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BRL Abstracts Database |
Your search for ultrasound produced 3296 results. Page 184 out of 330
Title |
New techniques for ultrasound mammography. |
Author |
Fry-Kelly E. |
Journal |
Radiology |
Volume |
|
Year |
1991 |
Abstract |
No abstract available. |
Title |
New ultrasound and related imaging techniques. |
Author |
Johnson SA, Greenleaf JF. |
Journal |
IEEE Trans Nucl Sci |
Volume |
|
Year |
1979 |
Abstract |
A brief history of medical ultrasound imaging is given to provide a setting for illustration and comparison of new imaging techniques. These new techniques are divinded into two classes, namely, transmission tomography and synthetic focus reflection tomography. The evolution of transmission tomography is presented and predictions are given for future developments such as synergistic, quatitative multiple acoustic parameter tissue imaging by solution of the wave equation. Reflection synthetic focus imaging is subdivided into two subclasses based respectively on a heuristic focusing by back projection method and a more abstract method based on inversion of a matrix which relates object and data. Those characteristics of acoustic tomography, not found in x-ray CT, are illustrated by the impedance gradient related, image cancellation artifact. |
Title |
Non-cavitational ultrasound and its biological effect. |
Author |
El'Piner IY. |
Journal |
Biofizika |
Volume |
|
Year |
1970 [1970] |
Abstract |
Review material is presented dealing with the mechanism of the origin of microscopic flows in liquid in an ultrasonic field. We have demonstrated the role of ultrasonic microflows in the degradation of macromolecules, destruction of cells and disturbance in the physiochemical states of the cell membranes. The character and the form of the microflows appearing at the liquid-cell boundary and within the cells are described. Experimental findings are outlined demonstrating the fine disturbances in the submicrostructures of the cells and their functional features due to the appearance of vortex flows in an ultrasonic field. The latter is probably connected with disturbance (reversible or irreversible) in the spatial relationships between the microscopic and submicroscopic structures and with change in the spatial orientation of the biomacromolecules and their complexes. |
Title |
Non-invasive breast tissue characterization using ultrasound speed and attenuation in vivo validation. |
Author |
Johnson SA, Abbott T, Bell R, Berggren M, Borup D, Robinson D, Wiskin J, Olsen S, Hanover B. |
Journal |
Acoust Imaging |
Volume |
|
Year |
2007 |
Abstract |
TechniScan Medical Systems, Inc. is using novel inverse scattering methods to provide a unique method for calculating ultrasound characteristics of speed and attenuation of sound traveling through human tissue. In this paper we describe basic system parameters and results of the first in vivo patient studies. It is concluded that this novel inverse scattering method provides a unique method for noninvasive breast tissue characterization that could assist physicians in assigning probability of cancer to breast abnormalities identified but not resolved with currently available imaging techniques. This application could have a major impact on patient management decisions and has the potential to reduce the number of currently unavoidable breast biopsies that result in a benign outcome. |
Title |
Non-invasive evaluation of breast cancer response to chemotherapy using quantitative ultrasonic backscatter parameters |
Author |
Sannachi L, Tadayyon H, Sadeghi-Naini A, Tran W, Gandhi S, Wright F, Oelze M, Czarnota G |
Journal |
Med Image Anal |
Volume |
|
Year |
2015 |
Abstract |
Tumor response to neoadjuvant chemotherapy in patients (n = 30) with locally advanced breast cancer (LABC) was examined using quantitative ultrasound. Three ultrasound backscatter parameters, the integrated backscatter coefficient (IBC), average scatterer diameter (ASD), and average acoustic concentration (AAC), were estimated from tumors prior to treatment and at four times during neoadjuvant chemotherapy treatment (weeks 0, 1, 4, 8, and prior to surgery) and compared to ultimate clinical and pathological tumor responses. Results demonstrated that among all parameters, AAC was the best indicator of tumor response early after starting treatment. The AAC parameter increased substantially in treatment responding patients as early as one week after treatment initiation, further increased at week 4, and attained a maximum at week 8. In contrast, the backscatter parameters from non-responders did not show any changes after treatment initiation. The two patient populations exhibited a statistically significant difference in changes of AAC (p < 0.001) and ASD (p = 0.023) over all treatment times examined. The best prediction of treatment response was achieved with the combination of AAC and ASD at week 4 (82% sensitivity, 100% specificity, and 86% accuracy) of 12–18 weeks of treatment. The survival of patients with
responsive ultrasound parameters was higher than patients with non-responsive ultrasound parameters (35 ± 11 versus 27 ± 11 months, respectively, p = 0.043). This study demonstrates that ultrasound parameters derived from the ultrasound backscattered power spectrum can potentially serve as non-invasive early measures of clinical tumor response to chemotherapy treatments. |
Title |
Non-invasive in vivo temperature mapping of ultrasound heating using magnetic resonance techniques. |
Author |
Smith NB, Webb AG, Ellis DS, Wilmes LJ, O'Brien WD Jr. |
Journal |
Proc Ultrason Symp IEEE |
Volume |
|
Year |
1994 |
Abstract |
A major problem with conventional methods of measuring heating in vivo is that they are invasive and therefore interfere with heat propagation. A sensitive non-invasive method for temperature measurement using in vivo magnetic resonance spectroscopy (MRS) of the temperature dependent chemical shift of the cobalt (III) nucleus has been developed. Initial experiments demonstrate that this technique can be used to measure ultrasound induced temperature changes in the liver. Tris(ethylenediamine) cobalt (III) trichloride was encapsulated in liposomes and injected into seven rats. Heating was performed using a calibrated unfocused transducer operating at 3.41 MHz. After 5 minutes of CW ultrasound exposure, the chemical shift of the cobalt complex indicated that the temperature rise within the liver was 2.0±1.2°C. This was seen to return to normal upon cessation of heating. The acoustic power was determined in a water bath using a calibrated hydrophone. Theoretical calculations based on the transducer calibration characteristics using the monopole-source solution for estimating tissue temperature increase yielded 2.0°C based on steady state conditions. These results indicate that experimental values agree with the heating theory. |
Title |
Non-invasive in-vivo temperature mapping of ultrasound heating using fluorine-based magnetic resonance imaging agents. |
Author |
Webb AG, Smith NB, Ellis DS, O'Brien WD Jr. |
Journal |
Proc Ultrason Symp IEEE |
Volume |
|
Year |
1995 |
Abstract |
The aim of this study was to investigate the feasibility of using fluorine based magnetic resonance to measure accurately hepatic heating from a focused ultrasound transducer in rats. This new method uses the temperature dependence of the difference in fluorine chemical shifts within a single molecule to provide internal compensation for complicating physiological effects. Female Sprague-Dawley rats were exposed to 5 minutes of CW irradiation at 1.37 MHz from a focused transducer. Theoretical calculations based on the monopole source solution to the bio-heat transfer equation gave a volume-averaged temperature rise of 2.1°C. Preliminary experiments using protein encapsulated perfluorooctylbromide targeted to the liver gave an empirical rise of 2.0±0.4°C |
Title |
Non-invasive low-intensity pulsed ultrasound accelerates bone healing in the rabbit. |
Author |
Pila AA, Mont MA, Nasser PR, Khan SA, Figueiredo M, Kaufman JJ, Siffert RS. |
Journal |
J Orthop Trauma |
Volume |
|
Year |
1990 |
Abstract |
The effect of ultrasound (US) on the rate of fibula osteotomy healing in 139 mature New Zealand white rabbits was assessed in this study. Bilateral midshaft fibular osteotomies were made using a 1-mm Gigli saw. US was noninvasively applied to one limb for 20 minutes daily, while the contralateral limb served as a control. A 2.5-cm PZT transducer was applied to both limbs, with the treated limb receiving a 200-microseconds burst of 1.5-MHz sine waves repeated at 1.0 kHz. The incident intensity was approximately 30 mW/cm2. Animals were killed at intervals between 14 and 28 days. Maximum strength increases (significant to p less than or equal to 0.01) ranged from 40 to 85% from postoperative day 14 to 23. On day 28, no significant difference in ultimate strength was noted. From day 17 through day 28, all US-treated fractures were as strong as intact bones (p less than or equal to 0.005). On the other hand, the ultimate strength of the control osteotomies attained intact values only by day 28. These results indicate that biomechanical healing is accelerated by a factor of nearly 1.7. This occurs with an overall acceleration of the healing curve in this fresh fracture model. If noninvasive low-intensity pulsed sine wave ultrasound can significantly accelerate bone repair in clinical application with an in-home treatment of 20 minutes daily, then US may be a useful adjunct for fracture care with a concomitant impact on patient morbidity. |
Title |
Non-linear beaviour and stability of trapped micron-sized cylindrical gas bubbles in an ultrasonic field. |
Author |
Neppiras EA, Nyborg WL, Miller DL. |
Journal |
Ultrasonics |
Volume |
|
Year |
1983 |
Abstract |
Stable arrays of cylindrical bubbles with diameters 3 and 4 mm were produced by trapping air in the pores of hydrophobic Nuclepore filters. These bubbles arrays were irradiated by beams of cw and pulsed ultrasound at carrier frequencies near the resonance frequencies of the trapped bubbles. By examining the frequency spectrum of the field scattered by the arrays it was found that the bubbles may oscillate as non-linear stable cavities of long duration. Using short pulses, the bubbles remain stable up to excitation pressure amplitudes of several bars. Mechanisms for the eventual growth and decay of the bubbles are discussed in light of the observations. |
Title |
Non-linear tissue elasticity: adaptive elasticity imaging for largedeformations. |
Author |
Emelianov SY, Erkamp RQ, Lubinski MA, Skovoroda AR, O'DonnellM. |
Journal |
Proc IEEE Ultrason Symp |
Volume |
|
Year |
1998 |
Abstract |
Ultrasound 's dynamic and interactive (i.e., real-time) nature is it's major advantage compared to other imaging modalities. For elasticity imaging, real-time data capture provides an excellent foundation for retrospective data processing, including adaptive speckle tracking, incompressibility processing, and adaptive elasticity imaging. In this paper, we explore adaptive imaging of elasticity to estimate nonlinear tissue elasticity. Remote assessment of nonlinear tissue elasticity (i.e., strain hardening) can both increase contrast in elasticity images and present an independent means of tissue differentiation. |
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