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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 167 out of 330
| Title |
Lung lesions induced by continuous- and pulsed-wave (diagnostic) ultrasound in mice, rabbits, and pigs. |
| Author |
Zachary JF, O'Brien WD Jr. |
| Journal |
Vet Pathol |
| Volume |
|
| Year |
1995 |
| Abstract |
These studies documented the presence or absence of macroscopic and microscopic intraparenchymal hemorrhage in individual lung lobes of mice, rabbits, and pigs exposed to continuous- and pulsed-wave (diagnostic) ultrasound; we described the character of and lesions associated with the hemorrhage and compared differences in the lesions among species and exposure conditions to investigate the pathogenic mechanisms and species differences associated with ultrasound-induced lung hemorrhage. In a series of three sequential interdependent studies, 312 mice, 91 rabbits, and 74 pigs were divided at random into experimental groups and exposed to continuous-wave ultrasound (3 kHz modulated at 120 Hz) of acoustic pressure levels ranging from 0 to 490 kPa for 5, 10, or 20 minutes. In a fourth study, three mice, 43 rabbits, and six pigs were divided at random into experimental groups and exposed to pulsed-wave ultrasound (3- and 6-MHz center frequency) of peak rarefactional acoustic pressure levels ranging from 0 to 5.6 MPa for 5 minutes. Macroscopic lesions induced by continuous- and pulsed-wave ultrasound consisted of dark red to black areas of hemorrhage that extended from visceral pleural surfaces into lung parenchyma. Hemorrhage appeared spatially related to the edges of lung lobes where pleura of dorsal and ventral surfaces met, occurred in specific lung lobes in all three species, and appeared anatomically related to lung that was closest to and in contiguous alignment with the ultrasound transducer and thus the path of the sound beam. Macroscopic lesions were similar in all species under all exposure conditions for both continuous- and pulsed-wave ultrasound; however, hemorrhage was not induced in pig lung exposed to pulsed-wave ultrasound at any peak rarefactional acoustic pressure level. Eighteen mice (145 kPa exposure pressure), 60 rabbits (145-460 kPa exposure pressure), and 58 pigs (145-490 kPa exposure pressure) from study 3 were used for microscopic evaluation of lung exposed to continuous-wave ultrasound; three mice (6 MHz; 2.9 and 5.4 MPa), 39 rabbits (3 and 6 MHz; 2.3-5.4 MPa), and six pigs (3 and 6 MHz; 3.3, 5.4, and 5.6 MPa) from study 4 were used for microscopic evaluation of lung exposed to pulsed-wave ultrasound. Microscopic lesions and the character of hemorrhage induced by continuous-wave ultrasound were different from those induced by pulsed-wave ultrasound. Lesions induced by continuous-wave ultrasound under all exposure conditions were similar in all three species. Lesions induced by pulsed-wave ultrasound under all exposure conditions were similar in all three species. |
| Title |
Lymph explorer: a new GUI using 3D high-frequency quantitative ultrasound methods to guide pathologists towards metastatic regions in human lymph nodes. |
| Author |
Mamou J, Saegusa-Beecroft E, Coron A, Oelze ML, Yamaguchi T, Hata M, Machi J, Yanagihara E, laugier P, Feleppa EJ. |
| Journal |
IEEE Int Ultrason Symp Proc |
| Volume |
|
| Year |
2012 |
| Abstract |
Histopathological detection of metastases in dissected lymph nodes of cancer patients is critical to proper staging and management but current histological methods fail to detect small, but clinically-relevant, metastases. Quantitative ultrasound (QUS) permits characterization of tissue microstructure using
system-independent estimates. In this study, more than 250 freshly-excised lymph nodes were evaluated using specifically designed QUS methods that demonstrated an ability to guide pathologists towards suspicious regions using an interactive and
easy-to-use GUI called Lymph Explorer. Radio-frequency (RF) data were acquired in 3D using a 26-MHz transducer and RF data were processed to yield 13 QUS estimates associated with tissue microstructure. The 13 QUS estimates were combined
using a linear discriminant classifier to derive cancer-probability estimates and classification performance was assessed using ROC methods. For gastrointestinal nodes, the areas under the ROC curves (AUCs) exceeded 0.95. Slightly poorer results (AUCs 0.85) were obtained for nodes of breast-cancer patients. Lymph
Explorer can interactively display any three orthogonal crosssectional B-mode images with overlaid color-coded cancer probabilities. In particular, Lymph Explorer permitted localization of small metastases in some partially-metastatic cases. The QUS approach integrated with Lymph Explorer potentially could drastically reduce the current rate of false-negative determinations by
efficiently guiding pathologists to suspicious regions in dissected lymph nodes. |
| Title |
Lysis and viability of cultured mammalian cells exposed to 1 MHz ultrasound. |
| Author |
Kaufman GE, Miller MW, Griffiths TD, Ciaravino V, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1977 |
| Abstract |
HeLa and CHO cells were exposed for 1 to 15 min to 1 MHz ultrasound at intensities up to 30 W/sq cm. The threshold for cell lysis was approximately 1 W/sq cm with the maximum effect at 10 W/sq cm. Among the intact cells there was a decreased viability as determined both by trypan blue exclusion and by colony-forming ability; the intensity vs. response curve was similar to that for cell lysis. Preliminary evidence also suggests that a decrease in proliferation rate and an increased incidence of giant cells occur for the remaining intact and viable cells. |
| Title |
Lysis of cells in Elodea leaves by pulsed and continuous wave ultrasound. |
| Author |
Carstensen EL, Child SZ, Crane C, Miller MW, Parker KJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Resonance lysis of the cells in the leaves of the aquatic plant Elodea originally reported by Miller have thresholds at intensities of a few W/cm2. With pulsed ultrasound, the resonance behavior vanishes and the thresholds are at much higher amplitudes. This is similar to the characteristics of the thresholds for killing of Drosophila larvae by pulsed ultrasound. Both organisms contain small gas bodies within the tissues which may serve as nuclei for a cavitation related phenomenon. The results suggest that the response of these bubbles to continuous wave fields and very short pulses is qualitatively different. |
| Title |
Lysis of erythrocytes by exposure to CW ultrasound. |
| Author |
Carstensen EL, Kelly P, Church CC, Brayman AA, Child SZ, Raeman CH, Schery L. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1993 |
| Abstract |
The threshold for lysis of erythrocytes suspended at concentrations of 0.5-1% in saline or plasma in rotating cylindrical exposure vessels is approximately spatial peak intensities of 2 W/cm2 at 1 MHz continuous wave (CW). Results of a series of experiments in which cell concentration, viscosity and gas composition of the suspending medium and rotation speed of the exposure vessel were varied.combined with observations of sonoluminescence are all consistent with a hypothesis that cells are lysed by inertial (transient) acoustic cavitation. For the proposed mechanism to operate in cell suspensions, it is necessary that bubbles be brought into contact with the cells. Rotation of the chamber recycles bubbles that are driven by radiation forces to the far wall of the chamber in a matter of milliseconds. The physical and chemical properties of the wall of the chamber appear to be important as stabilizing sites for nuclei that serve as seeds for cavitation events. |
| Title |
Macromolecular interaction in the absorption of ultrasound in biological material. |
| Author |
Kremkau FW. |
| Journal |
Thesis(PhD): Univ of Rochester |
| Volume |
|
| Year |
1972 |
| Abstract |
The primary mechanism for the absorption of ultrasound in biological material appears to lie at the macromolecular level. To account for this absorption both solute-solvent and solute-solute (macromolecular) interaction mechanisms have been proposed. The purpose of the present work is to investigate the importance of macromolecular interactions in the absorption process. Absorption coefficients of amino acid and polypeptide solutions, protein solutions, cell suspensions, cell membrane suspensions, and paracrystalline and fixed cell suspensions were measured. The results are combined with acoustic data from the literature on various biological systems. It is seen that, from amino acids through polypeptides, proteins, and systems where interactions of proteins are encouraged, the specific absorption increases as the level of organization increases. It is concluded that macromolecular interactions are an important factor in the absorption of ultrasound in biological material. |
| Title |
Macromolecular interaction in the absorption of ultrasound in fixed erythrocytes. |
| Author |
Kremkau FW, Carstensen EL, Aldridge WG. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1973 |
| Abstract |
Whereas it has been recognized for some time that the absorption of sound in suspensions of erythrocytes is primarily a macromolecular phenomenon, recent observations have led us to believe that interactions between macromolecules may play a significant role as well. Two tests of the interaction postulate are reported: (i) Acrolein or glutaraldehyde fixing of bovine erythrocytes, which cross-links macromolecular hydrophobic groups, causes an increase in specific absorption by as much as a factor of five at 30 MHz. The absorption increase is greatest at 30 MHz and above. (ii) Suspension of fixed erythrocytes in low-dielectric constant liquids (ethylene glycol and ethanol), thus increasing forces between ionic groups, further increases the specific absorption by as much as a factor of four at 10 MHz. The absorption increase associated with solvent changes is greatest at 10 MHz and below. Scattering, viscous relative motion, and thermal absorption have been ruled out as explanations for the observations. The explanation is more apt to lie in some forms of chemical or structural relaxations. |
| Title |
Macrophage responsiveness to therapeutic ultrasound. |
| Author |
Young SR, Dyson M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Macrophages area source of many important growth factors which can act as wound mediators during tissue repair. The aim of this work was to find out if levels of ultrasound which accelerate repair could stimulate the release of fibroblast mitogenic factors from an established macrophage-like cell line (U937). The U937 cells were exposed in vitro to continuous ultrasound at a space average, temporal average intensity of 0.5 W/cm2 at either 0.75 MHz or 3.0 MHz, for 5 min. The macrophage-conditioned medium was removed either 30 min or 12 h after exposure, and placed on 3T3 fibroblast cultures. Fibroblast proliferation (defined here as increase in cell number) was assessed over a 5-day period. The results showed that 0.75 MHz ultrasound appeared to be effective in liberating preformed fibroblast affecting substances from the U937 cells, possibly by producing permeability changes, whereas 3.0 MHz ultrasound appeared to stimulate the cell's ability to synthesize and secrete fibroblast mitogenic factors. |
| Title |
Magnetic resonance-guided focused ultrasound surgery (MRgFUS). Four ablation treatments of a single canine hepatocellular adenoma. |
| Author |
Kopelman D, Inbar Y, Hanannel A, Dank G, Freundlich D, Perel A, Castel D, Greenfeld A, Salomon T, Sareli M, Valeanu A, Papa M. |
| Journal |
HPB (Oxford) |
| Volume |
|
| Year |
2006 |
| Abstract |
Background. Canine hepatocellular adenomas are benign, well-differentiated, primary hepatic tumors. Surgical resection is technically demanding and is considered a major procedure with relatively high morbidity rates. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) uses focused ultrasonic energy to non-invasively create a heat-coagulated lesion deep within the body. This effect can be achieved in a controlled, accurate manner. The aim of this study was to evaluate the safety, accuracy and efficacy of non-invasive focal ablation of tissue volumes of a canine benign liver tumour by consecutive MRgFUS sonications. Materials and methods. Four MRgFUS procedures were performed in a 10-year-old, male, mixed large breed dog (45 kg) under general anaesthesia. The exact location and volume of the ablated areas were planned on the MR images. Real-time MR imaging and temperature mapping enabled the immediate evaluation of the effect of each sonication. Different areas were chosen within the tumour. These volumes of tumoral tissue were ablated by multiple sonications. To allow accurate targeting and quality imaging, sonications were performed during 20-30 s of apnoea. Between the sonications the dog was normally ventilated. The dog was operated 21 days after the fourth ablative procedure. The tumour was resected and histopathologically examined. Results. The MRgFUS created necrosis with contiguous areas of complete tissue destruction within the liver tumour, in full accordance with the planning. A focal thermal injury to the cartilage of the right lower ribs was noted after the fourth treatment. This lesion became infected and was treated surgically. Ten months after the last treatment the dog is well and healthy. Conclusions. Focused ultrasound ablation of liver tumoral tissue with MR guidance under general anaesthesia and controlled apnoea is a safe and accurate treatment modality. Its main advantage is that it is a completely non-invasive image-guided treatment. The ablation of significant volumes of a highly vascular liver tumoral tissue was achieved. Such tissue can be ablated in a very accurate manner, exactly according to the pretreatment planning on the MR images. The MR imaging characteristics, including real-time temperature mapping, enable real-time control of every step of the ablation process. Mechanical ventilation with intermittent apnoea periods overcomes the problem of the respiratory movements of the liver. Care must be taken to avoid the passage of the ultrasound beam through energy-absorbing calcified tissue. |
| Title |
Magnetic resonance-guided high-intensity ultrasound ablation of the prostate. |
| Author |
Pauly KB, Diederich CJ, Rieke V, Bouley D, Chen J, Nau WH, Ross AB, Kinsey AM, Sommer G. |
| Journal |
Top Magn Reson Imaging |
| Volume |
|
| Year |
2006 |
| Abstract |
OBJECTIVES: This paper describes our work in developing techniques and devices for magnetic resonance (MR)-guided high-intensity ultrasound ablation of the prostate and includes review of relevant literature. METHODS: Catheter-based high-intensity ultrasound applicators, in interstitial and transurethral configurations, were developed to be used under MR guidance. Magnetic resonance thermometry and the relevant characteristics and artifacts were evaluated during in vivo thermal ablation of the prostate in 10 animals. Contrast-enhanced MR imaging (MRI) and diffusion-weighted MRI were used to assess tissue damage and compared with histology. RESULTS: During evaluation of these applicators, MR thermometry was used to monitor the temperature distributions in the prostate in real time. Magnetic resonance-derived maximum temperature thresholds of 52 degrees C and thermal dose thresholds of 240 minutes were used to control the extent of treatment and qualitatively correlated well with posttreatment imaging studies and histology. The directional transurethral devices are selective in their ability to target well-defined regions of the prostate gland and can be rotated in discrete steps to conform treatment to prescribed boundaries. The curvilinear applicator is the most precise of these directional techniques. Multisectored transurethral applicators, with dynamic angular control of heating and no rotation requirements, offer a fast and less complex means of treatment with less selective contouring. CONCLUSIONS: The catheter-based ultrasound devices can produce spatially selective regions of thermal destruction in prostate. The MR thermal imaging and thermal dose maps, obtained in multiple slices through the target volume, are useful for controlling therapy delivery (rotation, power levels, duration). Contrast-enhanced T1-weighted MRI and diffusion-weighted imaging are useful tools for assessing treatment. |
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