.e., the axis joining the two transducers. The use of such techniques for measuring changes in tissue state, though successful, encounters two major problems. Firstly, it is difficult to compensate for overlying soft tissue and secondly, the sites of measurements at the different healing times may not be identical. These problems can be overcome to a great extent by three-dimensional imaging with the aid of computerized tomography. In this paper, an ultrasonic imaging system that simultaneously collects
attenuation, time of flight, and backscatter data from multiple views to make tomographic images is described. By using eighty such cross sections, three-dimensional images of turkey and dog limbs are constructed. The images are of high quality and provide detailed information on geometry and nature of structures that constitute bone and surrounding soft tissue. Also, these images reveal topological information of regions of interest without shadow and artifacts, and thus provide a distinct advantage over conventional single line methods for measuring tissue properties. |
| Title |
Ultrasound transmission in tissue visualization. |
| Author |
Fry Wj, Fry FJ, Kelly E, Fry TA, Leichner GH. |
| Journal |
Diagn Ultrasound |
| Volume |
|
| Year |
1966 |
| Abstract |
No abstract available. |
| Title |
Ultrasound transmission tomography image distortions caused by the refraction effect. |
| Author |
Opielinski KJ, Gudra T. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
2000 |
| Abstract |
This paper presents the influence of ultrasonic beam ray refraction effect on the internal object structure imaging using the ultrasound transmission tomography method (UTT), in parallel ray projection geometry, for ultrasonic pulse run-time measurements. Simulation calculations carried out using specially elaborated software were verified experimentally by means of real measurements on a research set-up for UTT. Simple ways to minimize image distortions caused by the refraction effect were also suggested. |
| Title |
Ultrasound treatment of Meniere's disease. Long-term.follow-up of 356 advanced cases. |
| Author |
Stahle J. |
| Journal |
Acta Otolaryngol |
| Volume |
|
| Year |
1976 |
| Abstract |
Twelve years' experience of ultrasound treatment of 356 patients is presented. For evaluating the.results a new multifacetted scoring system was developed, where each individual patient was.evaluated on the basis of four parameters. According to this evaluation 71% of the patients.improved after the operation, while 29% remained unchanged or deteriorated. Because of lack of.improvement, 42 patients underwent reoperation by different methods; in half of them ultrasonic.irradiation was again used. The hearing deteriorated in about 40% of the patients, to which result.the long observation times also contributed. The caloric response became reduced in 70% of the.patients. Marked depression of the caloric response characterized the patients who were relieved.of vertigo. Transient facial paralysis in 4 patients was the only complication. |
| Title |
Ultrasound treatment to reduce extracorporeal shock-wave lithotripsy ( ESWL® )-generated fragments:In vitro results. |
| Author |
Griffith SL,Snoddy AM,Pauletzski SJ, Fry FJ,Franklin TD Jr. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1990 |
| Abstract |
The initial result of biliary extracorporeal shock-wave lithotripsy ( ESWL® ) is multiple gallstone fragments in the gallbladder. Therapeutic ultrasound has been evaluated in this study in an attempt to reduce the burden of ESWL-generated fragments bathed in human bile in vitro system. Four different ultrasound SPTP intensities (3.0,6.0,9.0 and 18 W/cm2) were utilized to identify the lowest optimal effective intensity. Mass reduction ranged from 7.33 +/- 10.41 mg/2 hrs. (n=3) for 3.0 W/cm2 to 353+/- 64.10 mg/2 hrs. (n=5) for 18.0 W/cm2 when an initial mass of 0.5g was employed. Exposure of 0.5g fragment burdens to 6.0, 9.0 and 18.0 W/cm2 (SPTP) for a total of 4hrs. resulted in an intensity-dependent reduction in mass. Three initial fragments burdens were selected to further investigate the kinetics of the process. Mass reductions of 111.48 +/- 38.00 mg/hr. (n=7), 245.90 +/- 52.70mg/hr. (n=5), and 310.10+/- 117.80 mg/hr. (n=5) were achieved for 0.5g, 1.5g, and 3.0g initial fragment burdens, respectively, when exposed to 18.0 W /cm2 for a total elapsed time of 4 hrs.
These data suggest that therapeutic ultrasound could be used as a post-treatment adjunct to ESWL to reduce the mass of retained biliary fragments, thus inherently shortening the time necessary for the patient to be stone-free. This study also demonstrates that he reduction in mass achieved is dependent upon the initial fragment burden as well as ultrasonic intensity.
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| Title |
Ultrasound velocity and attenuation of porcine soft tissues with respect to structure and composition: I. Muscle. |
| Author |
Koch T, Lakshmanan S, Brand S, Wicke M, Raum K, Mörlein D. |
| Journal |
Meat Sci |
| Volume |
|
| Year |
2011 |
| Abstract |
Ultrasound velocity and attenuation of soft tissues have been widely investigated. However, few studies completely covered considerable variations of both, structure and composition. The aim of this study was to collect acoustic reference data of porcine Longissimus muscle and associate them with compositional traits. In addition, measurements were conducted on fresh, formalin fixed, and frozen-thawed samples to evaluate the effect of processing on ultrasound parameters and comparisons with earlier investigations. Measurement conditions (temperature and fibre orientation) were realised close to hanging carcasses conditions. Sound velocity ranged from 1617 ± 6 to 1622 ± 5 ms(-1), while attenuation mostly ranged from 1.0 ± 0.3 to 1.2 ± 0.3 dB MHz(-1)cm(-1). Only formalin fixed samples showed significantly higher attenuation (2.2 ± 0.6 dB MHz(-1)cm(-1)). Highest correlations have been observed between intramuscular fat and attenuation (up to r = .7). The obtained results are anticipated to improve ultrasound based estimation of the intramuscular fat of pig muscle on intact carcasses. |
| Title |
Ultrasound velocity in fixed human liver: Empirical anova and regression modelling on histologically assessed abnormalities. |
| Author |
Zimmermann KP, Smith JC. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
1983 |
| Abstract |
Anova and "dummy variables" least squares regression methods are used to investigate the dependence of ultrasound propagation velocity on the presence or absence of fat and on the rank ordered level of cirrhosis in fixed human liver. Cirrhosis is found to affect velocity in a nonlinear fashion, while fat depresses the velocities toward lower values. Quantifications of these effects and statistical analyses of their magnitudes are presented. The results represent a contribution toward the empirical understanding of the effects of tissue abnormalities on the velocity of ultrasound propagation in fixed human tissues. |
| Title |
Ultrasound velocity in major bovine blood vessel walls. |
| Author |
Shung KK, Reid JM. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1978 |
| Abstract |
Data on ultrasound velocity, compressibility. and specific acoustic impedance in bovine aorta, pulmonary artery, vena cava, and myocardium are reported and analyzed based on amounts of structural proteins present in these tissues. |
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