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 In vivo liver differentiation by ultrasound using an artificial neural network.
Author Zatari D, Botros N, Dunn F.
Journal J Acoust Soc Am
Volume
Year 1994
Abstract A pattern recognition algorithm and instrumentation for in vivo ultrasound human liver differentiation are presented. An available 16-MHz microprocessor-based data acquisition and analysis system with 6-bit resolution is used to capture, digitize, and store the backscattered ultrasound signal. The algorithm is based on a multilayer perceptron neural network using the backpropagation training procedure. The network is implemented to differentiate between normal and abnormal liver. Data earlier obtained from 18 volunteers with normal liver history and from 12 volunteers with liver abnormalities are used to test the algorithm. The power spectra of the backscattered signal from depths of 5, 6.5, and 8 cm in the liver are calculated. The acoustic attenuation coefficient is calculated by the log spectral difference technique over the frequency range from 1.5 to 4.5 MHz. The change of speed of sound with frequency (dispersion) is estimated over the 3-MHz bandwidth. The attenuation and velocity dispersion are used as differentiation features. The results show that of the 22 tested cases, the system differentiated correctly 19 and 20 cases when using the attenuation and the velocity dispersion, respectively. The average magnitude of dispersion of liver is estimated to be 1.67?0.1 m/s/MHz and about 2.3?0.18 m/s/MHz in the normal and abnormal cases, respectively. The overall performance of the system for liver differentiation is 91% for normal cases, and 86% for abnormal cases. The data files are also differentiated using the nearest neighbor statistical classifier. The results show that of the 30 tested cases, 23 files are differentiated correctly using the attenuation coefficient.


Title In vivo multiparametric ultrasound imaging of structural and functional tumor modifications during therapy.
Author Dizeux A, Payen T, Le Guillou-Buffello D, Comperat E, Gennisson J-L, Tanter M, Oelze M, Bridal L.
Journal Ultrasound in Med & Biol
Volume
Year 2017
Abstract Longitudinal imaging techniques are needed that can meaningfully probe the tumor microenvironment and its spatial heterogeneity. Contrast-enhanced ultrasound, shear wave elastography and quantitative ultrasound are ultrasound-based techniques that provide information on the vascular function and micro-/macroscopic tissue structure. Modifications of the tumor microenvironment induced by cytotoxic and anti-angiogenic molecules in ectopic murine Lewis lung carcinoma tumors were monitored. The most heterogenous structures were found in tumors treated with anti-angiogenic drug that simultaneously accumulated the highest levels of necrosis and fibrosis. The anti-angiogenic group presented the highest number of correlations between parameters related to vascular function and those related to the micro-/macrostructure of the tumor microenvironment. Results suggest how patterns of multiparametric ultrasound modifications can be related to provide a more insightful marker of changes occurring within tumors during therapy.


Title In vivo opthalmological tissue characterization by scattering.
Author Lizzi FL, Feleppa EJ, Shung KK,Thieme GA.
Journal Book Chapter
Volume
Year 1993
Abstract A patient presenting with a small, solid subretinal mass may have one of a variety of neoplastic conditions including (1) benign nevi and hemangiomas, (2) primary malignant, choroidal melanomas of different potential for growth,invasion and metastasis, and (3) several types of carcinomas metastatic to the eye from other sites. Some of the possible conditions are life threatening,and some forms of melanomaq can become rapidly invasive.Each of these possible conditions require a different response,and biopsy of intraocular masses is rarely considered possible. An urgent need exists for an accurate,noninvasive method of differently diagnosing such masses.Furthermore, some cases may warrant treatment using ionizing radiation or ultrasonic hyperthermia. In such cases, a reliable, quantitative means for monitoring the effect of therapy may greatly increase its efficacy. Ultrasonic tissue characterization based on spectrum analysis of backscattered ultrasound has shown the potrntial to provide the information needed for effective diagnosis and monitoring. This chapter provides an overview of the evolution of our opthalmological tissue-characterization studies,describe data-acquisition and data processing system features, discusses the underlying theoritical framework, and presents a summary of clinical applications.


Title In vivo recording of blood velocity profiles and studies in vitro of profile alterations induced by known stenoses.
Author Bassini M, Gatti E, Longo T, Martinis G, Pignoli P, Pizzolati PL.
Journal Tex Heart Inst J
Volume
Year 1982
Abstract Recordings of blood velocity profiles and their behavior in the time domain in some peripheral human vessels (carotid arteries and limb vessels) are reported. Measurements have been obtained with a pulsed ultrasonic instrument based on the analysis of the cross-correlation function of blood-diffused echoes. The alterations of blood velocity profiles and of the velocity in the time domain, induced by known stenosis, have been studied in vitro as a function of the distance between stenosis and measuring point, and the position of the sample volume along the diameter. These studies may be useful for a better comprehension of blood velocity measurements made with ultrasound equipment for clinical noninvasive diagnostic purposes.


Title In vivo targeting of acoustically reflective liposomes for intravascular and transvascular ultrasonic enhancement.
Author Demos SM, Alkan-Onyuksel H, Kane BJ, Ramani K, Nagaraj A, Greene R, Klegerman M, McPherson DD.
Journal J Am Coll Cardiol
Volume
Year 1999
Abstract OBJECTIVES: The purpose of this study was to target acoustically reflective liposomes to atherosclerotic plaques in vivo for ultrasound image enhancement. BACKGROUND: We have previously demonstrated the development of acoustically reflective liposomes that can be conjugated for site-specific acoustic enhancement. This study evaluates the ability of liposomes coupled to antibodies specific for different components of atherosclerotic plaques and thrombi to target and enhance ultrasonic images in vivo. METHODS: Liposomes were prepared with phospholipids and cholesterol using a dehydration/ rehydration method. Antibodies were thiolated for liposome conjugation with N-succinimidyl 3-(2-pyridyldithio) propionate resulting in a thioether linkage between the protein and the phospholipid. Liposomes were conjugated to antifibrinogen or anti-intercellular adhesion molecule-1 (anti-ICAM-1). In a Yucatan miniswine model, atherosclerosis was developed by crush injury of one carotid and one femoral artery and ingestion of a hypercholesterolemic diet. After full plaque development the arteries were imaged (20-MHz intravascular ultrasound catheter and 7.5-MHz transvascular linear probe) after injection of saline, unconjugated liposomes and antibody conjugated liposomes. RESULTS: Conjugated liposomes retained their acoustically reflective properties and provided ultrasonic image enhancement of their targeted structures. Liposomes conjugated to antifibrinogen attached to thrombi and fibrous portions of the atheroma, whereas liposomes conjugated to anti-ICAM-1 attached to early atheroma. CONCLUSIONS: Our data demonstrate that this novel acoustic agent can provide varying targeting with different antibodies with retention of intravascular and transvascular acoustic properties.


Title In vivo ultrasound scatterer size imaging on liver tumors with a clinical scanner.
Author Liu W.
Journal thesis(PHD): Univ of Wisconsin-Madison
Volume
Year 2007
Abstract Benign liver tumors are common and usually symptom free. The most common type is cavernous hemangioma, which occurs in about 5% of the population. The vast majority of these tumors are small, asymptomatic, and do not require treatment. However, with increasing frequency they are being detected as incidental findings in CT, MRI, and abdominal ultrasound studies, requiring further diagnosis. Their differentiation from malignant liver tumors is difficult without biopsy, so noninvasive differentiation is highly desired. The specific aim of this thesis is to differentiate between hemangiomas and malignant liver tumors using ultrasound parametric imaging based on scatterer size. Histological specimens show that hemangiomas exhibit significantly larger internal inhomogeneities, likely the sources of acoustic scattering, than malignant tumors. To investigate whether scatterer size imaging can provide this differentiation, simulations, in vitro measurements, and in vivo studies were conducted. Scatterer size imaging is done by measuring absolute backscatter coefficients of samples and performing a modified least squares fit between the measured values and scatterer size-dependent theoretical backscatter coefficients. Algorithms for performing this task were developed and factors that contribute to accurate and precise scatterer size images were investigated, as were limitations of currently used clinical scanners when forming parametric images. Performance tests of different spectral estimation methods were done, showing that the Welch method yields the best results when attempting to keep the computational load low. Averaging 7–12 independent samples with 9–15 wavelength axial windows (4–7 pulse lengths) optimized tradeoffs between spatial resolution and signal-to-noise ratio (SNR). Angular and elevational compounding were also used to improve the SNR. Theoretical derivations showed that spectral compounding often performs better than parameter compounding, and this was verified experimentally. Experiments on spectral and scatterer size estimation correlation were performed to determine the best compounding strategy. Clinically, hemanigomas generally had larger effective scatterer sizes than surrounding normal liver, whereas a malignant tumor had smaller relative scatterer sizes. Combining B-mode features, such as halo, with scatterer size estimates may be helpful to confirm a benign or malignant classification. Scatterer size imaging using a capacitive microfabricated ultrasonic transducer (CMUT) is also introduced.


Title In-utero sound levels when vibroacoustic stimulation is applied to the.maternal abdomen: an assessment of the possibility of cochlea damage in.the fetus.
Author Arulkumaran S, Talbert D, Hsu TS, Chua S, Anandakumar C, Ratnam SS.
Journal Br J Obstet Gynaecol
Volume
Year 1992
Abstract OBJECTIVE: To measure sound pressure level in utero while a vibro acoustic stimulator is applied to maternal abdomen and.to calculate whether the estimated effect on fetal cochlea cilia vibration would be hazardous. DESIGN: Prospective descriptive.study. SETTING: Labour ward, National University Hospital, Singapore. SUBJECTS: Eight women undergoing induction of.labour. INTERVENTION: A hydrophone was introduced via the cervix into the uterus and placed under ultrasound guidance.near the fetal ear. Sound pressure was recorded when a vibroacoustic stimulator was applied directly to the maternal abdomen.and also when separated by 2 cm of air. MAIN OUTCOME MEASURES: Sound pressure levels in utero. RESULTS: The.sound level recorded from the vibrator diaphragm in air was 107 dB at 2 cm and 74 dB at 1 m. The mean sound pressure.level in utero was 90.7 dB (range 75-96 dB) when the vibrator was in contact with the abdominal wall and 80.1 dB (range.70-88 dB) when separated by 2 cm of air. CONCLUSIONS: Analysis of factors affecting displacement of cochlear sensing.cilia in utero show that, for equal sound pressures, sound intensity and sound vibration are about 4000 times less in amniotic.fluid, compared to that produced in air. Further protection is provided by viscous and hydrodynamic features of the ear. The.estimated effect on cilia vibration by the mean sound pressure registered in utero, about 90 dB, corresponds to that produced.postnatally by an airborne sound registering about 40 dB, which would not be hazardous.


Title In-vivo effects of diagnostic ultrasound.
Author Frost HM, Stratmeyer ME.
Journal Lancet
Volume
Year 1977
Abstract No abstract available.


Title In-vivo fetal ultrasound exposimetry.
Author Daft CMW, Siddiqi TA, Fitting DW, Meyer RA, O'Brien WD Jr.
Journal IEEE Trans UFFC
Volume
Year 1990
Abstract An instrument has been developed to measure the acoustic pressure field in vivo during an obstetric ultrasound examination. This provides for improved intensity values for exposure calculations, to assist in assessment of bioeffects. The ultrasonic field is sampled using a calibrated seven-element linear array hydrophone of poly(vinylidene difluoride) transducers, which is placed as close as possible to the ovary, embryo, or fetus using a vaginal approach. The RF signals from the hydrophone are digitized at 50 MHz, and the maximum amplitude waveform received in the examination is recorded. The output of the clinical B-scanner is calibrated by a measurement with the hydrophone in a water bath. From the hydrophone measurements, the in vivo I(SPTA), I(SPTP), and I(SPPA) are computed. Further analysis allows the frequency-dependent tissue attenuation to be assessed.


Title In-vivo fetal ultrasound exposimetry.
Author Daft CMW, Siddiqi TA, Fitting DW, O'Brien WD Jr.
Journal Proc Ultrason Symp IEEE
Volume
Year 1989
Abstract An instrument has been developed to measure the acoustic pressure field during an obstetric ultrasound examination. This permits a more accurate assessment of possible bioeffects since the pressure is sensed at or near the site of the organs under investigation. The ultrasonic field is sampled using a calibrated seven-element linear array hydrophone of PVDF transducers, which is placed as close as possible to the ovary, embryo, or fetus, using a vaginal approach. The RF signals from the hydrophone are digitized at 50 Ms/s, and the maximum amplitude waveform received in the examination is recorded. The output of the clinical B-scanner is calibrated by the hydrophone in a water bath. From the hydrophone measurements, the in-vivo ISPTA, ISPTP, and ISPPA can be computed. Further analysis allows the frequency-dependent tissue attenuation to be assessed


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