Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

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Your search for ultrasound produced 3296 results.

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Title A spherical-section ultrasound phased array applicator for deep localized hyperthermia.
Author Ebbini ES, Cain CA.
Journal IEEE Trans Biomed Eng
Volume
Year 1991
Abstract Computer simulation shows that a new ultrasound phased-array with nonplanar geometry has considerable potential as an applicator for deep localized hyperthermia. The array provides precise control over the heating pattern in three dimensions. The array elements form a rectangular lattice on a section of a sphere. Therefore, the array has a natural focus at its geometric center when all its elements are driven in phase. When compared to a planar array with similar dimensions, the spherical-section array provides higher focal intensity gain which is useful for deep penetration and heat localization. Furthermore, the relative grating-lobe level (with respect to the focus) is lower for scanned foci synthesized with this array (compared to a planar array with equal center-to-center spacing and number of elements). This could be the key to the realization of phased-array applicator systems with a realistic number of elements. The spherical-section array is simulated as a spot-scanning applicator and, using the pseudo-inverse pattern synthesis method, to directly synthesize heating patterns overlaying the tumor geometry. A combination of the above two methods can be used to achieve the desired heating pattern in the rapidly varying tumor environment.


Title A spline-based approach for computing spatial impulse responses.
Author Ellis MA, Guenther D, Walker WF.
Journal IEEE Trans UFFC
Volume
Year 2007
Abstract Computer simulations are an essential tool for the design of phased-array ultrasonic imaging systems. FIELD II, which determines the two-way temporal response of a transducer at a point in space, is the current de facto standard for ultrasound simulation tools. However, the need often arises to obtain two-way spatial responses at a single point in time, a set of dimensions for which FIELD II is not well optimized. This paper describes an analytical approach for computing the two-way, far-field, spatial impulse response from rectangular transducer elements under arbitrary excitation. The described approach determines the response as the sum of polynomial functions, making computational implementation quite straightforward. The proposed algorithm, named DELFI, was implemented as a C routine under Matlab and results were compared to those obtained under similar conditions from the well-established FIELD II program. Under the specific conditions tested here, the proposed algorithm was approximately 142 times faster than FIELD II for computing spatial sensitivity functions with similar amounts of error. For temporal sensitivity functions with similar amounts of error, the proposed algorithm was about 1.7 times slower than FIELD II using rectangular elements and 19.2 times faster than FIELD II using triangular elements. DELFI is shown to be an attractive complement to FIELD II, especially when spatial responses are needed at a specific point in time.


Title A statistical analysis of recieved signal from blood during laminar flow.
Author Ferrara KW, Algazi RV.
Journal IEEE Trans UFFC
Volume
Year 1994
Abstract In order to determine the limiting velocity resolution that can be achieved using ultrasound, and to provide a model which can be generalized for the analysis of disturbed flow, a theoretical and experimental evaluation of the statistics of the received signal from laminar flow following the transmission of a train of short pulses is presented. We derive the autocorrelation function and determine the length of the correlated signal for various flow rates, comparing experimental measurements to theoretical predictions. High resolution experimental RF M-mode images are used to verify the theoretical model. Using a fluid with a density, viscosity, volume concentration, particle size, and speed of sound which is similar to that of blood, we show that the signal remains correlated for a long interval under many conditions of clinical interest. Including a comparison with experimental data, the effect of the lateral transit time through the sample volume and the axial velocity spread within the sample volume on the correlation of the received signal is evaluated. When a significant range of velocity components is present within the sample volume, this range is the limiting factor in the length of the correlated signal interval. Therefore, the use of a wideband signal, which reduces the sample volume size, produces a returned signal that may be correlated for a larger number of pulses, or for a longer time.


Title A strategy for blood biomarker amplification and localization using ultrasound.
Author D'Souza AL, Tseng JR, Pauly KB, Guccione S, Rosenberg J, Gambhir SS, Glazer GM.
Journal Proc Natl Acad Sci USA
Volume
Year 2009
Abstract Blood biomarkers have significant potential applications in early detection and management of various diseases, including cancer. Most biomarkers are present in low concentrations in blood and are difficult to discriminate from noise. Furthermore, blood measurements of a biomarker do not provide information about the location(s) where it is produced. We hypothesize a previously undescribed strategy to increase the concentration of biomarkers in blood as well as localize the source of biomarker signal using ultrasound energy directly applied to tumor cells. We test and validate our hypothesis in cell culture experiments and mouse tumor xenograft models using the human colon cancer cell line LS174T, while measuring the biomarker carcinoembryonic antigen (CEA) before and after the use of ultrasound to liberate the biomarker from the tumor cells. The results demonstrate that the application of low-frequency ultrasound to tumor cells causes a significant release of tumor biomarker, which can be measured in the blood. Furthermore, we establish that this release is specific to the direct application of the ultrasound to the tumor, enabling a method for localization of biomarker production. This work shows that it is possible to use ultrasound to amplify and localize the source of CEA levels in blood of tumor-bearing mice and will allow for a previously undescribed way to determine the presence and localization of disease more accurately using a relatively simple and noninvasive strategy.


Title A strategy for localized chemotherapy of tumors using ultrasonic hyperthermia.
Author Lele PP.
Journal Ultrasound Med Biol
Volume
Year 1979
Abstract No abstract available.


Title A study of high frequency ultrasound scattering from non-nucleated biological specimens.
Author Falou O, Baddour RE, Nathanael G, Czarnota GJ, Kumaradas JC, Kolios MC.
Journal J Acoust Soc Am
Volume
Year 2008
Abstract The high frequency backscatter from cells with a nucleus to cell volume ratio of 0.50 cannot be adequately modeled as a homogeneous sphere. It was hypothesized that the cytoplasm of such cells is of fluid nature. This work attempts to model the ultrasound backscatter (10-62 MHz) from some non-nucleated biological specimens. This was done by measuring the backscatter response from individual sea urchin oocytes and comparing it to theoretical predictions in both the time and frequency domains. A good agreement was found between the experimental and theoretical results suggesting that the non-nucleated oocytes are of fluid nature.


Title A study of reception with the use of focused ultrasound. I. Effects on the skin and deep receptor structures in man.
Author Gavrilov LR, Gersuni GV, Ilyinski OB, Tsirulnikov EM, Shchekanov EE.
Journal Brain Res
Volume
Year 1977
Abstract The possibility of use of focused ultrasound (focused beam of high-frequency mechanical waves) for stimulation of nerve structures was investigated. The stimulation of human hand resulted in various sensations: tactile, temperature, pain etc. The corresponding thresholds were determined and characteristic features of ultrasonically induced sensations were studied. The modality of temperature sensation (warmth-cold) was found to depend on the environmental.temperature. The character of pain was dependent upon the type of tissue stimulated. Effective factors in ultrasonic stimulation are discussed.


Title A study of reception with the use of focused ultrasound. II. Effects on the animal receptor structures.
Author Gavrilov LR, Gersuni GV, Ilyinsky OB, Tsirulnikov EM, Shchekanov EE.
Journal Brain Res
Volume
Year 1977
Abstract The possibility of stimulation of receptor structures with focused ultrasound (focused beam of high frequency mechanical waves) was investigated. Stimulation of single Pacinian corpuscle isolated from cat's mesentery resulted in receptor and action potentials. Stimulation of frog's ear labyrinth resulted in evoked potentials recorded from midbrain auditory area, their characteristics being much the same as those for responses to adequate sound stimuli. It is concluded that focused ultrasound is an advantageous agent for stimulation of various mechanoreceptors both isolated and, especially, located deep in the body. Some problems related to sensory specificity.are discussed.


Title A study of some properties of a sample of bovine cortical bone using ultrasound.
Author Lees S, Heeley JD, Cleary PF.
Journal Calcif Tissue Int
Volume
Year 1979
Abstract No abstract available.


Title A study of sonoporation dynamics affected by ultrasound duty cycle.
Author Pan H, Zhou Y, Izadneghdar O, Cui J, Deng CX.
Journal Ultrasound Med Biol
Volume
Year 2005
Abstract Sonoporation is the ultrasound-induced membrane porosity and has been investigated as a means for intracellular drug delivery and nonviral gene transfection. The dynamic characteristics of sonoporation, such as formation, duration and resealing of the pores in the cell membrane, determine the process of intracellular uptake of molecules or agents of interest that are otherwise obstructed by the cell membrane barrier. Sonoporation dynamics is also important for postultrasound cell survival. In this study, we investigated the effects of ultrasound duty cycle on sonoporation dynamics using Xenopus oocyte as a model system. Transducer with a center frequency of 0.96 MHz was used to generate pulsed ultrasound of desired duty cycle (5%, 10% and 15%) at a pulse repetition frequency of 1 Hz and an acoustic pressure of 0.4 MPa in our experiments. Employing voltage clamp techniques, we measure the transmembrane current as the direct result of decreased membrane resistance due to pore formation induced by ultrasound application. We characterized the sonoporation dynamics from these time-resolved recordings of transmembrane current to indicate cell membrane status, including pore formation, extension and resealing. We observed that the transmembrane current amplitude increased with increasing duty cycle, while the recovering process of membrane pores and cell survival rate decreased at higher duty cycles.


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