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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 164 out of 330
| Title |
Letter:Comments on 'On the mechanism of the photographic effect of ultrasound' by C.G. Stephanis, G.D. Hampsas, and D.A. Pittlinger. |
| Author |
Nyborg WL. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1982 |
| Abstract |
No abstract available. |
| Title |
Letter:Safety of ultrasound diagnosis. |
| Author |
Nyborg WL. |
| Journal |
Science |
| Volume |
|
| Year |
1974 |
| Abstract |
No abstract available. |
| Title |
Limited angle ultrasonic transmission tomography of the compressed female breast. |
| Author |
Krueger M, Burow V. Hiltawsky KM, Ermert H. |
| Journal |
Proc IEEE Ultrasonic Symposium |
| Volume |
|
| Year |
1998 |
| Abstract |
A modified ultrasonic time-of-flight tomography algorithm which the authors presented before (1996) is implemented in a system composed by a commercially available ultrasound scanner, a PC, and a special applicator which compresses the female breast like in X-ray mammography. An acquisition time of two minutes per frame was obtained and allows the clinical evaluation of the concept. The limited total angle leads to a coarse axial resolution and to artifacts. However, B-mode images which are stained with a color-coded representation of the reconstructed velocity and of the attenuation, respectively, can significantly improve breast diagnostics. In the work the authors present phantom and in vivo results of the time-of-flight mode to demonstrate the potentials of this method which is part of a new imaging concept, “CARISMA” (Computer Assisted Reconstructive Imaging by Sonographic and Mechano-Elastic Analysis). |
| Title |
Line and boundary detection in speckle images. |
| Author |
Czerwinski RN, Jones DL, O'Brien WD Jr. |
| Journal |
IEEE Trans Image Process |
| Volume |
|
| Year |
1998 |
| Abstract |
This paper considers the problem of detecting lines in speckle imagery, such as that produced by synthetic aperture radar (SAR) or ultrasound techniques. Using the physical principles that account for the speckle phenomenon, we derive the optimal detector for lines in fully developed speckle, and we compare the optimal detector to several suboptimal detection rules that are more computationally efficient. We show that when the noise is uncorrelated, a very simple suboptimal detection rule is nearly optimal, and that even in colored speckle, a related class of detectors can approach optimal performance. Finally, we also discuss the application of this technique to medical ultrasonic images, where the detection of tissue boundaries is considered as a problem of line detection. |
| Title |
Linear system models for ultrasonic imaging: Application to signal statistics. |
| Author |
Zemp RJ, Abbey CK, Insana MF. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
2003 |
| Abstract |
Linear equations for modeling echo signals from shift-variant systems forming ultrasonic B-mode, Doppler, and strain images are analyzed and extended. The approach is based on a solution to the homogeneous wave equation for random inhomogeneous media. When the system is shift-variant, the spatial sensitivity function-defined as a spatial weighting function that determines the scattering volume for a fixed point of time-has advantages over the point-spread function traditionally used to analyze ultrasound systems. Spatial sensitivity functions are necessary for determining statistical moments in the context of rigorous image quality assessment, and they are time-reversed copies of point-spread functions for shift variant systems. A criterion is proposed to assess the validity of a local shift-invariance assumption. The analysis reveals realistic situations in which in-phase signals are correlated to the corresponding quadrature signals, which has strong implications for assessing lesion detectability. Also revealed is an opportunity to enhance near- and far-field spatial resolution by matched filtering unfocused beams. The analysis connects several well-known approaches to modeling ultrasonic echo signals. |
| Title |
Liposomes in ultrasonic drug and gene delivery. |
| Author |
Huang SL. |
| Journal |
Adv Drug Deliv Rev |
| Volume |
|
| Year |
2008 |
| Abstract |
Liposome-based drug and gene delivery systems have potential for significant roles in a variety of therapeutic applications. Recently, liposomes have been used to entrap gas and drugs for ultrasound-controlled drug release and ultrasound-enhanced drug delivery. Echogenic liposomes have been produced by different preparation methods, including lyophilization, pressurization, and biotin-avidin binding. Presently, significant in vivo applications of liposomal ultrasound-based drug and gene delivery are being made in cardiac disease, stroke and tumor therapy. Translation of these vehicles into the clinic will require a better understanding of improved physical properties to avoid rapid clearance, as well as of possible side effects, including those of the ultrasound. The aim of this review is to provide orientation for new researchers in the area of ultrasound-enhanced liposome drug and gene delivery. |
| Title |
Lithothripter shock waves with cavitation nucleation agents produce tumor growth reduction and gene transfer in vivo. |
| Author |
Miller DL, Song J. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2002 |
| Abstract |
Cavitation nucleation agents (CNA) can greatly enhance DNA transfer and cell killing for therapeutically useful applications of nonthermal bioeffects of ultrasound (US). Renal carcinoma (RENCA) tumor cells were implanted and grown to about 400 µL tumor volumes on the hind legs of syngeneic Balb/c mice. Before treatment, mice were anesthetized, the tumor region was shaved and depilated, and a DNA plasmid coding for marker proteins was injected into the tumor. Two sets of tests were completed: the first set involved measurement of tumor growth for 4 days and use of a ß-galactosidase marker plasmid for localization of transfection, and the second set involved 2 days of growth and use of a luciferase marker plasmid for assessing overall protein expression. Either saline, Optison® US contrast agent, a vaporizing perfluoropentane droplet suspension (SDS) or air bubble was also injected intratumorally at 10% of tumor volume as a CNA. In some tests, droplets or contrast agent were injected IV. Shock waves (SW) were generated from a spark-gap lithotripter at 7.4 MPa peak negative pressure amplitude. For sham exposure, tumor volume increased by a factor of 3.6 in 4 days. With 500-SW treatment, all the CNA reduced 4-day tumor growth about the same amount (to factors of 1.2 to 1.9). Marker gene expression was generally localized to the region around the needle injection path. All the agents, except saline, produced statistically significant increases of 11.8- to 14.6-fold in luciferase expression after 2 days, relative to sham exposure. IV injection of Optison? or droplet nucleation agents before SW treatment reduced tumor growth to factors of 1.0 and 0.7, but did not increase transfection. These results demonstrate the efficacy of CNA in vivo and should lead to improved strategies for simultaneous SW tumor ablation and cancer gene therapy.
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| Title |
Liver glycogen and water storage: Effect on ultrasound attenuation. |
| Author |
Tuthill TA, Baggs RB, Parker KJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1989 |
| Abstract |
Glycogen has been shown in vitro to have a high specific absorption coefficient (ultrasound absorption in water per concentration) compared to other proteins. Depending on the amount of water which may accompany glycogen flux into and out of liver cells, the ultrasound attenuation coefficient of the liver may rise and fall with stored hepatic glycogen. This paper reports ex vivo studies on rats and in vivo studies on normal human volunteers before and after fasting. The results show a statistically significant different in liver attenuation between well fed and fasted individuals. Generally, the attenuation difference is greater than 10%, and indicates that liver wet weight may not be strictly constant over glycogen storage cycles, as suggested in classic works. In contrast, no significant change in ultrasound backscatter is noted. The results point to the possible role of ultrasound attenuation measurements as a sensitive indicator of tissue physiology, and suggest that glycogen (feeding or fasting) must be controlled in tissue characterization experiments which compare liver attenuation coefficients of individuals and groups. |
| Title |
Liver hemostasis using high-intensity focused ultrasound. |
| Author |
Vaezy S, Martin R, Schmiedl U, Caps M, Taylor S, Beach K, Carter S, Kaczkowski P, Keilman G, Helton S, Chandler W, Mourad P, Rice M, Roy R, Crum L. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1997 |
| Abstract |
Liver haemorrhage, the major cause of death in hepatic trauma, is notoriously difficult to control. The authors report on the use of high-intensity focused ultrasound (HIFU) to arrest the bleeding from incisions made in rabbit livers. A HIBU transducer, with a spherically curved aperture of 6.34 cm(^2) area, a focal length of 4 cm and a frequency of 3.3 MHz was used. In approximately 94% of the incisions, the haemorrhage was reduced to a slow oozing of blood in less than 2 min. The maximum temperature of liver tissue around the incision area, during HIFU application, was measured to be 86 degrees C. The mechanism of hemostasis, confirmed by histological examination, appears to be coagulative necrosis of a volume of liver tissue around the incision. The authors believe that acoustic hemostasis, with the unique characteristic of "volume cauterization," offers a novel method for the management of liver haemorrhage and, thus, has major clinical implications. |
| Title |
Local hyperthermia by ultrasound for cancer therap. |
| Author |
Lele PP. |
| Journal |
Hyperthermia Cancer Therapy |
| Volume |
|
| Year |
1983 |
| Abstract |
No abstract available. |
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