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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 179 out of 330
| Title |
Monitoring blood flow in the fetal umbilical vein. |
| Author |
Gill RW, Garrett WJ, Warren PS, Trudinger BJ, Kossoff G. |
| Journal |
Proc Second Meet World Fed Ultrasound Med Biol - Miyazaki |
| Volume |
|
| Year |
1979 |
| Abstract |
No abstract available. |
| Title |
Monitoring formation of high intensity focused ultrasound (HIFU) induced lesions using backscattered ultrasound. |
| Author |
Anand A, Kaczkowski PJ. |
| Journal |
Acoust Res Letters Online |
| Volume |
|
| Year |
2004 |
| Abstract |
Backscattered radio frequency (RF) data collected in a series of in vitro experiments, in which HIFU lesions were created in bovine liver tissue, were analyzed using two signal processing approaches to visualize temporal evolution of lesion formation. Change in round-trip travel time provides information related to temperature change during and after therapy. Changes in the RF spectrum related to changes in scattering properties of the heated region were observed before visible changes appeared on B-mode images. Effect of increased attenuation in the necrosed tissue region was also observed. Results demonstrate potential for these two techniques in image-guided HIFU therapy. © 2004 Acoustical Society of America. |
| Title |
Monitoring of cell death in epithelial cells using high frequency ultrasound spectroscopy. |
| Author |
Brand S, Solanki B, Foster DB, Czarnota GJ, Kolios MC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2009 |
| Abstract |
Spectral and wavelet analyses were performed on ultrasound radiofrequency (RF) data collected from centrifuged cell samples containing HEp-2 cells after induction of apoptosis by exposure to camptothecin. Samples were imaged at several time points after drug exposure using high-frequency ultrasound in the range from 10-60 MHz. A 20-MHz transducer with a f-number of 2.35 and a 40-MHz transducer with a f-number of 3 were used for collecting the RF data. Normalized power spectra were computed from the backscattered ultrasound signals within a region-of-interest (ROI) for further analysis. Spectral slopes, integrated backscatter coefficients (IBCs) and wavelet parameters were estimated as a function of treatment time to monitor acoustic property changes during apoptosis. Changes in spectral parameters were detected starting six hours after treatment and coincided with changes in corresponding histology. Throughout the course of chemotherapy, variation in estimates of the spectral slope of up to 35% were observed. During the treatment, IBCs increased by 400% compared with estimates obtained from the control samples. Changes in spectral parameters are hypothesized to be linked to structural cell changes during apoptosis. In addition, the sensitivity of a wavelet-based analysis to the ultrasonic assessment of cellular changes was investigated. Results of the wavelet analysis showed variations similar to the spectral parameters. Where values of the spectral slope decreased, estimates of the scaling factors increased. Because wavelet analysis preserves the signal-time localization, its application will be potentially beneficial for assessing treatment responses in vivo. The current study contributes toward the development of a non-invasive method for monitoring apoptosis as a measure of the success of chemotherapeutic treatment of cancer. |
| Title |
Monitoring of thermal therapy based on shear modulus changes: I. shear wave thermometry . |
| Author |
Arnal B, Pernot M, Tanter M. |
| Journal |
IEEE Trans Ultrason Ferroelectr Freq Control |
| Volume |
|
| Year |
2011 |
| Abstract |
The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is currently hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to a precise mapping of the lesion. HIFU treatment and monitoring were respectively performed using a confocal setup consisting of a 2.5-MHz single element transducer focused at 34 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Ultrasound-based strain imaging was combined with shear wave imaging on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created with pushing beams of 100 μs at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Thus, elasticity and strain mapping was achieved every 3 s, leading to real-time monitoring of the treatment. When thermal damage occurs, tissue stiffness was found to increase up to 4-fold and strain imaging showed strong shrinkages that blur the temperature information. We show that strain imaging elastograms are not easy to interpret for accurate lesion characterization, but SWI provides a quantitative mapping of the thermal lesion. Moreover, the concept of shear wave thermometry (SWT) developed in the companion paper allows mapping temperature with the same method. Combined SWT and shear wave imaging can map the lesion stiffening and temperature outside the lesion, which could be used to predict the eventual lesion growth by thermal dose calculation. Finally, SWI is shown to be robust to motion and reliable in vivo on sheep muscle. |
| Title |
Monitoring structural changes in cells with high-frequency ultrasound signal statistics. |
| Author |
Tunis AS, Czarnota GJ, Giles A, Sherar MD, Hunt JW, Kolios MC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2005 |
| Abstract |
We investigate the use of signal envelope statistics to monitor and quantify structural changes during cell death using an in vitro cell model. Using a f/2.35 transducer (center frequency 20 MHz), ultrasound backscatter data were obtained from pellets of acute myeloid leukemia cells treated with a DNA-intercolating chemotherapy drug, as well as from pellets formed with mixtures of treated and untreated cells. Simulations of signals from pellets of mixtures of cells were generated as a summation of point scatterers. The signal envelope statistics were examined by fitting the Rayleigh and generalized gamma distributions. The fit parameters of the generalized gamma distribution showed sensitivity to structural changes in the cells. The scale parameter showed a 200% increase (p<0.05) between untreated and cells treated for 24 h. The shape parameter showed a 50% increase (p<0.05) over 24 h. Experimental results showed reasonable agreement with simulations. The results indicate that high-frequency ultrasound signal statistics can be used to monitor structural changes within a very low percentage of treated cells in a population, raising the possibility of using this technique in vivo. |
| Title |
Morphological and functional relations of Graafian follicle growth to ovulation in women using ultrasonic, laparoscopic and biochemical measurements. |
| Author |
Kerin JF, Edmonds DK, Warnes GM, Cox LW, Seamark RF, Matthews CD, Young GB, Baird DT. |
| Journal |
Br J Obstet Gynaecol |
| Volume |
|
| Year |
1981 |
| Abstract |
The daily growth rates of ovarian follicles were recorded ultrasonically for five days until ovulation in 56 spontaneously ovulating women and related to endocrine and clinical parameters. Over the 5-day period, the average diameter of the follicle destined to ovulate increased from 12 to 23 mm, the second largest follicle from 6 to 12 mm, the third largest follicle from 5 to 9 mm and the fourth largest follicle from 4 to 8 mm. Similar but lesser growth rates occurred in the follicles in the contralateral ovary. Ovulation occurred within 24 hours of the luteinizing hormone (LH) peak, and the mean peak diameter of the ovulating follicle was 23.2 +/- 0.3 (SEM) mm, (range 18-29 mm) before ovulation, and subsequent luteal function was judged to be normal. Follicular growth was most closely correlated with increasing.peripheral blood oestrogen levels. In 16 women who had a laparoscopy within 12 hours of the last ultrasound and following the LH peak, the mean diameter of the largest follicle as measured by ultrasound (23.6 +/- 0.4 mm) was similar to that measured at laparoscopy (22.8 +/- 0.04 mm) and estimated from the volume of follicular fluid aspirated (average 5.8 +/- 0.2 ml), 22.5 mm. The follicular fluid levels of progesterone were high on the day of the LH peak and blood progesterone levels had risen significantly indicating that luteinization of the dominant Graafian follicles had already occurred prior to.ovulation. This study confirms that ultrasonic monitoring provides a reliable measure of follicular growth and allows studies correlating morphological changes with both normal and abnormal endocrine function of the human ovary. |
| Title |
Morphological changes in the surface characteristics of cultured cells after exposure to diagnostic ultrasound. |
| Author |
Liebeskind D, Bases R, Koenigsberg M, Koss L, Raventos C. |
| Journal |
Radiology |
| Volume |
|
| Year |
1981 |
| Abstract |
Morphological changes in the surface membranes of cultured Balb/c 3T3, clone 1-13 cells were studied by scanning electron microscopy after the cells were exposed to diagnostic ultrasound. Abundant irregular, dense microvilli appeared in transformed clones as well as in cells that had been exposed to ultrasound, but had not been morphologically transformed. This increased density of microvilli was detected as early as three days after ultrasound and was still present 37 days later. In comparison, unexposed control cells were smooth with occasional microvilli. Further studies are needed of the effects of diagnostic ultrasound. |
| Title |
Morphological changes induced in the frog semitendinosus muscle fiber by localized ultrasound. |
| Author |
Ravitz MJ, Schnitzler RM. |
| Journal |
Exp Cell Res |
| Volume |
|
| Year |
1970 |
| Abstract |
The effects of highly localized ultrasonic vibration on frog semitendinosus muscle fibers were examined by electron microscopy. A barium titanate transducer, resonant at 85 kHz, to which a stainless steel acoustic horn was cemented, served as the sound source. Sound displacement amplitudes of one to five micra were produced at the horn tip. Thermal effects and cavitation were absent. ..A spectrum of structural changes was observed which depended on amplitude and duration of sonation. The mitochondrial cristae and components of the sarcotubular system appear most sensitive to ultrasound. With increasing amplitudes and treatment durations, decrease in glycogen content, Z and M line disruption, and misalignment of the filaments within the myofibrils occur. In the most severely treated fibers, there is a complete breakdown of band structure. The generation of steady intracellular stresses produced by the sound field, predicted by nonlinear acoustic theory, is postulated to explain these results. The results provide evidence that many effects of sound on muscle reported in the literature and ascribed to heating or cavitation can be produced in the absence of these factors. |
| Title |
Morphological changes to mouse testicular tissue from in vivo ultrasonic irradiation (preliminary report). |
| Author |
O'Brien WD Jr, Brady JK, Dunn F. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1979 |
| Abstract |
Mouse testes have been ultrasonically irradiated in vivo and subsequently examined morphologically. Each testis was sequentially exposed for 30 sec at a spatial peak intensity of 25 W/cm2 at a frequency of 1 MHz. The testes were removed at varying times post irradiation, from immediate to 19 days, fixed and histologically prepared and stained with hematoxylin and eosin and periodic acid Schiff. The results suggest that two types of ultrasonically induced damage occur wherein, for different specimens under identical exposure conditions, there is either semeniferous tubule disruption with a suggestion of minor intertubule space involvement or a more severe form of tubule damage with significant interstitial tissue involvement. It appears that spermatocytes are affected earlier that spermatogonia, contrary to the situation following ionizing radiation. |
| Title |
Morphological effects of pulsed ultrasound in the lung. |
| Author |
Penney DP, Schenk EA, Maltby K, Hartman-Raeman C, Child SZ, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1993 |
| Abstract |
We have previously described the induction of subcapsular hemorrhage in the murine lung by extracorporeal shock wave lithotripsy at exposures of 2 MPa.(Hartman et al. 1990) and pulsed ultrasound (Child et al. 1990). Since extravasation of erythrocytes and alveolar flooding are prominent, we proposed to determine whether or not the injury was progressive, by continuing to develop following termination of exposure, and by localizing where the injury was developing. Mice were exposed to 10 microsecond impulses at 1.6 MPa for 3 min and sacrificed either immediately or 5 min following exposure. When observed with both light and transmission electron microscopy, there was no gradation in lung injury, with a sharp demarcation of the hemorrhagic area. Moreover, both type I pneumocytes and capillary endothelial cells were injured, causing direct continuities between vessel lumina and alveolar spaces. In the absence of extravasation, the tissue appeared normal. There was no evidence that.injury increased in severity during the first 5 min after exposure. |
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