Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
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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 Ultrasonic threshold dosages for the mammalian central nervous system.
Author Dunn F, Fry FJ.
Journal IEEE Trans Biomed Eng
Volume
Year 1971
Abstract The ultrasonic threshold doses (acoustic intensity and time duration of a single pulse) to produce functional and structural irreversible effects in the mouse, rat, cat, monkey, and human central nervous systems are presented for a wide range of the pertinent parameters. There does not appear to be an important dependence upon frequency in the range from 1 to 6 MHz. Embryonic tissue is found to be appreciably more sensitive than adult tissue. From considerations of the measured outputs of commercially available ultrasonic diagnostic instruments, the experimentally determined threshold dosages necessary to produce these irreversible effects, and reports of clinical experience, it is concluded that ultrasound does not present a hazard, as currently employed for medical diagnostic purposes.


Title Ultrasonic thresholds for structural changes in the mammalian liver.
Author Chan SK, Frizzell LA.
Journal Proc Ultrason Symp IEEE
Volume
Year 1977
Abstract The liver of anesthetized cats was exposed to 3 MHz focused ultrasound at intensities from 300 to 20000 W/cm2 with pulse durations from 1 sec to 10 msec, respectively. The animals were sacrificed 24 hrs after irradiation and histological preparations were made with hematoxylin and eosin staining for microscopic examination for possible structural changes. A threshold curve of acoustic intensity at the lesion site vs. duration of exposure, giving the ultrasonic dosages just sufficient to create a lesion has been found. For this exposure range, as for exposure durations of 1 s and longer, the threshold for liver is similar to, but approximately 100% greater than that for brain (liver is less sensitive than brain). Significant differences in the appearance of near threshold lesions are observed between exposures at 550 W/cm2 and 3000 W/cm2. This may suggest a difference in the mechanism(s) responsible for producing the damage at these two intensities.


Title Ultrasonic tissue characterization and histopathology in tumor xenografts following ultrasonically induced hyperthermia.
Author Silverman RH, Coleman DJ, Lizzi FL, Torpey JH, Driller J, Iwamoto T, Burgess SE, Rosado A.
Journal Ultrasound Med Biol
Volume
Year 1986
Abstract Cells derived from human skin malignant melanoma were implanted subcutaneously in athymic nude mice. Tumors which developed at the implant site were treated with ultrasonically induced hyperthermia at 49 degrees C for 30 min. Tumors were scanned with a computerized diagnostic ultrasound system before and after treatment. Light (LM) and electron (EM) micrographs of tumors were obtained after scanning. Changes in ultrasonic tissue characterization parameters following treatment were well correlated with histopathologic changes observed in tumors. The results are significant in terms of clinical application of ultrasonically induced hyperthermia for treatment of intraocular tumors and the noninvasive monitoring of tumors by use of diagnostic ultrasound.


Title Ultrasonic tissue characterization of atherosclerosis by a speed-of-sound microscanning system.
Author Saijo Y, Filho ES, Sasaki H, Yambe T, Tanaka M, Hozumi N, Kobayashi K, Okada N.
Journal IEEE Trans UFFC
Volume
Year 2007
Abstract We have been developing a scanning acoustic microscope (SAM) system for medicine and biology featuring quantitative measurement of ultrasonic parameters of soft tissues. In the present study, we propose a new concept sound speed microscopy that can measure the thickness and speed of sound in the tissue using fast Fourier transform of a single pulsed wave instead of burst waves used in conventional SAM systems. Two coronary arteries were frozen and sectioned approximately 10 μm in thickness. They were mounted on glass slides without cover slips. The scanning time of a frame with 300 ? 300 pixels was 90 s and two-dimensional distribution of speed of sound was obtained. The speed of sound was 1680 ? 30 m/s in the thickened intima with collagen fiber, 1520 ? 8 m/s in the lipid deposition underlying the fibrous cap, and 1810 ? 25 m/s in a calcified lesion in the intima. These basic measurements will help in the understanding of echo intensity and pattern in intravascular ultrasound images.


Title Ultrasonic tissue characterization of infarcted myocardium by scanning acoustic microscopy.
Author Saijo Y, Tanaka M, Okawai H, Sasaki H, Nitta SI, Dunn F.
Journal Ultrasound Med Biol
Volume
Year 1997
Abstract The purpose of this study was to ultrasonically characterize infarcted human.myocardial tissue at the microscopic level by scanning acoustic microscopy..Infarcted myocardial specimens from ten cases with acute myocardial infarction.were studied. Specimens were formalin fixed, paraffin embedded and sectioned.to 10-micron thickness. A specially developed scanning acoustic microscope.system, operating in the 100- to 200-MHz ultrasound frequency range, was used.for the measurements. The values of the attenuation constant were 0.94 +/- 0.04.dB/mm/MHz in normal myocardium, 0.71 +/- 0.12 dB/mm/MHz in degenerated.myocardium, 0.88 +/- 0.47 dB/mm/MHz in granulation tissue and 1.75 +/- 0.11.dB/mm/MHz in fibrosis. The values of sound speed were 1620.2 +/- 8.2 m/s in.normal myocardium, 1572.4 +/- 10.6 m/s in degenerated myocardium, 1590.2.+/- 32.5 m/s in granulation tissue and 1690.3 +/- 9.1 m/s in fibrosis. The.ultrasonic properties of the diseased myocardium at the microscopic level will.provide important information for ultrasonic tissue characterization at the.macroscopic level. ..


Title Ultrasonic tissue characterization using kurtosis.
Author Kuc R.
Journal IEEE Trans UFFC
Volume
Year 1986
Abstract A procedure is presented to estimate the value of the kurtosis, or the normalized fourth central moment, which is denoted by K, from the radio-frequency ultrasound signal reflected from soft tissue. The K value is a measure of the peakiness of the signal and has been employed as an indicator of the distribution of the random signal. This is demonstrated through simulations employing random variables with uniform and Gaussian distributions. The problem of estimating the K value for signals having a nonstationary variance, caused by diffraction and inappropriate gain settings, is illustrated. A digital automatic gain control is suggested to compensate for these nonstationary effects. The K value is estimated from signals reflected from a tissue-equivalent phantom and in vivo livers, both normal and fatty-infiltrated. The phantom results indicate that the K value estimate is robust with respect to diffraction and frequency-dependent attenuation effects. The clinical potential of the K value as an additional parameter that can be employed for tissue characterization is suggested by comparing the values observed for a population of 50 normal livers and a fatty-infiltrated liver. These results suggest that the reflectors in the normal liver approximate a Gaussian distribution, while those in the phantom and fatty liver are uniformly distributed.


Title Ultrasonic tissue characterization.
Author Lele PP, Sleefe GE.
Journal Ultrasound
Volume
Year 1987
Abstract No abstract available.


Title Ultrasonic tissue characterization.
Author Scheipers U.
Journal Book Chapter
Volume
Year 2009
Abstract This chapter represents the results achieved over a period of several years of research in the field of ultrasonic tissue characterization.Mainly focusing on the development of a computer-aided diagnostic system for the detection of prostate cancer and on the discussion of the results of the underlying clinical study,this chapter may also be of help to scientists working in the field of ultrasonic tissue characterization and focusing on other organs. Eight different groups of tissue describing parameters and features applicable for tissue characterization and typically used by the tissue characterizing community have been evaluated and discussed in this chapter. This discussion may be a valuable overview for scientists approaching the field of tissue characterization and facing the problem of which types of tissue characterization parameters to focus on. A modern nonlinear classifier,the so-called adaptive netwrok-based fuzzy inference system,is introduced and described to a degree that will facilitate application and usage of the classifier by the reader who intends to establish a higher order classification system. Although most parts of the tissue characterization system have been designed for prostate cancer detection,studies on the classificatin of coronart plaques in intravascular ultrasound,on monitoring of thermal ablation therapy of the liver;on staging of deep venous thrombosis,and on classification of tumors of the parotid gland have recently proven th reliability of the approach described in this chapter. In the following sections, all details of the multifeature tissue characterization system are discussed. At first, the clinical background is reviewed in detail in section "Clinical Background". Readers with a solid clinical background on prostate cancer diagnostics might want to skip this section and are motivated to go directly to section "Former Work".Former work of the same author and of other groups is presented and discussed here. The technical issues of the system will be dealt with in the methods section. The methods section is subdivided into several parts dealing with the acquisition and preprocessing of the radiofrequency (RF) data in Data Acquisition and processing, the parameter or feature extraction steps in section "Parameter Extraction",the classification procedure in section " Classification," and last but not least the data visualization in section " Visualization." In the following section "Results" the underlying clinical study is described and the results of the classification are presented. After a general discussion of the clinical study, the final classification results of the system will be presented in section "Results of Tissue Characterization". In addition to the numerical results, two exemplary cases taken from the 100 patients included in the clinical study are discussed in sections "Case A" and "Case B". Possible applications of the system, including perspectives for the future,are discussed in section "Discussion."The work closes with a few concluding remarks in section "Conclusion.


Title Ultrasonic tissue characterization: Towards high-intensity focused ultrasound treatment monitoring.
Author Bloch S.
Journal Thesis(MS): Univ of Washington
Volume
Year 1998
Abstract Non-invasive monitoring of high-intensity focused ultrasound (HIFU) treatment by diagnostic ultrasound is currently limited by a poor understanding of the biophysical effects of tissue heating. It is a challenge to obtain acoustic data above the temperature range in which tissue is irreversibly denatured for several reasons, including changes in tissue dimensions associated with thermal denaturation process. This thesis focuses on the development of a system to measure the sound speed and acoustic attenuation of tissue sample during controlled heating, with the purpose of collecting relevant experimental data for the modeling and monitoring of HIFU treatments. The system is simple, yet precise, and the data collected from freshly excised porcine liver samples compard favorably with previously published results [Bamber and Hill 1979; Damianou et al. 1997]. The sound speed of tissue increases monotonically as the tissue is heated to 50°C, and decreases with continued heating, with a total change on the order of 1%. The acoustic attenuation stays approximately constant until 45°C, and increases monotonically thereafter as the tissue is thermally denatured, at least doubling its original value. These results have promising implications for the ultrasonic monitoring of HIFU treatment.


Title Ultrasonic tomography for differential thermography.
Author Haney MJ, O'Brien WD Jr.
Journal Acoust Imaging
Volume
Year 1982
Abstract This paper describes work in progress in the study of ultrasound computer aided tomography (UCAT) and its application to differential thermography. There are many situations in which it is desirable to determine the amount of induced heating generated by applied hyperthermia (microwave or ultrasound). However, it is not always possible or safe to insert a temperature sensitive probe into the subject. The application of assessing tissue temperature from the temperature dependence of ultrasonic speed has been suggested by others (Bowen, et al., 1979; Nasoni, et al., 1979; Rajagopalan, et al., 1979). But it may be possible to refine the assessment of temperature change from the simultaneous determination of the acoustic speed and the ultrasonic attenuation coefficient. A method is outlined for producing maps of temperature change after heating. Pulses of ultrasound are transmitted through the subject. Time of flight and frequency content measurements are made to analyze the speed of propagation and attenuation coefficient of the regions of the subject. Algebraic reconstruction, based on an interpolated model of the ray paths, is used to form transit time (inverse speed) and attenuation coefficient images. (An error estimation is performed to be used in later analyses.) Differential images (before and after heating) are used to estimate temperature change.


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