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BRL Abstracts Database |
Your search for ultrasound produced 3296 results. Page 273 out of 330
Title |
Therapeutic ultrasound in the treatment of retinal detachment: Clinical observations and light and electron microscopy. |
Author |
Rosecan LR, Iwamoto T, Rosado A, Lizzi FL, Coleman DJ. |
Journal |
Retina |
Volume |
|
Year |
1985 |
Abstract |
Osmotically-induced retinal detachments were created in rabbit eyes and treated with therapeutic ultrasound. Control eyes showed spontaneous retinal reattachment after ten days (range, 8-10 days), while eyes treated with therapeutic ultrasound showed retinal reattachment in a shorter time (average, 4.5 days). Light and electron microscopy demonstrates at least three major differences in the ultrasound-treated eyes compared to the controls. These findings are evidence of an earlier retinal reattachment, a stronger chorioretinal adhesion, less damage and faster repair in the ultrasound-treated retina than in the control retina. This method of producing chorioretinal adhesions may have applications in certain types of retinal detachments where choroidal thickness or vitreous opacity preclude conventional cryopexy, diathermy or photocoagulation techniques. |
Title |
Therapeutic ultrasound in the treatment of retinal detachment: clinical observations and light and electron microscopy. |
Author |
Rosecan LR, Iwamoto T, Rosado A, Lizzi FL, Coleman DJ. |
Journal |
Retina |
Volume |
|
Year |
1985 Spring-Summer |
Abstract |
Osmotically-induced retinal detachments were created in rabbit eyes and treated with therapeutic ultrasound. Control eyes showed spontaneous retinal reattachment after ten days (range, 8-10 days), while eyes treated with therapeutic ultrasound showed retinal reattachment in a shorter time (average, 4.5 days). Light and electron microscopy demonstrates at least three major differences in the ultrasound-treated eyes compared to the controls. These findings are evidence of an earlier retinal reattachment, a stronger chorioretinal adhesion, less damage and faster repair in the ultrasound-treated retina than in the control retina. This method of producing chorioretinal adhesions may have applications in certain types of retinal detachments where choroidal thickness or vitreous opacity preclude conventional cryopexy, diathermy or photocoagulation techniques. |
Title |
Therapeutic ultrasound. |
Author |
Coleman DJ, Lizzi FL, Silverman RH, Dennis PH JR, Driller J, Rosado A, Iwamoto T. |
Journal |
Ultrasound Med Biol |
Volume |
|
Year |
1986 |
Abstract |
Currently the most widely applied use of therapeutic ultrasound in ophthalmology is for the treatment of refractory glaucoma. This new technique is described, histologic changes in experimental animals discussed, and mode of action postulated. The intraocular pressure (IOP) results obtained after treatment of 187 patient eyes are presented, with a review of complications and visual acuity changes. This study demonstrates that 70% of patients treated had an IOP reduction to 25 mm Hg or less one year after ultrasound therapy.
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Title |
Therapeutic ultrasound: a promising future in clinical medicine. |
Author |
Crum L, Bailey M, kaczkowski P, Makin I, Mourad P, Beach K, Carter S, Schmiedl U, Chandler W, Martin R, Vaezy S, keilman G, Cleveland R, Roy R. |
Journal |
J Acoust Soc Am |
Volume |
|
Year |
1998 |
Abstract |
No abstract available. |
Title |
Thermal and heart rate response to ultrasonic exposure in the second and third trimester dog fetus. |
Author |
Gross DR, Williams AR, Wagner-Mann C, McCord F, Miller DL. |
Journal |
J Ultrasound Med |
Volume |
|
Year |
1986 |
Abstract |
A total of 39 fetuses from five pregnant dogs were used in this study. Following pentobarbital anesthesia of the dams the gravid uterus was exposed and partially exteriorized. Fetal and maternal electrocardiograms were recorded, along with fetal.abdominal temperatures, during ultrasound exposures of 3.4 MHz and 2, 4, 6, 8 or 12 W/cm2 (continuous wave), spatial average intensities, for 6 minutes. Baseline fetal abdominal temperatures were 35.2 +/- 1.5 (SD) degrees C. Baseline fetal.heart rates were 176.8 +/- 4.3 (SD) beats per minute. These studies indicate that the product of intensity and time of exposure, under the conditions of these experiments, is directly related to increases in fetal abdominal temperature and fetal.heart rate. |
Title |
Thermal dose optimization for ultrasound tissue ablation. |
Author |
Wan H, Aarsvold J, O'Donnell M, Cain C. |
Journal |
IEEE Trans UFFC |
Volume |
|
Year |
1999 |
Abstract |
In this paper, a formal and general thermal dose optimization method is developed and tested. Prior methods require brute force searches wherein the temperature and dose distributions must be computed at each iteration by solving the bioheat transfer equation (BHTE) numerically. This is extremely time-consuming and can only be used to compare a few prespecified startegies instead of obtaining a more general optimal result. With the method developed in this paper, dose distribution can be calculated without solving the BHTE numerically. This can be done in a matter of a few minutes compared with many hours. Moreover, general thermal dose optimization can now be performed to find the optimal strength and location of each focus so that an optimal dose distribution is obtained while the specified constraint is satisfied. The algorithm developed in this paper consists of a closed-form solution to the BHTE, a Gaussian model for parameterizing a temperature distribution created by a power deposition pattern, and a two-step optimization technique for obtaining the model parameters that optimize the thermal dose distribution. Several examples are given to demonstrate the effectiveness of the algorithm and its robustness under different initial conditions and under assumptions of different sizes of the target region and different numbers of foci. The algorithm developed here provides and efficient and effective tool for treatment planning in ultrasound tissue ablation. |
Title |
Thermal effects of focused ultrasound on the brain: Determination with MR imaging. |
Author |
Hynynen K, Vykhodtseva NI, Chung AH, Sorrentino V, Colucci V, Jolesz FA. |
Journal |
Radiology |
Volume |
|
Year |
1997 |
Abstract |
PURPOSE: To determine the feasibility of the use of temperature-sensitive magnetic resonance (MR) imaging for the detection of local temperature elevations at the focus of a low-power ultrasound beam in the brain.
MATERIALS AND METHODS: The brains in 28 rabbits were sonicated at acoustic power levels of 3.5-17.5 W. Four to five different locations were sonicated at different acoustic power levels in each rabbit. MR images were obtained 2 hours, 48 hours, 10 days, and 23 days after the sonications, depending on when the animals were sacrificed. Histologic evaluation of whole brain was performed.
RESULTS: Forty of 43 (93%) of the lowest-power (3.5-W) sonications were visible on temperature-sensitive MR images and did not result in any short- or long-term histologic or MR imaging evidence of tissue damage. A contrast-to-noise ratio of approximately 6 and a temperature elevation of 7 degrees-8 degrees C were observed.
CONCLUSION: Temperature elevations induced by means of focused ultrasound exposures that do not cause damage in the in vivo rabbit brain can be detected at temperature-sensitive MR imaging. |
Title |
Thermal model for ultrasonic treatment of glaucoma. |
Author |
Lizzi FL, Driller J, Ostromogilsky M. |
Journal |
Ultrasound Med Biol |
Volume |
|
Year |
1984 |
Abstract |
Focused ultrasound, at a frequency of 4.6 MHz, was used to create lesions of the sclera in the proptosed glaucomatous eye of the anesthetized albino rabbit, with the result that elevated intra-ocular pressures were reduced to normal levels. Initial trials on carefully selected glaucoma patients have also shown that pressure reductions can be produced with high-intensity ultrasound. A theoretical model was developed to compute the spatio-temporal features of temperature rises induced in the sclera during these treatments. Experimental data confirmed the accuracy of the model. |
Title |
Thermal therapy for breast tumors by using a cylindrical ultrasound phased array with multifocus pattern scanning: a preliminary numerical study. |
Author |
Ho C-S, Ju K-C, Cheng T-Y, Chen Y-Y, Lin W-L. |
Journal |
Phys Med Biol |
Volume |
|
Year |
2007 |
Abstract |
The purpose of this study is to investigate the feasibility of using a 1 MHz cylindrical ultrasound phased array with multifocus pattern scanning to produce uniform heating for breast tumor thermal therapy. The breast was submerged in water and surrounded by the cylindrical ultrasound phased array. A multifocus pattern was generated and electrically scanned by the phased array to enlarge the treatment lesion in single heating. To prevent overheating normal tissues, a large planning target volume (PTV) would be divided into several planes with several subunits on each plane and sequentially treated with a cooling phase between two successive heatings of the subunit. Heating results for different target temperatures (Ttgt), blood perfusion rates and sizes of the PTV have been studied. Furthermore, a superficial breast tumor with different water temperatures was also studied. Results indicated that a higher target temperature would produce a slightly larger thermal lesion, and a higher blood perfusion rate would not affect the heating lesion size but increase the heating time significantly. The acoustic power deposition and temperature elevations in ribs can be minimized by orienting the acoustic beam from the ultrasound phased array approximately parallel to the ribs. In addition, a large acoustic window on the convex-shaped breast surface for the proposed ultrasound phased array and the cooling effect of water would prevent the skin overheating for the production of a lesion at any desired location. This study demonstrated that the proposed cylindrical ultrasound phased array can provide effective heating for breast tumor thermal therapy without overheating the skin and ribs within a reasonable treatment time.
|
Title |
Thermocouple probes. |
Author |
Fry WJ. |
Journal |
Ultrasound Biol Med |
Volume |
|
Year |
1957 |
Abstract |
unavailable. |
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