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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 124 out of 330
| Title |
Failure to demonstrate an effect of in vivo diagnostic ultrasound on sister chromatid exchange frequency in amniotic fluid cells. |
| Author |
Lundberg M, Jerominski L, Livingston G, Kochenour N, Lee T, Fineman R. |
| Journal |
Am J Med Genet |
| Volume |
|
| Year |
1982 |
| Abstract |
Antepartum use of diagnostic ultrasound has markedly reduced radiation exposure of the fetus. Previous investigations have documented the safety of ultrasound, but concern persists regarding its long-term effects. As new methods become available to study possible subtle effects of ultrasound, it is important to reevaluate this technique continually because of its universal use in obstetrics and elsewhere. We report results of in vivo studies of effect of diagnostic ultrasound on the sister chromatid exchange (SCE) frequency in amniotic fluid cells. SCE is a cytogenetic.phenomenon believed to be a sensitive indicator of environmental perturbations and chromosome stability. In amniotic fluid cells from six pregnancies without ultrasound exposure and in 34 pregnancies that received varying amount of ultrasound immediately before amniocentesis, there was no difference in SCE frequency in exposed verus nonexposed cells. These data, which appear to confirm again the safety of ultrasound, are reassuring to both patients and clinicians. |
| Title |
Fast envelope detection for thinned display of finely digitized ultrasound. scans. |
| Author |
Koral KF, Dupuy ME, Meyer CR. |
| Journal |
IEEE Trans Biomed Eng |
| Volume |
|
| Year |
1985 |
| Abstract |
In ultrasound tissue characterization, the backscattered RF signal is finely digitized. The signal envelope is displayed in a version thinned 1-8. Three implementations of Hilbert-transform envelope detection with thinning were timed. An array processor speeds up DFT implementation by a factor of 2.5, but convolution implementation is even faster. |
| Title |
Fat estimation in beef ultrasound images using texture and adaptive logic networks. |
| Author |
Mccauley JD, Thane BR, Whittaker AD. |
| Journal |
Biomed Imaging Res |
| Volume |
|
| Year |
1994 |
| Abstract |
Overviews of Adaptive Logic Networks and co-- occurrence image texture are presented. These tools are used for both prediction and classification of intramuscular fat in beef from ultrasonic images of both live beef animals and slaughtered carcasses. Results showed that Adaptive Logic Networks perform better than any fat prediction method for beef ultrasound images to date and are a viable alternative to statistical techniques. |
| Title |
Fat estimation in beef ultrasound images using texture and adaptive logic networks. |
| Author |
Mccauley JD, Thane BR, Whittaker AD. |
| Journal |
Biomed Imaging Res |
| Volume |
|
| Year |
1992 |
| Abstract |
Overviews of Adaptive Logic Networks and co-- occurrence image texture are presented. These tools are used for both prediction and classification of intramuscular fat in beef from ultrasonic images of both live beef animals and slaughtered carcasses. Results showed that Adaptive Logic Networks perform better than any fat prediction method for beef ultrasound images to date and are a viable alternative to statistical techniques. Keywords. Meat, Grading, Automation, Ultrasonic, Images. |
| Title |
FDA wants users warned against high-intensity ultrasound of fetuses. |
| Author |
Hess TP. |
| Journal |
Diagn Imaging |
| Volume |
|
| Year |
1986 |
| Abstract |
No abstract available. |
| Title |
FDTD simulations for ultrasound propagation in a 2-D breast model. |
| Author |
Manry CW Jr, Broschat SL. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
1996 |
| Abstract |
To increase the survival rates of patients with breast cancer, an ultrasound imaging system must detect tumors when they are small, with a diameter of 5 mm or less. This requires an understanding of how propagation of ultrasound energy is affected by the complex structure of the breast. In this paper, a Finite-Difference Time-Domain (FDTD) method is developed to simulate ultrasound propagation in a two-dimensional model of the human breast. The FDTD simulations make it possible to better understand the behavior of an ultrasound signal in the breast. For example, here the simulations are used to investigate the effect of fat lobes adjacent to the skin layer in a simple breast model. Experimental work performed at the University of Pennsylvania has shown that strong refraction caused by the fat lobes results in nulls in the forward transmitted field. This result was duplicated with the FDTD simulations, and it was shown that the effect of refraction is clearly evident for energy exiting the breast. The existence of strong refraction has a significant impact on ultrasound imaging since it implies that an imaging method based on a weak scattering assumption is unlikely to work well. |
| Title |
Feasibility and toxicity of transrectal ultrasound hyperthermia in the treatment of locally advanced adenocarcinoma of the prostate. |
| Author |
Fosmire H, Hynynen K, Drach GW, Stea B, Swift P, Cassady JR. |
| Journal |
Int J Radiat Oncol Biol Phys |
| Volume |
|
| Year |
1993 |
| Abstract |
PURPOSE: This Phase I trial tests the ability of a new hyperthermia device, the transrectal ultrasound probe, to heat the prostate gland, and evaluates the toxicity of transrectal ultrasound hyperthermia (TRUSH) given with concurrent standard external beam irradiation in the treatment of locally-advanced adenocarcinoma of the prostate. METHODS AND MATERIALS: Between June, 1990 and August, 1991, 14 patients with American Urological Society Stage C2 or D1 adenocarcinoma of the prostate were treated with TRUSH concurrently with standard external beam radiotherapy to the prostate. Twenty-two heat treatments were delivered in 14 patients; 8 patients received two TRUSH procedures, each separated by 1 week. Patient age ranged between 53-86 (mean: 72) years. Three patients had well-, 6 patients had moderately-, and 5 patients had poorly-differentiated adenocarcinoma of the prostate. Karnofsky status ranged from 70-90. Standard radiotherapy to the prostate and periprostatic tissues was delivered using a four-field approach with 1.8-2 Gy daily fractions delivered 5 x/week to a total dose of 67-70 Gy calculated to the minimum tumor volume. TRUSH was delivered after transperineal placement of multipoint thermometry probes by a urologist, under transrectal ultrasound guidance. Two to three thermocouple probes containing seven sensors each were placed in the prostate in an attempt to sample temperatures throughout the gland. The sensor depth from the rectal wall ranged from 5-25 mm. RESULTS: Thirty-six percent of all sensors were heated above 42.5 degrees C averaged over 30 min; and all patients had at least some sensors within the prostate heated to temperatures > or = 42.5 degrees C. The average temperature of all sensors of all sensors (T(ave) +/- s.d.) over all treatments, however, was only 41.9 degrees C +/- 0.9 degrees C over 30 min. The maximum temperature for normal tissues outside the gland was 41.1 degrees C +/- 1.3 degrees C. Treatments have been well-tolerated with few complications. Tolerance has been "good" in 17/22, "fair" in 3/22, and "treatment limiting" in 2/22 treatments secondary to position intolerance and/or pain. There has been one episode of hypotension related to narcotic administration and three episodes of rapidly resolving pain during hyperthermia treatment. Mild hematuria has occurred in 5/22, and moderate hematuria has occurred in 2/22 transperineal thermometer catheter placements. CONCLUSION: In conclusion, TRUSH is well-tolerated and has great potential for consistently heating the prostate gland. We anticipate that further equipment modifications will improve our ability to heat the entire prostate to temperatures > 42.5 degrees C. |
| Title |
Feasibility of half-data image reconstruction in 3-D reflectivity tomography with a spherical aperture. |
| Author |
Anastasio MA, Zhang J, Sidky EY, Zou Y, Xia D, Pan X. |
| Journal |
IEEE Trans Med Imaging |
| Volume |
|
| Year |
2005 |
| Abstract |
Reflectivity tomography is an imaging technique that seeks to reconstruct certain acoustic properties of a weakly scattering object. Besides being applicable to pure ultrasound imaging techniques, the reconstruction theory of reflectivity tomography is also pertinent to hybrid imaging techniques such as thermoacoustic tomography. In this work, assuming spherical scanning apertures, redundancies in the three-dimensional (3-D) reflectivity tomography data function are identified and formulated mathematically. These data redundancies are used to demonstrate that knowledge of the measured data function over half of its domain uniquely specifies the 3-D object function. This indicates that, in principle, exact image reconstruction can be performed using a "half-scan" data function, which corresponds to temporally untruncated measurements acquired on a hemi-spherical aperture, or using a "half-time" data function, which corresponds to temporally truncated measurements acquired on the entire spherical aperture. Both of these minimal scanning configurations have important biological imaging applications. An iterative reconstruction method is utilized for reconstruction of a simulated 3-D object from noiseless and noisy half-scan and half-time data functions. |
| Title |
Feasibility of ultrasound hyperthermia in the treatment of malignant brain tumors. |
| Author |
Britt RH Lyons BE Pounds DW Prionas SD. |
| Journal |
Med Instrum |
| Volume |
|
| Year |
1983 |
| Abstract |
In order to test the biological feasibility of using ultrasound-generated hyperthermia for the treatment of brain tumors, damage threshold studied and thermal dosimetry studies as a function of temperature were performed in 44 acute experiments in cats. Bilateral craniotomies were performed to expose the dural surface. Ultrasonic radiation was applied for 50 minutes at different intensities to generate temperatures up to 48 degrees C. Thermal fields were mapped using an electrode array of three triple-junction thermocouple probes. Each probe left a track easily identified histologically. Serial sections of each brain were cut and stained, allowing for precise correlation of histology and thermocouple location and temperature. At temperatures of less than 42 degrees C for 50 minutes, no evidence of damage could be detected in either gray or white matter. At 43 degrees C partial loss of neurons was seen in the brain adjacent to the probe, but at the same temperature in white matter, only edema was seen. At temperatures of 44-45 degrees C there was definite loss of both neurons in the gray matter and myelin tracts in the white matter. The lesions created by using ultrasound-generated hyperthermia were sharply marginated. This sharp demarcation histologically correlated well with the abrupt fall off in temperature as a function of distance from the lesion edge. The results of this study are important in two respects. First, it demonstrates that ultrasound can effectively heat the brain in an extremely controlled and precise manner. Second, the brain can withstand temperatures to 42 degrees C without showing histological evidence of damage, which is the temperature range at which neoplastic cells begin to show cytotoxic effects.
|
| Title |
Feasibility of ultrasound phase contrast for heating localization |
| Author |
Farny CH, Clement GT. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2008 |
| Abstract |
Ultrasound-based methods for temperature monitoring could greatly assist focused ultrasound visualization and treatment planning based on sound speed-induced change in phase as a function of temperature. A method is presented that uses reflex transmission integration, planar projection, and tomographic reconstruction techniques to visualize phase contrast by measuring the sound field before and after heat deposition. Results from experiments and numerical simulations employing a through-transmission setup are presented to demonstrate feasibility of using phase contrast methods for identifying temperature change. A 1.088-MHz focused transducer was used to interrogate a medium with a phase contrast feature, following measurement of the baseline reference field with a hydrophone. A thermal plume in water and a tissue phantom with multiple water columns was used in separate experiments to produce a phase contrast. The reference and phase contrast field scans were numerically backprojected and the phase difference correctly identified the position and orientation of the features. The peak temperature reconstructed from the phase shift was within 0.2 degrees C of the measured temperature in the plume. Simulated results were in good agreement with experimental results. Finally, employment of reflex transmission imaging techniques for adopting a pulse-echo arrangement was simulated, and its future experimental application is discussed. |
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