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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 325 out of 330
| Title |
Use of diagnostic ultrasound devices in Canada. |
| Author |
Benwell DA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1981 |
| Abstract |
Information on diagnostic ultrasound devices and their use in Canada in 1977 is presented. The information was obtained from the results of a mail survey. All hospitals in Canada (1341) were sent the questionnaire, 111 (8.3%) reporting the use of diagnostic ultrasound, using a total of 393 devices. The survey results indicated that between 340,000 and 620,000 patients were examined by diagnostic ultrasound in Canada in 1977 and that cardiology, obstetrics and radiology were the medical services in which diagnostic ultrasound was most used. Survey limitations are also discussed. |
| Title |
Use of focused ultrasound for stimulation of nerve structures. |
| Author |
Gavrilov LR. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1984 |
| Abstract |
Pulsed focused ultrasound can stimulate the receptor and conductive nerve structures of humans and animals as well.as the neurons of the central nervous system of invertebrates. The possibility of a wide practical use of this method.in medicine and physiology is considered. For example, the stimulating ability of focused ultrasound is applied to.the diagnosis of neurological diseases, to the study of skin and tissue sensitivity in man, to the diagnosis of hearing.disorders, and to the introduction of auditory information to the deaf with certain forms of hearing pathology. The.factors that affect focused ultrasound as a stimulus for the irritation of nerve structures are discussed. ..Publication Types:.. Review |
| Title |
Use of focused ultrasound to accelerate the "maturing" of a cataract. |
| Author |
Gavrilov LR, Narbut NP, Fridman FE. |
| Journal |
Sov Phys Acoust |
| Volume |
|
| Year |
1974 |
| Abstract |
The feasibility of accelerating the "maturing" of cataracts by irradiation of the crystalline lens with focused ultrasound is demonstrated in tests on rabbits. It is shown that the mechanism of cataract production is attributable to local heating of the lens tissue by the absorption of ultrasonic energy in it. The appropiate ultrasonic dosages are determined for the production of cataracts wihtout the accompaniment of pathological changes in the tissues and functions of the eye. |
| Title |
Use of high-intensity focused ultrasound to control bleeding. |
| Author |
Vaezy S, Martin R, Kaczkowski P, Keilman G, Goldman B, Yaziji H, Carter S, Caps M, Crum L. |
| Journal |
J Vasc Surg |
| Volume |
|
| Year |
1999 |
| Abstract |
OBJECTIVE: High-intensity focused ultrasound (HIFU) has been shown to be effective in controlling hemorrhage from punctures in blood vessels. The objective of the current study was to investigate the capability of HIFU to stop bleeding after a more severe type of vascular injury, namely longitudinal incisions of arteries and veins. METHODS: The superficial femoral arteries, common femoral arteries, carotid arteries, and jugular veins of four anesthetized pigs were exposed surgically. A longitudinal incision, 2 to 8 mm in length, was produced in the vessel. HIFU treatment was applied within 5 seconds of the onset of the bleeding. The HIFU probe consisted of a high-power, 3.5-MHz, piezoelectric transducer with an ellipsoidal focal spot that was 1 mm in cross section and 9 mm in axial dimension. The entire incision area was scanned with the HIFU beam at a rate of 15 to 25 times/second and a linear displacement of 5 to 10 mm. A total of 76 incisions and HIFU treatments were performed. RESULTS: Control of bleeding (major hemosatsis) was achieved in all 76 treatments, with complete hemostasis achieved in 69 treatments (91%). The average treatment times of major and complete hemostasis were 17 and 25 seconds, respectively. After the treatment, 74% of the vessels in which complete hemostasis was achieved were patent with distal blood flow and 26% were occluded. The HIFU-treated vessels showed a consistent coagulation of the adventitia surrounding the vessels, with a remarkably localized injury to the vessel wall. Extensive fibrin deposition at the treatment site was observed. CONCLUSION: HIFU may provide a useful method of achieving hemostasis for arteries and veins in a variety of clinical applications. |
| Title |
Use of intense ultrasound in neurological research. |
| Author |
Fry WJ. |
| Journal |
Am J Phys Med |
| Volume |
|
| Year |
1958 |
| Abstract |
No abstract available. |
| Title |
Use of miniature hydrophones to determine peak intensities typical of medical ultrasound devices. |
| Author |
Shombert DG, Harris GR. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1986 |
| Abstract |
It has been argued that due to nonlinear behavior of the polyvinylidene fluoride (PVDF) element, the uncertainty in hydrophone measurement of very high spatial- and temporal-peak intensities is so great as to render the measurement meaningless. Therefore the intensity of the field can be accurately specified only in terms of spatial and temporal averages. This paper reports the results of a comparison among nine different PVDF hydrophones used to determine the spatial peak-temporal peak (SPTP) and spatial peak-pulse average (SPPA) intensities of a highly focused medical transducer, typical of the highest levels encountered in clinical instruments. The mean value obtained for the SPTP intensity was 1580 W/cm2, and the greatest deviation from this mean for any one hydrophone was +28 percent. Hydrophones that did not have an integral amplifier were found to be susceptible to transmission line reflections at the higher intensities. This can drastically distort the waveform and cause large amplitude spikes to appear that do not represent the actual acoustic pressure. The use of a low-pass filter circuit to help eliminate this distortion is discussed. An analysis of the AIUM-NEMA test for hydrophone linearity is also presented. |
| Title |
Use of non-Rayleigh statistics for the identification of tumors in ultrasonic B-scans of the breast. |
| Author |
Shankar PM, Reid JM, Ortega H, Piccoli CW, Goldberg BB. |
| Journal |
IEEE Trans Med Imaging |
| Volume |
|
| Year |
1993 |
| Abstract |
A model for the scattering of ultrasound from breast tissue is proposed. The model is based on the use of non-Rayleigh statistics, specifically the K distribution to describe the backscattered echo from the tissue. A multiparameter test based on this model has been designed to characterize the tissue. The data from the B-scan images of the breasts of 6 different patients were analyzed using this model. The results indicate that the non-Rayleigh statistics seem to be useful in characterizing and identifying malignant, benign, and normal tissue regions. |
| Title |
Use of overpressure to asses the role of bubbles in focused ultrasound lesion shape in vitro. |
| Author |
Bailey MR Couret LN Sapozhnikov OA Khokhlova VA ter Haar G Vaezy S Shi X Martin R Crum LA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2001 |
| Abstract |
Overpressure--elevated hydrostatic pressure--was used to assess the role of gas or vapor bubbles in distorting the shape and position of a high-intensity focused ultrasound (HIFU) lesion in tissue. The shift from a cigar-shaped lesion to a tadpole-shaped lesion can mean that the wrong area is treated. Overpressure minimizes bubbles and bubble activity by dissolving gas bubbles, restricting bubble oscillation and raising the boiling temperature. Therefore, comparison with and without overpressure is a tool to assess the role of bubbles. Dissolution rates, bubble dynamics and boiling temperatures were determined as functions of pressure. Experiments were made first in a low-overpressure chamber (0.7 MPa maximum) that permitted imaging by B-mode ultrasound (US). Pieces of excised beef liver (8 cm thick) were treated in the chamber with 3.5 MHz for 1 to 7 s (50% duty cycle). In situ intensities (I(SP)) were 600 to 3000 W/cm(2). B-mode US imaging detected a hyperechoic region at the HIFU treatment site. The dissipation of this hyperechoic region following HIFU cessation corresponded well with calculated bubble dissolution rates; thus, suggesting that bubbles were present. Lesion shape was then tested in a high-pressure chamber. Intensities were 1300 and 1750 W/cm(2) ( +/- 20%) at 1 MHz for 30 s. Hydrostatic pressures were 0.1 or 5.6 MPa. At 1300 W/cm(2), lesions were cigar-shaped, and no difference was observed between lesions formed with or without overpressure. At 1750 W/cm(2), lesions formed with no overpressure were tadpole-shaped, but lesions formed with high overpressure (5.6 MPa) remained cigar-shaped. Data support the hypothesis that bubbles contribute to the lesion distortion. |
| Title |
Use of second-harmonic superimposition to induce chemical effects of ultrasound. |
| Author |
Kawabata K, Umemura S. |
| Journal |
J Phys Chem |
| Volume |
|
| Year |
1996 |
| Abstract |
We investigated the effect of second-harmonic superimposition (SHS) on the oxidation of iodide ions induced by ultrasound with two frequency components: 1.03 and 2.06 MHz. With SHS, the oxidation rate reached a maximum when the acoustic intensity ratio of the fundamental to the second harmonic was about 1:1, while conventional single-frequency exposure at either one of the two frequencies did not induce oxidation even at an acoustic intensity 10 times the threshold for SHS. The rate of oxidation strongly depended on the phase of the second harmonic relative to the fundamental. The reaction was observed only at the second-harmonic phase ranging from maximizing the peak rarefaction to maximizing the rarefaction increasing rate. Simultaneously measured subharmonic emission, an indicator of cavitation, suggested that the effect of SHS on sonochemical reaction is due to its ability to induce cavitation efficiently.
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| Title |
Use of smoothing splines for analysis of backscattered ultrasonic waveforms: application to monitoring of steroid treatment of dystrophic mice. |
| Author |
Hughes MS, Marsh JN, Agyem KF, McCarthy JE, Maurizi BN, Wickerhauser MV, Wallace KD, Lanza GM, Wickline SA. |
| Journal |
IEEE Trans Ultrason Ferroelectr Freq Control |
| Volume |
|
| Year |
2011 |
| Abstract |
Duchenne muscular dystrophy (DMD) is an X-linked genetic disease characterized by progressive weakness and wasting of skeletal and cardiac muscle; boys present with weakness by the age of 5 years and, if left untreated, are unable to walk without assistance by the age of 10 years. Therapy for DMD has been primarily palliative, with oral steroids emerging as a first-line approach even though this treatment has serious side-effects. Consequently, low-cost imaging technology suitable for improved diagnosis and treatment monitoring of DMD would be of great value, especially in remote and underserved areas. Previously, we reported use of the logarithm of the signal energy, log [E(f)], and a new method for ultrasound signal characterization using entropy, H(f), to monitor prednisolone treatment of skeletal muscle in a dystrophin-deficient mouse model. Three groups were studied: mdx mice treated with prednisolone, a control group of mdx mice treated with saline, and a control group of wild-type mice treated with saline. It was found that both log [E(f)] and H(f) were required to statistically differentiate the three groups. In the current study, we show that preprocessing of the raw ultrasound using optimal smoothing splines before computation of either log [E(f)] or a rapidly computable variant of Hf, denoted I(f,∞), permits delineation of all three groups by either metric alone. This opens the way to the ultimate goal of this study, which is identification and implementation of new diagnostically sensitive algorithms on the new generation of low-cost hand-held clinical ultrasonic imaging systems. |
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